Channel Quality Reporting in a
Mobile Communication System
FIELD OF THE INVENTION
The invention relates methods for triggering and reporting on a downlink channel quality
(channel quality feedback) experienced by a terminal (e.g. a mobile terminal or a user
equipment) by means of channel quality information for at least one of plural component
carriers of a communication system available for downlink transmission to the terminal.
Furthermore, the invention also relates to an implementation of these methods in
hardware and software.
TECHNICAL BACKGROUND
Long Term Evolution (LTE)
Third-generation mobile systems (3G) based on WCDMA radio-access technology are
being deployed on a broad scale all around the world. A first step in enhancing or
evolving this technology entails introducing High-Speed Downlink Packet Access
(HSDPA) and an enhanced uplink, also referred to as High Speed Uplink Packet Access
(HSUPA), giving a radio-access technology that is highly competitive.
In order to be prepared for further increasing user demands and to be competitive
against new radio access technologies 3GPP introduced a new mobile communication
system which is called Long Term Evolution (LTE). LTE is designed to meet the carrier
needs for high speed data and media transport as well as high capacity voice support to
the next decade. The ability to provide high bit rates is a key measure for LTE.
The work item (Wl) specification on Long-Term Evolution (LTE) called Evolved UMTS
Terrestrial Radio Access (UTRA) and UMTS Terrestrial Radio Access Network (UTRAN)
is to be finalized as Release 8 (LTE). The LTE system represents efficient packet-based
radio access and radio access networks that provide full IP-based functionalities with low
latency and low cost. The detailed system requirements are given in. In LTE, scalable
multiple transmission bandwidths are specified such as 1.4, 3.0, 5.0, 10.0,15.0, and 20.0

MHz, in order to achieve flexible system deployment using a given spectrum. In the
downlink, Orthogonal Frequency Division Multiplexing (OFDM) based radio access was
adopted because of its inherent immunity to multipath interference (MPI) due to a low
symbol rate, the use of a cyclic prefix (CP), and its affinity to different transmission
bandwidth arrangements. Single-carrier frequency division multiple access (SC-FDMA)
based radio access was adopted in the uplink, since provisioning of wide area coverage
was prioritized over improvement in the peak data rate considering the restricted
transmission power of the user equipment (UE). Many key packet radio access
techniques are employed including multiple-input multiple-output (MIMO) channel
transmission techniques, and a highly efficient control signaling structure is achieved in
LTE (Release 8).
LTE architecture
The overall architecture is shown in Fig. 1 and a more detailed representation of the E-
UTRAN architecture is given in Fig. 2. The E-UTRAN consists of eNodeB, providing the
E-UTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol
terminations towards the user equipment (UE). The eNodeB (eNB) hosts the Physical
(PHY), Medium Access Control (MAC), Radio Link Control (RLC), and Packet Data
Control Protocol (PDCP) layers that include the functionality of user-plane header-
compression and encryption. It also offers Radio Resource Control (RRC) functionality
corresponding to the control plane. It performs many functions including radio resource
management, admission control, scheduling, enforcement of negotiated uplink Quality of
Service (QoS), cell information broadcast, ciphering/deciphering of user and control
plane data, and compression/decompression of downlink/uplink user plane packet
headers. The eNodeBs are interconnected with each other by means of the X2 interface.
The eNodeBs are also connected by means of the S1 interface to the EPC (Evolved
Packet Core), more specifically to the MME (Mobility Management Entity) by means of
the S1-MME and to the Serving Gateway (SGW) by means of the S1-U. The S1 interface
supports a many-to-many relation between MMEs/Serving Gateways and eNodeBs. The
SGW routes and forwards user data packets, while also acting as the mobility anchor for
the user plane during inter-eNodeB handovers and as the anchor for mobility between
LTE and other 3GPP technologies (terminating S4 interface and relaying the traffic
between 2G/3G systems and PDN GW). For idle state user equipments, the SGW
terminates the downlink data path and triggers paging when downlink data arrives for the

user equipment. It manages and stores user equipment contexts, e.g. parameters of the
IP bearer service, network internal routing information. It also performs replication of the
user traffic in case of lawful interception.
The MME is the key control-node for the LTE access-network. It is responsible for idle
mode user equipment tracking and paging procedure including retransmissions. It is
involved in the bearer activation/deactivation process and is also responsible for
choosing the SGW for a user equipment at the initial attach and at time of intra-LTE
handover involving Core Network (CN) node relocation. It is responsible for
authenticating the user (by interacting with the HSS). The Non-Access Stratum (NAS)
signaling terminates at the MME and it is also responsible for generation and allocation
of temporary identities to user equipments. It checks the authorization of the user
equipment to camp on the service provider's Public Land Mobile Network (PLMN) and
enforces user equipment roaming restrictions. The MME is the termination point in the
network for ciphering/integrity protection for NAS signaling and handles the security key
management. Lawful interception of signaling is also supported by the MME. The MME
also provides the control plane function for mobility between LTE and 2G/3G access
networks with the S3 interface terminating at the MME from the SGSN, The MME also
terminates the S6a interface towards the home HSS for roaming user equipments.
Channel Quality Report in LTE (Release 8)
Channel quality information is used in a multi-user communication system to determine
the quality of channel resource(s) for one or more users. This information may be used to
aid in a multi-user scheduler algorithm of the eNodeB (or other radio-access elements
such as a relay node) to assign channel resources to different users, or to adapt link
parameters (e.g. modulation scheme, coding rate, or transmit power) so as to exploit the
assigned channel resource to its fullest potential.
Assuming a multi-carrier communication system, e.g. employing OFDM, as for example
discussed in the "Long Term Evolution" work item of 3GPP, the smallest unit of
resources that can be assigned/allocated by the scheduler is one "resource block". A
physical resource block is defined as consecutive OFDM symbols in the time
domain and consecutive subcarriers in the frequency domain as exemplified in
Fig. 3. In 3GPP LTE (Release 8), a physical resource block thus consists of
resource elements, corresponding to one slot in the time domain and 180 kHz in the

frequency domain (for further details on the downlink resource grid, see 3GPP TS
36.211, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and
Modulation (Release 8)", version 8.7.0, section 6.2, available at http://www.3gpp.org and
incorporated herein by reference). In the ideal case, channel quality information for all
resource blocks for all users should be always available to the scheduler so as to take an
optimum scheduling decision. However, due to constrained capacity of the feedback
channel it is not possible/feasible to ensure this type of up-to-dateness of channel quality
information. Therefore, reduction and/or compression techniques are required so as to
transmit - for example - channel quality information only for a subset of resource blocks
for a given user. In 3GPP LTE, the smallest unit for which channel quality is reported is
called a sub-band, which consists of multiple (n) frequency-adjacent resource blocks (i.e.
subcarriers).
Channel Quality Feedback Elements
In 3GPP LTE, there exist three basic elements which may or may not be given as
feedback for the channel quality:
- Modulation and Coding Scheme Indicator (MCSI), which is also referred to as
Channel Quality Indicator (CQI) in the 3GPP LTE specifications,
- Precoding Matrix Indicator (PMI) and
- Rank Indicator (Rl)
The MCSI suggests a modulation and coding scheme that should be employed for
downlink transmission to a reporting user equipment, while the PMI points to a precoding
matrix/vector that is to be employed for multi-antenna transmission (MlMO) using an
assumed transmission matrix rank or a transmission matrix rank that is given by the Rl.
Details on channel quality reporting and transmission mechanisms are can be found in
3GPP TS 36.212, "Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing
and channel coding (Release 8)", version 8.7.0, sections 5.2 and 3GPP TS 36.213,
"Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures
(Release 8)", version 8.7.0, section 7.2 (all documents available at http://www.3gpp.org
and incorporated herein by reference).
All of these elements are summarized as under the term channel quality feedback
herein. Hence, a channel quality feedback can contain any combination of or multiple

MCSI, PMI, Rl values. Channel quality feedback reports may further contain or consist of
metrics such as a channel covariance matrix or elements, channel coefficients, or other
suitable metrics as apparent to those skilled in the art.
Triggering and Transmission of Channel Quality Feedback
In 3GPP LTE (Release 8) there are different possibilities defined, how to trigger the user
equipments to send channel quality feedback on the downlink channel quality. Besides
periodic CQI reports (see section 7.2.2 in 3GPP TS 36.213, version 8.7.0), there is also
the possibility to use L1/L2 control signaling to a user equipment to request the
transmission of the so-called aperiodic CQI report (see section 7.2.1 in 3GPP TS 36.213,
version 8.7.0). This L1/L2 control signaling can also be used in the random access
procedure (see section 6 in 3GPP TS 36.213, version 8.7.0, incorporated herein by
reference). In both these cases, a special CQI request field/bit/flag is included in the
control message from the eNodeB/relay node.
The L1/L2 control signaling that conveys information about an Uplink assignment is
sometimes called UL-DCI (Uplink Dedicated Control Information). Fig. 4 shows an
example of the DCI format 0 for FDD operation as defined in 3GPP TS 36.212, section
5.3.3.1.1 which serves to convey uplink DCI (please note that the CRC field of DCI
format 0 is not shown in Fig. 4 for simplicity. The CQI request flag contains information
whether the receiver should transmit CQI within the allocated uplink resources or not.
Whenever such a trigger is received, the user subsequently transmits the feedback
generally together with uplink data on the assigned Physical Uplink Shared CHannel
(PUSCH) resources (the detailed procedure is described in section 7.2 et seq. in 3GPP
TS 36.213, version 8.7.0).
Further Advancements for LTE - LTE-Advanced (LTE-A)
The frequency spectrum for IMT-Advanced was decided at the World
Radiocommunication Conference 2007 (WRC-07) in November 2008. Although the
overall frequency spectrum for IMT-Advanced was decided, the actual available
frequency bandwidth is different according to each region or country. Following the
decision on the available frequency spectrum outline, however, standardization of a radio
interface started in the 3rd Generation Partnership Project (3GPP). At the 3GPP TSG
RAN #39 meeting, the Study Item description on "Further Advancements for E-UTRA
(LTE-Advanced)" was approved which is also referred to as "Release 10". The study item

covers technology components to be considered for the evolution of E-UTRA, e.g. to
fulfill the requirements on IMT-Advanced. Two major technology components which are
currently under consideration for LTE-A are described in the following.
In order to extend the overall system bandwidth, LTE-A (Release 10) uses carrier
aggregation, where two or more component carriers are aggregated in order to support
wider transmission bandwidths e.g. up to 100 MHz and for spectrum aggregation. It is
commonly assumed that a single component carrier does not exceed a bandwidth of 20
MHz.
A terminal may simultaneously receive and/or transmit on one or multiple component
carriers depending on its capabilities:
- An LTE-Advanced (Release 10) compatible mobile terminal with reception and/or
transmission capabilities for carrier aggregation can simultaneously receive and/or
transmit on multiple component carriers. There is one Transport Block (in absence of
spatial multiplexing) and one HARQ entity per component carrier.
- An LTE (Release 8) compatible mobile terminal can receive and transmit on a single
component carrier only, provided that the structure of the component carrier follows
the Release 8 specifications.
It is also envisioned to configure all component carriers LTE (Release 8)-compatible, at
least when the aggregated numbers of component carriers in the uplink and the downlink
are same. Consideration of non-backward-compatible configurations of LTE-A
component carriers is not precluded.
Channel Quality Feedback in LTE-A (Release 10)
As there is only one component carrier defined in LTE (Release 8), there is no ambiguity
at the user equipment on which portion of the system bandwidth CQI reporting is to be
done. The CQI request flag (together with the current transmission mode) is
unambiguously indicating to the user equipment how to provide CQI feedback to the
eNodeB.
With the introduction of carrier aggregation in LTE-A (Release 10) and assuming that the
LTE (Release 8) CQI reporting procedures should be reused, there are different
possibilities how a CQI request can be interpreted by the user equipment. As shown in

Fig. 5, it may be generally assumed that UL-DCI (containing the CQI request) for uplink
transmission that is transmitted from a eNodeB or relay node to a user equipment is
placed within a single downlink component carrier. A simple rule to handle the CQI
request at the user equipment would be that whenever a UL-DCI requests a CQI
transmission by the user equipment, same applies to the downlink component carrier
where the corresponding UL-DCI is transmitted. I.e. the user equipment would only send
aperiodic CQI feedback in a given UL transmission for those downlink component
carriers that comprised a UL-DCI requesting a CQI report at the same time.
An alternative handling of UL-DCI comprising a CQI request is shown in Fig. 6.
Whenever a UL-DCI requests a CQI transmission by the user equipment, the user
equipment applies said request to all downlink component carriers available for downlink
transmission to the user equipment.
When downlink transmission can occur on multiple component carriers, an efficient
scheduling and link adaptation depends on the availability of accurate and up-to-date
CQI. However, in order to make efficient use of the control signaling and CQI
transmission resources, it should be possible to control for how many and which
component carriers a CQI is to be requested (from the network side) and transmitted
(from the terminal side).
According to the first solution discussed above with respect to Fig. 5, in order to request
CQI for multiple component carriers the number of component carriers for which CQI is
requested is identical to the number of required transmitted UL-DCI messages. In other
words, to request CQI for five component carriers it is required to transmit five times
more UL-DCI messages than for the case of requesting CQI for just a single component
carrier. This solution is therefore not very efficient from a downlink control overhead point
of view. According to the second solution above illustrated in Fig. 6, a single uplink DCI
message requests CQI for all component carriers. Therefore the downlink control
overhead is very small. However, the resulting uplink transmission always requires a
large amount of resources to accommodate the transmission of CQI for all component
carriers, even though the network knows that it currently requires CQI only for a single
selected component carrier. Therefore this is not efficient for the usage of uplink
resources, and does not offer any flexibility for the number of requested component
carrier CQI.

SUMMARY OF THE INVENTION
One object of the invention is to suggest a mechanism for triggering channel quality
feedback from a mobile terminal where the downlink control signaling overhead for the
selection of component carrier(s) to be reported on is minimized.
The object is solved by the subject matter of the independent claims. Advantageous
embodiments of the invention are subject to the dependent claims.
One aspect of the invention is to suggest a new interpretation of a predetermined format
for dedicated control information (also referred to as downlink control information)
comprising a CQI request flag, which is depending on the status of the CQI request flag.
In case the CQI request flag is set, i.e. is requesting the provision of channel quality
feedback from the mobile terminal, at least one further bit of the dedicated control
information is interpreted as information indicative of the one or more component carriers
available for downlink transmission to the mobile terminal and the mobile terminal is
providing channel quality feedback on the channel quality experienced on the indicated
component carrier or component carriers. Furthermore, in an alternative implementation,
the combination of the CQI request flag and the at least one further bit of the dedicated
control information is used to indicate the one or more component carriers available for
downlink transmission to the mobile terminal on which the mobile terminal is to provide
channel quality feedback.
According to another, alternative aspect of the invention, the indication of the component
carrier or component carriers the mobile terminal is requested to provide channel quality
feedback on is indicated by the time and/or frequency resources on which the dedicated
control information is received at the terminal and/or the transport format of the dedicated
control information.
Both aspects may be combined, i.e. the indication of the component carrier(s) for which
channel quality feedback is to be sent may be indicated to the mobile terminal by means
of the resource (in the time and/or frequency domain) and/or transport format utilized for
transmitting the dedicated control information, and in addition at least one further bit of
the dedicated control information. In one example where the both aspects are combined,
the at least one further bit of the dedicated control information may be the CQI request
flag.

One embodiment of the invention is providing a method for reporting on a downlink
channel quality (channel quality feedback) experienced by a terminal (e.g. a mobile
terminal or a user equipment) by means of channel quality information for at least one of
plural component carriers of a communication system available for downlink transmission
to the terminal. According to this exemplary method the terminal receives dedicated
control information having a predetermined format. The dedicated control information
comprises a CQI request flag (first control information field) for requesting channel
quality reporting by the terminal and at least one further, second control information field
consisting of at least one bit. According to this embodiment of the invention, if the CQI
request flag is set, the terminal is interpreting at least one bit of the second control
information field as CQI control information indicative of one or more of the component
carriers available for downlink transmission to the terminal on which the terminal is to
report channel quality information, and transmits channel quality information for each
indicated component carrier. Hence, in this exemplary embodiment, one or more control
information fields of the dedicated control information can convey the CQI control
information.
In one further exemplary embodiment, the terminal interprets the at least one second
control information field according to the default specification of the predetermined format
of the dedicated control channel information, if the CQI request flag is not set.
In alternative embodiment of the invention, the status of the CQI request flag is not
decisive for the interpretation of the remaining fields within the dedicated control
information. In this exemplary alternative embodiment of the invention a combination of
at least one bit of the second control information field and the CQI request flag is
unconditionally interpreted as the CQI control information indicative of one or more of the
component carriers available for downlink transmission to the terminal on which the
terminal is to report channel quality information.
Generally, the invention can be used in 3GPP-based communication systems, in
particular in a 3GPP LTE-(Release 10) system. For example, in one implementation, the
dedicated control information of the predetermined format is Dedicated Control
Information of DCI format 0 defined in 3GPP LTE (Release 8).
The dedicated control information may be for example received via one of the plural
component carriers of the communication system. In one further exemplary embodiment,
the terminal is transmitting channel quality information for at least the component carrier

on which the dedicated control information is received, if the CQI request flag is set
within the dedicated control information. In a more specific example, the at least one bit
of the second control information field interpreted as CQI control information indicates at
least one further component carrier of the plural component carriers other than the
component carrier on which the dedicated control information has been received.
There are different possibilities which fields of the dedicated control information'
predetermined format are used to indicate the CQI control information. In an embodiment
of the invention, the at least one bit of the at least one second control information field
interpreted as the CQI control information is one of or a combination of:
- a hopping flag defined for the predetermined format of the dedicated control channel
information indicating whether or not the terminal should employ uplink resource
hopping,
- at least one padding bit defined for the predetermined format of the dedicated control
channel information for aligning the size of the dedicated control information to a
predetermined number of bits,
- at least one bit of a resource assignment field defined for the predetermined format of
the dedicated control channel information for assigning resources to the terminal,
- at least one bit of a DMRS field defined for the predetermined format of the dedicated
control channel information for configuring the cyclic shift between the terminal and
another terminal for uplink transmission on at least partly overlapping uplink
resources, and
- at least one bit of an uplink carrier indicator field defined for the predetermined format
of the dedicated control channel information for indicating to the terminal for which
component carrier or component carriers the dedicated control information is valid.
In one exemplary embodiment of the invention, the dedicated control information
consists of:
- an uplink carrier indicator field defined for said predetermined format of the dedicated
control channel information for indicating to the terminal for which component carrier
the dedicated control information is valid,

- a format flag for distinguishing different formats of dedicated control information
having the same number of bits/size, wherein the format flag is set to zero,
- a hopping flag for indicating whether or not the terminal should employ uplink
resource hopping,
- a resource block assignment field assigning uplink resources on an uplink component
carrier to the terminal,
- a modulation and coding scheme field that is indicating the modulation scheme,
coding rate and the redundancy version for the transmission on the assigned
resources on the uplink component carrier,
- a new data indicator to indicate whether the terminal has to send new data or a
retransmission,
- a DMRS field for configuring the cyclic shift applied to the reference symbol
sequence,
- said CQI request flag, and
- optionally one or more padding bit(s) to align the size of the dedicated control
information to a predetermined number of bits.
Please note that in one exemplary implementation, the fields of the dedicated control
information are provided in the order stated above. In another implementation, the order
of the fields is as stated above, with the exception that the CQI request flag follows the
uplink carrier indicator field, the format flag or the hopping flag, or resides in any position
that does not depend on variable parameters such as the system bandwidth or the
number of fields within the dedicated control information.
In another embodiment of invention, it is assured that the CQI control information
indicate at least a first channel quality feedback option, where the terminal provides
cannel quality feedback for one available component carrier and a second channel
quality feedback option, where the terminal provides channel quality feedback on all
available component carriers. Accordingly, in an exemplary implementation, a first value
of the at least one bit of the at least one second control information field interpreted by
the terminal as CQI control information is requesting the terminal to provide channel
quality information for one available downlink component carrier of the plurality of

component carriers and a second value of the at least one bit of the at least one second
control information field interpreted by the terminal as CQI control information is
requesting the terminal to provide channel quality indices for all downlink component
carriers of the plurality of component carriers available for downlink transmission to the
terminal.
In one further embodiment of the invention the second control information field of the
dedicated control information is a carrier indicator field which, if said CQI request flag is
set, is indicative of the CQI control information, and may be optionally further indicative of
an uplink component carrier on which the dedicated control information assigns uplink
resources. As stated before, the CQI control information indicates one or more of the
component carriers available for downlink transmission to the terminal for which the
terminal is to report channel quality information.
In a variation of this embodiment, a first subset of the values that can be signaled in the
carrier indicator field indicates that the terminal is to report channel quality information for
the downlink component carrier on which the dedicated control information is received by
the terminal, and a second subset of the values that can be signaled in the carrier
indicator field indicates that the terminal is to report channel quality information for all
downlink component carriers of the plurality of component carriers available for downlink
transmission to the terminal at the time of receiving the dedicated control information.
In a further variation of the embodiment, there is third subset of the values that can be
signaled in the carrier indicator field which indicates that the terminal is to report channel
quality information for at least one downlink component carrier according to a semi-static
configuration. This semi-static configuration may for example be configured by means of
RRC signaling.
In another variation of the embodiment, the carrier indicator field indicates that the uplink
component carrier is a linked uplink component carrier linked to the downlink component
carrier on which the dedicated control information is received, and further indicates to the
terminal to report channel quality information on one of or all downlink component
carriers. This "link" between the linked uplink component carrier and the corresponding
downlink component carrier could be for example pre-configured.
In another embodiment of the invention, the values that can be signaled in the carrier
indicator field further indicate a respective uplink component carrier on which the
dedicated control information assigns uplink resources.

Furthermore, the dedicated control information can be provided to the terminal using
different messages and channels. In one exemplary embodiment, the dedicated control
information is received by the terminal via a Physical Downlink Control CHannel
(PDCCH). In another exemplary embodiment of the invention, the dedicated control
information is comprised in a random access response grant message during non-
contention based random access.
In accordance with the second aspect mentioned above, the invention is also providing
another embodiment related to another method for reporting on a downlink channel
quality (channel quality feedback) experienced by a terminal by means of channel quality
information for at least one of plural component carriers of a communication system
available for downlink transmission to the terminal. In this method, the terminal receives
dedicated control information having a predetermined format, wherein the dedicated
control information comprises a CQI request flag for requesting channel quality reporting
by the terminal. In this exemplary embodiment, if the CQI request flag is set, the terminal
interprets time and/or frequency resources on which the dedicated control information is
received at the terminal and/or the transport format of the dedicated control information
as CQI control information indicative of one or more of the component carriers available
for downlink transmission to the terminal on which the terminal is to report channel
quality information, and transmits channel quality information for each indicated
component carriers.
It should be noted that this solution is also applicable to situations, where the status of
the CQI request flag is having no influence on the interpretation of the content of the
dedicated control information. For example, in another embodiment, the dedicated
control information are interpreted by the terminal according to the predetermined format,
and the terminal interprets time and/or frequency resources on which the dedicated
control information is received at the terminal and/or the transport format of the dedicated
control information as CQI control information indicative of one or more of the component
carriers available for downlink transmission to the terminal on which the terminal is to
report channel quality information, and transmits channel quality information for each
indicated component carriers
In another embodiment of the invention in line with the second aspect of the invention
mentioned above, the dedicated control information comprises at least one further,
second control information field consisting of at least one bit, and in the step of
interpreting interprets:

- at least one bit of the at least one further, second control information field and
- the time and/or frequency resources on which the dedicated control information is
received at the terminal and/or the transport format of the dedicated control
information as CQI control
as the CQI control information indicative of one or more of the component carriers
available for downlink transmission to the terminal on which the terminal is to report
channel quality information. Hence, the different embodiments of the invention in line
with the two aspects of the invention discussed above can be readily combined.
The invention according to another embodiment is also providing a mobile terminal for
reporting on a downlink channel quality experienced by the terminal by means of channel
quality information for at least one of plural component carriers of a communication
system available for downlink transmission to the mobile terminal. The mobile terminal
comprises a receiver for receiving dedicated control information having a predetermined
format. The dedicated control information comprises a CQI request flag for requesting
channel quality reporting by the terminal and at least one further, second control
information field consisting of at least one bit.
Furthermore, the mobile terminal further comprises a processing unit for interpreting, if
the CQI request flag is set, at least one bit of the second control information field as CQI
control information indicative of one or more of the component carriers available for
downlink transmission to the terminal on which the terminal is to report channel quality
information, and a transmitter for transmitting channel quality information for each
indicated component carrier.
Another alternative embodiment of the invention is related to a mobile terminal for
reporting on a downlink channel quality experienced by the terminal by means of channel
quality information for at least one of plural component carriers of a communication
system available for downlink transmission to the mobile terminal. This mobile terminal
comprises a receiver for receiving dedicated control information having a predetermined
format, wherein the dedicated control information comprises a CQI request flag for
requesting channel quality reporting by the terminal, a processing unit for interpreting, if
the CQI request flag is set, time and/or frequency resources on which the dedicated
control information is received at the terminal and/or the transport format of the dedicated
control information as CQI control information indicative of one or more of the component
carriers available for downlink transmission to the terminal on which the terminal is to

report channel quality information, and a transmitted for transmitting channel quality
information for each indicated component carrier.
The mobile terminal according to another embodiment of the invention, is further adapted
(e.g. by comprising respective operational units or means) to perform the steps of the
methods for terminal for reporting on a downlink channel quality experienced by the
terminal according to one the different embodiments and aspects of the invention
discussed herein.
Further, according to another embodiment, the invention also provides a computer
readable medium storing instructions that, when executed by the processor of a terminal,
cause the terminal to report on a downlink channel quality experienced by the a terminal
by means of channel quality information for at least one of plural component carriers of a
communication system available for downlink transmission to the terminal, by receiving
dedicated control information having a predetermined format, wherein the dedicated
control information comprises a CQI request flag for requesting channel quality reporting
by the terminal and at least one further, second control information field consisting of at
least one bit, interpreting at least one bit of the second control information field as CQI
control information indicative of one or more of the component carriers available for
downlink transmission to the terminal on which the terminal is to report channel quality
information, if the CQI request flag is set, and transmitting channel quality information for
each indicated component carrier.
A computer readable medium storing instructions that, when executed by the processor
of a terminal, cause the terminal to report on a downlink channel quality experienced by
the a terminal by means of channel quality information for at least one of plural
component carriers of a communication system available for downlink transmission to
the terminal, by receiving by the terminal dedicated control information having a
predetermined format, wherein the dedicated control information comprises a CQI
request flag for requesting channel quality reporting by the terminal, interpreting, if the
CQI request flag is set, time and/or frequency resources on which the dedicated control
information is received at the terminal and/or the transport format of the dedicated control
information as CQI control information indicative of one or more of the component
carriers available for downlink transmission to the terminal on which the terminal is to
report channel quality information, and transmitting channel quality information for each
indicated component carrier.

The computer readable media according to another embodiment of the invention can
further store instructions, that when executed by the processor of the mobile terminal,
cause the mobile terminal to perform the steps of the methods for terminal for reporting
on a downlink channel quality experienced by the terminal according to one the different
embodiments and aspects of the invention discussed herein.
Further embodiments of this invention related to the operation of the network node in the
access network of a communication system that is triggering the aperiodic channel
quality feedback of the terminal on at least one component carrier available for downlink
transmission to the terminal. Such node may be for example a base station, eNodeB or
relay node. According to one of these exemplary embodiments the node in the access
network of the communication system selects at least one component carrier available
for downlink transmission to the mobile terminal out of a plurality of component carriers
configured in the communication system, and transmits to the mobile terminal dedicated
control information comprising a CQI request flag that is set by the node in order to
trigger aperiodic channel quality feedback and at least one further, second control
information field at least one bit of which is set to indicate the selected at least one
component carrier. In response to this dedicated control information the node receives
channel quality feedback on each selected component carrier from the mobile terminal.
In a further embodiment of the invention the node may be further equipped with a
scheduler that is scheduling downlink transmissions to the mobile terminal on the based
on the available component carrier or carriers based on the channel quality feedback
received from the mobile terminal. Furthermore, in a more detailed exemplary
implementation, the node in the access network may receive channel quality feedback
from other mobile terminals than said mobile terminal and schedules the other mobile
terminals and said mobile terminal based on the channel quality feedback received from
the other mobile terminals and said mobile terminal.
Another embodiment of the invention relates to a computer readable medium storing
instructions that, when executed by a processor of a node in an access network of a
communication system, cause the node to trigger aperiodic channel quality feedback of a
terminal on at least one component carrier available for downlink transmission to the
terminal in the communication system, by selecting at least one component carrier
available for downlink transmission to the mobile terminal out of a plurality of component
carriers configured in the communication system, transmitting to the mobile terminal
dedicated control information comprising a CQI request flag that is set by the node in

order to trigger aperiodic channel quality feedback and at least one further, second
control information field at least one bit of which is set to indicate the selected at least
one component carrier and receiving from the mobile terminal, in response to the
dedicated control information, channel quality feedback on each selected component
carrier.
BRIEF DESCRIPTION OF THE FIGURES
In the following the invention is described in more detail in reference to the attached
figures and drawings. Similar or corresponding details in the figures are marked with the
same reference numerals.
Fig. 1 shows an exemplary architecture of a 3GPP LTE system,
Fig. 2 shows an exemplary overview of the overall E-UTRAN architecture of
LTE,
Fig. 3 shows an exemplary downlink resource grid as defined for 3GPP LTE
(Release 8),
Fig. 4 shows the format "DCI format 0" of dedicated control information (DCI)
according to 3GPP LTE (Release 8) for FDD operation,
Figs. 5 & 6 show exemplary solutions for triggering aperiodic CQI reporting from a
user equipment in a 3GPP LTE-A (Release 10) system,
Fig. 7 shows the format "DCI format 0" of dedicated control information (DCI)
according to 3GPP LTE (Release 8) for FDD operation, when frequency
hopping is activated,
Figs. 8 to 12 show different interpretations of the content of dedicated control
information (DCI) according to "DCI format 0" of 3GPP LTE (Release 8)
for FDD operation, when reusing the format in 3GPP LTE-A (Release 10)
system,
Figs. 13 to 17 show different formats of dedicated control information (DCI) according to
different embodiments of the invention, when considering the
interpretations of Figs. 8 to 12 as individual formats of the dedicated
control information,

Fig. 18 shows flow chart of an exemplary operation of a node in the access
network and a terminal according to an embodiment of the invention
Fig. 19 shows an exemplary format for dedicated control information according to
an embodiment of the invention,
Fig. 20 shows the maximum size of allocatable physical resource blocks
depending on the overall system bandwidth, when using and not using
hopping in the uplink, in a 3GPP LTE (Release 8) system, and
Fig. 21 shows the signaling messages of a contention free random access
procedure in a 3GPP LTE (Release 8) system
Figs. 22 & 23 show two exemplary formats for dedicated control information according
to further embodiments of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The following paragraphs will describe various embodiments of the invention. For
exemplary purposes only, most of the embodiments are outlined in relation to an
orthogonal single-carrier uplink radio access scheme according to 3GPP LTE (Release
8) and LTE-A (Release 10) mobile communication systems discussed in the Technical
Background section above. It should be noted that the invention may be advantageously
used for example in connection with a mobile communication system such as 3GPP LTE
(Release 8) and LTE-A (Release 10) communication systems previously described, but
the invention is not limited to its use in this particular exemplary communication network.
The explanations given in the Technical Background section above are intended to better
understand the mostly 3GPP LTE (Release 8) and LTE-A (Release 10) specific
exemplary embodiments described herein and should not be understood as limiting the
invention to the described specific implementations of processes and functions in the
mobile communication network. Nevertheless, the improvements to the random access
procedure proposed herein may be readily applied in the architectures/systems
described in the Technical Background section and may in some embodiments of the
invention also make use of standard and improved procedures of theses
architectures/systems.

As indicated in the Summary of Invention section, one aspect of this invention is to
suggest a new interpretation of a predetermined format for dedicated control information
comprising a CQI request flag. The CQI request flag is a flag (e.g. 1 bit) that is used to
request a terminal receiving the dedicated control information to provide channel quality
feedback. The interpretation of the content of the dedicated control information may or
may not depend on the status of the CQI request flag, depending on the implementation.
In one exemplary implementation, the predetermined format of the dedicated control
information is the "DCI format 0" as defined for 3GPP LTE (Release 8) that is interpreted
in a different manner depending on the status of at least the CQI request flag comprised
therein. Fig. 4 exemplarily shows the "DCI format 0" as defined for 3GPP LTE
(Release 8) for the FDD operation.
As indicated above, in some exemplary embodiment of the invention that will be outlined
in the following in more detail, the status of the CQI request flag comprised in the
dedicated control information according the predetermined dedicated control information
format is determining how the remaining content of the dedicated control information is
interpreted by the terminal. The terminal may be for example a mobile terminal, a user
equipment or a relay node. To put this differently, in these examples, the CQI request
flag could also be considered a format identification: In case the CQI request flag is not
set, the content of the dedicated control information is interpreted as defined for the
predetermined format. In case the CQI request flag is set, the dedicated control
information is not interpreted as defined for the predetermined format, i.e. has a different
format than the predetermined format.
In case the CQI request flag is set, at least one further bit of the dedicated control
information for uplink transmission is interpreted by a terminal receiving the dedicated
control information as information indicative of the one or more component carriers
available for downlink transmission to the terminal and the terminal is providing channel
quality feedback on the channel quality experienced on the indicated component carrier
or component carriers. This at least one further bit that can be considered as CQI control
information could correspond to
- a part or parts of one or more control information fields comprised in the dedicated
control information according to the definition of the predetermined format, or
- one or more control information fields comprised in the dedicated control information
according to the definition of the predetermined format, or

- a mixture between a part or parts of and entire control information fields comprised in
the dedicated control information according to the definition of the predetermined
format.
In one example, the control information field or fields (part or parts of which are)
interpreted as CQI control information include a hopping flag, a resource assignment
field, a DMRS field, an uplink carrier indicator field and padding bits. When implementing
the invention in an LTE-A (Release 10) system, the number of padding bits within the
dedicated control information may depend on the system's bandwidth. In typical
scenarios, one can expect that there are 0,1 or 2 padding bits (depending on the system
bandwidth).
In another alternative exemplary implementation, the combination of the CQI request flag
and the at least one further bit of the dedicated control information is used to indicate the
one or more component carriers available for downlink transmission to the terminal on
which the terminal is to report channel quality feedback. Hence, in this example, the
interpretation of the dedicated control information may not depend on the status of the
CQI request flag. Instead, a combination of the CQI request flag and at least a part of at
least one further control information field indicates the one or more component carriers
available for downlink transmission to the terminal and the terminal is providing channel
quality feedback on the channel quality experienced on the indicated component carrier
or component carriers
According to another, alternative aspect of the invention, the indication of the component
carrier or component carriers the terminal is requested to provide channel quality
feedback on is indicated by the time and/or frequency resources on which the dedicated
control information is received at the terminal and/or the transport format of the dedicated
control information. For example, it can be assumed that the one or more control channel
elements onto which the dedicated control information for a terminal is mapped is/are
themselves mapped to the physical resources of one or more component carriers for
downlink transmission according to different patterns. Each pattern could thereby
indicate a combination of component carriers (at least one) available for downlink
transmission to the terminal on which the terminal is to provide channel quality feedback.
Generally, it should be noted that "available" in formulations like "component carriers
available for downlink transmission" or "available component carriers" should refer to the
fact that there may be more component carriers configured or existing in the system than

at a given point of time used for downlink transmission to the terminal. Available in this
context refers to the component carriers actually used for downlink transmission to the
terminal.
Available component carriers may therefore be one of:
- all component carriers that the base station (e.g. eNodeB or relay node) can use for
conveying data on the downlink to the terminal (e.g. user equipment),
- all component carriers that a terminal assumes for reception of data (e.g. this may be
configured individually per terminal by the network/eNodeB/relay node using higher-
layer signaling such as RRC signaling),
- all component carriers where a terminal detects reception of data,
- all component carriers that a terminal is configured to consider for channel quality
feedback reporting (which may be a superset or subset of the component carriers in
the preceding bullet point, and which can be configured using higher-layer signaling
such as RRC signaling)
- all component carriers that are within the reception capability of the receiver (this is
mostly related to hardware restrictions or capabilities of the terminal, such as radio
frequency circuitry complexity and power consumption)
Typically, terminals that are most suitable for a high data rate in the downlink are those
that are close to the transmitter ("cell-centre") and that do not move fast, i.e. where the
channel characteristics of the downlink barely fluctuate over a certain time. The reason is
that for cell-centre terminals, the available transmission power can be very efficiently
used for high code rates (close to rate r = 1) or high-order modulation schemes (such as
64-QAM), and for slowly moving terminals, the channel characteristics is nearly constant
over time. This means that one can also assume that channel quality feedback of such
slow-moving terminal that has been reported has a very long validity, allowing a very
accurate and efficient link adaptation.
Accordingly, in order to exploit the capability of those slow-moving, cell-centre terminals,
it is advantageous to configure same to use component carrier aggregation, i.e. to use
multiple component carriers at least for downlink transmissions. Generally it can be
assumed that higher layer configuration or semi-static configuration is available to the
network, so that a node in the access network is able to configure a terminal to operate

in a single or multiple component carrier transmission/reception mode. The terminal is
thus aware of whether or not multiple component carriers are available in the downlink so
that it can judge whether a dedicated control information for an uplink transmission
where the CQI request flag is set must be interpreted as a request to provide channel
quality feedback for a single downlink component carrier (only one component carrier is
available) or as a request for channel quality feedback on one or more of the multiple
downlink component carriers identified within the dedicated control information (multiple
component carriers are available). Accordingly, depending on the number of downlink
component carriers configured for a terminal, the terminal interprets the dedicated control
information differently.
Similarly, the access network node (typically a base station, eNodeB or relay node) is
also aware of the number of downlink component carriers that have been configured for
the terminal and may therefore control the channel quality feedback reporting behavior of
the terminal accordingly (e.g. by setting the CQI request flag, or by signaling the
dedicated control information according to special pattern on time and/or frequency
resources, as will be explained further down below). Hence, the access network node
can request channel quality feedback from the terminals so as to properly schedule
downlink transmissions to the respective terminals.
Fig. 18 shows a flow chart of an exemplary operation of a node in the access network
and a terminal according to an embodiment of the invention. The node of the access
network (or access network node) is for example a base station in the access network of
a mobile communication system. In a 3GPP-based communication system, such as LTE-
A, a base station is also referred to as an eNodeB or relay node. Furthermore, the
terminal may be for example a mobile terminal such as a user equipment in a 3GPP-
based communication system. Please note that the terminal may also be a relay node as
far as communication between an eNodeB and a relay node are concerned.
The terminal and the node may for example communicate with each other via an air
interface. The system bandwidth available for communication may be considered to be
divided into a plurality of component carriers. For example, the system bandwidth could
be for example divided into 2,3, 4 or 5 component carriers.
The operation of the node of the access network is shown on the left hand side of Fig.
18. The node first selects 1801 one or more component carriers available for downlink
transmission to the terminal on which it desires to receive channel quality feedback.

Based on the selection of component carrier(s) the node further transmits 1802
dedicated control information to the terminal that include an indication of the selected
component carrier(s) on which the terminal is to provide channel quality feedback. As will
be outlined in more detail below, there exist numerous possibilities how the selected
component carrier(s) can be indicated to the terminal. The dedicated control information
also comprises a resource allocation on the uplink for the terminal, on which the terminal
is to send the channel quality feedback. Therefore the dedicated control information may
also be referred to as an uplink grant.
It is assumed for exemplary purposes in Fig. 18 that the dedicated control information
has a predetermined format and comprises a CQI request flag being set in order to
trigger aperiodic channel quality feedback from the terminal and CQI control information
(CQI control info) that is indicating which component carrier(s) have been selected,
respectively on which component carrier(s) the terminal is to report. As will be outlined in
more detail below, there exist numerous possibilities how the selected component
carrier(s) can be indicated to the terminal by means of the CQI control information
comprised in the dedicated control information.
The terminal receives 1803 transmission of the dedicated control information from the
node of the access network on downlink. The dedicated control information may be
transmitted via a control channel to the terminal. In this example, the terminal checks
whether the CQI request flag is set in the dedicated control information. If the CQI
request flag is not set, the terminal would interpret the contents of the dedicated control
information using the standard definition of the dedicated control channel information
format used.
If the CQI report flag is set, i.e. is requesting channel quality feedback from the terminal,
the terminal will interpret the content of the dedicated control information differently than
in the case where the CQI request flag is not set. More specifically, if the CQI report flag
is set, the terminal will interpret at least a part/one bit of at least one further field
comprising control information (second control information field) within the dedicated
control information as the CQI control information and will determine 1804 the CQI
control information indicating the access network node selection of the component
carrier(s) to provide channel quality feedback for. Next, the terminal generates 1805 a
channel quality feedback message identifying the channel quality experienced by the
terminal on the selected component carrier(s) indicated within the dedicated control
information received from the access network node. This could for example involve that

the terminal is performing some channel quality measurement on the selected
component carrier(s). In a more detailed exemplary implementation, the terminal
determines a SINR or channel covariance measurement, based on e.g. the reception of
so-called reference symbols, for the selected component carrier(s) and may optionally
further convert the measurement results into channel quality feedback, such as for
example an MCSI or Channel Quality Indicator (CQI) as in an LTE or LTE-A
specifications, a PMI or Rl. Channel quality feedback may also be provided in form of
directly measured or measurement-derived metrics such as a channel covariance matrix
or elements, channel coefficients, or other suitable metrics.
The terminal transmits 1806 a message containing the channel quality feedback for the
selected component carrier(s) to the node in the access network, which receives the
message and extracts the channel quality feedback information. The terminal sends the
channel quality feedback on the selected component carrier(s) indicated in the dedicated
control information on the uplink resources that are also indicated in the dedicated
control information. Optionally, the terminal may multiplex the channel quality feedback
and further control or user data in this transmission. The node may store the obtained
channel quality feedback and may make the channel quality feedback available to a
scheduler (which could be located in the node) so that the downlink channel quality
experienced by the terminal on the selected component carrier(s) can be considered in
the scheduling of the terminal, i.e. in the process of deciding on the allocation of physical
downlink or uplink resources to the terminal.
Although Fig. 18 shows only the triggering and transmission of channel quality feedback
from a single terminal, it should be noted that the access network node may of course
serve multiple terminals. Accordingly, the access network node may request multiple
terminals to provide (aperiodic) channel quality feedback on the downlink component
carries available to the respective terminals. Furthermore, the access network node may
schedule not only one terminal, but may schedule multiple terminals in a resource
assignment process taking into account the channel quality experienced by the different
terminals on the different component carriers of the system in its scheduling decision.
In a more detailed exemplary embodiment of the invention, it may be assumed that the
procedure shown in Fig. 18 is implemented in a 3GPP LTE-A (Release 10)
communication system. In this exemplary embodiment, the node of the access network
may be an eNodeB or a relay node. The terminal is a user equipment (UE). The eNodeB
selects the component carrier(s) on which the user equipment is to report channel quality

feedback and indicates its selection to the user equipment by means of L1/L2 control
signaling on the PDCCH.
More specifically, the L1/L2 control signaling is comprising dedicated control information
(DCI) that comprises a trigger of aperiodic channel quality feedback by the user
equipment, e.g. by means of the CQI report flag, and an indication of the component
carrier(s) for which channel quality feedback, e.g. by means of a so-called CQI report, is
requested. This indication of the component carrier(s) is the CQI control information that
may also be referred to as a CQI carrier indicator field (CQI-CI) of the uplink dedicated
control information.
In one further more detailed exemplary implementation the employed dedicated control
information has one of a plurality of predetermined formats, e.g. the DCI format 0 as
defined for LTE (Release 8) and an exemplary structure of which is shown in Fig. 4 and
Fig. 7 in case of operating the LTE-A (Release 10) communication system in FDD mode.
In this case the CQI-CI may be for example composed of part(s) of one or more control
information fields that already exist in the DCI format 0 of Release 8.
As shown in Fig. 4 and Fig. 7, the UL-DCI for FDD consists of:
- a format flag (Flag Format 0/1A) for distinguishing DCI Format 0 and DCI format 1 A,
which are defined to have the same number of bits/size,
- a hopping flag (Hopping Flag) indicating whether or not the user equipment should
employ uplink resource hopping,
- a resource block assignment field assigning uplink resources on the PUSCH to the
user equipment (when triggering aperiodic channel quality feedback, the channel
quality feedback and optionally further user data is multiplexed and transmitted on
these assigned resources via that PUSCH),
- a modulation and coding scheme field (MCS&RV) that is indicating the modulation
scheme, coding rate and the redundancy version for the transmission on the
assigned resources on the PUSCH,
- a new data indicator (NDI) to indicate whether the user equipment has to send new
data or a retransmission,

- a DMRS field (Cyclic Shift DMRS) for configuring the cyclic shift applied to the
reference symbol sequence,
- a CQI request flag for triggering an aperiodic channel quality feedback report from the
user equipment, and
- if required one or more padding bit(s) to align the size of the dedicated control
information to a predetermined number of bits.
If the hopping flag is set, the first 1 or 2 bits of the resource block assignment field are
used to indicate the hopping sequence or hopping configuration to the user equipment.
This means that the resource block assignment field has 1 or 2 bits less, and may
therefore only indicate a smaller resource block allocation size.
Another possibility according to another embodiment of the invention is to reuse the
definition of DCI format 0 as defined for LTE (Release 8) and to extend same for the use
in LTE-A (Release 10), i.e. to define a new DCI format 0 for the use in LTE-A
(Release 10) based on DCI format 0 as defined for LTE (Release 8). Such an exemplary
DCI format 0 for LTE-A (Release 10) according to one embodiment of the invention is
shown in Fig. 19. In LTE (Release 8) there is only one component carrier defined, so that
there is no question for which component carrier an uplink or downlink resource
assignment is pertaining to.
When using multiple component carriers, the association between the resource
assignment and the component carrier(s) for which it should be valid is not self-evident.
When reusing the DCI format 0 as defined for LTE (Release 8) in a multiple-component
carrier system like LTE-A (Release 10), the user equipment may for example assume
that the resource allocation in the dedicated control information is pertaining to the
downlink component carrier on which the dedicated control information is received (for
downlink resource assignment), respectively, an uplink component carrier associated
(linked) to the downlink component carrier on which the dedicated control information is
received (for uplink resource assignments). Alternatively, in this embodiment and as
shown in Fig. 19, the DCI format 0 as defined for LTE (Release 8) can be extended by
an uplink carrier indicator field (UCI) for indicating to the user equipment for which
component carrier or component carriers the dedicated control information is valid. It
should be noted that the uplink carrier indicator field (UCI) can be placed also on other
locations within the exemplary DCI format 0 for LTE-A (Release 10). Assuming that only
one component carrier can be indicated by the uplink carrier indicator field (UCI) and the

system may be configured with up to five component carriers, the uplink carrier indicator
field (UCI) should have a size of 1, 2 or 3 bits, depending on the number of available or
existing component carriers. If the uplink carrier indicator field (UCI) should be able to
indicate arbitrary combinations of the valid or existing component carriers for which the
dedicated control information is valid, the number of bits required for the uplink carrier
indicator field is upper-bounded by [log2 NoC], where NoC ls the number of different
combinations of component carriers being possible.
It should be also noted that the invention may also be implemented in a LTE-A
(Release 10) communication system operating in TDD mode. In this case the dedicated
control information for the uplink (UL-DCI) according to DCI format 0 as defined for LTE
(Release 8) or LTE-A (Release 10) - according to the exemplary embodiment in the
paragraphs above - further comprises an uplink index field (UL index) or a Downlink
Assignment Index (DAI) field (see 3GPP TS 36.212, version 8.7.0, section 5.3.3.1.1 and
3GPP TS 36.213, version 8.7.0, sections 5.1.1.1, 7.3 and 8 incorporated herein by
reference).
In the following several exemplary embodiments of the invention are described with
respect to Figs. 8 to 17 that are intended to exemplify how the CQI control information
may be comprised into the dedicated control channel information. Please note that for
exemplary purposes, the different examples are based on a reuse of DCI format 0
defined for dedicated control information in LTE (Release 8) that has been discussed
previously. Nevertheless, the exemplary embodiments may equally make use - for
example - of the format for dedicated control information as shown in Fig. 19 or of other
dedicated control information formats. In all embodiments, it may be assumed that the
user equipment has already been configured to use component carrier aggregation, i.e.
there are plural component carriers available for downlink transmission to a particular
user equipment.
In one embodiment of the invention, the dedicated control information comprises a CQI
request flag and at least a hopping flag. The "hopping" flag (typically 1 bit) is included to
determine whether a user equipment should employ uplink resource hopping for
transmission. The main merit of employing hopping is to obtain frequency diversity, i.e. to
exploit different channel and/or interference characteristics to be more robust against
instantaneous and limited Signal to Interference-plus-Noise Ratio (SINR) fluctuations in
time or frequency. Such fluctuations can for example occur if the user equipment is
moving at a high speed, or when it is in a radio channel scenario where the impulse

response results in a very frequency-selective transmission characteristic, or when it is
close to a radio cell boundary where generally the interference experienced from other
user equipments in the same or adjacent cell can be relatively high compared to the
received signal power from the target user equipment.
In general, a downlink transmission using multiple component carriers at the same time
is interesting to increase the instantaneous data rate for a user equipment. Traditionally,
the user equipments which are most suitable for a high data rate are those that are close
to the transmitter ("cell-centre") and that do not move fast, i.e. where the channel
characteristics barely fluctuate over a certain time. The reason is that for cell-centre user
equipments, the available transmission power can be very efficiently used for high code
rates (close to rate r = 1) or high-order modulation schemes (such as 64-QAM), and for
slowly moving user equipments, the channel is nearly constant over time, such that a
CQI that is reported has a very long validity, allowing a very accurate and efficient link
adaptation. It should be understood that even though the terms "cell-centre" and "cell
boundary" are originating from the geographical position of the terminal with respect to
the position of the radio network element (such as an eNodeB or relay node), the term
"cell centreTcell boundary" also refers to a terminal that faces generally/on average
good/bad radio conditions, respectively. This is not only a function of the geographical
distance but also of e.g. the existence of obstacles that block a line-of-sight connection
between the two ends of the radio communication. Therefore, even a terminal that has a
very small Euclidean distance to an eNodeB or relay node could be considered to be in a
cell boundary environment, if the transmission path(s) are blocked by obstacles such as
walls, buildings, vegetation, metal shields, and the like.
Consequently, slow moving cell-centre user equipments are traditionally not associated
with conditions where uplink hopping is required. Therefore the Hopping flag (and
consequently the Hopping configuration bits - see Fig. 4 and Fig. 7) are rarely
activated/employed, if ever, when CQI for multiple component carriers is requested.
Generally, higher layer or semi-static configuration can be used to configure a user
equipment to operate in a single or multiple component carrier transmission/reception
mode. Therefore a user equipment can know whether a CQI request flag being set in an
uplink dedicated control information (UL-DCI) should be used for single or multiple
component carrier channel quality feedback request. Accordingly, in case there are,
multiple component carriers available for a user equipment for downlink transmission the
user equipment can interpret the hopping flag as CQI control information that is
indicating the component carrier(s) on which the user equipment is to report.

A further reason why hopping should not be applied for a slow-moving, cell-centre user
equipment, or why not being able to employ hopping does not jeopardize the system
operation significantly, is that for downlink as well as for uplink these user equipments
can convey large packets per allocated transmission due to their generally advantageous
radio channel conditions. Generally, this means that the user equipment should be able
to transmit over a large portion of the available spectrum, i.e. the number of allocated
resource blocks should be large. However, as can be seen in Fig. 20, the maximum
resource allocation size in case hopping is activated (Hopping Flag = 1 - see also Fig. 7)
is employed is radically smaller than without hopping. Additionally, the number of bits
taken from the Resource Block Allocation field depends on the system bandwidth in
terms of available resource blocks in the cell (or component carrier). Fig. 20 shows on
the y-Axis, the effect on the maximum allocatable number of resource blocks and on the
x-Axis the bandwidth of the system. It can be seen that only a limited fraction of the
available resources can be allocated to a single user equipment in the uplink when
employing hopping, which will have a negative effect on the system and cell throughput.
Therefore, it is preferable that cell-centre slow-moving user equipments do not use
hopping.
In a typical implementation of the LTE-A (Release 10) communication system, it can be
assumed that the dedicated control channel information according to the formats (such
as DCI format 0) exemplified in Fig. 4 and Fig. 19 will have at least one padding bit to
match the size of the dedicated control information to that of DCI format 1A - generally to
match the size of a first DCI format to the size of a second DCI format. Accordingly, if the
payload for DCI format 0 is smaller than the payload for DCI format 1A (including any
padding bits appended to DCI format 1A), zeros are appended to DCI format 0 until the
payload size equals that of DCI format 1A. Even though the value of these padding bits
is fixed, they are not defined for any particular purpose other than to adjust the payload
size. Consequently, in one embodiment of the invention, the padding bit(s) within the
dedicated control information are used to signal the CQI control information to indicate
the component carrier(s) on which the user equipment should report. In this embodiment
of the invention, the dedicated control information transmitted to the user equipment
comprises the CQI request flag and at least one padding bit.
Fig. 9 shows an exemplary interpretation of the content of dedicated control information
(DCI) according to DCI format 0 of 3GPP LTE (Release 8) for FDD operation (see
Fig. 4), when reusing the format in 3GPP LTE-A (Release 10) system, to exemplify this
embodiment of the invention. Of course this example could be likewise realized using a

DCI format 0 as of Fig. 19 or on DCI format 0 for TDD operation, since it can be
assumed that the fields available for FDD operation are also available for TDD operation.
The user equipment that is receiving the dedicated control information according to Fig. 9
is checking whether or not the CQI request bit is set (=1) to trigger aperiodic channel
quality feedback from the user equipment. Assuming that this is the case, the user
equipment will interpret the padding bit(s) of the dedicated control information as the CQI
control information, i.e. an indication of the downlink component carrier(s) to be reported
and will send channel quality feedback for the indicated component carrier(s).
The interpretation of the padding bits as CQI control information as exemplified above
may also be viewed as a new DCI format 0 for cases where the CQI request bit is set
(=1). Fig. 14 exemplary shows this new dedicated control channel format. Hence, similar
to the case of using the hopping flag for signaling the CQI control information as
described with respect to Fig. 8 and Fig. 13 above, the CQI request flag may also be
viewed as a format indicator that is indicating whether the dedicated control information
has a first format (CQI request flag is not set (=0)) - that is the dedicated control
information is interpreted by the user equipment according to the default definition of the
DCI format - or has a second format (CQI request flag is set (=1)) - that is a format
where the portion of the dedicated control information that is carrying padding bit(s)
according to the default definition of the DCI format is carrying the CQI control
information as exemplified in Fig. 14.
According to a further embodiment of the invention, the bits used to determine a cyclic
shift applied to the transmission of demodulation reference symbols (DMRS) at the
terminal ("Cyclic Shift DMRS bits") are used to indicate on which and how many of the
available component carrier(s) a user equipment is to report channel quality feedback.
Accordingly, in this exemplary embodiment of the invention the uplink dedicated control
information provided to the user equipment comprises a CQI request flag and at least
some Cyclic Shift DMRS bits. In one exemplary implementation, there are Cyclic Shift
DMRS bits foreseen in the predetermined format of the dedicated control information.
The cyclic shift for the DMRS is typically employed in a 3GPP-based communication
system to enable transmission from two different terminals using the same or at least
partly overlapping time-frequency resources in the uplink. By means of a cyclic shift of
the DMRS between the two transmitting terminals, it is possible for the eNodeB to
distinguish/decompose the two interfering signals received from the terminals again and

to decode both successfully. This is sometimes referred to as employing a multi-user
MIMO uplink scheme (UL MU-MIMO).
A fundamental requirement of a multi-user MIMO uplink scheme is that the radio
channels on which the two terminals send their uplink data should be statistically
independent as possible, otherwise the decomposition and decoding will be suboptimal
and may result in a lot of decoding errors. Looking at the case of slow-moving cell-centre
terminals, it is however highly likely that the radio channels are highly correlated,
particularly if looking at line-of-sight scenarios. Therefore it is unlikely that two such
terminals will be assigned to transmit on the same frequency resource. Consequently,
the Cyclic Shift DMRS field in the uplink dedicated control information is commonly not
used for such terminals and can be re-used for indicating the component carrier(s) for
which a user equipment should send channel quality feedback.
Even if the Cyclic Shift DMRS bits are reused as for example in DCI format 0 exemplified
in Fig. 4 and Fig. 19, employing a multi-user MIMO uplink transmission from two (or
more) terminals is still possible. The only constraint for such a scenario would be then
that the two (or more) terminals which share part or all uplink time/frequency resources
at the same time should not receive a CQI trigger at the same time. If this is ensured by
the access network node (e.g. the eNodeB or relay node), the terminal receiving a trigger
for reporting channel quality feedback would employ a predefined cyclic shift of which
both sides - the network (eNodeB) and the reporting terminal - are aware (e.g. by
specification or control signaling). The eNodeB or relay node can therefore determine
another orthogonal cyclic shift(s) for the other terminal(s) and signal same using the
Cyclic Shift DMRS field for the other terminal(s) not receiving the CQI trigger (if the CQI
request flag is not set, the cyclic shift signaled in the Cyclic Shift DMRS field is applied by
the terminal as usual). Therefore effectively the eNodeB or relay node can ensure that
the DMRS transmitted by these terminals are mutually orthogonal, even if one of the
terminals is triggered to send channel quality feedback. This method can further be
extended such that multiple terminals can be triggered to send channel quality feedback,
under the condition that the mentioned predefined cyclic shift for each such terminal is
different, resulting in mutually orthogonal employed DMRS sequences.
Fig. 11 shows an exemplary interpretation of the content of dedicated control information
(DCI) according to DCI format 0 of 3GPP LTE (Release 8) for FDD operation (see
Fig. 4), when reusing the format in 3GPP LTE-A (Release 10) system, to exemplify this
embodiment of the invention. Of course this example could be likewise realized using a

DCI format 0 as of Fig. 19 or on DCl format 0 for TDD operation. An eNodeB or relay
node that is requiring a user equipment to send channel quality feedback on one or more
component carriers available for downlink transmission to this user equipment can signal
dedicated control information for an uplink transmission to the user equipment in which
the CQI request flag is set. The eNodeB or relay node includes an indicator of the
component carrier(s) to be reported into the Cyclic Shift DMRS field which would be
commonly used to signal the cyclic shift to be applied by the user equipment for the
uplink transmission. The user equipment that receives the dedicated control information
recognizes the CQI request flag being set and interprets the content of the Cyclic Shift
DMRS field within the dedicated control information as CQI control information indicating
the component carrier(s) for which the user equipment is to provide channel quality
feedback.
In case the user equipment recognizes the CQI request flag set, the user equipment may
apply a cyclic shift to the DMRS that has been previously configured by higher-layer
control signaling or a default cyclic shift for the uplink transmission, and transmit the
channel quality feedback for the indicated component carrier(s) and optionally further
uplink data.
In one further embodiment of the invention, not all of the bits of the Cyclic Shift DMRS
field are used for indicating the CQI control information. For example, assuming that
there are 3 bits foreseen for the Cyclic Shift DMRS field, 2 bits thereof could be used to
indicate to the user equipment for which component carrier(s) available for downlink
transmission to the user equipment, the user equipment should report, while the
remaining 1 bit could be used to signal the application or non-application of a cyclic shift
to the DMRS sequence for the uplink transmission. Hence, in case this 1 bit is set, the
user equipment applies a configured or predetermined cyclic shift to the uplink
transmission, while it does not do so, if this 1 bit is not set.
Again, the interpretation of the Cyclic Shift DMRS bits of the dedicated control
information as CQI control information as exemplified above may also be viewed as a
new DCI format 0 for cases where the CQI request bit is set (=1). Fig. 16 exemplary
shows this new dedicated control channel format. Again, the CQI request flag can be
viewed as a format indicator that is indicating whether the dedicated control information
has a first format (CQI request flag is not set (=0)) - that is the dedicated control
information is interpreted by the user equipment according to the default definition of the
DCI format - or has a second format (CQI request flag is set (=1)) - that is a format

where (a portion of) the Cyclic Shift DMRS bits in the dedicated control information is
carrying the CQI control information as exemplified in Fig. 16.
In the examples that have been discussed in the preceding paragraphs, there has been
a further, second control information field (in addition to the CQI request flag) that has
been used to indicate the component carrier(s) for which a terminal (e.g. user equipment)
is to report channel quality feedback. It should be noted that it is also possible to interpret
more than one further second field as indicative of the component carrier(s) for which
channel quality feedback is to be provided by the terminal.
For example, in a further embodiment of the invention, the hopping configuration bits that
are foreseen to signal the hopping configuration in a conventional dedicated control
information format as exemplified in Fig. 7 are used to signal the CQI control information
to the user equipment in an LTE-A (Release 10) communication system. As explained
before, hopping may be generally undesirable for slow-moving cell-centre user
equipments, so that the 1-2 bits that indicate the hopping configuration would rarely if
ever be used. However, the interpretation of the Resource Block Assignment (RBA) field
in case hopping is activated (see Fig. 7) can be re-used for the case that channel quality
feedback for one or more of multiple component carriers is requested, such that the 1-2
bits originally used as Hopping Configuration Bits are used as CQI control information
(CQI-CI). The advantage of this solution is that the use of hopping in the uplink would still
be possible, as the Hopping Flag retains its original function and meaning. The hopping
configuration may be for example configured in advance by higher layer signaling (e.g.
RRC signaling). The potential drawback of this solution is that the maximum allocatable
uplink resource size is quite strictly limited (see Fig. 20), which may not be in the interest
for the operator. Therefore, in a variant of this embodiment it may be a good trade-off to
"steal" only one bit from the Resource Block Assignment field for CQI control information,
so that the CQI control information space is extended by 1 bit but the limitation on the
maximum allocatable uplink resource size is less severe than shown in Fig. 20.
In another exemplary embodiment, a combination of the Hopping Flag and (one bit of)
the Hopping Configuration Bits are used as CQI control information. As exemplified in
Fig. 10, in case the CQI request flag is set (=1) in the dedicated control information, the
user equipment is interpreting a combination of the hopping flag and hopping
configuration bit(s) that span into the resource block Assignment field as the CQI control
information. In this example, as the Hopping Flag is also used for the CQI control
information signaling, it is not possible to utilize hopping for the uplink transmission by

the user equipment any longer. However, this solution may be advantageous as for
example only one bit of the Hopping Configuration Bits could be used in combination w,th
the Hopping Rag for indicating the CQI control information, so that this solution imposes
fewer restrictions to the maximum allocatable uplink resource size. As further illustrated
in Fig. 15, this exemplary solution may be again considered a new dedicated control
information format for cases where the CQI request flag is set.
Another exemplary implementation and embodiment of the invention is the use of a
combination of the Hopping flag and (at least a part of) the Cyclic Shift DMRS bits for the
signaling of the component carrier(s) for which the user equipment is to provide channel
quality feedback. This is exemplified in Fig. 12, where - in case the CQI request flag is
set (=1) - the user equipment will combine the bit of the Hopping flag and (at least a part
of) the Cyclic Shift DMRS bits and will interpret this combination as CQI control
information indicating the component carrier(s) for which it should report. This way, there
is up to a total number of 4 bits that is available to signal different combinations of one or
more component carriers for which the user equipment is to provide channel quality
feedback. Again this exemplary implementation may be considered a definition of a new
format for the dedicated control information in case the CQI request flag is set. Fig. 17 is
illustrating the new dedicated control information format that is corresponding to the
interpretation of a combination of the Hopping flag and (at least a part of) the Cyclic Shift
DMRS bits as the CQI control information as discussed above.
In one further embodiment of the invention, a combination of the Hopping flag, the
padding bit(s) and (at least a part of) the Cyclic Shift DMRS bits is used for signaling the
combination of one or more component carriers for which channel quality feedback is to
be reported. If the CQI request flag is set in the dedicated control information, the user
equipment will combine the bits of all three fields in a predetermined fashion and will
interpret the resulting combined bit combination as the CQI control information that
indicates the component carrier(s) for which channel quality feedback is to be reported.
This exemplary embodiment would allow to use up to 5 bits (or even more, depending on
the number of the padding bits) for signaling combinations of component carrier(s) for
which channel quality feedback is to be reported, so that any arbitrary combination of
component carriers can be indicated, assuming that there is a maximum aggregation of
five component carriers for downlink transmission.
In another exemplary embodiment of the invention, there are uplink carrier indicator bits
foreseen in the format of the dedicated control information in order to indicate the

which downlink component carriers the user equipment should provide channel quality
feedback can be quite different, depending also on the actual number of downlink
component carriers that are available, it can be generally assumed that the ith CQI
control information value denotes an ith combination of component carrier(s) for which
channel quality feedback is requested. In the following paragraphs, different examples
are discussed how to use the different possible numbers of bits available for CQI control
information.
In one exemplary embodiment, the carrier indicator field (UCI) of the dedicated control
information determines the target uplink component carrier(s) of the uplink resource
assignment (UL-DCI) and is further indicating CQI control information, if the CQI request
flag is set. As outlined above, the carrier indicator field (UCI) may for example consist of
3 bits which allows the signaling of 8 different bit combinations (values) - which are
required for distinguishing the component carriers of a communication system using a
maximum of five uplink component carriers.
As the carrier indicator field (UCI) still needs to indicate the uplink component carrier for
which the uplink resource assignment is valid, in this exemplary embodiment, the bit
combinations of the carrier indicator field (UCI) are used to implicitly or explicitly indicate
the uplink component carrier to which the resource assignment pertains as well as to
indicate the downlink component carrier(s) for which channel quality feedback is
requested and to be provided.
The following tables show different examples how the carrier indicator field (UCI) within
an UL-DCI could be interpreted, if the CQI request flag is set. The column "UCI value"
indicates the different bit combinations (also referred to as values or code-points) that
can be signaled in the carrier indicator field, while the other columns define the different
meanings for the given bit combinations.
The column "Uplink Component Carrier Index" indicates for which component carrier in
the uplink (UL) the UL-DCI is valid (i.e. on which uplink component carrier the UL-DCI is
assigning resources). Unless stated otherwise, the examples below assume that there
are up to five component carriers in the uplink identified by a respective index # i, where
i = [l 5]. The "linked UL CoCa" is the uplink component carrier that is (commonly)
linked (paired) to the downlink component carrier on which the UL-DCI is received,
"semi-statically configured UL CoCa" means that the UL-DCI pertains to a component
carrier that has been semi-statically configured, e.g. using RRC signaling. The semi-

static configuration may be under certain circumstances be identical to the "linked UL
CoCa", however it may generally be determined based on other criteria. The "semi-
statically configured UL CoCa" could therefore indicate the "linked UL CoCa", i.e.
includes a reference to the corresponding downlink component carrier, the "semi-
statically configured UL CoCa" can also be an uplink component carrier where it is
irrelevant whether or to which downlink component carrier it is linked.
As can be told from the name, the column "Downlink Component Carrier(s) to be
Reported" indicates for which downlink (DL) component carrier or carriers channel quality
information is requested and to be provided in the uplink. "CoCa carrying UL-DCI" means
that the terminal is to report for the downlink component carrier on which the UL_DCI
(with the CQI flag being set) has been received. "All available DL CoCas" means all
available downlink component carriers as has been defined previously herein,, while
"semi-statically configured DL CoCa(s)" means that the terminal should report for one or
more of the downlink component carriers according to a semi-static configuration, e.g.
configured by means of RRC signaling between the terminal and the access network

As mentioned previously, in the physical layer of a 3GPP-based system such as 3GPP
LTE or LTE-A, the dedicated control information is part of the L1/L2 control signaling that
is transmitted via the PDCCH to the user equipments. The eNodeB that is signalling the
L1/L2 control information in a 3GPP-based system may send several DCI messages to a
single user equipment, wherein each DCI may be transmitted on different downlink
component carriers.

At least in those cases where an UL-DCI does not contain a carrier indicator field (UCI)
even though there are multiple uplink component carriers available, it can be assumed
that a downlink component carrier is linked to a single uplink component carrier, where
that link may be established by means of e.g. semi-static configuration. Consequently,
the user equipment can assume that UL-DCI transmitted on a downlink component
carrier is valid for the single linked uplink component carrier, just in the same way it
would be valid in case no carrier indicator field was present. Where applicable, it is
assumed in the following embodiments and examples that this component carrier linkage
is established even though a carrier indicator field (UCI) may be present in the UL-DCI.
The values representable by the carrier indicator field may be divided in different subsets
associated with respective common properties. In a first subset of values or code-points
"000" to "100" is used for signalling the uplink component carrier to which the resource
assignment of the UL-DCI pertains and it is so to say common to these values that
channel quality feedback is to be provided by the terminal for the downlink component
carrier on which the UL-DCI is received. Moreover, a second subset may be formed by
the values signalling that channel quality feedback is to be provided for all downlink
component carriers. In the example of this second subset thus only contains the code-
point "110", however as mentioned before, only shows one possible implementation,
and there may be others where more than a single code-point indicates that channel
quality feedback is to be provided for all downlink component carriers.
Further, it should be noted that the UCI value "101" is redundant in the example shown in
assuming that there are up to five uplink carriers available. In case there are up to five
uplink component carriers available, the UCI value "101" is not required in this form, as
the "linked UL CoCa" can only refer to one of uplink component carriers #1 to #5, so that
effectively also one of UCI values "000" to "100" could be used for the same purpose.
Nevertheless, if there are more than five uplink component carriers available, the code-
points "000" to "100" of the component carrier indicator field could be used to indicate a
defined uplink component carriers index, while one code-point could identifies the linked
uplink component carrier. For example, if there are six component carriers in the uplink,
the implementation of would allow to individually indicating each of the uplink component
carriers - UCI values "000" to "100" could be used to indicate uplink component carriers
#1 to #5 respectively, while e.g. UCI value "101" could indicate uplink component carrier
index #6 provided that the UL-DCI is transmitted on a DL component carrier that is
linked to uplink component carrier #6.

Another exemplary implementation relates to a scenario where there are six, seven or
eight uplink component carriers available. In this case, one or more of the UCI values
"101", "110" and "111", depending on the exact number of uplink component carriers,
could be used to indicate the respective component carrier(s) in a similar fashion as for
UCI values "000" to "100". In an further alternative implementation, UCI values ""110"
and "111" could be used as discussed above with respect to (or at least one of them
could be reserved for future use), while the UCI value "101" is used to implicitly identify
one of uplink component carriers #6 to #8 by transmitting the UL-DCI (PDCCH) on the
respective linked downlink component carrier of these uplink component carriers #6 to
#8.
The embodiments, implementations and examples that have been described with
respect to are particularly beneficial in case that the network wants to have a very
flexible control over the uplink transmissions from the user equipments in a cell, and
where there are actually many uplink allocations (i.e. transmissions) in the same
subframe. In that case, the eNodeB needs to send many PDCCHs carrying UL-DCI,
where not all PDCCHs may be transmitted in the desired linked component carrier.
Therefore the eNodeB needs to be flexible in balancing the load between the user
equipments and the uplink component carriers by being able to explicitly assign many
user equipments with channel quality feedback transmission to the uplink component
carriers.
In a further exemplary implementation - and again assuming for exemplary purposes up
to five component carriers in the uplink - and as shown in Table 2, the UCI value "101"
could also be used to indicate that the uplink assignment is valid for a component carrier
that has been defined and configured semi-statically, e.g. by RRC signalling. In an
exemplary embodiment, this uplink component carrier is a default or fallback component
carrier that is used to convey control information such as HARQ feedback messages in
the absence of an implicit or explicit uplink component carrier indication. This may further
preferably be the one out of multiple uplink component carriers with the smallest path-
loss, or that is configured to occupy the largest bandwidth.


Furthermore, the UCI value "111" in and Table 2 indicates channel quality feedback for
one or more downlink component carriers according to a semi-static configuration. Such
a semi-static configuration can preferably encompass the downlink component carriers
with a path-loss below a certain threshold, or simply the component carriers that are
facing the smallest path-loss(es). Alternatively, the UCI value "111" can further be
modified to request channel quality feedback for semi-statically configured downlink
component carriers and assigns uplink resources on a semi-statically configured uplink
component carrier. It should be understood that both these semi-static configurations can
be done independently from each other. Alternatively, the value "111" could also be
reserved for future use. Similarly, for example if there are six uplink component carriers,
six of the UCI values could be used to indicate the respective six uplink component
carriers, while the two remaining UCI values may be reserved for future use.
It may be further beneficial to be able to indicate with the component indicator field (UCI)
that channel quality feedback for all downlink component carriers ("all available DL
CoCas") should be transmitted in a single uplink component carrier without any higher
layer data. In the context of LTE Release 8 and Release 10, higher layer data would be
for example any data belonging to a MAC PDU which is transmitted on UL-SCH (see
3GPP TS 36.321, "Medium Access Control (MAC) protocol specification", version 8.5.0.
section 5.4 and its subsections, available at http://www.3gpp.org and incorporated herein
by reference). In that respect, "without any higher layer data" would mean that no MAC
PDU data is transmitted (multiplexed) with the channel quality feedback, or equivalently
that there is no associated UL-SCH available in the assigned uplink resource. It may be

further noted that a MAC PDU is usually associated with a transport block on the
physical layer. On the other hand, it may still be desired that lower layer control channels
or signals such as HARQ feedback (ACK/NACK) still multiplexed with the channel quality
feedback, i.e. in this case the UL-DCI would allow for sending the channel quality
feedback, but no higher layer data except for control signaling, e.g. HARQ feedback. In
another embodiment, at least one entry of the component indicator field indicates that
neither higher layer nor lower layer channels or signals are transmitted by the user
equipment together with the channel quality feedback, with the exception of signals that
are required to successfully receive the uplink transmission such as reference symbols.
Hence, in another exemplary implementation, the code-points could be defined as in or
Table 2, but the code-point "101" or "111" indicates the UL-DCI to be valid for the "linked
UL CoCa" and requests sending only channel quality feedback (e.g. CQI) on the
allocated resources (i.e. particularly no higher layer data, even though other control
signals such as HARQ feedback (ACK/NACK) may still be included in the transmission
on the allocated resources together with the channel quality feedback).
The examples that have been described with respect to Table 2 provide basically the
same advantageous as the exemplary implementations that have been described in
connection with .
However, since it is possible to address and request for semi-statically configured uplink
and downlink component carriers respectively, the exemplary implementations that have
been outlined with respect to Table 2 are also applicable in case there is a preferred
uplink or downlink component carrier available in a system. For example, one or more
"special" uplink component carrier(s) could be defined where all control messages for
uplink are conveyed, unless explicitly requested otherwise. This "special" uplink
component carrier may be chosen because it has generally favourable transmission
characteristics for a user equipment. According to another embodiment of the invention,
the network (eNodeB) can request the channel quality feedback to be transmitted on that
special uplink component carrier. Likewise, one or more "special" downlink component
carrier(s) could be identified, where e.g. channel conditions are generally favourable,
where the major part of downlink control and/or data transmission happens. In this case,
the network (eNodeB) may request channel quality feedback for those "special" downlink
component carriers in order to allow an optimum scheduling or link adaptation decision.
In these cases, the "special" component carrier(s) should constitute the "semi-statically

configured" uplink and downlink component carrier(s), respectively, as outlined
previously.
In addition, it should be noted that the possibility to explicitly request a channel quality
feedback message without higher layer data or channels is an efficient way to save
uplink resources for channel quality feedback, or to establish more control over the
quality of the channel quality feedback transmission, since then the assigned forward
error correction coding needs to be optimised just for the channel quality feedback,
without need to care of implications to the error correction coding performance for the
higher layer data or channels. It should be also noted that in this context, unless explicitly
stated otherwise, it is possible to transmit the channel quality feedback together with
higher layer or other lower layer data or channels on the assigned uplink resources.
As can be seen from various figures, e.g. Fig. 4 or Fig. 19, the dedicated control
information format may have a varying size depending on the length of the Resource
Block Assignment (RBA) field - this is because the size of the RBA field may depend on
the respective component carrier's bandwidth. For example, in 3GPP LTE (Release 8)
the DCI Format 0 for a single antenna transmission on a component carrier with 20 MHz
bandwidth has a size of 30 bits. The DCI size for a transmission to use spatial
multiplexing in a 5 MHz component carrier and PMI of 4 bits could be also 30 bits.
Hence, also in cases where the uplink component carriers have different bandwidth, it
should be known to the terminal for which component carrier the dedicated control
information is valid, e.g. by means of a carrier indicator field as discussed previously
herein.
As can be anticipated, the interpretation of the carrier indicator field (UCI) in cases where
the CQI request flag is not set can be assumed to be defined as shown in Table 1 for
UCI values "000" to "100". However, there may be cases that UCI values would be
interpreted in a different fashion in case the CQI request flag is set, as shown e.g. in
Table 3. Since the interpretation of the carrier indicator field therefore possibly depends
on whether CQI request flag in the DCI is set or not, it is advantageous if the CQI request
field is located at a fixed (i.e. known, independent of the format or bandwidth of the
component carrier on or for which it is transmitted) position within the DCI. For example,
Fig. 22 shows an exemplary format for dedicated control information according to an
embodiment of the invention that is similar to that shown in Fig. 19 regarding the
contained information. However, in contrast to Fig. 19, the carrier indicator field (CIF) -
that is the UCI field of Fig. 19 - is located at the beginning of the DCI information in this

exemplary format. Generally, it should be noted that the "fixed position" is not necessarily
the beginning of the DCI, but a position that irrespective of the usage or size of other
fields. In a specific example, such a position is before the first variable length field of the
DCI or in a block which has identical fields independent of the DCI format (e.g. before the
RBA field). In another specific example, such a position is close to the end such that the
same criterion can be met if checking the contents of the DCI information from end to
beginning, as it were. In this context, in a further embodiment of the invention, also the
CQI request flag may be located at a fixed position as shown in Fig. 23, illustrating a
further exemplary format for dedicated control information according to an embodiment
of the invention.
In the examples discussed above with respect to and Table 2, the carrier indicator field
(UCI) has been interpreted so as to still (explicitly) indicate the uplink component carrier
(index) on which the UL-DCI grants resources, while the downlink component carrier(s)
to be reported for have been either identified as the component carrier carrying the UL-
DCI, all component carriers, or according to semi-static configuration. In the example
shown in Table 3 below, the uplink component carrier (index) is interpreted such that
there is more flexibility in indicating the downlink component carrier(s) to be reported for,
trading off the flexibility in the identification of the uplink component carrier to which the
UL-DCI pertains.

In Table 3 the carrier indicator field is essentially no longer explicitly indicating the uplink
component carrier, but the terminal assumes that the UL-DCI refers to the linked uplink
component carrier of the downlink component carrier on which the UL-DCI is received, if


In the example of Table 4 again two subsets of code-points are provided. The first subset
is indicating a single uplink component carrier to which the UL-DCI pertains, and further
a single downlink component carrier for which channel quality feedback is to be provided.
Please note that the same index numbers being used for the uplink and downlink
component carriers for the respective code-points of the first subset is only exemplarily -
for the example shown in Table 4 it is only important that each component carrier in
uplink and downlink is indicated once by the respective four code-points of the first sub-
set. More specifically, it should be understood that downlink component carrier #n is not
necessarily linked to an uplink component carrier #n, i.e. having the same index, but the
index numbers are just for exemplary purposes herein to distinguish the component
carriers in uplink and downlink, respectively. The remaining code-points "100" to "111"
can be considered to form a second subset of code-points, which have in common that
they indicate that the terminal is to provide channel quality feedback for all available
downlink component carriers (i.e. available for downlink transmission to the terminal at
the time of receiving the dedicated control information).
In another example, it is assumed that there are only three uplink component carriers
available for uplink transmission to the user equipment. In this case, the carrier indicator
field (UCI) code-points could have a meaning as exemplified in Table 5 below.


This example is - in part - similar to Table 4, as the first subset of values ("000", "001",
"010") indicates a single uplink component carrier to which the UL-DCI pertains, and
further a single downlink component carrier for which channel quality feedback is to be
provided, while the second subset of values ("011", "100", "101") indicates that the
terminal is to provide channel quality feedback for all available downlink component
carriers. The code-point "110" triggers the transmission of channel quality feedback for
all available downlink component carriers, while the uplink assignment on the linked
uplink component carrier can be used by the terminal for signalling channel quality
feedback and uplink higher layer data simultaneously. The code-point "111" triggers the
transmission of channel quality feedback for all available downlink component carriers,
while the uplink assignment on the linked uplink component carrier is to be used for
signalling channel quality feedback only (no UL higher layer data). Again it should be
noted that in one exemplary embodiment, HARQ feedback, e.g. ACK/NACK, may be
signalled together with the channel quality information, even in cases where no (other)
uplink higher layer or lower layer data or channels should be transmitted.
In another further example, it is assumed that there are only two uplink component
carriers and two downlink component carriers available to the user equipment. As can be
seen from Table 6, the values representable by the 3 bit of the carrier indicator field are
split up into four subsets. Again, identical numbering for uplink and downlink component
carriers should not be read as restricting that carriers of the same index in uplink and
downlink are required to be linked to each other. The first subset is formed by values
"000" and "001", and triggers channel quality feedback for the first downlink component

carrier, while the UL-DCI pertains to either the first or second uplink component carrier,
respectively. The second subset of values is formed by values "010" and "011", and
triggers channel quality feedback for the second downlink component carrier, while the
UL-DCI pertains to either the first or second uplink component carrier, respectively.
The third subset is formed by values "100" and "101", and triggers channel quality
feedback for all available component carriers in the downlink (e.g. the first and second
downlink component carrier), while the UL-DCI pertains to either the first or second
uplink component carrier, respectively. The fourth subset is formed by values "110" and
"111", and triggers channel quality feedback for all available component carriers in the
downlink (e.g. the first and second downlink component carrier), while the UL-DCI
pertains to either the first or second uplink component carrier, respectively and only the
channel quality feedback for both downlink component carriers should be sent on the
allocated uplink resources. It should be obvious that this example can be applied to any
case where there are two uplink component carriers and an arbitrary number of downlink
component carriers.
It can be observed that in the example of Table 6 , the last bit of the code-points
determines the uplink component carrier to which the UL-DCI refers to, which may
beneficially exploited in an implementation.


In another example, it is assumed that there are only two uplink component carriers
available to the user equipment, but the number of available downlink component
carriers is arbitrary (i.e. one or more). In this case, the carrier indicator field (UCI) code-
points could have a meaning as exemplified in Table 7 below.

In this example, it is further envisioned that UCI values "010" and "011" request channel
quality feedback reports for all available downlink component carriers that are linked to
uplink component carriers #1 and #2 respectively. As outlined before, it is assumed that
a single downlink component carrier is linked to just a single uplink component carrier;
however a single uplink component carrier may be linked to several downlink component
carriers, particularly in asymmetric downlink-to-uplink component carrier scenarios where
each downlink component carrier is required to be linked to an uplink component carrier.
Reporting channel quality feedback for the linked downlink component carriers may help
the network to decide, if and which component carriers should be disabled for a given
user equipment. For example, in case that all downlink component carriers that link to
the same uplink component carrier can be disabled (e.g. because they report low quality
CQI), it would subsequently also be possible to disable that linked uplink component
carrier since no related control signals (such as HARQ feedback) are required to be
transmitted thereon.
Furthermore, it should be noted that in the example discussed above, it has been
assumed that the carrier indicator field (UCI) is comprised in each UL-DCI. However, in

another embodiment of the invention, the eNode B may decide for each UL-DCI
transmitted to a user equipment, whether the UL-DCI is including a carrier indicator field
(UCI) - see Fig. 19, Fig. 22, or Fig. 23 - or not - see Fig. 4 or Fig. 7. In this embodiment,
if a UL-DCI does not contain an carrier indicator field (UCI), the terminal assumes that
the UL-DCI relates to the linked uplink component carrier and that CQI control
information are included in the UL-DCI (if the CQI request flag is set) as described with
respect to Fig. 8 to Fig. 17 herein. If the carrier indicator field (UCI) is included in the UL-
DCI, the terminal will interpret the carrier indicator field (UCI) as discussed with respect
to to Table 6 herein.
In the following sections there further exemplary implementations for implementing the
signalling of CQI control information depending on the number of bits available for the
CQI control information are provided. Please note that these examples may also be
employed when using (a part of) the carrier indicator field for signaling the CQI control
information.
CQI-CI field: 1 bit
In case of only 1 bit is available for the CQI control information (see for example Fig. 8 or
Fig. 9), according to one exemplary embodiment of the invention, this bit is used to
switch between two possible states: Requesting channel quality feedback for a first
combination of component carrier(s), or for a second combination of component
carrier(s). The two combinations of component carrier(s) to be reported may be for
example predefined (e.g. determined by the user equipment based on a predetermined
rule or procedure) or could be configured by higher-layer control signaling (e.g. RRC
signaling). In one exemplary implementation, the first combination corresponds to only
the single downlink component carrier where the UL-DCI carrying the set CQI request
flag is transmitted, and the second combination corresponds to all available downlink
component carriers.


In one exemplary implementation, component carrier #n would be identified with the
component carrier number that carries the UL-DCI carrying the set CQI request flag.
CQI-CI field: 2 bits
In cases where there are 2 bits available to signal the CQI control information (e.g. when
using a combination of Hopping flag and one Hopping Configuration bit), this could be
seen as an extension to the one-bit case discussed above, where an additional third and
fourth combination of downlink component carrier(s) can be indicated. Assuming that the
downlink component carrier where the requesting UL-DCI is transmitted can be identified
by index #n, in one exemplary embodiment of the invention, the third combination of
component carrier(s) corresponds to the downlink component carrier with index #n+m,
and the fourth combination of component carrier(s) corresponds to the downlink
component carrier with index #n+k.

The integer numbers k and m can be generally any integer number. Advantageously, k
should not be equal to m, and k and m are both non-zero, for improved efficiency. It may
be further preferable to set k=+1 and m=-1, which can be beneficially employed to
"probe" the channel quality for component carriers adjacent to component carrier #n.
In another alternative and exemplary embodiment of the invention, the third combination
of component carrier(s) corresponds to downlink component carrier #n and #n+m, while
the fourth combination of component carrier(s) corresponds to #n and #n+k (see Table
10).


Again, k and m can be generally any integer number. Advantageously, k should not be
equal to m, and k and m are both non-zero, for improved efficiency.
In a further alternative and exemplary embodiment of the invention, the third combination
of component carrier(s) corresponds to downlink component carrier #n to #n+m, while
the fourth combination of component carrier(s) corresponds to #n to #n+k. The number m
may be for example a positive integer and the number k may be a negative integer (see

In a further extension to this embodiment, in case that #n+k or #n+m overflows or
underflows the available component carrier indices, a "cyclic wrap-around" is employed

as for example given by the modulo function to generate only numbers within the
available index range.
In all the embodiments discussed above where there are 2 bits available for signaling the
combination of component carrier(s) channel quality feedback for which is to be reported,
it may further be beneficial to set k=-m to achieve a kind of symmetric behavior.
CQI-CI field: 3 bits
In cases where there are 3 bits available to signal the CQI control information (e.g. when
using the cyclic shift DMRS field), this could be seen as an extension to the two-bit case
discussed above, where an additional fifth to eighth combination of downlink component
carrier(s) can be indicated. The exemplary embodiments for the two-bit case can be
extended to the three-bit case mutatis mutandis, e.g. to request channel quality feedback
for component carrier(s) #n, #n+m1, #n+m2, #n+m3, #n+k1, #n+k2, #n+k3, or for all
available component carriers, respectively. The same holds to extend requesting channel
quality feedback for multiple component carriers or ranges of component carriers mutatis
mutandis. This exemplary implementation is summarized in the Table 12 below:


Another exemplary implementation would be to extend the implementation exemplified
above with respect to Table 10 to the 3-bit case:

CQI-CI field: 4 bits when 5 downlink component carriers are available
In case there are 4 bits available, it is possible to address 16 combinations of component
carriers. Assuming that there are 5 downlink component carriers configured (numbered 0
to 4) and usable by a user equipment, there is a total number of 32 possible
combinations of available component carriers. Hence, using 4 bits, not ail 32 possible
combinations of component carriers can be signaled. It can be assumed that it is more
interesting to represent the cases of requesting channel quality feedback for few
component carriers than for many component carriers, because then it is more
applicable to user equipments that are operating in the grey zone between cell-centre
and cell-edge, where it would be interesting to probe the channel quality for one or two

component carriers to check where the radio conditions are generally favorable.
Therefore, according to one embodiment of the invention, one of the following two
correspondences of CQI-CI value and combinations of component carrier(s) is
suggested:

Inclusion of Component Carrier containing the UL-DCI/CQI request
in the examples on how to establish a correspondence between the logical value
signaled in the CQI control information in Table 8 to Table 14, it has been assumed that
the indication of the component carrier(s) on which the user equipment is to provide
channel quality feedback is indicated by the bits of the dedicated control information
interpreted as CQI control information. For the examples in Table 9 to Table 11, the

index #n of the component carrier on which the dedicated control information (UL-DCI) is
received is considered in the determination of the combination of combination carrier(s)
on which is to be reported in that it is the reference index for determining the component
carrier(s) to report for the first, third and fourth combination.
In one further embodiment of the invention, the component carrier on which the
dedicated control information (UL-DCI) including a request for channel quality feedback
(CQI request flag is set) is always to be reported for. In one exemplary variant of this
embodiment, the network configures whether to include the channel quality experienced
by the user equipment on the component carrier on which a dedicated control
information (UL-DCI) including a request for channel quality feedback (CQI request flag
is set) is received, to the channel quality feedback in addition to that of another or other
component carriers. For example, the eNodeB or relay node may use control signaling
(such as RRC signaling) to configure the user equipment to include or not include by
default a measure of the channel quality of the downlink component carrier on which the
a dedicated control information (UL-DCI) including a request for channel quality feedback
(CQI request flag is set) is received to the channel quality feedback. In such a way, there
is one component carrier less for which CQI control information is required.
With this strategy, the correspondences of Table 10 and Table 11 for scenarios where
there are 2 bits available for the CQI control information can be considered as an
alternative embodiment also making use of the component carrier on which the
dedicated control information is received. If the component carrier on which a dedicated
control information (UL-DCI) including a request for channel quality feedback (CQI
request flag is set) is received, and is further configured to be always included as a
requested component carrier, then component carrier #n can be identified with any of the
other available component carriers,. For scenarios, where there are more than 2 bits
available for signaling the CQI control information, this exemplary implementation can be
particularly advantageous. For example, employing this implementation in a scenario
where 4 bits are available for the CQI control information (CQI-CI) and where there are 5
component carriers available, the default inclusion of the component carrier on which the
UL-DCI triggering channel quality feedback is received to the channel quality feedback
effectively reduces the number of component carriers that have to be addressed by the
CQI control information from five to four. Hence, the 4 bits of CQI control information
(CQI-CI) can now address the full range of combinations of four component carriers in
the finest possible granularity. For example, in one implementation a CQI-CI value of 0
could indicate that channel quality feedback for only the component carrier conveying the

corresponding UL-DCI is requested, while a CQI-CI value of 15 could indicate a CQI
request for all available (i.e. five) component carriers.
In most of the embodiments discussed in further detail so far, the CQI request bit has
been a trigger for determining how to interpret other control information field(s) contained
in the dedicated control information. In an alternative embodiment of the invention, the
CQI control information also includes the CQI request flag so that the CQI request flag
essentially loses its original meaning of triggering a channel quality feedback report from
the user equipment. For example in one exemplary implementation of this embodiment,
the CQI request flag can be combined with the e.g. Hopping flag and the combination of
the two flags is the CQI control information. Essentially, the combination of the CQI
request flag and the Hopping flag would result into two bits that can be used to configure
the channel quality feedback from the user equipment. An exemplary interpretation of the
two flags could look like as Table 15.

When interpreting certain fields of the dedicated control information in a different fashion
as defined original format, some functionality may be "lost". For example, when using the
Hopping Flag for signaling the CQI control information, this effectively means that the
dedicated control information cannot be longer used for activating/deactivating hopping
in the uplink. Similar, considering the example, where the Hopping Configuration Bits are
used for the CQI control information, hopping may be still activated/deactivated by
means of the Hopping flag; however, there is no longer the possibility to configure the
hopping configuration in the dedicated control information. A similar observation can also
be made for using the Cyclic Shift DMRS field for signaling the CQI control information.

In all these examples where certain information can no longer be signed in the dedicated
control information, according to one further embodiment, the "lost" functionality may be
maintained by using dynamic to higher layer/semi-static signaling.
For example, as already indicated previously, the hopping configuration could be for
example signaled by RRC signaling. Similarly, a default cyclic shift to be applied to the
uplink transmission could also be configured by RRC signaling or semi-static
configuration, so that the user equipment would use this default cyclic shift for uplink
transmission, if the Cyclic Shift DMRS field is reused for signaling the CQI control
information.
Furthermore, in most of the examples above, the component carrier(s) on which the
terminal is to provide channel quality feedback has been (at least to some extent)
explicitly indicated by the CQI control information. In a further exemplary embodiment of
the invention, the component carrier(s) on which the terminal is to provide channel
quality feedback may also be signaled implicitly or by combining explicit and implicit
signaling. For example, Table 10 and Table 11 above show an example, where implicit
(downlink component carrier used for the UL-DCI defines the index #n) and explicit (the
two bits of the UL-DCI containing the CQI control information indicates one of the four
options shown in the tables) signaling. Similarly, in the example where the component
carrier on which the dedicated control information (UL-DCI) including a request for
channel quality feedback (CQI request flag is set) is always to be reported on can be
also considered using a combination of implicit and explicit signaling for indicating for
which component carrier(s) the terminal is to provide channel quality feedback.
In general, it can be assumed that the UL-DCI, or the corresponding PDCCH, is
transmitted to a receiver using one of multiple time/frequency resource combinations. For
example, in LTE (Release 8), there is a choice by the eNodeB on what resources and
with which parameters any dedicated control information (DCI) is transmitted. This
encompasses such parameters as the modulation scheme, coding rate, aggregation
level, and the mapping onto time/frequency resources corresponding to a common or
user equipment-specific search space. Details of these characteristics can be found e.g.
in St. Sesia, I. Toufik, M. Backer, "LTE The UMTS Long Term Evolution", Wiley and Sons
Ltd., 2009 (ISBN: 978-0-470-69716-0), sections 9.3.2.2, 9.3.2.3, 9.3.3.2, 9.3.4,
incorporated herein by reference.

Consequently, it is further possible to link the requested component carrier CQI not only
to the CQI-CI as mentioned above, but also to the format or location of the corresponding
UL-DCI. For example, a UL-DCI which is transmitted with a modulation and coding
scheme (MCS) offering a high spectral efficiency (e.g. above a certain threshold) is most
applicable for cell-centre user equipments. Therefore, in one further embodiment of the
invention a CQI trigger (in form of a CQI request flag being set) in UL-DCI employing a
highly-efficient MCS (e.g. above a certain threshold value) for the transmission of UL-DCI
transmission triggers a channel quality feedback for all available component carriers.
Conversely, a CQI trigger using a poorly-efficient modulation and coding scheme (e.g.
below or equal to the certain threshold value) for the transmission of the UL-DCI triggers
channel quality feedback from the terminal for a single component carrier. This single
component carrier is for example the component carrier conveying that UL-DCI message
or a pre-configured set of component carriers. Alternatively, the desired channel quality
feedback content could also be signaled by means of the code rate or modulation
scheme of the modulation and coding scheme instead of modulation and coding scheme.
Please note that in this exemplary embodiment, no further control information fields in
the UL-DCI need to be interpreted in fashion different of their default meaning. It is
however also possible to use this alternative implementation of indicating the desired
content of the channel quality feedback by a certain modulation and coding scheme in
combination with the other solutions that are discussed herein, so that more conditions
can generate more flexibility. For example, a code rate criterion as mentioned above can
be combined with the Hopping flag to form the CQI control information, resulting in a total
of four combinations that can be used along the lines of the examples outlined above.
Furthermore, it is to be noted that not only the modulation and coding scheme or the
code rate or modulation scheme thereof, but also transmission parameters like the
PDCCH transmit power, mapping pattern to physical resource elements, transmission on
certain resource blocks or transmission on certain component carriers, or combinations
of these with the other methods applied to the UL-DCI message can be employed to
deliver information to expand the flexibility of the requested channel quality feedback (i.e.
the indication of different (combinations of) available component carriers for which
channel quality feedback should be provided). Furthermore, different RNTIs for masking
the CRC sequence (see e.g. Sesia et al., section 9.3.2.3 "CRC attachment") for a UL-
DCI can be employed, such that e.g. the choice of a first RNTI indicates that channel
quality feedback is triggered for one component carrier (e.g. the one on which the UL-

DCI is received by the user equipment) and the choice on a second RNTI indiactes
channel quality feedback is triggered for all component carriers.
The concepts outlined above are also applicable for random access of terminals the
access network. Fig. 21 is illustrating the contention-free random access procedure of
LTE (see also 3GPP TS 36.213, version 8.7.0, section 6.2 incorporated herein by
reference). The eNodeB provides 2101 the user equipment with the preamble to use for
random access so that there is no risk of collisions, i.e. multiple user equipment
transmitting the same preamble. Accordingly, the user equipment is sending 2102 the
preamble which was signaled by eNodeB in the uplink on a PRACH resource. After
eNodeB has detected a RACH preamble, it sends 2103 a Random Access Response
(RAR) on the PDSCH (Physical Downlink Shared Channel) addressed on the PDCCH
with the (Random Access) RA-RNTI identifying the time-frequency slot in which the
preamble was detected (Please note that the Random Access Response is sometimes
also referred to as the Random Access Response Grant). The Random Access
Response itself conveys the detected RACH preamble, a timing alignment command (TA
command) for synchronization of subsequent uplink transmissions, an initial uplink
resource assignment (grant) for the transmission of the first scheduled transmission by
the user equipment and an assignment of a Temporary Cell Radio Network Temporary
Identifier (T-CRNTI). This T-CRNTI is used by eNodeB in order to address the mobile(s)
whose RACH preamble were detected until RACH procedure is finished, since the "real"
identity of the mobile is at this point not yet known by eNodeB.
Although the Random Access Response also contains initial uplink resource assignment
for the first uplink transmission by a user equipment, same is not identical to the UL-DCI
formats discussed previously herein, such as for example the formats shown in Fig. 4 or
Fig. 19. The initial uplink resource assignment however also contains inter alia a CQI
request flag and the Hopping flag, as well as a 10-bit "Fixed size resource block
assignment". Hence, also during random access the user equipment can be requested
by the eNodeB or relay node to provide channel quality feedback within the allocated
resources for the initial transmission (i.e. setting the CQI request flag in the Random
Access Response). When reusing the random access procedure as outlined with respect
to Fig. 21 above in a communication system using component carrier aggregation, e.g. in
LTE-A (Release 10), again the Hopping flag and/or (one or more bits of) the "Fixed size
resource block assignment" could be used for indicating to the user equipment, on which
of the available downlink component carriers the user equipment should provide channel
quality feedback in the initial uplink transmission. For example, an implementation as

discussed with respect to Fig. 8 and Fig. 10 can be directly applied to the interpretation
of the contents of the Random Access Response message by the user equipment.
Another embodiment of the invention relates to the implementation of the above
described various embodiments using hardware and software. It is recognized that the
various embodiments of the invention may be implemented or performed using
computing devices (processors). A computing device or processor may for example be
general purpose processors, digital signal processors (DSP), application specific
integrated circuits (ASIC), field programmable gate arrays (FPGA) or other
programmable logic devices, etc. The various embodiments of the invention may also be
performed or embodied by a combination of these devices.
Further, the various embodiments of the invention may also be implemented by means of
software modules, which are executed by a processor or directly in hardware. Also a
combination of software modules and a hardware implementation may be possible. The
software modules may be stored on any kind of computer readable storage media, for
example RAM, EPROM, EEPROM, flash memory, registers, hard disks, CD-ROM, DVD,
etc.
It should be further noted that the individual features of the different embodiments of the
invention may individually or in arbitrary combination be subject matter to another
invention.
It would be appreciated by a person skilled in the art that numerous variations and/or
modifications may be made to the present invention as shown in the specific
embodiments without departing from the spirit or scope of the invention as broadly
described. The present embodiments are, therefore, to be considered in all respects to
be illustrative and not restrictive.

CLAIMS
1. A method for reporting on a downlink channel quality experienced by a
terminal by means of channel quality information, the method comprising the
following steps performed by the terminal:
receiving dedicated control information having a predetermined format,
wherein said dedicated control information comprises a CQI request flag for
requesting channel quality reporting by the terminal and at least one further,
second control information field consisting of at least one bit,
if said CQI request flag is set, interpreting at least one bit of the second
control information field as CQI control information indicative of one or more
of the component carriers available for downlink transmission to the terminal
on which the terminal is to report channel quality information, and
transmitting channel quality information for each indicated component carrier.
2. The method according to claim 1, wherein the channel quality information is
channel quality information for at least one of plural component carriers of a
communication system available for downlink transmission to the terminal.
3. The method according to claim 1 or 2, further comprising the step of
interpreting the at least one second control information field according to the
default specification of the predetermined format of the dedicated control
channel information, if said CQI request flag is not set.
4. The method according to one of claims 1 to 3, wherein the dedicated control
information is received via one of the plural component carriers of the
communication system, and wherein the step of transmitting comprises
transmitting channel quality information for at least the component carrier on
which the dedicated control information is received, if said CQI request flag is
set within the dedicated control information
5. The method according to claim 4, wherein the at least one bit of the second
control information field interpreted as CQI control information indicates at
least one further component carrier of the plural component carriers other

than the component carrier on which the dedicated control information has
been received.
The method according to one of claims 1 to 5, wherein the at least one bit of
the at least one second control information field interpreted as the CQI control
information is one of or a combination of:
a hopping flag defined for said predetermined format of the dedicated
control channel information indicating whether or not the terminal
should employ uplink resource hopping,
at least one padding bit defined for said predetermined format of the
dedicated control channel information for aligning the size of the
dedicated control information to a predetermined number of bits,
at least one bit of a resource assignment field defined for said
predetermined format of the dedicated control channel information for
assigning resources to the terminal,
at least one bit of a DMRS field defined for said predetermined format
of the dedicated control channel information for configuring the cyclic
shift between the terminal and another terminal for uplink transmission
on at least partly overlapping uplink resources, and
at least one bit of a carrier indicator field defined for said predetermined
format of the dedicated control channel information for indicating to the
terminal for which uplink component carrier or component carriers the
dedicated control information is valid.
The method according to one of claims 1 to 6, dedicated control information
consists of:
an uplink carrier indicator field defined for said predetermined format of
the dedicated control channel information for indicating to the terminal
for which component carrier the dedicated control information is valid,
a format flag for distinguishing different formats of dedicated control
information having the same number of bits/size, wherein the format
flag is set to zero,

a hopping flag for indicating whether or not the terminal should employ
uplink resource hopping,
a resource block assignment field assigning uplink resources on an
uplink component carrier to the terminal,
a modulation and coding scheme field that is indicating the modulation
scheme, coding rate and the redundancy version for the transmission
on the assigned resources on the uplink component carrier,
a new data indicator to indicate whether the terminal has to send new
data or a retransmission,
a DMRS field for configuring the cyclic shift applied to the reference
symbol sequence,
said CQI request flag, and
optionally one or more padding bit(s) to align the size of the dedicated
control information to a predetermined number of bits.
The method according to one of claims 1 to 6, wherein a first value of the at
least one bit of the at least one second control information field interpreted as
CQI control information is requesting the terminal to provide channel quality
information for one available downlink component carrier of the plurality of
component carriers and
a second value of the at least one bit of the at least one second control
information field interpreted as CQI control information is requesting the
terminal to provide channel quality indices for all downlink component carriers
of the plurality of component carriers available for downlink transmission to
the terminal.
The method according to one of claims 1 to 7, wherein the communication
system is a 3GPP LTE system and the dedicated control information of the
predetermined format is Dedicated Control Information of DCI format 0
defined in 3GPP LTE (Release 8).
The method according to one of claims 1 to 8, wherein the second control
information field of the dedicated control information is a carrier indicator field

which, if said CQI request flag is set, is indicative of the CQI control
information and is further indicative of an uplink component carrier on which
the dedicated control information assigns uplink resources.
The method according to claim 10, wherein a first subset of the values that
can be signaled in the carrier indicator field indicates that the terminal is to
report channel quality information for the downlink component carrier on
which the dedicated control information is received by the terminal, and
wherein a second subset of the values that can be signaled in the carrier
indicator field indicates that the terminal is to report channel quality
information for all downlink component carriers of the plurality of component
carriers available for downlink transmission to the terminal at the time of
receiving the dedicated control information.
The method according to claim 11, wherein a third subset of the values that
can be signalled in the carrier indicator field indicates that the terminal is to
report channel quality information for at least one downlink component carrier
according to a semi-static configuration.
The method according to claim 12, wherein the semi-static configuration is
configured by means of RRC signalling.
The method according to one of claims 11 to 13, wherein the values that can
be signalled in the carrier indicator field further indicate a respective uplink
component carrier on which the dedicated control information assigns uplink
resources.
The method according to claim 10 wherein the carrier indicator field indicates
that the uplink component carrier is a linked uplink component carrier linked
to the downlink component carrier on which the dedicated control information
is received, and further indicates to the terminal to report channel quality
information for one of or all downlink component carriers,
wherein said link between the linked uplink component carrier and the
corresponding downlink component carrier is pre-configured.
The method according to one of claims 1 to 15, wherein the dedicated control
information is received by the terminal via a PDCCH or comprised in a

random access response grant message during non-contention based
random access.
The method according to one of claims 1 to 9, wherein a combination of at
least one bit of the second control information field and the CQI request flag is
unconditionally interpreted as the CQI control information indicative of one or
more of the component carriers available for downlink transmission to the
terminal on which the terminal is to report channel quality information.
A method for reporting on a downlink channel quality experienced by a
terminal by means of channel quality information, the method comprising the
following steps performed by the terminal:
receiving dedicated control information having a predetermined format,
wherein said dedicated control information comprises a CQI request flag for
requesting channel quality reporting by the terminal,
if said CQI request flag is set, interpreting time and/or frequency resources on
which the dedicated control information is received at the terminal and/or the
transport format of the dedicated control information as CQI control
information indicative of one or more of the component carriers available for
downlink transmission to the terminal on which the terminal is to report
channel quality information, and
transmitting channel quality information for each indicated component carrier.
The method according to claim 18, wherein said dedicated control information
comprises at least one further, second control information field consisting of
at least one bit, and in the step of interpreting interprets:
- at least one bit of the at least one further, second control information field
and
- the time and/or frequency resources on which the dedicated control
information is received at the terminal and/or the transport format of the
dedicated control information as CQI control

as said CQI control information indicative of one or more of the component
carriers available for downlink transmission to the terminal on which the
terminal is to report channel quality information.
The method according to claim 18 or 19, further comprising the steps of the
method according to one of claims 2 to 17.
A terminal for reporting on a downlink channel quality experienced by the
terminal by means of channel quality information, the terminal comprising:
a receiver for receiving dedicated control information having a predetermined
format, wherein said dedicated control information comprises a CQI request
flag for requesting channel quality reporting by the terminal and at least one
further, second control information field consisting of at least one bit,
a processing unit for interpreting, if said CQI request flag is set, at least one
bit of the second control information field as CQI control information indicative
of one or more of the component carriers available for downlink transmission
to the terminal on which the terminal is to report channel quality information,
and
a transmitter for transmitting channel quality information for each indicated
component carrier.
The terminal according to claim 212, further adapted to perform the steps of
the method according to one of claims 2 to 17.
A terminal for reporting on a downlink channel quality experienced by the
terminal by means of channel quality information, the terminal comprising:
a receiver for receiving dedicated control information having a predetermined
format, wherein said dedicated control information comprises a CQI request
flag for requesting channel quality reporting by the terminal,
a processing unit for interpreting, if said CQI request flag is set, time and/or
frequency resources on which the dedicated control information is received at
the terminal and/or the transport format of the dedicated control information
as CQI control information indicative of one or more of the component carriers

available for downlink transmission to the terminal on which the terminal is to
report channel quality information, and
a transmitted for transmitting channel quality information for each indicated
component carrier.
The terminal according to claim 23, further adapted to perform the steps of
the method according to one of claims 18 to 20.
A computer readable medium storing instructions that, when executed by the
processor of a terminal, cause the terminal to report on a downlink channel
quality experienced by the a terminal by means of channel quality information,
by:
receiving dedicated control information having a predetermined format,
wherein said dedicated control information comprises a CQI request flag for
requesting channel quality reporting by the terminal and at least one further,
second control information field consisting of at least one bit,
if said CQI request flag is set, interpreting at least one bit of the second
control information field as CQI control information indicative of one or more
of the component carriers available for downlink transmission to the terminal
on which the terminal is to report channel quality information, and
transmitting channel quality information for each indicated component carrier.
The computer readable medium according to claim 25, further storing
instructions that, when executed by the processor of the terminal, cause the
terminal to perform the steps of the method according to one of claims 1 to
17.
A computer readable medium storing instructions that, when executed by the
processor of a terminal, cause the terminal to report on a downlink channel
quality experienced by the a terminal by means of channel quality information,
by:
receiving by the terminal dedicated control information having a
predetermined format, wherein said dedicated control information comprises
a CQI request flag for requesting channel quality reporting by the terminal,

if said CQI request flag is set, interpreting time and/or frequency resources on
which the dedicated control information is received at the terminal and/or the
transport format of the dedicated control information as CQI control
information indicative of one or more of the component carriers available for
downlink transmission to the terminal on which the terminal is to report
channel quality information, and
transmitting channel quality information for each indicated component carrier.
The computer readable medium according to claim 27, further storing
instructions that, when executed by the processor of the terminal, cause the
terminal to perform the steps of the method according to one of claims 18 to
20.
A method for triggering aperiodic channel quality feedback of a terminal on at
least one component carrier available for downlink transmission to the
terminal in a communication system, the method comprising the following
steps performed by a node in an access network of the communication
system:
selecting at least one component carrier available for downlink transmission
to the mobile terminal out of a plurality of component carriers configured in
the communication system,
transmitting to the mobile terminal dedicated control information comprising a
CQI request flag that is set by the node in order to trigger aperiodic channel
quality feedback and at least one further, second control information field at
least one bit of which is set to indicate the selected at least one component
carrier and
receiving from the mobile terminal, in response to the dedicated control
information, channel quality feedback on each selected component carrier.
The method according to claim 29, further comprising the step of scheduling
downlink transmissions to the mobile terminal on the based on the available
component carrier or carriers based on the channel quality feedback received
from the mobile terminal.

The method according to claim 30, further comprising the steps of receiving
channel quality feedback from other mobile terminals than said mobile
terminal and scheduling the other mobile terminals and said mobile terminal
based on the channel quality feedback received from the other mobile
terminals and said mobile terminal.
A node for use in an access network of a communication system and for
triggering aperiodic channel quality feedback of a terminal on at least one
component carrier available for downlink transmission to the terminal in the
communication system, the node comprising:
a processing unit for selecting at least one component carrier available for
downlink transmission to the mobile terminal out of a plurality of component
carriers configured in the communication system,
a transmitter for transmitting to the mobile terminal dedicated control
information comprising a CQI request flag that is set by the node in order to
trigger aperiodic channel quality feedback and at least one further, second
control information field at least one bit of which is set to indicate the selected
at least one component carrier and
a receiver for receiving from the mobile terminal, in response to the dedicated
control information, channel quality feedback on each selected component
carrier.
The node according to claim 32, further comprising a scheduler for scheduling
downlink transmissions to the mobile terminal on the based on the available
component carrier or carriers based on the channel quality feedback received
from the mobile terminal.
The node according to claim 33, wherein the receiver is adapted to receive
channel quality feedback from other mobile terminals than said mobile
terminal and the scheduler is adapted to schedule the other mobile terminals
and said mobile terminal based on the channel quality feedback received
from the other mobile terminals and said mobile terminal.
A computer readable medium storing instructions that, when executed by a
processor of a node in an access network of a communication system, cause
the node to trigger aperiodic channel quality feedback of a terminal on at least

one component carrier available for downlink transmission to the terminal in
the communication system, by:
selecting at least one component carrier available for downlink transmission
to the mobile terminal out of a plurality of component carriers configured in
the communication system,
transmitting to the mobile terminal dedicated control information comprising a
CQI request flag that is set by the node in order to trigger aperiodic channel
quality feedback and at least one further, second control information field at
least one bit of which is set to indicate the selected at least one component
carrier and
receiving from the mobile terminal, in response to the dedicated control
information, channel quality feedback on each selected component carrier.

ABSTRACT
The invention relates methods for triggering channel quality feedback for at least one of plural component carriers
of a communication system available for downlink transmission. The invention suggests a mechanism for triggering channel quality feedback from a terminal where the downlink control signaling overhead for the selection of component carrier(s) to be reported on is minimized. One aspect of the invention is a new interpretation of a predetermined format for dedicated control information comprising a CQI request flag, which is depending on the status of the CQI request flag. In case the CQI request flag is set at
least one further bit of the dedicated control information is interpreted as information indicative of the one or more component
carriers available for downlink transmission to the terminal and the terminal is providing channel quality feedback on the channel
quality experienced on the indicated component carrier or component carriers.