Technical Field
The present invention relates to a communication system. The invention has
particular but not exclusive relevance to wireless communication systems and devices
thereof operating according to the 3rd Generation Partnership Project (3GPP) standards
or equivalents or derivatives thereof, such as the Universal Terrestrial Radio Access
Network (UTRAN) and the Long Term Evolution (LTE) of UTRAN (E-UTRAN),
including LTE-Advanced. The invention has particular although not exclusive
relevance to the implementation of Physical Uplink Control Channels (PUCCH) in
carrier aggregation scenarios.
Background Art
LTE, more recently incorporating the enhancements of L TE-A, has proved to be an
extremely successful platform for meeting the increasing demand for wireless
broadband data capabilities. In parallel with this continuing increase in demand, LTE
related technologies have been enhanced further with new features such as carrier aggregation
(CA) in which a plurality of component carriers (CC) are aggregated to
increase the total bandwidth available to items of user equipment (UEs) such as conventional
mobile (cellular) communication devices (cell phones, mobile telephones,
smartphones etc.) and machine type communication (MTC) devices.
[0003] Carrier aggregation can be used to provide a 'primary' cell (PCell), on a so-called
[0004]
'primary' component carrier (PCC) and one or more secondary cells (SCells) on other
'secondary' component carriers (SCC). Downlink control signalling (e.g. on a Physical
Downlink Control Channel, 'PDCCH', or an enhanced PDCCH, 'ePDCCH') may be
provided on any component carrier in any serving cell. However, downlink control
signalling may be provided one carrier in one cell (e.g. the PCell) may be used for
scheduling resources on other carriers. Such scheduling is referred to as cross-carrier
scheduling.
Another enhancement provided in L TE is the development of heterogeneous network
comprising a combination of one or more large 'macro' cells each provided via an associated
macro base station (macro-eNB) with one or more smaller cells. Each smaller
cell is provided via a low-power node (LPNs). An LPN may comprise any communication
node that is capable of providing a small cell, for example a low power base
station ('eNB' in LTE), home base station ('HeNBs' in LTE), relay node (RN), remote
radio head (RRH), or the like. Small cells are primarily added to increase capacity in
hot spots with high user demand and to fill in areas not covered by the macro network -
2
wo 2017/043074 PCT/JP2016/004070
both outdoors and indoors. They can also improve network performance and service
quality by offloading from the large macro-cells. Whilst these small cells can be
provided as essentially independent cells they are typically provided as SCells located
within (or overlapping with) a PCell provided by an associated macro base station and
may be controlled by that macro base station.
[0005] Historically, for deployments involving carrier aggregation, uplink control Information
(UCI) such as and hybrid automatic repeat request (ARQ) acknowledgments
(ACKs) and negative acknowledgments (NACKs), and scheduling requests (SRs),
were provided in a single physical uplink control channel (PUCCH) in the PCell only.
Such a configuration was, however, considered unsuitable for dual connectivity
scenarios, in which a master base station (MeNB) provides control plane communication
in a PCell and a secondary base station (SeNB) provides user plane communication
in one or more SCells. Accordingly, a PUCCH was developed, for dual connectivity
scenarios, on a special SCell (referred to as the Primary SCell or PSCell) of
the SeNB. More recently it has been decided to specify a separate PUCCH for SCells
of carrier aggregation deployments based on the UCI mechanism for dual connectivity.
[0006] As demand increases, there continues to be an increasing need for yet further features
[0007]
that complement existing LTE I LTE-Advanced technology and can be used to
enhance their service further. This has led to unlicensed or 'public' spectrum (typically
in the 5GHz band) being considered as a potential source of further enhancements.
Whilst the benefits of communication via unlicensed spectrum cannot currently
compare to those provided via a licensed regime, the efficient use of unlicensed
spectrum as a complement to the use of licensed spectrum has the potential to enhance
significantly the overall service provided. The technique of using unlicensed 'public'
spectrum, in combination with licensed spectrum, to augment conventional (LTE)
provision via a licensed band is referred to as licensed-assisted access (or LAA).
In most countries, regulatory requirements exist which seek to minimize the potential
interference between users of the unlicensed spectrum. Even where regulatory requirements
are not particularly strict the fair coexistence between LTE and other technologies
such as Wi-Fi is considered necessary. It is not, therefore, enough to minimize
interference simply to meet regulatory requirements- it is also important that a
deployed system will operate as a "good neighbour" and not, therefore, significantly
impact other users of the unlicensed spectrum.
[0008] One mechanism for coexistence is the so called 'listen-before-talk' (LBT)
mechanism, which governs when communication equipment may access a channel on
an unlicensed band. For example, according to the European regulations for load-based
equipment, clear channel assessment (CCA) (also referred to as channel sensing, 'CS')
must be performed prior to starting a new transmission. CCA involves listening to the
3
wo 2017/043074 PCT/JP2016/004070
[0009]
communication channel to determine whether it is occupied before transmitting on that
channel. An extended CCA may be performed if, on listening to the channel, the communication
medium is determined to be occupied during the initial CCA, and
transmission is then postponed until the channel is considered clear.
Summary of Invention
Technical Problem
However the introduction of LAA to LTE communication networks (and potentially
similar networks using non-LTE technology) presents a number of challenges and Introduces
potential conflicts with existing technology that will have to be resolved
before such technology can be deployed successfully.
[0010] The present invention seeks to provide a communication device and associated
apparatus and methods for at least partially addressing the above issues.
Solution to Problem
[0011] In one aspect, the invention provides a communication device for a communication
system, the communication device comprising: a transceiver adapted to communicate
with communication apparatus that operates a cell within which the communication
device is located, wherein the cell is operated as a licensed assisted access, LAA, cell
and has an associated physical uplink control channel (PUCCH); and a controller
adapted: to generate at least one control signal for transmitting to said communication
apparatus; to perform a clear channel assessment (CCA) (or other LBT action) on said
PUCCH before said at least one control signal is transmitted; to block transmission of
said at least one control signal on said PUCCH when said CCA (or other LBT action)
indicates that said channel is not clear; wherein the transceiver is further adapted, when
said controller has not blocked said transmission of said at least one control signal, to
transmit said at least one control signal to said communication apparatus in said
PUCCH.
[0012] In another aspect, the invention provides communication apparatus for a commu-
[0013]
nication system, the communication apparatus comprising: a controller adapted: to
operate a cell via which at least one communication device can communicate with the
communication apparatus, wherein the cell is operated as a licensed assisted access,
LAA, cell and has an associated physical uplink control channel (PUCCH); and to
receive at least one control signal from said communication apparatus in said PUCCH.
In one aspect, the invention provides a method performed by communication device
of a communication system, the method comprising: communicating with communication
apparatus that operates a cell within which the communication device is
located, wherein the cell is operated as a licensed assisted access, LAA, cell and has an
associated physical uplink control channel (PUCCH); generating at least one control
4
wo 2017/043074 PCT/JP2016/004070
[0014]
[0015]
signal for transmitting to said communication apparatus; performing a clear channel
assessment (CCA) on said PUCCH; blocking transmission of said at least one control
signal on said PUCCH when said CCA indicates that said channel is not clear; and
transmitting said at least one control signal to said communication apparatus in said
PUCCH when said transmission is not blocked.
In another aspect, the invention provides a method performed by communication
apparatus of a communication system, the method comprising: operating a cell via
which at least one communication device can communicate with the communication
apparatus that operates, wherein the cell is operated as a licensed assisted access, LAA,
cell and has an associated physical uplink control channel (PUCCH); and receiving at
least one control signal from said communication apparatus in said PUCCH.
In one aspect, the invention provides a communication device for a communication
system, the communication device comprising: a transceiver adapted to communicate
with communication apparatus that operates a cell within which the communication
device is located, wherein the cell is operated as a cell in an unlicensed part of a
frequency spectrum and has an associated physical uplink control channel (PUCCH).
[0016] In one aspect, the invention provides communication apparatus for a communication
[0017]
[0018]
system, the communication apparatus comprising: a controller adapted to operate a cell
via which at least one communication device can communicate with the communication
apparatus; and a transceiver adapted to receive a report (e.g. an (immediate)
Minimisation of Drive Tests (MDT) and/or Radio Link Failure (RLF) report) of at
least one scheduling request related parameter; wherein said controller is operable to
generate, based on said at least one scheduling request related parameter, information
for configuring said communication device to transmit an SR on a first PUCCH of a
plurality of different PUCCHs, in preference to a second PUCCH of said plurality
different PUCCHs, in the event that a timing configured for transmitting an SR on said
first PUCCH coincides with a timing configured for transmitting an SR on said second
PUCCH; and wherein said transceiver is adapted to send said information to said at
least one communication device.
Aspects of the invention extend to computer program products such as computer
readable storage media having instructions stored thereon which are operable to
program a programmable processor to carry out a method as described in the aspects
and possibilities set out above or recited in the claims and/or to program a suitably
adapted computer to provide the apparatus recited in any of the claims.
Each feature disclosed in this specification (which term includes the claims) and/or
shown in the drawings may be incorporated in the invention independently (or in combination
with) any other disclosed and/or illustrated features. In particular but without
limitation the features of any of the claims dependent from a particular independent
5
wo 2017/043074 PCT/JP2016/004070
[0019]
claim may be introduced into that independent claim in any combination or individually.
Exemplary embodiments of the invention will now be described by way of example
only with reference to the attached figures in which:
Brief Description of Drawings
[0020] [fig.l]Figures la and lb illustrate schematically a cellular telecommunication system
[0021]
to which exemplary embodiments of the invention may be applied;
[fig.2]Figure 2 is a block diagram of a mobile device forming part of the system shown
in Figure 1;
[fig.3]Figure 3 is a block diagram of a base station forming part of the system shown in
Figure 1;
[fig.4]Figure 4 is a simplified message sequence diagram illustrating a procedure that
may be implemented in the telecommunication system of Figure 1;
[fig.5]Figure 5 is a simplified message sequence diagram illustrating a procedure that
may be implemented in the telecommunication system of Figure 1;
[fig.6]Figure 6 is a simplified message sequence diagram illustrating a procedure that
may be implemented in the telecommunication system of Figure 1;
[fig.7]Figure 7 is a simplified message sequence diagram illustrating a procedure that
may be implemented in the telecommunication system of Figure 1;
[fig.8]Figure 8 is a simplified message sequence diagram illustrating a procedure that
may be implemented in the telecommunication system of Figure 1; and
[fig.9]Figure 9 is a simplified message sequence diagram illustrating a procedure that
may be implemented in the telecommunication system of Figure 1.
Description of Embodiments

Figures la and lb schematically illustrate a mobile (cellular) telecommunication
network 100 in which a mobile device 3 (or other such user equipment) can communicate
with other such devices and/or other communication entities via a E-UTRAN
base station 5, operating an associated primary cell (PCell) 9 on a primary component
carrier (PCC), and/or any of a number of low power nodes (LPNs) 7-1,7-2 operating
respective secondary cells (SCells) ll-1, ll-2 on associated secondary component
carriers (SCCs). Communication via the base station 5 and/or LPNs 7 is typically
routed through a core network (not shown) which is accessed using an E-UTRA radio
access technology (RAT). As those skilled in the art will appreciate, whilst one mobile
device 3, one base station 5 and two LPN s 7 are shown in Figure 1 for illustration
purposes, the system, when implemented, will typically include other base stations,
LPN s and mobile devices.
6
wo 2017/043074 PCT/JP2016/004070
[0022] The low power nodes (LPNs) 7-1,7-2 operate their respective secondary cells
[0023]
(SCells) 11-1, 11-2 on SCCs in unlicensed spectrum (e.g. in the 5GHz band) in accordance
with licensed assisted access (LAA) protocols. Accordingly, the SCells are
operated as LAA SCells that are subject to listen-before-talk (LBT) requirements that
necessitate the performance of clear channel assessment (CCA) I channel sensing (CS).
Each LPN 7 may comprise a communication node that is capable of providing a
small cell on unlicensed spectrum, for example a low power base station ('eNB'),
home base station ('HeNBs'), relay node (RN), remote radio head (RRH), or the like.
[0024] The mobile device 3 comprises a medium access control layer (MAC) entity and a
physical layer (PHY) entity. The MAC entity is responsible for performing hybrid
ARQ operations (e.g. generating HARQ ACK/NACKs for transmission via the PHY
entity and for handling HARQ ACK/NACKs received via the PHY entity). The MAC
entity is responsible for resource request operations (such as the triggering of
scheduling requests (SRs)). The PHY entity transmits the HARQ ACK/NACKs and
SRs, triggered by the MAC entity, onto a physical uplink control channel (PUCCH).
The base station 5 (and LPNs 7) has similar complementary MAC and PHY entities.
[0025] Advantageously, and somewhat counter-intuitively given the requirement for LBT on
[0026]
[0027]
such cells, each LAA SCell is provided with its own independent physical uplink
control channel (PUCCH). In the case of a PUCCH in an LAA SCell, the PHY entity
of the mobile device 3 performs CCA, in accordance with associated LBT requirements,
before a HARQ ACK/NACK and/or SR can be transmitted.
The provision of such a PUCCH would generally be considered, by those skilled in
the art, to be inappropriate because of the potential for the LBT requirement to block
signalling on the PUCCH thereby preventing, for example, the LPN 7 from receiving
HARQ feedback and/or scheduling requests.
Scheduling Reguest Handling
Efficient handling of scheduling requests (SRs) for the LAA SCells 11 is, for
example, a particular challenge. This is because there is a relatively high possibility
that SRs for the LAA SCells 11 will, in effect, be blocked by the LBT requirement,
when CCA is performed, if the channel is found not to be clear. This contrasts with the
situation in which SRs are transmitted in PCells or conventional SCells that use
licensed spectrum in which SR failure is relatively rare.
[0028] Moreover, the possibility of SR configuration collision, in which the configured opportunity
for sending an SR in the PCell clashes with the configured opportunity for
sending an SR in the SCell, has a potentially greater impact for networks having LAA
SCells than for networks having only cells that use licensed spectrum. For example, if
the mobile device 3 decides to send the SR on the PUCCH of an LAA SCell that
operates using spectrum that is often occupied then the LBT requirement will result in
7
wo 2017/043074 PCT/JP2016/004070
[0029]
[0030]
that SR being repeatedly blocked meaning that the UE has to wait significantly longer
for uplink shared channel resources. However, transmitting the SR on the PUCCH of a
PCell may require a higher transmission power than would be necessary if the SR were
successfully transmitted on the PUCCH of an LAA SCell. Similarly, transmitting the
SR on the PUCCH of a PCell may be undesirable because of poorer quality channel
conditions and/or relatively high load (i.e. resource usage) in the PCell.
Notwithstanding the above challenges, as illustrated in Figure la when the mobile
device 3 requires communication resources to transmit data on the uplink shared
channel (UL-SCH I PUSCH) in a particular cell9, 11, the mobile device 3 will send,
subject to LBT requirements being met, an SR to the corresponding base station 5 or
LPN 7 to notify the radio network when the mobile device 3 wants to transmit data.
These SRs are transmitted by the mobile device 3 on a physical uplink control channel
(PUCCH) for the corresponding PCell (e.g. PUCCH group 1) or LAA SCell (e.g.
PUCCH group 2 for SCell 11-1 and PUCCH group 3 for SCell 11-2). The mobile
device 3 has a configured periodic timeslot (1, 2, 5, 10, 20, 40, and 80 ms) for
transmitting the SRs which can be configured using radio resource control (RRC)
signalling. The period configured for SRs sent in the PCell 9 are typically longer the
period configured for SRs the SCells 7.
Advantageously, in this example, when the MAC entity of the mobile device 3
triggers transmission of an SR on one of the LAA SCells but the PHY entity is unable
to transmit the SR, as a result of LBT requirements (i.e. because the channel is not
clear) the PHY entity informs the MAC entity of the mobile device 3 of the LBT
failure in SR transmission. The MAC entity therefore knows not to increment the SR
transmission counter and does not treat the SR as pending. Instead, the MAC entity
initiates a new SR transmission in the next available TTL In essence, therefore, in the
event of LBT blocking an SR on an LAA SCell this is treated differently to an SR that
may have been prevented from reaching its destination by a radio failure.
[0031] In the event of a collision between the SR configuration for SRs on an LAA SCell 11
[0032]
[0033]
and the SR configuration for SRs on the PCell 9, the MAC entity of the mobile device
3 may select whether to send the SR transmission on either the PUCCH for the LAA
SCell11 or the PUCCH for the PCell9. However, beneficially, the base station 5 is
also able to configure the mobile device 3 to transmit an SR on a specific PUCCH
group (PCell or SCell) in the event of SR configuration collision.
Advantageously, the mobile device 3 of this example is also configured to report, to
the base station 5 I LPN 7, a number of new parameters to facilitate improved SR
handling in the case of LBT.
In relation to scheduling requests blocked by LBT the new parameters include a
parameter indicating the number of SR transmissions blocked by LBT. In relation to
8
wo 2017/043074 PCT/JP2016/004070
scheduling configuration collisions the new reporting parameters include a parameter
indicating the number of SR transmissions carried on each different PUCCH group
(e.g. LAA SCell, conventional SCell or PCell) when, in the event of SR configuration
collision, the mobile device 3 has selected one of the conflicting PUCCH groups to
use.
[0034] The base station 5 and/or LPN 7 are beneficially configured to update SR configuration
based on this reported information for example to configure the mobile
device 3 such that SR transmission takes place on the PCell PUCCH or a particular
LAA SCell PUCCH (which may be different to the current LAA SCell PUCCH).
[0035] HARO ACK/NACK and DTX Handling
[0036]
Another challenge, for implementing a PUCCH for an LAA SCell is the potential
impact of LBT on the transmission of hybrid automatic repeat request (HARQ) acknowledgments
(ACKs) and negative acknowledgments (NACKs) for LAA SCells.
Conventionally, HARQ ACK/NACKs are sent by a UE on a PUCCH in response to a
scheduling command sent, using the PDCCH, by the base station and the subsequent
transmission of data to the UE on the PDSCH. The HARQ ACKs or NACKs respectively
indicate that data was received successfully or failed. Accordingly, a base
station (or other communication node operating a cell) respectively moves to a new
transmission, or performs a retransmission, after receiving an HARQ ACK or an
HARQ NACK from UE. On receipt of HARQ NACKs the base station will continue to
perform data retransmission to the UE until it reaches a preconfigured maximum
number of retransmissions allowed before data transmission is finally dropped. When
retransmitting, if the base station knows that its earlier transmission has been received
but incorrectly decoded (because it has received a NACK), then it may send only part
of the original data transmission (referred to as a 'Redundancy Version (RV)') and this
redundancy version may change between retransmissions. The UE can buffer the
original data as received (albeit containing errors) and attempt to recombine it incrementally
with each subsequent redundancy version in an attempt to form a correct
version of the original transmission (e.g. using incremental redundancy HARQ). When
a correct version of the received data has been formed an ACK can be sent. When
transmitting new data, the base station includes a 'New Data Indicator (NDI)' (single
bit) that is set to indicate the transmission of new data (the NDI is not set for retransmissions).
[0037] Hybrid ARQs ACK/NACKs are sent on the PUCCH using an appropriate format. In
the case of carrier aggregation with two serving cells the so called PUCCH format lb
with channel selection may be used as defined in 3GPP Technical Standard (TS)
36.213 v12.6.0. PUCCH format lb allows the delivery of a two bit HARQ ACK/
NACK indicator (b(O),b(l)) using a PUCCH resource selected from up to four
9
wo 2017/043074 PCT/JP2016/004070
different PUCCH resources albeit that in this example only two of the possible
PUCCH resources are used (parameter 'A' equals 2 in TS36.213). The base station Interprets
the combination of the selected PUCCH resource used by the UE, and the
pattern of two bits transmitted, as indicated in Table 1 below:
[0038] [Table 1]
[0039]
HARQ-ACK(O) HARQ-ACK(1} }~ CCH
b(O)b(l)
ACK ACK {1)
npucCH,l 1,1
ACK NACK/DTX (1)
11PUCCH,o 1,1
NACK/DTX ACK
(1)
11PuccH,l 0,0
NACK NACKIDTX (1)
11PuccH,o 0,0
DTX NACKIDTX No Transmission
Table 1- Interpretation of HARQ ACKINACK on PUCCH format 1b
(1st column corresponds HARQ indication for 1st cell; 2nd column corresponds
HARQ indication for 2nd cell; 3rd column corresponds to selected PUCCH
resource; and 41
h column corresponds to transmitted bit pattern)
In Table 1, the references to 'DTX' refer to situations where the UE has failed to
receive a downlink scheduling command. The references to 'NACK/DTX' refer to
situations where it is ambiguous whether the UE has received a downlink scheduling
command in the 2nd cell but failed to properly decode the associated PDSCH data, or
the UE has completely failed to receive a downlink scheduling command.
[0040] Accordingly, referring to the bottom row of Table 1, if the base station has signalled
[0041]
[0042]
a downlink scheduling command in the 1st cell the absence of any transmission on the
PUCCH format 1b is interpreted, by the base station, as arising from the UE having
failed to receive a downlink scheduling command in the 1st cell resulting in no explicit
HARQ ACK/NACK being sent (DTX). If the base station has signalled a downlink
scheduling command in the 2nd cell an absence of any transmission on the PUCCH
format 1b is ambiguous because it may have resulted from the UE failing to receive a
downlink scheduling command in the 2nd cell or it may have resulted from the UE
having received a downlink scheduling command in the 2nd cell but failed to properly
decode the associated PDSCH data (NACK/DTX).
It can be seen, therefore, that additional ambiguity for feedback relating to two LAA
SCells because the base station has no way of determining whether: an absence of a
HARQ transmission arises from the LBT requirement preventing such transmission; or
the absence of a HARQ transmission has arisen as a result of the UE having failed to
receive a downlink scheduling command I failed to decode a PDSCH transmission (i.e.
DTX, DTX/NACK in Table 1).
As illustrated in Figure 1 b, in the telecommunication network 100, the mobile device
10
wo 2017/043074 PCT/JP2016/004070
3 is configured to send, via a PUCCH of an LAA SCell11, HARQ ACK/NACK
feedback in a similar manner to HARQ ACK/NACK feedback on a PUCCH that is unaffected
by LBT. Thus, when the mobile device 3 receives a downlink resource allocation,
the mobile device 3 will attempt to send an associated HARQ ACK, on the
PUCCH of an LAA SCell, to indicate successful receipt and decoding of the PDCCHI
PDSCH transmission. Similarly, the mobile device 3 will try to send a HARQ NACK
on the PUCCH of the LAA SCell if decoding is unsuccessful. The HARQ feedback
transmissions are subject to LBT requirements and so when the feedback is sent on the
PUCCH for an LAA SCell the transmissions may be blocked by the LBT requirement
when channel is not clear.
[0043] Advantageously, unlike conventional systems, for a pair of serving LAA SCells the
[0044]
mobile device 3 is configured to always explicitly signal an explicit HARQ NACK, in
the event of a decoding failure of the PDSCH, regardless of which of the two LAA
SCells 11 the decoding failure relates to (i.e. NACK/DTX ambiguity does not occur).
Accordingly, if the LPN 7 does not receive any HARQ ACK/NACK transmission
following downlink scheduling, this will not be interpreted as a NACK/DTX situation.
Instead, the lack of transmission will be interpreted as resulting either from the mobile
device 3 failing to receive the downlink scheduling command or the PUCCH of the
SCell being blocked by the LBT requirement (DTXILBT).
To facilitate discrimination between the DTX situation and LBT blocking, the mobile
device 3 of this example is also configured to report, to the base station 5 I LPN 7, a
number of new parameters to facilitate improved HARQ ACK/NACK and DTX
handling in the case of LBT.
[0045] The parameters include one or more of: a parameter indicating a number of HARQ
[0046]
[0047]
[0048]
NACK transmissions blocked by LBT; a parameter indicating a number of HARQ
ACK transmissions blocked by LBT; and a parameter indicating a number of successfully
received UE DL scheduling commands. Similarly, the parameters may
include a parameter indicating the total number of HARQ ACKs and/or NACKs
transmitted.
The base station 5 I LPN 7 can determine, from this information when reported, the
number of missed DL scheduling commands because it knows the total number of such
commands sent to the UE.
Accordingly, based on the reported parameters for HARQ ACK/NACK transmissions
on a PUCCH group for an LAA SCell, the base station 5 is beneficially able
to distinguish, albeit after the fact, between HARQ ACK/NACK blocked by LBT, and
no UE transmission because of UE missing scheduling command (DTX), on a
particular PUCCH for an LAA SCell.

11
wo 2017/043074 PCT/JP2016/004070
[0049]
[0050]
[0051]
Figure 2 is a block diagram illustrating the main components of the mobile device 3
shown in Figures la and lb. As shown, the mobile device 3 has a transceiver circuit 31
that is operable to transmit signals to and to receive signals from a base station 5 via
one or more antenna 33. The mobile device 3 has a controller 37 to control the
operation of the mobile device 3. The controller 37 is associated with a memory 39 and
is coupled to the transceiver circuit 31. Although not necessarily shown in Figure 2, the
mobile device 3 will of course have all the usual functionality of a conventional mobile
device 3 (such as a user interface 35) and this may be provided by any one or any combination
of hardware, software and firmware, as appropriate. Software may be preinstalled
in the memory 39 and/or may be downloaded via the telecommunication
network or from a removable data storage device (RMD), for example.
The controller 37 controls overall operation of the mobile device 3 by, in this
example, program instructions or software instructions stored within the memory 39.
As shown, these software instructions include, among other things, an operating
system 41, a communications control module 43, a scheduling request module 44, a
HARQ feedback module 45, a reporting module 47 and an LBT module 49.
The communications control module 43 controls the communication between the
mobile device 3 and the base station 5. The communications control module 43 also
controls the separate flows of control data and user data (for uplink and downlink) that
are to be transmitted to the base station 5 and other LPNS 7.
The scheduling request module 44 manages the generation of SRs (by the MAC
entity) and their transmission (by the PHY entity) to the base station 5 and LPN s 7 on
the corresponding PUCCH. The scheduling request module 44 also manages the configuration
of SRs at the mobile device 3 (e.g. responsive to an SR configuration request
from a base station I LPN) and selection a particular PUCCH group (PCell or LAA
SCell) in the event of SR configuration.
[0052] The HARQ feedback module 45 manages the generation of HARQ ACK/NACKs
(by the MAC entity) and their transmission (by the PHY entity) to the base station 5
and LPNs 7 on the corresponding PUCCH. The HARQ feedback module 45 also
manages any HARQ feedback received from the base station I LPN.
[0053] The reporting module 47 manages the logging of information relating to SRs and/or
HARQ feedback. In relation to SR handling, this information may include, for
example, the number of SR transmissions blocked by LBT and/or the respective
number of SR transmissions carried on each different PUCCH group. In relation to
HARQ feedback handling, this information may include, for example, the number of
HARQ NACK transmissions blocked by LBT, the number of HARQ ACK transmissions
blocked by LBT, the number of missed UE DL scheduling commands, and/or
the number of HARQ ACKs and/or NACKs transmitted. The reporting module 47 also
12
wo 2017/043074 PCT/JP2016/004070
manages the generation of reports to report the logged information and the configuration
of SRs and/or HARQ feedback reporting (e.g. responsive to an associated
configuration request received from a base station I LPN).
[0054] The LBT module 49 manages the performance of clear channel assessment (CCA) I
[0055]
[0056]
[0057]
[0058]
channel sensing (CS) for LAA cells such as the LAA SCells 11 necessitated by LBT
requirements. The LBT module 49 also manages the blocking of transmissions,
including PUCCH transmissions, in the event that the communication channel is not
clear.

Figure 3 is a block diagram illustrating the main components of communication
apparatus, for operating a cell, such as the base station 5 (PCell 9) or LPN 7 (SCellll)
shown in Figures la and lb.
As shown, the base station 5 I LPN 7 has a transceiver circuit 51 for transmitting
signals to and for receiving signals from the mobile devices 3 via one or more antenna
53, at least one (but typically a plurality) of network interfaces 54 for transmitting
signals to and for receiving signals from other network entities such as, for example,
other cell operating apparatus (e.g. a base station via an X2 interface) and core network
entities (e.g. a mobility management entity via an Sl interface). The base station 5 I
LPN 7 has a controller 57 to control the operation of the base station 5 I LPN 7. The
controller 57 is associated with a memory 59. Although not necessarily shown in
Figure 3, the base station 5 I LPN 7 will of course have all the usual functionality of a
cellular telephone network base station I LPN and this may be provided by any one or
any combination of hardware, software and firmware, as appropriate. Software may be
pre-installed in the memory 59 and/or may be downloaded via the communication
network 1 or from a removable data storage device (RMD), for example.
The controller 57 is configured to control the overall operation of the base station 5 I
LPN 7 by, in this example, program instructions or software instructions stored within
the memory 59. As shown, these software instructions include, among other things, an
operating system 61, a communications control module 63, a scheduling request
module 64, a HARQ feedback module 65, a reporting management module 67 and, in
the case of communication apparatus operating a cell in an unlicensed band (e.g. an
LPN 7 operating an LAA SCell 11) an LB T module 69.
The communications control module 63 controls the communication between the
base station 5 I LPN 7 and the mobile device 3 and other network entities via the
network interface 54. The communications control module 63 also controls the
separate flows of uplink/downlink user traffic and control data received from and
transmitted to the mobile device 3.
[0059] The scheduling request module 64 manages the generation of SRs (by the MAC
13
wo 2017/043074 PCT/JP2016/004070
entity) and their transmission (by the PHY entity) to the base station 5 and LPN s 7 on
the corresponding PUCCH. The scheduling request module 64 also manages the configuration
of SRs at the mobile device 3 (e.g. responsive to an SR configuration request
from a base station I LPN) and selection a particular PUCCH group (PCell or LAA
SCell) in the event of SR configuration.
[0060] The HARQ feedback module 65 manages the receipt of HARQ ACK/NACKs from
the mobile device 3 on the corresponding PUCCH. The HARQ feedback module 65
also manages the generation of any HARQ ACK/NACKs (by the MAC entity) and
their transmission (by the PHY entity) to the mobile device 3.
[0061] The reporting management module 67 manages the receipt and interpretation of information
relating to SRs and/or HARQ feedback reported by the mobile device 3. The
reporting management module 67 also manages the configuration and reconfiguration
of SR reporting (e.g. to configure a mobile device 3 to use a particular PUCCH group
(PCell of SCell) in the event of SR configuration collision).
[0062] The LBT module 69, where present, manages the performance of clear channel as-
[0063]
sessment (CCA) I channel sensing (CS) for LAA cells such as the LAA SCells 11 necessitated
by LBT requirements. The LBT module 69 also manages the blocking of
transmissions in the downlink in the event that the communication channel is not clear.

As explained above scheduling requests (SRs) are used by a mobile device 3 to
notify the radio network when it wants to transmit data. The handling of SRs will now
be described in more detail with reference to Figures 4 to 6.
[0064] Figure 4 illustrates, in simplified form, a process for requesting and receiving a grant
of uplink shared channel resources on a PCell and the potential impact of LBT in an
LAA SCell.
[0065] As shown generally at 400, for cells using licensed spectrum such as the PCell 9, the
mobile device 3 sends, in a preconfigured periodic timeslot, an SR to the base station
5. The SR, being a single bit, is insufficient to inform a scheduler of the amount of data
that the device needs to transfer. Accordingly, a small "uplink grant" is initially sent to
the requesting mobile device 3 that is just large enough to communicate the size of the
pending buffered data. Once the mobile device 3 receives its first uplink grant the
mobile device 3 sends a Buffer Status Report (BSR) indicating the amount of application
data pending in its upload buffers. After receipt of the BSR message, the
necessary uplink resources are allocated in the uplink shared channel for the mobile
device 3 and an associated uplink grant sent to the mobile device 3.

claims.
Claims
A communication device for a communication system, the communication
device comprising:
a transceiver adapted to communicate with communication
apparatus that operates a cell within which the communication device is
located, wherein the cell is operated as a licensed assisted access, LAA,
cell and has an associated physical uplink control channel, PUCCH;
and
a controller adapted: to generate at least one control signal for
transmitting to said communication apparatus; to perform a clear
channel assessment, CCA, on said PUCCH before said at least one
control signal is transmitted; to block transmission of said at least one
control signal on said PUCCH when said CCA indicates that a channel
is not clear;
wherein the transceiver is further adapted, when said controller
has not blocked said transmission of said at least one control signal, to
transmit said at least one control signal to said communication
apparatus in said PUCCH.
A communication device as claimed in claim 1 wherein said at least
one control signal that said controller is adapted to generate comprises
at least one scheduling request, SR.
A communication device as claimed in claim 2 wherein said communication
device comprises a medium access control layer, MAC, entity
and a physical layer, PHY, entity and wherein said controller is
adapted: to cause said MAC entity to generate said SR and to trigger
said PHY entity to attempt to transmit said SR using said transceiver;
and to cause said PHY entity to perform said CCA.
A communication device as claimed in claim 3 wherein said controller
is adapted to cause said PHY entity to provide feedback to said MAC
entity to indicate at least one of: when said CCA indicates that said
channel is not clear, blocking of transmission of said at least one SR on
said PUCCH; and when said CCA indicates that said channel is clear,
successful transmission of said at least one SR on said PUCCH.
A communication device as claimed in claim 4 wherein said controller
is adapted to control said MAC entity to determine whether or not to
increment an SR transmission counter based on said feedback.
A communication device as claimed in claim 3 wherein said controller
wo 2017/043074
[Claim 7]
[Claim 8]
[Claim 9]
[Claim 10]
24
PCT/JP2016/004070
is adapted to control said MAC entity to increment an SR transmission
counter regardless of whether said CCA indicates that said channel is
not clear or said CCA indicates that said channel is clear.
A communication device as claimed in any of claims 2 to 6 wherein
said communication device is configured to communicate with each of
a plurality of different communication apparatus', including said communication
apparatus that operates said LAA cell, via a different respective
PUCCH; wherein said controller is adapted to trigger
transmission of SRs on each PUCCH in accordance with a timing
configured by respective SR configuration information for that
PUCCH; wherein said transceiver is adapted to receive information
from at least one of said different communication apparatus' for configuring
said communication device to transmit an SR on a first of said
different PUCCHs, in preference to a second of said different PUCCHs,
when said timing configured by the SR configuration information for
the first and the second different PUCCH coincides.
A communication device as claimed in any of claims 1 to 7 wherein
said at least one control signal that said controller is adapted to generate
comprises at least one Hybrid Automatic Repeat Request, HARQ,
feedback signal.
A communication device as claimed in claim 8 wherein said transceiver
is adapted to receive (e.g. from said communication apparatus that
operates said LAA cell or a different communication apparatus that
operates a different cell) scheduling information for scheduling
downlink data transmissions to said communication device in at least
one of said LAA cell and a different cell; wherein said controller is
configured to generate HARQ feedback for said scheduling information
and downlink data transmission using a PUCCH format (e.g. PUCCH
format lb) in which a single HARQ indicator is generated that
represents HARQ feedback for both said LAA cell and a different cell;
wherein, in the event of a decoding failure of said downlink data
transmission in either one of said LAA cell or said different cell, said
single HARQ indicator represents an explicit HARQ negative acknowledgement,
NACK, for that cell, regardless of which of said LAA cell
and said different cell the decoding failure relates to, and regardless of
the type of HARQ feedback HARQ indicator represents in relation to
the other of said LAA cell and said different cell.
A communication device as claimed in any of claims 1 to 9 wherein
wo 2017/043074
[Claim 11]
[Claim 12]
[Claim 13]
[Claim 14]
[Claim 15]
[Claim 16]
25
PCT/JP2016/004070
said controller is operable to acquire at least one parameter related to
said at least one control signal and to generate a report (e.g. an
(immediate) Minimisation of Drive Tests, MDT, and/or Radio Link
Failure, RLF, report) for reporting said at least one parameter.
A communication device as claimed in claim 10 wherein said at least
one parameter comprises at least one scheduling request, SR, related
parameter.
A communication device as claimed in claim 11 wherein said at least
one SR related parameter comprises at least one of: a parameter indicating
a quantity of SR transmissions blocked as a result of said CCA
(e.g. as a result of a listen-before-talk, LBT, requirement); a parameter
indicating a quantity of SR transmissions on said PUCCH; and a
parameter indicating a respective quantity of SR transmissions carried
on each of a plurality of different PUCCHs (e.g. when an SR configuration
collision has occurred between respective SR configurations
for each of, or each of a subset of, said plurality of PUCCHs).
A communication device as claimed in any of claims 10 to 12 wherein
said at least one parameter comprises at least one Hybrid Automatic
Repeat Request, HARQ, feedback parameter.
A communication device as claimed in claim 13 wherein said at least
one parameter comprising at least one HARQ feedback parameter
comprises at least one of: a parameter indicating a quantity of HARQ
Negative Acknowledgement, NACK, transmissions blocked as a result
of said CCA (e.g. as a result of a listen-before-talk, LBT, requirement);
a parameter indicating a number of HARQ Acknowledgement, ACK,
transmissions blocked as a result of said CCA (e.g. as a result of a
listen-before-talk, LBT, requirement); a parameter indicating a number
of successfully received user equipment downlink, UE DL, scheduling
commands; and a parameter indicating the total number of HARQ
ACKs and/or NACKs transmitted on said PUCCH (optionally per
PUCCH where there are a plurality of PUCCHs).
A communication device as claimed in any of claims 1 to 14 wherein
said LAA cell is operated as LAA secondary cell, LAA SCell.
Communication apparatus for a communication system, the communication
apparatus comprising:
a controller adapted:
to operate a cell via which at least one communication device
can communicate with the communication apparatus, wherein the cell
wo 2017/043074
[Claim 17]
[Claim 18]
[Claim 19]
26
PCT/JP2016/004070
is operated as a licensed assisted access, LAA, cell and has an associated
physical uplink control channel, PUCCH; and
to receive at least one control signal from said communication
apparatus in said PUCCH.
A method performed by communication device of a communication
system, the method comprising:
communicating with communication apparatus that operates a cell
within which the communication device is located, wherein the cell is
operated as a licensed assisted access, LAA, cell and has an associated
physical uplink control channel, PUCCH;
generating at least one control signal for transmitting to said communication
apparatus;
performing a clear channel assessment, CCA, on said PUCCH;
blocking transmission of said at least one control signal on said
PUCCH when said CCA indicates that a channel is not clear; and
transmitting said at least one control signal to said communication
apparatus in said PUCCH when said transmission is not blocked.
A method performed by communication apparatus of a communication
system, the method comprising:
operating a cell via which at least one communication device can
communicate with the communication apparatus that operates, wherein
the cell is operated as a licensed assisted access, LAA, cell and has an
associated physical uplink control channel, PUCCH; and
receiving at least one control signal from said communication
apparatus in said PUCCH.