The present invention relates to mobile communications devices and networks, particularly
but not exclusively those operating according to the 3rd Generation
Partnership Project (3GPP) standards or equivalents or derivatives thereof. The
invention has particular although not exclusive relevance to the Long Term Evolution
(LTE) of UTRAN (called Evolved Universal Terrestrial Radio Access Network
(E-UTRAN)), including LTE-Advanced.
Background Art
[0002] In a mobile (cellular) communications network, (user) communication devices (also
known as user equipment (UE), for example mobile telephones) communicate with
remote servers or with other communication devices via base stations. In their communication
with each other, communication devices and base stations use licensed radio
frequencies, which are typically divided into frequency bands and/or time blocks.
[0003] In order to be able to communicate via the base stations, communication devices
need to monitor control channels operated by the base stations. One of these control
channels, the so-called physical downlink control channel (PDCCH) and/or the socalled
evolved PDCCH (EPDCCH) in Rel-13, carries the scheduling assignments and
other control information. The (E)PDCCH serves a variety of purposes. Primarily, it is
used to convey the scheduling decisions to individual communication devices, i.e.
scheduling assignments for uplink and downlink communication.
[0004] The information carried on the (E)PDCCH is referred to as downlink control in-
[0005]
formation (DCI). Physical control channels, such as the (E)PDCCH, are transmitted on
an aggregation of one or several consecutive control channel elements (CCEs), where a
control channel element corresponds to nine resource element groups (REGs). Each
REG has four resource elements (REs).
Another control channel, the so-called physical random access channel (PRACH) is
provided for synchronising transmissions between a communication device and the
network (e.g. when setting up an initial access for the communication device and/or
whenever re-synchronisation is necessary). In the current standard specification (from
Rel-8), the resource (preamble, time, frequency) allocated to the PRACH is configured
in advance and the applicable PRACH parameters are broadcast by the network as part
of system information in the so-called System Information Block 2 (SIB2). One of the
parameters specifies the so-called random access preamble, which consists of a cyclic
prefix part and a sequence part. The length of the preamble (i.e. the overall length of
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[0006]
the two parts combined) depends on the frame structure and the random access configuration.
When an idle mode communication device needs to communicate with other communication
nodes, it needs to change its operation mode to the so-called radio resource
control (RRC) connected mode (from RRC idle mode). In order to do so, the communication
device performs a random access (RA) procedure with a suitable base station
(e.g. a base station having the strongest signal and/or a base station that the communication
device is authorised to use). The random access procedure includes the communication
device selecting and transmitting to the base station (over the PRACH advertised
via the SIB2) an appropriate preamble sequence along with a temporary
identifier for identifying the communication device for the base station. The temporary
identifier is also referred to as the random access radio network temporary identifier
(RA-RNTI), which unambiguously identifies the time-frequency resource using which
the communication device transmitted the random access preamble. If the communication
device's transmission is received successfully, then the base station sends an
appropriate random access response (in which the base station identifies the communication
device using the received temporary identifier) and allocates resources for the
communication device for communicating with the network.
[0007] Thus, once the base station responds to a preamble transmission by the communication
device with an appropriate random access response (RAR), the communication
device is able to request in its next message the establishment of an RRC
connection (and/or the like) using the allocated resources. Once an RRC connection is
established between the communication device and the base station, the communication
device is able to communicate with other communication nodes via that base
station (and via the core network) using the appropriate resources allocated to it by the
base station.
[0008] Recent developments in telecommunications have seen a large increase in the use of
[0009]
machine-type communications (MTC) devices which are networked devices arranged
to communicate and perform actions without human assistance. Examples of such
devices include smart meters, which can be configured to perform measurements and
relay these measurements to other devices via a telecommunication network. Machinetype
communication devices are also known as machine-to-machine (M2M) communication
devices.
MTC devices connect to the network (after performing an appropriate random access
procedure, if necessary) whenever they have data to send to or receive from a remote
'machine' (e.g. a server) or user. MTC devices use communication protocols and
standards that are optimised for mobile telephones or similar user equipment.
However, MTC devices, once deployed, typically operate without requiring human su3
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pervision or interaction, and follow software instructions stored in an internal memory.
MTC devices might also remain stationary and/or inactive for a long period of time.
The specific network requirements to support MTC devices have been dealt with in the
3GPP technical specification (TS) 22.368 V13.1.0, the contents of which are Incorporated
herein by reference.
[0010] For the Release 13 (Rel-13) version of the standards relating to MTC devices,
[0011]
[0012]
support for a reduced bandwidth of 1.4 MHz in downlink and uplink is envisaged.
Thus, some MTC devices will support only a limited bandwidth (typically 1.4 MHz)
compared to the total LTE bandwidth and/or they may have fewer/simplified
components. This allows such 'reduced bandwidth' MTC devices to be made more
economically compared to MTC devices supporting a larger bandwidth and/or having
more complicated components. Beneficially, the EPDCCH is transmitted over a
relatively narrow frequency spectrum (1.4 Mhz) that makes it compatible with Rel-13
reduced bandwidth MTC devices.
The lack of network coverage (e.g. when deployed indoors), in combination with the
often limited functionality of MTC devices, can result in such MTC devices having a
low data rate and therefore there is a risk of some messages or channels, such as the
EPDCCH, not being received by an MTC device. In order to mitigate this risk, it has
been proposed to increase the coverage of transmissions to support such MTC devices
(e.g. corresponding to 20dB for frequency division duplex (FDD) transmissions).
One approach proposed for the enhancement of coverage, for so-called 'coverage
enhanced MTC devices', is the repetition of the same information (e.g. a DCI sent over
the EPDCCH) across multiple subframes (e.g. two, three, or four subframes). In other
words, for coverage enhanced (CE) MTC devices, the base station duplicates the
transmitted information in the time domain (the base station re-transmits the same Information
in one or more subframes subsequent to the subframe in which that information
is first sent). Such a coverage enhanced MTC device can be configured to
combine the multiple copies of the (same) information received in the multiple
subframes, and after combining the received information, the coverage enhanced MTC
device is more likely to be able to decode the received information successfully than
based on a single copy of the transmitted information. Similarly to the repetition of the
same information by the base station, coverage enhanced MTC devices are also
configured to duplicate (in the time domain) information transmitted to the base station
to facilitate successful reception of that information at the base station.
[0013] In practice, MTC devices may be deployed in different locations and they may experience
different channel conditions. Therefore, the number of repetitions may need
to be tailored for each device's situation or coverage level, and each MTC device
informs its serving base station of the amount of coverage required (e.g.
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5dB/10dB/15dB/20dB coverage enhancement) to allow the base station to adjust its
control signalling appropriately.
Summary of Invention
Technical Problem
[0014] In the current 3GPP standards, so-called cross-subframe scheduling is supported for
unicast physical downlink shared channel (PDSCH) transmissions, which makes it
possible to send control data to a single MTC device in one subframe for scheduling
transmissions for that MTC device in another (subsequent) subframe. However, such
cross-subframe scheduling is relatively inflexible and limited.
[0015] Accordingly, the present invention seeks to provide systems, devices and methods
which alleviate or at least partially ameliorate the above issues by providing improved
cross-subframe scheduling.
[0016] In particular, the inventors have realised that it would be beneficial to provide cross-
[0017]
subframe scheduling for broadcast transmissions (such as RA messages 2, 4, and
paging messages) as well, especially for MTC devices, and have conceived an efficient
way of achieving such cross-subframe scheduling for broadcast transmissions.
However, such cross-subframe scheduling not currently possible for broadcast transmissions,
is not trivial, and cannot be achieved by simply re-using the existing
procedures available for unicast transmissions over the PDSCH. This is especially true
for MTC devices, which might operate over a limited bandwidth and hence they cannot
receive both the control data (in one subframe) relating to a scheduled broadcast
transmission and monitor the associated broadcast transmissions (such as a RAR or
paging message) in the same or in another subframe. A further problem primarily associated
with MTC devices is that since all MTC devices are allocated the same
PRACH resources, the same temporary identifier may be used by more than one MTC
device (since the RA-RNTI is derived from the PRACH resource used for sending the
first message of the random access procedure). Consequently, the base station may be
required to transmit associated RAR messages with the same RA-RNTI across
different subframes (in time) and over different resource blocks in order to be able to
respond to each MTC device within the prescribed time window. However, MTC
devices (due to their limited bandwidth and low complexity) are unable to concurrently
monitor all possible subframe and resource block combinations in order to check for
their own preamble sequence ID in the RAR messages having their (common) RARNTI.
Solution to Problem
In one aspect, the invention provides a mobile station which communicates with a
base station, the mobile station comprising; means for receiving a first parameter and a
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second parameter;
means for transmitting a first message; means for receiving a control channel based on
the first parameter and the second parameter; and means for decoding a downlink
shared channel associated with the control channel based on information in the control
channel, wherein the first parameter is related to at least one sub-frame to receive the
control channel, wherein the second parameter is related to at least one narrow band to
receive the control channel.
[0018] In one aspect, the invention provides a base station which communicates with a
[0019]
[0020]
[0021]
mobile station, the base station comprising; means for transmitting a first parameter
and a second parameter;
means for receiving a first message; means for transmitting a control channel based
on the first parameter and the second parameter; and means for transmitting a
downlink shared channel associated with the control channel based on the control part
of the first message, wherein the first parameter is related to at least one sub-frame to
receive the control channel, wherein the second parameter is related to at least one
narrow band to receive the control channel.
Aspects of the invention extend to corresponding 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
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
[0022] [fig.1]Figure 1 schematically illustrates a telecommunication system to which embodiments
of the invention may be applied;
[fig.2]Figure 2 is a block diagram illustrating the main components of the communication
device shown in Figure 1;
[fig.3]Figure 3 is a block diagram illustrating the main components of the base station
shown in Figure 1;
[fig.4]Figure 4 illustrates exemplary ways in which random access related trans6
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[0023]
[0024]
[0025]
missions (with cross-subframe scheduling) can be realised in the system shown in
Figure 1;
[fig.5]Figure 5 illustrates an exemplary way in which paging transmissions (with crosssubframe
scheduling) can be employed in the system shown in Figure 1;
[fig.6]Figure 6 illustrates a modification of the random access related transmissions
shown in Figure 4;
[fig.7]Figure 7 illustrates another modification of the random access related transmissions
shown in Figure 4;
[fig.8]Figure 8 illustrates another modification of the random access related transmissions
shown in Figure 4;
[fig.9]Figure 9 illustrates another modification of the random access related transmissions
shown in Figure 4;
[fig.10]Figure 10 illustrates another modification of the random access related transmissions
shown in Figure 4; and
[fig.11]Figure 11 illustrates another modification of the random access related transmissions
shown in Figure 4.
Description of Embodiments

Figure 1 schematically illustrates a mobile (cellular) telecommunication system 1 in
which communication devices 3 (such as mobile telephone 3-1 and MTC device 3-2)
can communicate with each other and/or with other communication nodes via an EUTRAN
base station 5 (denoted 'eNB') and a core network 7. As those skilled in the
art will appreciate, whilst one mobile telephone 3-1, one MTC device 3-2, and one
base station 5 are shown in Figure 1 for illustration purposes, the system, when implemented,
will typically include other base stations and communication devices.
The base station 5 is connected to the core network 7 via an S 1 interface. The core
network 7 includes, amongst others: a gateway for connecting to other networks, such
as the Internet and/or to servers hosted outside the core network 7; a mobility
management entity (MME) for keeping track of the locations of the communication
devices 3 (e.g. the mobile telephone and the MTC device) within the communication
network 1; and a home subscriber server (HSS) for storing subscription related information
(e.g. information identifying which communication device 3 is configured as
a machine-type communication device) and for storing control parameters specific for
each communication device 3.
Each communication device 3 may fall into one or more categories of UEs. A first
category of UEs include communication devices that support only an earlier release of
the LTE standard (e.g. Rel-8, Rel-9, Rel-10, Rel-11, and/or Rel-12). Such commu7
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nication devices are commonly referred to as legacy UEs (assuming that the base
station 5 is operating in accordance with Rel-13 of the LTE standards). It will be appreciated
that some communication devices that belong to this category may not
support the EPDCCH (only PDCCH). A second category of UEs include communication
devices that support the current release of the LTE standard (e.g. Rel-13 and/
or later). A third category of UEs include reduced bandwidth UEs (e.g. Rel-13 MTC
devices capable of using a 1.4 Mhz bandwidth only), which are not able to communicate
over the entire bandwidth available in the cell of the base station 5. A fourth
category of UEs includes coverage enhanced UEs (e.g. some MTC devices), which
require certain base station functionalities to be simplified and/or relaxed (although
such coverage enhanced UEs may support other functionalities as normal).
[0026] In this example, the mobile telephone 3-1 comprises a Rel-13 UE, and the MTC
device 3-2 comprises a reduced bandwidth MTC device (which may also be configured
for an appropriate level of coverage enhancement). Although not shown in Figure 1, it
is assumed that a number of other MTC devices are also present within the cell of the
base station 5.
[0027] The base station 5 is configured to transmit a physical downlink control channel
(PDCCH) and an evolved PDCCH (EPDCCH) for reception by the communication
devices 3 located within the base station's 5 cell. The (E)PDCCH allocates uplink and
downlink resources to the communication devices 3. One difference between the
PDCCH and the EPDCCH is that the EPDCCH uses a relatively narrow frequency
spectrum (1.4 Mhz) that makes it compatible with Rel-13 reduced bandwidth MTC
devices, whilst PDCCH uses a wider frequency spectrum in order to provide backward
compatibility with legacy communication devices.
[0028] The so-called common search space (CSS) carries downlink control information
[0029]
(DCI) in the cell which is common to all communication devices 3. For example, the
CSS may include: system information blocks (SIBs) which contain information related
to cell access parameters; random access channel (RACH) messages (e.g. a Random
Access Response (RAR) and/or Contention Resolution); and/or the paging channel
(PCH). In LTE Rel-13, the CSS (also referred to as 'eCSS') forms part of the
EPDCCH. The (time-frequency) resources allocated for the CSS may be indicated via
the so-called physical broadcast channel (PBCH) or via system information block #1
(SIB1).
Due to the reduced bandwidth of 1.4 MHz in downlink and uplink, the MTC device
3-2 cannot receive the PDCCH which is densely spread across the entire cell
bandwidth (i.e. it may be transmitted over frequencies falling outside the 1.4 MHz
supported by the MTC device 3-2). However, the MTC device 3-2 can receive the
EPDCCH CSS (eCSS) which is transmitted over 6 RBs, i.e. within the 1.4 MHz band
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supported by the MTC device 3-2.
[0030] Furthermore, the base station's 5 bandwidth includes a number of subbands (e.g.
[0031]
non-overlapping subbands), each subband having 6 RBs (or less). Beneficially, since
bandwidth reduced MTC devices are able to communicate over a maximum of
1.4MHz bandwidth (which roughly corresponds to 6 RBs), the communication device
3-2 is able to send and receive (eCSS and other) data over the particular subband that
its transceiver is currently tuned to. Advantageously, the base station 5 has some
scheduling flexibility in the frequency location by being able to select an appropriate
subband for communicating paging/RAR messages (and/or the like) to the communication
devices 3 within its cell.
In order to achieve such scheduling flexibility, the base station 5 transmits control
data via the eCSS in a subband of a particular subframe, and the control data includes
information (DCI) which informs communication devices 3 in the base station's 5 cell
that random access/paging transmission is scheduled (and for which communication
device(s) 3) in a subsequent subframe.
[0032] Thus, effectively, the eCSS (in the EPDCCH) comprises a common search space for
[0033]
[0034]
dynamic scheduling of random access (RA) messages (which are transmitted over the
PDSCH). In this case, DCI format transmitted via the eCSS includes the number of
physical resource blocks (PRBs), transport block size (TBS), frequency locations
(and/or the like) associated with the RA message scheduled via that DCI format.
Communication devices 3 within the base station's 5 cell are configured to monitor
the control information transmitted via the eCSS in order to determine whether any
RA/paging transmission is scheduled for them.
However, whilst the base station 5 is typically configured to transmit the eCSS on a
subband located around the central portion of the base station's bandwidth (i.e. a
subband allocated to the EPDCCH), RA/paging messages may be (and often need to
be) transmitted over a different subband (e.g. over a channel, such as the PDSCH, that
is allocated to a different subband to the EPDCCH subband).
[0035] Therefore, when employing cross-subframe scheduling, the base station 5 is advantageously
configured to indicate via the eCSS (using an appropriately formatted DCI)
which subsequent subframe and which subband will carry the RA/paging message for
which communication device(s) 3. For RAR Message 2, communication devices 3
sharing the same RA-RNTI (e.g. MTC devices that initiated a random access
procedure using the same PRACH resources) are grouped into a number of different
groups (at least for the given scheduling round). For each group of communication
devices, the base station 5 schedules the associated RA/paging message such that an
appropriate 'retuning time' is included between the transmission of the eCSS
scheduling a particular RA/paging message (in one subframe), and the transmission of
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[0036]
[0037]
[0038]
[0039]
[0040]
the corresponding RA/paging message (in a subsequent subframe). The appropriate
retuning time is determined in such a way that if the eCSS and the RA/paging message
are transmitted over the same subband, then the retuning time is effectively zero
subframes, and if the eCSS and the RA/paging message are transmitted over different
subbands, then the retuning time is one subframe (although it may also be set to more
than one subframe, if appropriate).
Thus, for example, if the RA/paging message for a given communication device 3 in
a particular group is scheduled for transmission over a different subband to the
subband carrying the eCSS, then the base station 5 schedules the RA/paging message
(via the associated DCI) such that a retuning time of at least one subframe is provided
between transmission of the eCSS and transmission of the RA/paging message
scheduled by (the DCI included in) the eCSS. Such retuning time of one subframe
makes it possible for the scheduled communication device 3 to timely tune its
transceiver to the subband carrying the RA/paging message (from the subband carrying
the eCSS).
Similarly, if the RA/paging message for a communication device 3 of a given group
is scheduled for transmission over the same subband as the subband carrying the eCSS
(but in a different subframe), then the base station 5 schedules the RA/paging message
such that a retuning time of zero subframes is provided between transmission of the
eCSS and transmission of the RA/paging message (since the scheduled communication
device's 3 transceiver is already tuned to the correct subband carrying the RA/paging
message).
In other words, the base station 5 employs a cross-subframe scheduling (at least for
MTC devices) in which an associated retuning time is dependent on: the group of communication
devices for which the broadcast transmission is scheduled; and/or the
subband used for transmitting the control information (eCSS) and the subband carrying
the broadcast message scheduled by that control information.
Moreover, paging messages are transmitted in this system separately for MTC
devices (e.g. low-complexity and/or coverage enhanced MTC devices) and for other
communication devices. Paging messages for MTC devices support PDSCH subframe
bundling/repetition with multiple bundle sizes/repetition levels (in accordance with the
required level of coverage enhancement). Beneficially, the base station 5 paging the
communication device 3-2 has knowledge that the communication device 3-2
comprises a low-complexity (bandwidth reduced) MTC device and/or an MTC device
configured for coverage enhancement. The base station 5 also has know ledge of the
amount of coverage enhancement (repetitions) required during paging message
transmission.
Similarly, RAR messages (i.e. message 2) for MTC devices are also transmitted
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separately from RAR messages for other communication devices. Furthermore, in this
system, multiple RAR messages can be multiplexed for a plurality of communication
devices (e.g. that belong to the same group). Beneficially, when multiplexing is used,
each multiplexed message includes RAR messages for those communication devices
(of the respective group) that are operating with the same level of coverage enhancement.
[0041] In more detail, a number of RAR messages can be multiplexed together (e.g.
similarly to multiplexing employed in Rel-8) into one unit of TBS. The exact transport
block size (i.e. the number of bits transferred in a lms transport block size) is
dependent on the modulation and coding scheme (MCS) and the number of resource
blocks assigned to the communication device. Details of how the exact TBS can be
derived are given in section 7.1.7 of 3GPP TS 36.213 V12.5.0, the contents of which
are included herein by reference.
[0042] Beneficially, the base station 5 may be configured to control the number of messages
[0043]
that are being multiplexed, and include in each multiplexed transmission only such
messages that need to be transmitted with the same level of coverage enhancement
(e.g. multiplex RAR messages for such MTC devices that are configured with the same
CE level). For example, RAR messages for low-complexity MTC devices in normal
coverage may be multiplexed into a first RAR message (that does not require
repetition) and RAR messages for MTC devices configured for (a particular level of)
CE may be multiplexed into a different RAR message (with repetitions as appropriate).
It will also be appreciated that the base station may multiplex RAR messages
intended only for a first set of MTC devices (for example, MTC devices in normal
coverage) and to transmit conventional (non-multiplexed) RAR messages for a second
set of MTC devices (such as CE mode MTC devices and/or MTC devices configured
with a particular CE level, e.g. 5dB, lOdB, and/or 15dB).
[0044] It will be appreciated that when multiple messages are multiplexed, the resulting
payload increases (and depending on the applicable CE level, the number of repetitions
in time domain may also increase). Beneficially, however, the above described
dynamic cross-subframe scheduling (using eCSS to indicate TBS size and assigned
PRB resources)- preferably in combination with grouping of communication devicescan
be employed to compensate for a potential payload increase resulting from multiplexing
of multiple messages, without requiring the MTC devices to monitor both the
eCSS and each RAR/paging transmission at the same time (which may be transmitted
over different 1.4 MHz subbands).
[0045] In summary, the base station is advantageously able to indicate to MTC devices
within its cell the resources used for their associated broadcast transmissions (e.g. RA
and/or paging message transmissions), and schedule broadcast transmissions in such a
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[0046]
[0047]
[0048]
[0049]
way (e.g. only after an appropriate retuning time and/or only for a given group) that
even limited bandwidth MTC devices can receive their associated broadcast transmissions.
In other words, the base station ensures that it responds to each communication
device's preamble transmission using communication resources that the respective
communication device is able to use in the particular subframe in which the
associated RAR message is transmitted. Similarly, the base station is configured to
page each communication device in a subframe in which that communication device's
transceiver is tuned (or can be tuned) to the communication resources carrying the associated
paging message.

Figure 2 is a block diagram illustrating the main components of the communication
device 3 shown in Figure 1. The communication device 3 may be an MTC device or a
mobile (or 'cellular') telephone configured as a machine-type communication device.
The communication device 3 comprises a transceiver circuit 31 which is operable to
transmit signals to, and to receive signals from, the base station 5 via at least one
antenna 33. Typically, the communication device 3 also includes a user interface 35
which allows a user to interact with the communication device 3, however this user
interface 35 may be omitted for some MTC devices.
The operation of the transceiver circuit 31 is controlled by a controller 37 in accordance
with software stored in memory 39. The software includes, among other
things, an operating system 41, a communication control module 43, an eCSS module
44, an MTC module 45, a random access module 47, and a paging module 48.
The communication control module 43 controls communications between the communication
device 3 and the base station 5 and/or other communication nodes (via the
base station 5). The communication control module 43 also ensures that the transceiver
31 is tuned to the subband/frequency (e.g. it remains tuned to the same subband or it is
timely re-tuned to a different subband) associated with the communication resources
scheduled/allocated for this communication device 3.
The eCSS module 44 monitors eCSS transmissions by the base station 5 and determines
whether the eCSS transmissions include information indicating that crosssubframe
broadcast transmissions are being scheduled for the communication device 3,
and determines the communication resources (e.g. subframe/subband) associated with
such broadcast transmissions. If appropriate, the eCSS module 44 notifies the communication
control module 43 to (re-)tune the transceiver 31 to the frequency/subband
indicated via the eCSS.
[0050] The MTC module 45 is operable to carry out machine-type communication tasks. For
example, the MTC module 45 may collect data for sending (e.g. periodically and/or
upon detecting a trigger) to a remote server (via the transceiver circuit 31).
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[0051] The random access module 47 is responsible for obtaining and maintaining synchronisation
of transmissions with the network. For example, the random access module 47
may send (via the transceiver circuit 31) a random access transmission (including a
selected preamble sequence) to the base station 5 when the communication device 3
needs to establish an RRC connection with the network. The random access module 47
receives a random access response from the base station 5 (using the communication
resources determined by the eCSS module 44).
[0052] The paging module 48 receives (over appropriate communication resources de-
[0053]
termined by the eCSS module 44) and processes paging messages addressed to the
communication device 3.

Figure 3 is a block diagram illustrating the main components of the base station 5
shown in Figure 1. The base station 5 comprises an E-UTRAN base station (eNB)
comprising a transceiver circuit 51 which is operable to transmit signals to, and to
receive signals from, the communication devices 3 via one or more antennas 53. The
base station 5 is also operable to transmit signals to and to receive signals from a core
network 7 via an appropriate core network interface 55 (such as an S1 interface). The
operation of the transceiver circuit 51 is controlled by a controller 57 in accordance
with software stored in memory 59.
[0054] The software includes, among other things, an operating system 61, a communication
control module 63, a paging module 65, a random access control module 67, and a UE
group allocation module 69.
[0055] The communication control module 53 controls communications with the commu-
[0056]
nication devices 3. The communication control module 53 is also responsible for
scheduling (via the eCSS) the resources to be used by the communication devices 3
served by this base station 5. Although not shown in Figure 3, the communication
control module 53 includes a broadcast portion which is responsible for broadcasting
system information (such as configuration of the cell of the base station 5) and/or other
broadcast transmissions for receipt by the communication devices 3 located within the
cell of the base station 5. For example, the broadcast portion transmits the PRACH
configuration(s) employed in the cell and/or the messages generated by the other
modules (e.g. paging IRA messages).
The paging module 65 generates and transmits paging messages (via the communication
control module 63) for communication devices 3 located within the cell of the
base station 5.
[0057] The random access control module 67 is responsible for communications over the
PRACH. The random access control module 67 handles (generates, sends, and
receives) messages relating to the random access procedure performed with commu13
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[0058]
[0059]
[0060]
nication devices 3 located within the cell of the base station 5.
The UE group allocation module 69 allocates each communication device 3 to a
group (and/or UE category) based on a parameter associated with the communication
device 3 (for example, based on the received preamble sequence, e.g. the time/
frequency resource the preamble sequence is sent on and/or the selected preamble).
When appropriate, the UE group allocation module 69 notifies the communication
control module 63 about each communication device's 3 allocated group/category so
that the communication control module 63 can adjust the operation of its broadcast
portion according! y.
In the above description, the communication device 3 and the base station 5 are
described for ease of understanding as having a number of discrete modules. Whilst
these modules may be provided in this way for certain applications, for example where
an existing system has been modified to implement the invention, in other applications,
for example in systems designed with the inventive features in mind from the outset,
these modules may be built into the overall operating system or code and so these
modules may not be discernible as discrete entities.

Figure 4 illustrates exemplary ways in which random access messages (RA msg2/4)
transmissions (with cross-subframe scheduling) can be employed in the communication
system 1 shown in Figure 1.
[0061] It will be appreciated that the base station 5 is configured to transmit a 'SIB2' in its
[0062]
cell for reception by the communication devices 3. The SIB2 includes the appropriate
parameters for the PRACH resource configuration currently in use in the cell of the
base station 5.
As explained above, the communication devices 3 need to establish an RRC
connection with the base station 5 in order to be able to communicate with other
devices via that base station 5 (and the core network 7). Therefore, each communication
device 3 is configured to perform an appropriate random access procedure (via
the PRACH) in order to synchronise their transmissions with the base station 5 and to
indicate to the network the reason for establishing the RRC connection. In this cell,
each type of communication device has its own set of PRACH parameters. Therefore,
the resources allocated for initiating a random access procedure by the MTC device
3-2 are different to the resources allocated for the mobile telephone 3-1.
[0063] It will be appreciated that each MTC device may be configured to estimate (e.g.
before initiating a random access procedure) an appropriate CE level (0-3) for that
MTC device based on, for example, downlink signal quality measurements, such as
reference signal received power (RSRP) measurements. Based on the estimated CE
level, the MTC devices can determine the number of repetitions required when com14
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municating messages of the random access procedure.
[0064] In summary, the random access procedure includes the following messages:
[0065]
[0066]
[0067]
[0068]
Message 1 ('Msg1 '):the MTC device transmits a PRACH preamble sequence to
the base station with appropriate time domain repetitions (if any);
Message 2 ('Msg2'): the base station transmits (broadcasts) a Random Access
Response (with appropriate repetitions, if any) to the MTC device within a time
window determined based on the subframe in which the MTC device's Msg1 was
transmitted;
Message 3 ('Msg3'): the MTC device transmits its associated mobile terminal
identity to the network (with appropriate repetitions, if any); and
Message 4 ('Msg4'): the base station transmits a contention resolution message
(with appropriate repetitions, if any) to a specific terminal.
However, the resources allocated for the MTC device 3-2 are shared by other MTC
devices that belong to the same category. Accordingly, when more than one MTC
devices initiate random access procedures substantially concurrently, the base station 5
needs to schedule appropriate resources for transmitting respective RAR messages
(Msg2) to each such MTC device within a short time period (defined by the time
window starting from Msg1).
In order to be able to respond to each MTC device, and to ensure that each MTC
device knows which subband to monitor for its RAR message (even if the RA-RNTI is
shared by a plurality of MTC devices), the base station 5 allocates (using its UE group
allocation module 69) each MTC device to a group. Next, the base station 5 informs
each group of MTC device about their respective allocated RAR resources via the
EPDCCH (using an appropriately formatted DCI).
The eCSS comprises a common search space, using which the base station 5 is able
to dynamically schedule (using its random access control module 67) RAR messages
for communication devices 3 located within its cell. In order to do so, the base station 5
includes in the DCI format information indicating which subband (identified by its
subband index) is scheduled for the PDSCH carrying the RAR message as well as the
associated resource allocation (number of RBs) within that subband.
In more detail, subframes denoted 'x' and 'y' (in Figure 4) include a respective eCSS
70 for those MTC devices that are scheduled to receive an RAR message from the base
station 5 in one of the subsequent subframes (assuming cross-subframe scheduling is in
place). Each MTC device (but at least those MTC devices that recently initiated a
random access procedure) monitors the eCSS 70 by turning on their transceiver 31
(and tuning it to the sub band carrying the eCSS 70) at least for the duration of the
eCSS transmission (subframes x andy in Figure 4).
[0069] The eCSS 70 includes one or more appropriate DCI(s), each of which comprises m15
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formation identifying the subframe and the physical resource block (subband, timing)
that carries the RAR for the MTC devices belonging to a particular group. Each MTC
device that receives the eCSS transmission (via its associated eCSS module 44) is
configured to determine (using its associated random access module 47) whether any
received DCI is for the group of communication devices that that MTC belongs to.
[0070] In one option, the DCI indicates that the RAR message will be transmitted over the
same subband 71 as the subband carrying the eCSS 70 but in a different subframe
(sub frame x + 1 in the example shown in Figure 4 ). In other words, the base station's 5
RAR transmissions use physical resource block(s) that fall within the subband 71 that
the communication device's 3 transceiver circuit 31 is already tuned to (because it is
tuned to receiving the eCSS in subframe x).
[0071] In accordance with another option, the DCI indicates that the RAR message will be
transmitted over a different subband 71' than the subband carrying the eCSS 70. In this
case, the DCI also indicates that the RAR message will be transmitted after an appropriate
retuning time after the transmission of the eCSS 70. For example, the DCI
may indicate that the RAR message will be transmitted in subframe x+2 (or later).
Preferably, the RAR message is transmitted after subframe x+ 1 but prior to subframe y
(carrying the next eCSS 70 transmission). By employing an appropriate retuning time,
it is possible for the scheduled communication devices 3 to tune their transceiver
circuit 31 (from the subband carrying the eCSS) to the subband carrying their respective
RAR/paging message.
[0072] An advantage associated with scheduling RAR messages via the EPDCCH CSS is
[0073]
[0074]
that the resulting scheduling flexibility contributes to an efficient system operation as
well as reduces the blocking probability for RAR messages.
In addition, eCSS makes it possible to multiplex a number of RAR messages (e.g.
RAR messages with the same coverage level) into a single TBS thus further improving
system efficiency (e.g. by reducing the associated overhead). However, if such multiplexing
is not appropriate (or not required), this approach also makes it possible to
employ single (non-multiplexed) RAR message transmissions to at least some communication
devices.
The above described dynamic scheduling via eCSS may also be used for scheduling
message 4 of the random access procedure (when cross-subframe scheduling is in
place). It will be appreciated that in this case, the DCI format also includes the subband
used for transmitting Msg4.
[0075]
Figure 5 illustrates an exemplary way in which paging transmissions (with crosssubframe
scheduling) can be employed in the communication system 1 shown in
Figure 1.
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[0076]
[0077]
[0078]
Similarly to the way in which RAR messages are scheduled (as described above with
reference to Figure 4), paging messages (that are transmitted over the PDSCH) may
also be scheduled using the eCSS (transmitted over the EPDCCH). In this case, since
the paging message size can vary (not fixed), the DCI format (included in the eCSS)
preferably also includes information identifying at least one of: an MCS associated
with the paging message; a TBS associated with the paging message; and a number of
RBs allocated for the paging message.
If the frequency location for the PDSCH carrying the paging message is different to
the frequency location for the eCSS, then cross-subframe scheduling is used. In this
case, the paging message is scheduled for transmission over one of the available
subbands (not exceeding 1.4 MHz I 6 RBs) and the associated subband number (index)
is also included in the DCI format. This approach beneficially increases scheduling
flexibility at the base station 5 and may also decrease the blocking probability of the
pagmg message.
As shown in Figure 5, subframes denoted 'x' and 'y' each include a respective eCSS
70A, 70B for those MTC devices that are scheduled to receive a paging message from
the base station 5 in one of the subsequent subframes (assuming cross-subframe
scheduling is in place). Each MTC device monitors the eCSS 70 by turning on their
transceiver circuit 31 (and tuning it to the subband carrying the eCSS 70) at least for
the duration of the eCSS transmission (subframes x andy in Figure 5).
[0079] The DCI included in the eCSS 70A (in subframe x) indicates that a paging message
[0080]
will be transmitted (after an appropriate retuning time) in subband 71A (identified by
its associated subband index) for communication devices 3 identified as 'UE2', 'UE3',
and 'UE5'. Similarly, the DCI included in the eCSS 70B (in subframe y) indicates that
a paging message will be transmitted (after an appropriate retuning time) in sub band
71B (identified by its associated subband index) for communication devices 3
identified as 'UE4', 'UE7', and 'UE8'.
Thus each identified communication devices 3 are able tune its transceiver circuit 31
to its respective allocated subband 71 (at least for the duration of the paging
transmission) and listen to the paging messages broadcast in that subband 71.
[0081] However, each communication devices 3 is configured to tune its transceiver circuit
[0082]
31 back to subband carrying the eCSS 70 after the paging message is transmitted
(including any repetition if CE is used) so that they can continue to receive control information
(DCI) from the base station 5 without delay.
Advantageously, the base station's 5 transmissions are scheduled such that there is
sufficient retuning time provided after each paging message and before transmitting a
subsequent eCSS (e.g. there is at least one subframe before each one of subframes x
andy and the end of the preceding paging transmission).
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[0083]
Detailed exemplary embodiments have been described above. As those skilled in the
art will appreciate, a number of modifications and alternatives can be made to the
above exemplary embodiments whilst still benefiting from the inventions embodied
therein.
[0084] Figures 6 to 11 illustrate further exemplary ways in which broadcast transmissions
[0085]
(such as RAR transmissions) can be scheduled via the eCSS for bandwidth reduced
MTC devices.
Figure 6 illustrates a modification of the random access procedure in which RAR
transmissions are scheduled via the eCSS. In this case, both the eCSS and Msg2 are
always transmitted on the same subband.
[0086] In this example, each one of UE1 to UE6 has the same RA-RNTI. The base station
[0087]
[0088]
allocates (using its UE group allocation module 69) UE1, UE2, and UE3 to a first
group, and allocates UE4, UE5, and UE6 to a second group.
The eCSS transmitted in both subframe x and subframe y includes the RA-RNTI that
is common to UE1 to UE6. However, in a first transmission round (in subframe x+ 1)
scheduled via the eCSS transmitted in subframe x, the RAR includes preamble IDs for
communication devices belonging to the first group. Accordingly, the RAR messages
multiplexed into this message are intended for the UE1, UE2, and UE3 belonging to
the first group. This also means that although communication devices belonging to the
second group have also received and decoded the RAR message in subframe x+ 1, this
message does not include their associated preamble IDs. Consequently, each communication
devices belonging to the second group determines (using their associated
random access module 47) that this RAR message does not include a valid response for
that communication device, and continues monitoring the EPDCCH for further eCSS
transmissions (i.e. in subframe y). On the other hand, the communication devices
belonging to the first group determine that the RAR message in subframe x+ 1 includes
a valid random access response, and proceed to generating and transmitting Msg3 to
the base station.
In the next transmission round (in sub frame y+ 1) scheduled via the eCSS transmitted
in sub frame y, the RAR includes preamble IDs for communication devices belonging
to the second group. Thus in sub frame y+ 1, the communication devices belonging to
the second group also determine that the RAR message in subframe y+ 1 includes a
valid random access response, and proceed to generating and transmitting Msg3 to the
base station.
[0089] It will be appreciated that any group may include a single communication device, in
which case no multiplexing is used for that group. It will also be appreciated that RAR
messages for more than one groups may be multiplexed together.
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[0090] Thus in this example RAR messages are multiplexed (if applicable) and transmitted
on a per group basis in the time domain, using the same subband as the eCSS. Advantageously,
there is no need to provide any retuning time and/or include a subband
index in the DCI format, whilst still benefitting from some of the flexibility associated
with the eCSS based RAR scheduling described with reference to Figure 4.
[0091] Figure 7 illustrates another modification of the random access procedure in which
RAR transmissions are scheduled via the eCSS. In this case, RAR messages for
different groups of communication devices are transmitted over different subbands.
[0092] In this case, a single TBS carrying one or more RAR messages with the same RARNTI
(but for different communication devices) and with the same coverage level is
scheduled on any subband. This means that the subband for the eCSS and the subband
for the RAR messages may be different, hence scheduling flexibility can be achieved
to some degree.
[0093] As can be seen, the eCSS included in subframe x schedules a (multiplexed) RAR
transmission for the group of communication devices with identifiers UEl to UE3 (but
with the RA-RNTI that is common to other communication devices UE4 to UE6 as
well). When a communication device that belongs to this group (e.g. UEl) decodes this
RAR message, it determines that this RAR message comprises a valid random access
response (since its selected preamble ID is included) and proceeds to transmitting
Msg3 to the base station.
[0094] However, when a communication device that does not belong to this group (e.g.
[0095]
UE4) decodes this RAR message, it determines that this RAR message was not meant
for this communication device (since its selected preamble ID is not included). Thus
UE4 returns to monitoring for the eCSS in the EPDCCH.
Beneficially, the timing of the RAR transmissions and the eCSS are defined such that
there is sufficient retuning time provided after each RAR message and before
transmitting a subsequent eCSS (e.g. there is at least one subframe before each one of
subframes x andy and the end of the preceding RAR transmission).
[0096] As can be seen, the RAR transmission for the group of communication devices with
[0097]
identifiers UE4 to UE6 are scheduled via the eCSS included in subframe y. However,
this RAR transmission uses a different subband to the subband used for the RAR
transmission scheduled via subframe x (although it may use the same subband). Thus
in this example RAR messages (multiplexed, if applicable) are transmitted on a per
group basis in the time domain (and possibly in the frequency domain as well). It will
be appreciated that communication devices UE4 to UE6 may require a different CE
level (and hence a different number of repetitions) to the CE level for communication
devices UEl to UE3.
Figure 8 illustrates another modification of the random access procedure in which
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[0098]
[0099]
RAR transmissions are scheduled via the eCSS. In this case, RAR messages for all
scheduled communication devices are transmitted over the same (albeit dynamically
scheduled) subband.
In this case, all RAR messages with the same RA-RNTI (but for different communication
devices) and with the same coverage level are scheduled on the same sub band
and arranged in sequence within a time window. This means that the subband for the
eCSS and the subband for the RAR messages may be different, hence scheduling
flexibility can be achieved to some degree. However, the transmission parameters for
RAR messages arranged in a single sequence need to be the same (signalled by the
same DCI format).
However, since a potentially large number of RAR messages need to be transmitted
in a single sequence, the RAR transmission may in some cases exceed the capacity of a
single subframe (using 6RBs only). Therefore, in order to inform the communication
devices that they should continue decoding from the indicated subband after the first
subframe of the RAR transmission, a flag may be included in (at least) the final RAR
message of the subframe to indicate that there is at least one further message after this
message. It will be appreciated however, that such flag may be included in each RAR
message that is followed by another RAR message (regardless whether the following
RAR message is located in the same subframe or in the subsequent one).
[0100] In the example shown in Figure 8, all communication devices (UEl to UE6) are
being scheduled via the eCSS included in subframe x. However, the respective RAR
messages for communication devices with identifiers UEl to UE3 are included in the
first part of the (multiplexed) RAR transmission sequence and RAR message for the
remaining communication devices are included in the second part of the RAR
transmission sequence. It will be appreciated that the RAR transmission sequence may
be repeated in accordance with the CE level required for the communication devices
(UEl to UE6) scheduled in this round.
[0101] Figure 9 illustrates another modification of the random access procedure in which
RAR transmissions are scheduled via the eCSS. In this case, however, the DCI format
also identifies the preamble range covered in the RAR messages scheduled via that
DCI format.
[0102] For example with 2bits in the DCI format, four groups (each group comprising 16
preamble IDs) can be signalled.
[0103] In this example, UEl (with preamble ID 10), UE2 (with preamble ID 3), UE3
(preamble ID 12), UE4 (preamble ID 14), UE5 (preamble ID 17), UE6 (preamble ID
19), UE7 (preamble ID22) and UE8 (preamble ID 31) have the same RA-RNTI.
Assuming that the first group includes preamble IDs 1 to 16, the second group includes
preamble IDs 17 to 32, the third group includes preamble IDs 33 to 48, and the fourth
20
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group includes preamble IDs 48 to 64; then UE1 to UE4 belong to the first group, and
UE5 to UE8 belong to the second group.
[0 104] Each communication device is configured to monitor for eCSS transmissions in the
prescribed subframes and determine whether its selected preamble ID falls within the
range identified by the DCI format. If it is determined that its selected preamble ID
falls within the range identified by the DCI format, then the communication device is
configured to retune its transceiver (following an appropriate retuning time) to the
subband indicated by the DCI format and decode its associated Msg2 from the base
station's RAR transmission.
[0105] As can be seen, beneficially, there is no need to provide any retuning time after the
[0106]
RAR transmissions and before the immediately following eCSS transmission, because
only those communication devices need to monitor the eCSS, at any given time, that
are not yet scheduled (based on their associated preamble ID) for transmission (e.g.
RAR transmission and/or the like).
Figure 10 illustrates a case without requiring multiplexing of multiple RAR messages
(or when such multiplexing is not permitted). In this case, it is beneficial to apply a
new RA-RNTI for each communication device (rather than the RA-RNTI that is
derived in accordance with legacy procedures).
[0107] The legacy RA-RNTI has a range of '1' to '60' and is determined as follows:
[0108]
RA-RNTI = 1 + t_id + 10*f_id
where t_id is the index of the first subframe of the transmitted PRACH
[Math.1]
(0:<:; t_id <1 0);
and f_id is the index of the transmitted PRACH in frequency domain of the same
sub frame
[Math.2]
(0:<:; f_id< 6).
In this modification, however, the RA-RNTI (at least for MTC devices) is derived by
employing the PRACH sequence index as well. This will prevent using the same RARNTI
for multiple communication devices (MTC devices) even if they select the same
PRACH resources (t_id and f_id) for transmitting Msg1, unless also using the same
PRACH sequence index. The value of this 'MTC RA-RNTI' or 'PRACH sequence
index based RA-RNTI' may be chosen from outside (above) the legacy RA-RNTI
range and may be determined as follows:
RA-RNTI = 61+64* f_id + PRA_id
where PRA_id is the transmitted PRACH sequence index
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[0109]
[Math.3]
(O:S PRA_id< 64);
and f_id is the index of the transmitted PRACH in frequency domain of the same
sub frame
[Math.4]
(O:S f_id< 6).
Accordingly, if the DCI is masked with such a PRACH sequence specific RA-RNTI,
then only the intended UE(s) (i.e. communication device(s) using the corresponding
PRACH sequence index) will be able to decode it and receive the associated RAR
message (after an appropriate retuning time). Any other UEs (that use a conventional
RA-RNTI or an RA-RNTI based on a different PRACH sequence index) will not be
able to decode such a DCI format that is not masked with their own RA-RNTI and
hence such UEs skip (tuning to and) receiving the associated PDSCH. This may result
in significant power savings.
[0110] Beneficially, this approach involving the new RA-RNTI may also result in reduced
power consumption (power saving) at the MTC device, at least while the MTC device
is operating in coverage enhanced mode.
[0111] Figure 11 illustrates a case in which the RA-RNTI is determined based on PRACH
[0112]
(preamble) sequence grouping. In this case the RA-RNTI is derived using the PRACH
sequence group index (assuming 4 groups) as follows:
RA-RNTI = 61+4* f_id + PRA_Group_id
where PRA_Group_id is the index of the PRACH sequence group
[Math.5]
(O:S PRA _Group id< 4)
in which the UE's PRACH (preamble) sequence index belongs to. A possible
preamble sequence ID grouping has been described above with reference to Figure 9
(although any suitable grouping may be used).
Accordingly, if the DCI is masked with such a group-specific RA-RNTI, then only
the intended UEs (i.e. communication device(s) using a preamble sequence ID from
the same group) will be able to decode it and receive the associated RAR message
(after an appropriate retuning time). Any other UEs (that selected their respective
PRACH sequence index from a different group) will not be able to decode such a DCI
format that is intended for a different group than their own and hence such UEs skip
(tuning to and) receiving the associated PDSCH. This approach may thus result in significant
power savings.
[0113] Alternatively, the subframe index (t_id) may also be included in the equation, for
example, as follows:
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[0114]
RA-RNTI = 61+t_id + 64* f_id + PRA_id
where PRA_id is the transmitted PRACH sequence index
[Math.6]
(0~ PRA_id< 64),
f_id is the index of the transmitted PRACH in frequency domain of the same subframe
[Math.7]
(0~ f_id< 6)
and t_id is the index of the first subframe of the transmitted PRACH
[Math.8]
(0~ t_id <10).
In the above exemplary embodiments, control data (DCI) transmitted via the eCSS is
used for scheduling a (multiplexed) broadcast transmission, such as RAR or paging
message transmission. However, it will be appreciated that a control-less RAR
message may be used instead. In this case, the number of PRBs is fixed to 6 RBs (or
less). The base station transmits (RAR/paging) messages using a single TBS (or a
limited set of TBS) and the communication devices are configured to perform a
number of blind decodings based on the TBS. The frequency location or sub band for
the RAR messages may be fixed to e.g. the central6 RBs (although it may also be
derived from PRACH resources). Although in this option the base station's scheduling
flexibility is restricted (as the frequency location may not be changed dynamically) and
the UE's power consumption may increase (due to blind decoding of all messages),
there is no need for the provision of any retuning time before transmissions (since there
is no control data). Beneficially, when a number of RAR messages need to be
transmitted on the same subband, a queueing mechanism may also be provided to
ensure that RAR messages are transmitted within their respective detection window
(calculated from Msg1).
[0115] In the above exemplary embodiments, a number of ways are given for cross-
[0116]
subframe scheduling of broadcast transmissions, such as RAR (message 2 of the
random access procedure) and paging messages. However, it will be appreciated that
the above embodiments may also be applicable to other messages, for example
message 4 of the random access procedure (even though message 4 is masked with an
identifier (TC-RNTI) that is uniquely associated with one UE only.
Figures 4 to 11 show three subbands (each subband comprising 6 RBs). However, it
will be appreciated that the number of subbands can be more (or less) than three (e.g.
depending on the base station's system bandwidth).
[0117] In the above exemplary embodiments, the retuning time is assumed to be (not more
than) one subframe in duration. However, it will be appreciated that a different
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retuning time (e.g. more than one subframe) may also be employed.
[0118] In the above description, repetition in time domain is assumed for all transmissions.
However, such repetitions are omitted in Figures 4 to 11 for simplicity.
[0119] A number of exemplary embodiments have been described above, with reference to
[0120]
Figures 4 to 11. It will be appreciated that these exemplary embodiments are not
mutually exclusive and any of the options may be combined within the same system,
either within a single cell and/or in neighbouring cells. For example, the base station
may be configured to change from one operation mode to another, e.g. periodically, in
dependence on the number/type of MTC devices in its cell, in dependence on the
overall load in the cell, in dependence on the number of preamble retransmissions (e.g.
due to collision), in dependence on the type of communication (e.g. random access/
paging/broadcast/unicast), and/or the like.
In the above examples described with reference to Figures 10 and 11, the RA-RNTI
is calculated without using the subframe index identifying the subframe in which the
preamble prefix (Msgl) was transmitted. However, it will be appreciated that the index
of the subframe in which Msgl was transmitted is still considered (by the base station
and the MTC device) at least in determining an appropriate time window within which
Msg2 needs to be transmitted.
[0121] In the above description, information relating to the PRACH configuration is
signalled via the SIB2. However, it will be appreciated that the PRACH configuration
(at least part of it) may be signalled via a different system information block, for
example, via one or more SIB specific to reduced bandwidth UEs and/or coverage
enhanced UEs. Alternatively or additionally, some or all of this information can be
obtained by the communication devices in a different manner - for example the
PRACH configuration may be signalled via system broadcast (e.g. PBCH) and/or via
higher layers (e.g. RRC).
[0122] It will be appreciated that although the communication system is described in terms
of the base station operating as a E-UTRAN base station (eNB), the same principles
may be applied to base stations operating as macro or pico base stations, femto base
stations, relay nodes providing elements of base station functionality, home base
stations (HeNB), or other such communication nodes.
[0123] In the above exemplary embodiments, an LTE telecommunications system was
[0124]
described. As those skilled in the art will appreciate, the techniques described in the
present application can be employed in other communications systems, including
earlier 3GPP type systems. Other communications nodes or devices may include user
devices such as, for example, personal digital assistants, laptop computers, web
browsers, etc.
In the exemplary embodiments described above, the base station and the commu24
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nication device each include transceiver circuitry. Typically, this circuitry will be
formed by dedicated hardware circuits. However, in some exemplary embodiments,
part of the transceiver circuitry may be implemented as software run by the corresponding
controller.
[0125] In the above exemplary embodiments, a number of software modules were described.
[0126]
As those skilled in the art will appreciate, the software modules may be provided in
compiled or un-compiled form and may be supplied to the base station or the user
device as a signal over a computer network, or on a recording medium. Further, the
functionality performed by part or all of this software may be performed using one or
more dedicated hardware circuits.
The base station may comprise: a processor configured to identify at least one
subframe in which a broadcast message, carrying information for at least one communication
device, is to be broadcast; a transmitter configured for: transmitting, in a
control channel, in a frequency subband in at least one subframe that precedes said at
least one subframe in which said broadcast message is to be broadcast, control information
to identify said at least one subframe in which said broadcast message is to
be broadcast; and broadcasting said broadcast message in said at least one subframe in
which said broadcast message is to be broadcast.
[0127] The at least one communication device may comprise at least one machine type com-
[0128]
[0129]
munication 'MTC' device (e.g. a reduced bandwidth or low complexity MTC device
and/or a coverage enhanced MTC device).
If the at least one communication device comprises at least one coverage enhanced
MTC device, the at least one subframe in which said control information is transmitted
may comprise a plurality of subframes in which said control information is to be first
transmitted and then repeated, and said at least one subframe in which a broadcast
message is to be broadcast may comprise a plurality of subframes in which said
broadcast message is to be first broadcast and then repeated.
The broadcast message may carry multiplexed information for each of a plurality of
communication devices. For example, the broadcast message may carry multiplexed
information for each of a plurality of coverage enhanced machine type communication
'MTC' devices sharing a common coverage enhancement level.
[0130] The processor may be further configured to identify a frequency subband in which
the broadcast message is to be broadcast. In this case the control information may be
arranged to identify said frequency subband in which said broadcast message is to be
broadcast; and said transmitter may be configured for broadcasting said broadcast
message in said frequency subband in which said broadcast message is to be broadcast.
[0131] The processor may be further configured to identify at least one frequency resource
(e.g. at least one physical resource block), within said frequency subband, on which
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said broadcast message is to be broadcast; said control information may be arranged to
identify said at least one frequency resource; and said transmitter may be configured
for broadcasting said broadcast message on said at least one frequency resource.
[0132] The frequency subband in which said broadcast message is to be broadcast and the
[0133]
frequency subband in which said control channel is transmitted may be different to one
another. In this case said processor may be configured to identify said at least one
subframe in which said broadcast message is to be broadcast such that there is at least
one further subframe between the at least one subframe in which said control channel
is transmitted and said at least one subframe in which said broadcast message is to be
broadcast (e.g. between the last subframe in which control information is repeated and
the first subframe in which said broadcast message is first broadcast).
The frequency subband in which said broadcast message is to be broadcast and the
frequency subband in which said control channel is transmitted may be the same. In
this case the processor may be configured to identify said at least one subframe in
which said broadcast message is to be broadcast such that there is no whole subframe
between the, or a last subframe of the, at least one subframe in which said control
channel is transmitted and the, or a first subframe of said at least one subframe in
which said broadcast message is to be broadcast.
[0134] The broadcast message may carry an indicator that a further broadcast message will
[0135]
[0136]
[0137]
follow in a subframe subsequent to (e.g. that immediately follows) the at least one
subframe in which said broadcast message is to be broadcast.
The control information may comprise information for identifying the at least one
device that said broadcast message carries information for. In this case, the information
for identifying may comprise at least one of: a group identifier for identifying a group
of devices of which said at least one device that said broadcast message carries information
for is a member; at least one preamble sequence identifier for identifying
said at least one device that said broadcast message carries information for; and an
identifier of a coverage enhancement level associated with the at least one device that
said broadcast message carries information for.
The base station may further comprise a receiver for receiving, from said at least one
communication device, a message carrying a random access preamble, wherein said
broadcast message comprises a message, carrying a random access response 'RAR' for
said at least one communication device.
The control information may comprise information for identifying the at least one
device that said broadcast message carries information for. For example, the information
for identifying the at least one device may comprise an identifier that equals
61 + 64 x f_id + PRA_id; where f_id may be an index of a frequency resource block
on which said message carrying a random access preamble was received and PRA_id
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may be a preamble sequence index. The information for identifying the at least one
device may also comprise an identifier that equals 61 + 4 x f_id + PRA_Group_id;
where f_id may be an index of a frequency resource block on which said message
carrying a random access preamble was received and PRA_Group_id may be an index
of a preamble sequence group of which said at least one device that said broadcast
message carries information for is a member. The information for identifying the at
least one device may also comprise an identifier that equals RA-RNTI = 61 + t_id + 64
x f_id + PRA_id; where t_id is an index of a subframe in which said message carrying
a random access preamble was received, f_id is an index of a frequency resource block
on which said message carrying a random access preamble was received, and PRA_id
is a preamble sequence index
[0138] The broadcast message may comprise a paging message broadcast using a paging
[0139]
channel.
The processor may be further configured to identify a modulation and coding scheme
'MCS' and/or transport block size 'TBS' for said paging message. The control Information
may be arranged to identify said MCS and/or TBS.
[0140] In the above exemplary embodiments, machine-type communication devices and
[0141]
[0142]
mobile telephones are described. However, it will be appreciated that mobile
telephones (and similar user equipment) may also be configured to operate as machinetype
communication devices. For example, the mobile telephone 3-1 may include
(and/or provide the functionality of) the MTC module 45.
Examples of MTC applications
It will be appreciated that each communication device may support one or more
MTC applications. Some examples of MTC applications are listed in the following
table (source: 3GPP TS 22.368 V13.1.0, Annex B). This list is not exhaustive and is
intended to be indicative of the scope of machine-type communication applications.
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[0143]
[0144]
[Table 1]
Service Area MTC applications
Security Surveillance systems
Backup for landline
Control of physical access (e.g. to buildings)
Car/driver security
Tracking & Tracing Fleet Management
Order Management
Pay as you drive
Asset Tracking
Navigation
Traffic information
Road tolling
Road traffic optimisation/steering
Payment Point of sales
Vending machines
Gaming machines
Health Monitoring vital signs
Supporting the aged or handicapped
Web Access Telemedicine points
Remote diagnostics
Remote Maintenance/Control Sensors
Lighting
Pumps
Valves
Elevator control
Vending machine control
Vehicle diagnostics
Metering Power
Gas
Water
Heating
Grid control
Industrial metering
Consumer Devices Digital photo frame
Digital carriera
eBook
Various other modifications will be apparent to those skilled in the art and will not be
described in further detail here.
The following is a detailed description of the way in which the present inventions
may be implemented in the currently proposed 3GPP standard. Whilst various features
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are described as being essential or necessary, this may only be the case for the
proposed 3GPP standard, for example due to other requirements imposed by the
standard. These statements should not, therefore, be construed as limiting the present
invention in any way.
[0 145] 1 Introduction
In the current RAN1 agreements, cross-subframe scheduling is supported for unicast
transmission (i.e. PDSCH for single UE). However, the scheduling methods for
broadcast transmission (i.e. RAR and Paging) has not been discussed yet.
[0146] In this contribution, we discuss the transmission of RAR messages and paging for
LTE Rel-13 MTC and provide some proposals at the end.
[0147] 2 Random Access Response (RAR) transmission
For MTC, the random access (RA) procedure is the same as legacy LTE system
which involves transmission of four messages (msg1-4). However, initially, MTC UE
should estimate the coverage level (0-3) based on some criteria for example using
downlink RSRP measurements in order to determine the number of repetitions for
PRACH message 1. Then, UE should select one of the PRACH resources allocated for
that coverage level and start random access procedure. eNB can determine the
coverage level from the PRACH resource used by the UE as there is one to one
mapping between PRACH resource set and PRACH repetition level. For the random
access response (RAR) message 2, it seems there are two different ways of scheduling
to the UEs as follows:
[0148] Option 1: Control-less RAR message- In this case, the number of PRBs can be fixed
to 6RBs, single TBS or limited set of TBS can be used where UE always tries a
number of blind decodings. The frequency location or sub band for RAR messages can
be fixed to center 6RBs or can be derived from PRACH resources. The main concern
is that this option lacks eNB scheduling flexibility as the frequency location cannot be
changed dynamically and it could also result a higher blocking probability for RAR
messages. In addition, in case a number of RAR messages end up on the same
subband, some kind of queueing will be necessary where UE tries to decode each RAR
message carried by PDSCH in the detection window. Hence, the power consumption at
the UE will be increased significantly.
[0149] Option 2: RAR message on EPDCCH CSS- another option is to define common
search space (eCSS) in EPDCCH to provide dynamic scheduling for RAR messages
where number of PRBs, TBS and frequency locations, etc. are included in the DCI
format. The disadvantage is the control overhead compare to Option 1 more
specifically for coverage enhanced mode where significant number of repetitions are
needed for eCSS transmission. The advantage is the eNodeB scheduling flexibility that
achieves an efficient system operation as well as reducing the blocking probability for
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RAR messages. In addition, it is possible to multiplex a number of RAR messages
which have same coverage level into a single TBS similar to Rel-8. If multiple
messages are multiplexed, the payload will increase and as a consequence the number
of repetitions in time domain will increase for a given coverage level. So, in order to
get a right balance, it is beneficial eNB to control the number of messages that can be
multiplexed depending on coverage level. For example, RAR messages for low
complexity MTC UEs in normal coverage can be multiplexed while enhanced
coverage mode (e.g. 5dB, 10dB and 15dB) single RAR message transmission is
preferable.
[0150] Furthermore, in order to reduce the power consumption at the UE, a new MTC RARNTI
may be necessary at least for coverage enhanced mode. The legacy RA-RNTI
has a range of 1 to 60 and is determined as follows:
RA-RNTI = 1 + t_id + 10*f_id
where t_id = index of the first subframe of the transmitted PRACH
[Math.9]
(0$. t_id <10)
and f_id = index of the transmitted PRACH in frequency domain of the same
sub frame
[Math.10]
( 0$./_id< 6).
[0151] One way is to re-think how RA-RNTI is derived by employing PRACH sequence
[0152]
index as an RA-RNTI. This will detach the new MTC RA-RNTI from multiple UEs
even if they select same t_id and f_id unless they pick up same PRACH sequence
index. The new MTC RA-RNTI can be placed above the legacy RA-RNTI range and
can be determined as follows:
RA-RNTI = 61+64* f_id + PRA_id
where PRA_id = the transmitted PRACH sequence index
[Math.11]
cos_ P RA td< 64).
So, if DCI is masked with sequence-specific RA-RNTI only intended UE(s) will be
able to receive, and other un-intended UEs will not be able to decode the DCI format
and subsequently will skip the associated PDSCH which will lead a significant power
saving. Therefore, from power saving perspective at the UE, Option 2 is preferable.
[0153] Observation 1: If new MTC RA-RNTI is employed based on PRACH sequence
[0154]
index, from power saving perspective at the UE, Option 2 (EPDCCH CSS) is
preferable for RAR messages.
Observation 2: For normal coverage, multiple RAR messages can be multiplexed
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[0155]
[0156]
[0157]
[0158]
together under the eNB control, however, for enhanced coverage mode (e.g. 5dB,
lOdB and 15dB), single RAR message transmission should be supported.
Proposal 1: EPDCCH CSS should be used for RA message 2 and 4 transmission
If EPDCCH CSS is adapted for RA messages, time domain repetition will be
necessary for both normal and enhanced coverage mode. In addition, the scheduled
subband index in frequency domain should be included in the DCI format in order to
achieve eNB scheduling flexibility. Hence, as shown in Figure 4, dynamic scheduling
via eCSS for RA message 2/4 using cross-subframe scheduling should be supported for
all MTC UEs.
Proposal 2: Cross-subframe scheduling is supported for RA message 2 and 4.
3 Paging transmission
The paging message is variable as the IDs of multiple UEs can be multiplexed.
Therefore, it is desirable to signal TBS in the DCI format that is transmitted on the
eCSS. In addition, for PDSCH carrying paging message, it is beneficial that the
subband index in frequency location should be selected dynamically from the available
sub-bands by utilizing cross-subframe scheduling as shown in Figure 5. This will
increase scheduling flexibility at the eNB and also decrease the blocking probability of
the paging messages.
[0159] Proposal3: EPDCCH CSS should be used for Paging transmission
[0160] Proposal4: Cross-subframe scheduling is supported for Paging transmission.
[0 161] 4 Conclusion
In this contribution, we have discussed the transmission of RAR messages and
paging for LTE Rel-13 MTC and we have the following observations and proposals.
[0162] Observation 1: If new MTC RA-RNTI is employed based on PRACH sequence
index, from power saving perspective at the UE, Option 2 (EPDCCH CSS) is
preferable for RAR messages.
[0163] Observation 2: For enhanced coverage mode (e.g. 5dB, 10dB and 15dB), single RAR
message transmission should be supported. However, for normal coverage, multiple
RAR messages can be multiplexed together under the eNB control.
[0164] Proposal1: EPDCCH CSS should be used for RA message 2, 4 and Paging
[0165]
[0166]
transmission
Proposal 2: Cross-subframe scheduling is supported for RA message 2, 4 and Paging
transmission
5 References
1) 3GPP TR 36.888 V12.0.0, "Study on provision of low-cost MTC UEs based on
LTE (Release-12)".
2) RP-150492, "Revised WI: Further LTE Physical Layer Enhancements for MTC",
Ericsson, RAN#67
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[0167]
[0168]
3) R1-151555, "Further details of Physical Downlink Control Channel for MTC",
NEC, RAN 1 #80bis
The whole or part of the exemplary embodiments disclosed above can be described
as, but not limited to, the following supplementary notes.
(Supplementary note 1). A base station for a communication system in which communication
devices communicate via said base station using radio frames made up of a
sequence of subframes and a frequency band made up of frequency subbands, the base
station comprising:
a processor configured to identify at least one subframe in which a broadcast
message, carrying information for at least one communication device, is to be
broadcast;
a transmitter configured for:
transmitting, in a control channel, in a frequency subband in at least one
subframe that precedes said at least one subframe in which said broadcast message is
to be broadcast, control information to identify said at least one subframe in which said
broadcast message is to be broadcast; and
broadcasting said broadcast message in said at least one subframe in which said
broadcast message is to be broadcast.
[0169] (Supplementary note 2). The base station according to Supplementary note 1,
wherein said at least one communication device comprises at least one coverage
enhanced machine type communication 'MTC' device, wherein said at least one
subframe in which said control information is transmitted comprises a plurality of
subframes in which said control information is to be first transmitted and then
repeated, and wherein said at least one subframe in which a broadcast message is to be
broadcast comprises a plurality of subframes in which said broadcast message is to be
first broadcast and then repeated.
[0170] (Supplementary note 3). The base station according to Supplementary note 1 or 2,
[0171]
wherein said broadcast message carries multiplexed information for each of a plurality
of communication devices.
(Supplementary note 4). The base station according to Supplementary note 3,
wherein said broadcast message carries multiplexed information for each of a plurality
of coverage enhanced machine type communication 'MTC' devices sharing a common
coverage enhancement level.
[0172] (Supplementary note 5). The base station according to any one of Supplementary
notes 1 to 4, wherein said processor is further configured to identify a frequency
subband in which said broadcast message is to be broadcast; wherein said control Information
is arranged to identify said frequency subband in which said broadcast
message is to be broadcast; and wherein said transmitter is configured for broadcasting
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said broadcast message in said frequency subband in which said broadcast message is
to be broadcast.
[0173] (Supplementary note 6). The base station according to Supplementary note 5,
[0174]
wherein said processor is further configured to identify at least one frequency resource
(e.g. at least one physical resource block), within said frequency subband, on which
said broadcast message is to be broadcast; wherein said control information is arranged
to identify said at least one frequency resource; and wherein said transmitter is
configured for broadcasting said broadcast message on said at least one frequency
resource.
(Supplementary note 7). The base station according to Supplementary note 5 or 6,
wherein when said frequency subband in which said broadcast message is to be
broadcast and said frequency subband in which said control channel is transmitted are
different to one another, said processor is configured to identify said at least one
subframe in which said broadcast message is to be broadcast such that there is at least
one further subframe between the at least one subframe in which said control channel
is transmitted and said at least one subframe in which said broadcast message is to be
broadcast (e.g. between the last subframe in which control information is repeated and
the first subframe in which said broadcast message is first broadcast).
[0175] (Supplementary note 8). The base station according to any one of Supplementary
notes 5 to 7, wherein when said frequency subband in which said broadcast message is
to be broadcast and said frequency subband in which said control channel is
transmitted are the same, said processor is configured to identify said at least one
subframe in which said broadcast message is to be broadcast such that there is no
whole subframe between the, or a last subframe of the, at least one subframe in which
said control channel is transmitted and the, or a first subframe of said at least one
subframe in which said broadcast message is to be broadcast.
[0176] (Supplementary note 9). The base station according to any one of Supplementary
notes 1 to 8, wherein said broadcast message carries an indicator that a further
broadcast message will follow in a subframe subsequent to (e.g. that immediately
follows) the at least one subframe in which said broadcast message is to be broadcast.
[0177] (Supplementary note 10). The base station according to any one of Supplementary
notes 1 to 9, wherein said control information comprises information for identifying
the at least one communication device that said broadcast message carries information
for.
[0178] (Supplementary note 11). The base station according to Supplementary note 10,
wherein said information for identifying comprises at least one of: a group identifier
for identifying a group of devices of which said at least one communication device that
said broadcast message carries information for is a member; at least one preamble
33
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sequence identifier for identifying said at least one communication device that said
broadcast message carries information for; and an identifier of a coverage enhancement
level associated with the at least one communication device that said
broadcast message carries information for.
[0179] (Supplementary note 12). The base station according to any one of Supplementary
[0180]
[0181]
notes 1 to 11, further comprising a receiver for receiving, from said at least one communication
device, a message carrying a random access preamble, wherein said
broadcast message comprises a message, carrying a random access response 'RAR' for
said at least one communication device.
(Supplementary note 13). The base station according to Supplementary note 12,
wherein said control information comprises information for identifying the at least one
communication device that said broadcast message carries information for and wherein
said information for identifying comprises an identifier that equals 61 + 64 x f_id +
PRA_id; where f_id is an index of a frequency resource block on which said message
carrying a random access preamble was received and PRA_id is a preamble sequence
index.
(Supplementary note 14). The base station according to Supplementary note 12,
wherein said control information comprises information for identifying the at least one
communication device that said broadcast message carries information for and wherein
said information for identifying comprises an identifier that equals 61 + 4 x f_id +
PRA_Group_id; where f_id is an index of a frequency resource block on which said
message carrying a random access preamble was received and PRA_Group_id is an
index of a preamble sequence group of which said at least one communication device
that said broadcast message carries information for is a member.
[0182] (Supplementary note 15). The base station according to Supplementary note 12,
wherein said control information comprises information for identifying the at least one
communication device that said broadcast message carries information for and wherein
said information for identifying comprises an identifier that equals RA-RNTI = 61 +
t_id + 64 x f_id + PRA_id; where t_id is an index of a subframe in which said message
carrying a random access preamble was received, f_id is an index of a frequency
resource block on which said message carrying a random access preamble was
received, and PRA_id is a preamble sequence index.
[0183] (Supplementary note 16). The base station according to any one of Supplementary
notes 1 to 11, wherein said broadcast message comprises a paging message broadcast
using a paging channel.
[0184] (Supplementary note 17). The base station according to Supplementary note 16,
wherein said processor is further configured to identify a modulation and coding
scheme 'MCS' and/or transport block size 'TBS' for said paging message; wherein
34
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said control information is arranged to identify said MCS and/or TBS.
[0185] (Supplementary note 18). The base station according to any one of Supplementary
[0186]
notes 1 to 17, wherein said at least one communication device comprises at least one
machine type communication 'MTC' device (e.g. a reduced bandwidth or low
complexity MTC device and/or a coverage enhanced MTC device).
(Supplementary note 19). A communication device for communicating with a base
station using radio frames made up of a sequence of subframes and a frequency band
made up of frequency subbands, the communication device comprising:
a receiver configured for receiving, in a control channel, in a frequency subband in at
least one subframe, control information to identify at least one later subframe in which
a broadcast message is to be broadcast; and
a processor configured to identify, from said control information, said at least one
later subframe in which said broadcast message is to be broadcast;
wherein said processor is configured to control said receiver to monitor said at least
one later subframe in which said broadcast message is to be broadcast for said
broadcast message and to receive said broadcast message when it has been broadcast.
[0187] (Supplementary note 20). A system comprising the base station according to any one
[0188]
of Supplementary notes 1 to 18 and the communication device according to Supplementary
note 19.
(Supplementary note 21). A method performed by a base station in a communication
system in which communication devices communicate via said base station using radio
frames made up of a sequence of subframes and a frequency band made up of
frequency subbands, the method comprising:
identifying at least one subframe in which a broadcast message, carrying information
for at least one communication device, is to be broadcast;
transmitting, in a control channel, in a frequency subband in at least one subframe
that precedes said at least one subframe in which said broadcast message is to be
broadcast, control information to identify said at least one subframe in which said
broadcast message is to be broadcast; and
broadcasting said broadcast message in said at least one subframe in which said
broadcast message is to be broadcast.
[0189] (Supplementary note 22). A method performed by a communication device for communicating
with a base station using radio frames made up of a sequence of subframes
and a frequency band made up of frequency subbands, the method comprising:
receiving, in a control channel, in a frequency subband in at least one subframe,
control information to identify at least one later subframe in which a broadcast
message is to be broadcast;
identifying, from said control information, said at least one subframe in which said
35
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[0190]
broadcast message is to be broadcast; and
monitoring said at least one later subframe in which said broadcast message is to be
broadcast for said broadcast message and receiving said broadcast message when it has
been broadcast.
(Supplementary note 23). A computer implementable instructions product
comprising computer implementable instructions for causing a programmable communications
device to perform the method of Supplementary note 21 or 22.
[0 191] This application is based upon and claims the benefit of priority from United
Kingdom Patent Application No. 1506151.8, filed on AprillO, 2015, the disclosure of
which is incorporated herein in its entirety by reference.
wo 2016/163126
[Claim 1]
[Claim 2]
[Claim 3]
[Claim 4]
[Claim 5]
[Claim 6]
[Claim 7]
[Claim 8]
[Claim 9]
[Claim 10]

Claims
A mobile station which communicates with a base station, the mobile
station comprising;
means for receiving a first parameter and a second parameter;
means for transmitting a first message;
means for receiving a control channel based on the first parameter and
the second parameter; and
means for decoding a downlink shared channel associated with the
control channel based on information in the control channel,
wherein the first parameter is related to at least one sub-frame to
receive the control channel,
wherein the second parameter is related to at least one narrow band to
receive the control channel.
The mobile station according to claim 1, wherein the control channel
and the downlink shared channel are in a second message.
The mobile station according to claim 1 or 2, wherein the mobile
station further comprises means for transmitting a third message based
on information in the downlink shared channel, wherein the information
in the downlink shared channel comprises a third parameter
which is related to at least one narrow band to transmit the third
message.
The mobile station according to any one of claims 1 to 3, wherein the
control channel comprises a third parameter which is related to
repetition of the downlink shared channel.
The mobile station according to any one of claims 1 to 4, wherein the
information in the downlink shared channel further comprises a fourth
parameter which is related to at least one narrow band to receive a
fourth message.
The mobile station according to any one of claims 1 to 5, wherein the
second parameter is a narrow band index.
The mobile station according to any one of claims 3 to 6, wherein the
third parameter is a narrow band index.
The mobile station according to any one of claims 5 to 7, wherein the
fourth parameter is a narrow band index.
The mobile station according to any one of claims 1 to 8, wherein the
first parameter is received by using System Information Block(SIB).
The mobile station according to any one of claims 1 to 8, wherein the
wo 2016/163126
[Claim 11]
[Claim 12]
[Claim 13]
[Claim 14]
[Claim 15]
[Claim 16]
37
PCT /JP2016/001950
second parameter is received by using another SIB.
The mobile station according to any one of claims 1 to 10, wherein the
control channel for the mobile station is multiplexed with control
channels for other mobile stations.
The mobile station according to any one of claims 1 to 11, wherein the
downlink shared channel for the mobile station comprises a multiplexed
data of other mobile stations.
A base station which communicates with a mobile station, the base
station comprising;
means for transmitting a first parameter and a second parameter;
means for receiving a first message;
means for transmitting a control channel based on the first parameter
and the second parameter; and
means for transmitting a downlink shared channel associated with the
control channel based on the control part of the first message,
wherein the first parameter is related to at least one sub-frame to
receive the control channel,
wherein the second parameter is related to at least one narrow band to
receive the control channel.
A method performed by a mobile station which communicates with a
base station, the method comprising;
receiving a first parameter and a second parameter;
transmitting a first message;
receiving a control channel based on the first parameter and the second
parameter; and
decoding a downlink shared channel associated with the control
channel based on information in the control channel,
wherein the first parameter is related to at least one sub-frame to
receive the control channel,
wherein the second parameter is related to at least one narrow band to
receive the control channel.
The method according to claim 14, wherein the control channel and the
downlink shared channel are in a second message.
The method according to claim 14 or 15, wherein the method further
comprises transmitting a third message based on information in the
downlink shared channel, wherein the information in the downlink
shared channel comprises a third parameter which is related to at least
one narrow band to transmit the third message.
wo 2016/163126
[Claim 17]
[Claim 18]
[Claim 19]
[Claim 20]
[Claim 21]
[Claim 22]
[Claim 23]
[Claim 24]
[Claim 25]
[Claim 26]
[Claim 27]
38
PCT /JP2016/001950
The method according to claim 14 or 15, wherein the control channel
comprises a third parameter which is related to repetition of the
downlink shared channel.
The method according to any one of claims 14 to 17, wherein the mformation
in the downlink shared channel further comprises a fourth
parameter which is related to at least one narrow band to receive a
fourth message.
The method according to any one of claims 14 to 18, wherein the
second parameter is a narrow band index.
The method according to any one of claims 16 to 19, wherein the third
parameter is a narrow band index.
The method according to any one of claims 18 to 20, wherein the fourth
parameter is a narrow band index.
The method according to any one of claims 14 to 21, wherein the first
parameter is received by using System Information Block (SIB).
The method according to any one of claims 14 to 21, wherein the
second parameter is received by using another SIB.
The method according to any one of claims 14 to 23, wherein the
control channel for the mobile station is multiplexed with control
channels for other mobile stations.
The method according to any one of claims 14 to 24, wherein the
downlink shared channel for the mobile station comprises a multiplexed
data of other mobile stations.
A method performed by a base station which communicates with a
mobile station, the method comprising;
transmitting a first parameter and a second parameter;
receiving a first message;
transmitting a control channel based on the first parameter and the
second parameter; and
transmitting a downlink shared channel associated with the control
channel based on the control part of the first message,
wherein the first parameter is related to at least one sub-frame to
receive the control channel,
wherein the second parameter is related to at least one narrow band to
receive the control channel.
A mobile station which communicates with a base station, the mobile
station comprising;
a receiver configured to receive a first parameter and a second
wo 2016/163126
[Claim 28]
39
PCT /JP2016/001950
parameter;
a transmitter for transmitting a first message; and
a controller,
wherein the receiver is further configured to receive a control channel
based on the first parameter and the second parameter,
wherein the controller is configured to decode a downlink shared
channel associated with the control channel based on information in the
control channel,
wherein the first parameter is related to at least one sub-frame to
receive the control channel,
wherein the second parameter is related to at least one narrow band to
receive the control channel.
A base station which communicates with a mobile station, the base
station comprising;
a transmitter configured to transmit a first parameter and a second
parameter; and
a receiver configured to receive a first message;
wherein the transmitter is further configured to transmit a control
channel based on the first parameter and the second parameter,
wherein the transmitter is further configured to transmit a downlink
shared channel associated with the control channel based on the control
part of the first message,
wherein the first parameter is related to at least one sub-frame to
receive the control channel,
wherein the second parameter is related to at least one narrow band to
receive the control channel.