0001] The present invention relates to mobile communications devices and networks, p ar
ticularly 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 commu
nication 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) carries the
scheduling assignments and other control information. The PDCCH serves a variety of
purposes. Primarily, it is used to convey the scheduling decisions to individual commu
nication devices, i.e. scheduling assignments for uplink and downlink communication.
[0004] The information carried on the PDCCH is referred to as downlink control in
formation (DCI). Physical control channels, such as the 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).
[0005] 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
the two parts combined) depends on the frame structure and the random access configuration.
The preamble format is controlled by higher layers (via the SIB2). Thus,
based on the parameters included in the SIB2, communication devices are able to
initiate access with the network over the correct PRACH resource and using the ap
propriate parameters (e.g. transmit an appropriate preamble). Further details of the
physical layer random access preamble can be found in section 5.7.1 of 3GPP
Technical Specification (TS) 36.21 1, the contents of which are incorporated herein by
reference.
[0006] When an idle mode communication device needs to communicate with other commu
nication 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 commu
nication device performs a random access 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. If the base station does not
receive the communication device's transmission successfully (e.g. because a plurality
of devices are transmitting preambles at the same time resulting in a collision) and/or
does not send an appropriate random access response, then the communication device
is configured to send another preamble sequence after a predetermined delay (and
possibly repeat this step until the base station responds). If the communication device's
transmission is received successfully (e.g. its transmission does not collide with trans
missions by others), 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 com
municating with the network.
[0007] Thus, once the base station responds to a preamble transmission by the commu
nication device, the communication device is able to request in its next message the e s
tablishment 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 resources allocated by
the base station.
[0008] Recent developments in telecommunications have seen a large increase in the use of
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) commu
nication devices.
[0009] 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 su
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 TS 22.368 standard, the contents of which are incorporated herein by reference.
[0010] For the Release 13 (Rel-13) version of the standards relating to MTC devices,
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.
[001 1] 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
PDCCH, not being received by an MTC device. In order to mitigate this risk, it has
been proposed to increase the coverage of the PDCCH (and/or the evolved physical
downlink control channel (EPDCCH) in Rel-13) to support such MTC devices (e.g.
corresponding to 20dB for frequency division duplex (FDD) transmissions).
[0012] One approach proposed for the enhancement of coverage, for so called 'coverage
enhanced MTC devices', is the repetition of the same EPDCCH information (e.g. DCI)
across multiple (e.g. two, three, four) subframes. In other words, for coverage
enhanced MTC devices, the base station duplicates the EPDCCH information in the
time domain (the base station re-transmits the same EPDCCH information in one or
more subframes subsequent to the subframe in which that EPDCCH information is first
sent). Such a coverage enhanced MTC device can be configured to combine the
multiple copies of the (same) EPDCCH 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 EPDCCH successfully than based on a
single copy of the EPDCCH information.
[0013] In practice, MTC devices may be deployed in different locations and they may ex
perience different channel conditions. Therefore, the number of repetitions (of the
EPDCCH information) may need to be tailored for each device's situation or coverage
level. Therefore, in order to facilitate such enhanced coverage, each MTC device will
need to inform its serving base station of the amount of coverage required (e.g.
5dB/10dB/15dB/20dB coverage enhancement) to allow the base station to adjust its
control signalling appropriately.
[0014] Ideally, however, physical layer control signalling (e.g. EPDCCH signalling) and
higher layer common control information (e.g. SIB, random access response (RAR),
paging messages, and/or the like) exhibit a high level of commonality between
solutions for reduced bandwidth communication devices and solutions for coverage
enhanced communication devices.
[0015] However, the inventors have realised that in order to support reduced bandwidth
MTC devices in release 13, the provision of PRACH for the reduced bandwidth MTC
devices needs to address a number of issues including, for example:
- due to the reduced bandwidth of 1.4 MHz in downlink and uplink, the reduced
bandwidth MTC devices cannot receive a PDCCH which is densely spread across an
entire cell bandwidth (i.e. it may be transmitted over frequencies falling outside the 1.4
MHz supported by the MTC device);
- consequently, reduced bandwidth MTC devices also cannot receive the
scheduling assignment included in legacy RAR messages transmitted in the PDCCH
(when it is spread across the entire cell bandwidth); and
- the EPDCCH Common Search Space (CSS) can be defined in such a way that
the physical broadcast channel (PBCH) indicates its location in time-frequency
resources; in which case a reduced bandwidth MTC device will be unable to receive
the CSS if either the PBCH or the EPDCCH is transmitted outside the 1.4 MHz band
supported by the MTC device.
[0016] It appears that there is no need to change the current PRACH design in order to
support reduced bandwidth MTC devices in Rel-13, except that DCI for RAR
messages will need to be transmitted in the EPDCCH Common Search Space (CSS),
rather than in the PDCCH CSS, for MTC devices (since a Rel-13 MTC device will
only monitor the EPDCCH CSS for potential dynamic scheduling of the common
control information). However, it is yet to be resolved how a base station can e f
ficiently and reliably identify a reduced bandwidth MTC device in Rel-13 so that the
corresponding DCI (e.g. a RAR message) is transmitted in the EPDCCH CSS (for the
bandwidth reduced MTC device).
[0017] In addition to the issues associated with reduced bandwidth MTC devices, the
provision of PRACH for coverage enhanced MTC devices in Rel-13 will need to
support the repetition of the PRACH, across multiple subframes in time domain, by
using the existing LTE Rel-8 preamble formats in order to enhance the coverage of the
PRACH channel and for backward compatibility.
[0018] Therefore, the provision of PRACH for coverage enhanced MTC UEs in Rel-13 also
needs to address at least the following issues:
- how to identify reduced bandwidth communication devices and coverage
enhanced MTC communication devices in Rel-13 (so that a DCI/RAR can be
transmitted in the EPDCCH CSS for such communication devices);
- how to reduce the collision probability (contention problem) between reduced
bandwidth communication devices and coverage enhanced (CE) communication
devices, and also between different CE levels; and
- because there is a lot of overhead associated with CE levels (due to time domain
repetitions), it is desirable to avoid PRACH preamble collision with other coverage
levels as well as reduced bandwidth communication devices (although collision/
contention with the same CE level should be allowed).
Summary of Invention
[0019] The present invention seeks to provide systems, devices and methods which at least
partially address the above issues.
[0020] According to one aspect the invention provides a communications node operable to
allocate resources for potential use by any of a plurality of user communication
devices, including first type (e.g. legacy) user communication devices and second type
(e.g. machine-type) communication devices, for communicating with the commu
nications node, the communications node comprising: means for sending, to said
plurality of user communication devices, control data defining communication
resources for potential use by any of said plurality of user communication devices, the
control data including information identifying at least; i) a first physical random access
channel, PRACH, resource configuration for said first type user communication
devices; and ii) a second PRACH resource configuration for said second type devices;
means for receiving, from a user communication device of said plurality of user com
munication devices, a random access message conforming to one of said first and
second PRACH resource configurations over communication resources defined by said
control data; and means for determining, based on the PRACH resource configuration
with which said received random access message conforms, whether said user commu
nication device comprises a first type user communication device or comprises a
second type device.
[0021] The means for sending may be operable to send a random access response (RAR)
mapped to a physical downlink control channel (PDCCH) when said user commu
nication device is determined to comprise a first type user communication device and
to send a random access response (RAR) mapped to an enhanced physical downlink
control channel (EPDCCH) when said user communication device is determined to
comprise an MTC device.
[0022] Each said PRACH resource configuration may define an associated preamble
sequence and wherein said random access message may include a prefix and a
preamble sequence conforming to one of said first and second PRACH resource con
figurations, and wherein said determining means may be operable to determine
whether said first user communication device comprises a first type user commu
nication device or comprises a second type device based on said preamble sequence
included in said random access message.
[0023] The first PRACH resource configuration may defines a first set of communication
resources for potential use by said first type user communication devices. The second
PRACH resource configuration may define a second set of communication resources,
different to said first set, for potential use by said second type devices. The de
termining means may be operable to determine that: i) the first user communication
device comprises a first type user communication device when said receiving means
receives said random access message over a communication resource that belongs to
said first set of communication resources. The determining means may be operable to
determine that: ii) the first user communication device comprises a second type device
when said receiving means receives said random access message over a commu
nication resource that belongs to said second set of communication resources.
[0024] The determining means may be operable to determine, when said user commu
nication device is a second type device, whether that second type device comprises a
reduced bandwidth second type device and/or a coverage enhanced second type device.
[0025] The determining means may be operable to determine, when said user commu
nication device is a coverage enhanced second type device, a level of coverage en
hancement required by said coverage enhanced second type device.
[0026] At least one of said first and said second PRACH resource configurations may define
a set of communication resources comprising no more than six physical resource
blocks.
[0027] The communications node may comprise a base station.
[0028] The communications node may comprise a base station operating in accordance with
the long term evolution, LTE, set of standards.
[0029] The communication resources may be resources provided in accordance with at least
one of a time, a frequency, and code sequence multiplexing scheme.
[0030] According to one aspect the invention provides a machine-type communication,
(MTC), device for a communication system in which a communications node allocates
resources for potential use by any of a plurality of user communication devices,
including first type (e.g. legacy) user communication devices and MTC communication
devices, the second type communications device comprising: means for
receiving, from the communications node, control data defining communication
resources for potential use by any of said plurality of user communication devices, the
control data including information identifying at least; i) a first physical random access
channel, PRACH, resource configuration for said first type user communication
devices; and ii) a second PRACH resource configuration for said MTC devices; and
means for sending, to the communications node, a random access message conforming
to said second PRACH resource configuration over communication resources defined
by said control data.
[0031] The means for receiving may be operable to receive a random access response (RAR)
mapped to an enhanced physical downlink control channel (EPDCCH) responsive to
said random access message.
[0032] According to one aspect the invention provides a method performed by a commu
nications node in a communication system in which the communications allocates
resources for potential use by any of a plurality of user communication devices,
including first type user communication devices and second type (e.g. machine-type)
communication devices, for communicating with the communications node, the
method comprising: sending, to said plurality of user communication devices, control
data defining communication resources for potential use by any of said plurality of
user communication devices, the control data including information identifying at
least; i) a first physical random access channel, PRACH, resource configuration for
said first type user communication devices; and ii) a second PRACH resource con
figuration for said second type devices; receiving, from a user communication device
of said plurality of user communication devices, a random access message conforming
to one of said first and second PRACH resource configurations over communication
resources defined by said control data; and determining, based on the PRACH resource
configuration with which said received random access message conforms, whether said
user communication device comprises a first type user communication device or
comprises a second type device.
[0033] The method may further comprise: sending a random access response (RAR) mapped
to a physical downlink control channel (PDCCH) when said user communication
device is determined to comprise a first type user communication device; and sending
a random access response (RAR) mapped to an enhanced physical downlink control
channel (EPDCCH) when said user communication device is determined to comprise a
second type device.
[0034] According to one aspect the invention provides a method performed by a machinetype
communication, 'MTC, device in a communication system in which a commu
nications node allocates resources for potential use by any of a plurality of user communication
devices, including first type user communication devices and MTC
devices, the method comprising: receiving, from the communications node, control
data defining communication resources for potential use by any of said plurality of
user communication devices, the control data including information identifying at
least; i) a first physical random access channel, PRACH, resource configuration for
said first type user communication devices; and ii) a second PRACH resource con
figuration for said MTC devices; and sending, to the communications node, a random
access message conforming to said second PRACH resource configuration over com
munication resources defined by said control data.
[0035] The method may further comprise receiving a random access response (RAR)
mapped to an enhanced physical downlink control channel (EPDCCH) responsive to
said random access message.
[0036] Aspects of the invention extend to corresponding systems, methods, and 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.
[0037] 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 com
bination 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 indi
vidually.
Brief Description of Drawings
[0038] Embodiments of the invention will now be described by way of example only with
reference to the attached figures in which:
[fig.l]Figure 1 schematically illustrates a telecommunication system to which em
bodiments of the invention may be applied;
[fig.2]Figure 2 is a block diagram illustrating the main components of the commu
nication 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 an exemplary way in which UE category specific PRACH
configurations can be employed in the system shown in Figure 1;
[fig.5]Figure 5 illustrates an exemplary way in which UE category specific PRACH
configurations can be employed in the system shown in Figure 1; and
[fig.6]Figure 6 illustrates an exemplary way in which UE category specific PRACH
configurations can be employed in the system shown in Figure 1.
Description of Embodiments
[0039]
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 im
plemented, will typically include other base stations and communication devices.
[0040] The base station 5 is connected to the core network 7 via an S1 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 in
formation (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.
[0041] Each communication device 3 may fall into one or more of 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 group of
communication 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 group may not
support the EPDCCH (only PDCCH). A second 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 third 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).
[0042] 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 common search space of 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 (pre-Rel-13) communication
devices.
[0043] The so-called common search space (CSS) carries downlink control information
(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 forms part of the EPDCCH. The (time-frequency)
resources allocated for the CSS are indicated via the so-called physical broadcast
channel (PBCH).
[0044] The base station 5 is configured to transmit a 'SIB2' in its 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. A
typical PRACH resource configuration for a cell and the associated parameters and
values are illustrated in Table 1.
[0045] [Table 1]
Table 1- PRACH resource configuration in SIB2
[0046] 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 commu
nication 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.
[0047] However, as also explained above, some communication devices may support only
an earlier release of the LTE standard (legacy UEs) than the release supported by the
base station 5, some communication devices may comprise reduced bandwidth UEs,
and some communication devices may comprise coverage enhanced UEs.
[0048] Beneficially, the PRACH is configured in the cell of the base station 5 in such a way
that different categories of communication devices are allocated different PRACH
resources and/or different PRACH preambles for use upon initiation of a random
access procedure with the base station 5. In this example, the different categories of
communication devices comprise: i) legacy UEs (MTC devices); ii) reduced bandwidth
UEs (MTC devices); and iii) coverage enhanced UEs (MTC devices). Accordingly, the
PRACH configuration by the base station 5 comprises separate PRACH configuration
parameters for each category of UEs (specifying the respective associated PRACH
resources and/or associated PRACH preambles per UE category).
[0049] Therefore, upon receipt of a random access preamble sequence, the base station 5 is
advantageously able to determine (by checking the PRACH resources and/or PRACH
preambles used) the category of the communication device 3 that sent the preamble
sequence. Specifically, the base station 5 is able to discern at least legacy UEs (MTC
devices), reduced bandwidth UEs (MTC devices), and coverage enhanced UEs (MTC
devices) from each other.
[0050] In the example shown in Figure 1, the mobile telephone 3-1 comprises a legacy UE
and the MTC device 3-2 comprises a reduced bandwidth MTC device. By listening to
the SIB2 information (broadcast by the base station 5), both the mobile telephone 3-1
and the MTC device 3-2 are able to derive the applicable PRACH configuration for its
category of UEs, and perform random access procedures accordingly. Thus, the mobile
telephone 3-1 selects one of the appropriate PRACH preambles associated with legacy
UEs and transmits the selected preamble to the base station 5 over the PRACH
resource associated with legacy UEs. On the other hand, the MTC device 3-2 selects
one of the appropriate PRACH preambles associated with reduced bandwidth UEs and
transmits the selected preamble to the base station 5 over the PRACH resource a s
sociated with reduced bandwidth UEs.
[0051] Therefore, based on the received preamble and/or the used PRACH resource, the
base station 5 is able to discern the mobile telephone 3-1 from the MTC device 3-2,
and send a random access response (RAR) accordingly. Specifically, the base station 5
is configured to send a RAR including an appropriate DCI: i) in the PDCCH CSS (in
response to a preamble sequence sent by a legacy UE); and in the EPDCCH CSS (in
response to a preamble sequence sent by a reduced bandwidth UE and/or a coverage
enhanced UE).
[0052] In summary, the base station is advantageously able to allocate PRACH resources
according to the category of the communication device (by broadcasting appropriate
PRACH configurations per category), and respond to preamble transmissions over
communication resources (PDCCH/EPDCCH) that the UE category of the sending
communication device is able to use.
[0053]
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.
[0054] The operation of the transceiver circuit 3 1 is controlled by a controller 37 in ac
cordance with software stored in memory 39. The software includes, among other
things, an operating system 41, a communication control module 43, an MTC module
45, and a random access module 47.
[0055] The communication control module 43 controls communications between the com
munication device 3 and the base station 5 and/or other communication nodes (via the
base station 5).
[0056] 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).
[0057] The random access module 47 is responsible for obtaining and maintaining synchro
nisation 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. When selecting/sending a
random access preamble sequence, the random access module 47 takes into account
the category of the communication device 3 and the PRACH configuration (broadcast
by the base station 5) applicable for that category of communication devices.
[0058]
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 SI interface). The
operation of the transceiver circuit 51 is controlled by a controller 57 in accordance
with software stored in memory 59.
[0059] The software includes, among other things, an operating system 61, a communication
control module 63, a broadcast module 65, a PRACH configuration module 67, and a
UE category determination module 69.
[0060] The communication control module 53 controls communications with the commu
nication devices 3. The communication control module 53 is also responsible for
scheduling the resources to be used by the communication devices 3 served by this
base station 5.
[0061] The broadcast module 65 transmits, via the broadcast channel, system information
(such as configuration of the cell of the base station 5) for receipt by the commu
nication devices 3 located within the cell of the base station 5. For example, the
broadcast module 65 transmits the PRACH configuration employed in the cell.
[0062] The PRACH configuration module 67 is responsible for configuring associated
random access parameters for use by each category of communication devices when
communicating over the PRACH. The PRACH configuration module 67 is responsible
for informing (via the broadcast module 65) the communication devices 3 located
within the cell of the base station 5 about the random access (PRACH) configuration
applicable for each category of communication devices.
[0063] The UE category determination module 69 determines, based on the received
preamble sequence (e.g. the time/frequency resource the preamble sequence is sent on
and/or the selected preamble) the category of the sending communication device 3.
[0064] 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.
[0065] A number of embodiments (options A to D) will be described below, with reference
to Figures 4 to 6. It will be appreciated that these embodiments are not mutually
exclusive and any of the options A to D may be combined within the same system,
either within a single cell and/or in neighbouring cells. For example, the base station 5
may be configured to change from one operation mode to another, e.g. periodically, in
dependence on the number of MTC devices 2 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), and/or the like.
[0066]
This embodiment is based on the concept of (PRACH) preamble sequence p ar
titioning. In other words, different (sets of) preamble sequences are reserved for
different categories of communication devices 3 (e.g. reduced bandwidth MTC
devices, coverage enhanced MTC devices, mobile telephones conforming to different
releases of the LTE standards, and/or communication devices operating in different
operation modes, such as MTC mode / UE mode).
[0067] In this example, the base station 5 (using its PRACH configuration module 67)
allocates a first set of preamble sequences to legacy communication devices, allocates
a second set of preamble sequences (different to the first set) to (MTC) communication
devices operating in reduced bandwidth (BW) mode, and allocates a third set of
preamble sequences (different to the first set and the second set) to (MTC) commu
nication devices operating in coverage enhanced (CE) mode. One or more of the sets
of preamble sequences may also be split into further sub-sets, when appropriate. An
exemplary preamble sequence partitioning is illustrated in Table 2 below, in which the
first set includes PRACH preambles 0-31, the second set includes PRACH preambles
32-42, and the third set includes PRACH preambles 43-63 (further divided into four
sub-sets for different levels of coverage enhancement).
[0068] [Table 2]
- preamble sequence partitioning
[0069] The base station 5 is beneficially configured to broadcast (using its broadcast module
65) in its cell information relating to the applicable preamble sequence partitioning via
higher layer signalling (e.g. SIB2), for example, by using an appropriate PRACH con
figuration index. This way the base station 5 is able to inform communication devices
3 within its cell which preamble sequence applies to each category of devices so that
the communication devices 3 are able to select and transmit a preamble sequence that
(implicitly) indicates to the base station 5 the category of that communication device 3.
[0070] For example, if the MTC device 3-2 is a reduced bandwidth UE, then it selects (using
its MTC module 45) a preamble from preambles no. 32 to 42 and transmits (using its
transceiver circuit 43) this preamble to the base station 5 over the PRACH (in any
subframe in which PRACH is configured). Based on the received preamble, the base
station 5 is able to determine (using its UE category determination module 69) that the
sending communication device 3-2 is a reduced bandwidth MTC device, and allocates
resources accordingly (sets a DCI for the MTC device 3-2 such that the allocated
resources fall within the bandwidth that the MTC device 3-2 is capable to use).
[0071] Advantageously, based on the received preamble sequence and the set to which that
preamble sequence belongs, the base station 5 is able to determine whether to transmit
a DCI in the PDCCH CSS (i.e. in response to a preamble sequence sent by a legacy
MTC device) or to transmit a DCI in the EPDCCH CSS (i.e. in response to a preamble
sequence sent by a reduced bandwidth MTC device or a coverage enhanced MTC
device). In other words, the base station 5 is configured to send Random Access
Response (RAR) messages (which include an appropriate DCI) via the EPDCCH
Common Search Space (EPDCCH CSS) for reduced bandwidth MTC devices and for
enhanced coverage MTC devices.
[0072] It will be appreciated that option A can be realised regardless of whether or not the
multiplexing scheme illustrated in Table 2 is used. However, if preamble sequence p ar
titioning is used, then the number of available preamble sequences for each partition
may be small which in turn may increase collision probability between the same
category of MTC devices.
[0073]
Figure 4 illustrates an exemplary way in which UE category specific PRACH config
urations can be employed in the system shown in Figure 1. In this example, the base
station 5 employs, for each category of communication devices 3, a respective a s
sociated PRACH configuration using different time resources (e.g. in a different
subframe for each device category).
[0074] The various PRACH configuration indices (and the associated preamble formats and
subframes) that may currently be used in LTE systems are disclosed in Table 5.7.1-2 of
3GPP TS 36.21 1. Some of the PRACH indices that may be used in this example are
also shown in Table 3 below.
[0075] However, rather than supporting a single PRACH configuration in its cell (as
currently defined for LTE in 3GPP TS 36.21 1), the base station 5 in this example is
configured to apply sequence partitioning for its PRACH configurations, i.e. the base
station 5 employs multiple PRACH configurations in the time domain.
[0076] Specifically, in this example the base station 5 is configured to transmit (using its
broadcast module 65): i) PRACH configuration index no. 9 to be applied in subframes
#1, #4, and #7 (e.g. for legacy UEs); ii) PRACH configuration index no. 10 to be
applied in subframes #2, #5, and #8 (e.g. for reduced bandwidth UEs); and iii) PRACH
configuration index no. 1 1 to be applied in subframes #3, #6, and #9 (e.g. for coverage
enhanced UEs). This information may be broadcast, for example, as part of the SIB2
information.
[0077]
[Table 3]
Table 3 - PRACH configurations (source: Table 5. 7. 1-2 of3GPP TS 36.211)
[0078] For example, the base station 5 may broadcast (e.g. in advance) the applicable
PRACH configuration index for each UE category. However, it will also be ap
preciated that the base station 5 may broadcast, in each subframe, the currently ap
plicable PRACH configuration index, and information identifying the associated UE
category (e.g. instead or in addition to any advance indication).
[0079] By listening to the base station's 5 broadcast information (e.g. SIB2), each commu
nication device 3 is able to obtain (using its MTC module 45) the applicable PRACH
configuration index for its category. Therefore, whenever a communication device
(e.g. the MTC device 3-2) needs to perform a random access procedure, it transmits
(using its random access module 47 and transceiver circuit 31) a preamble sequence
within the subframe allocated to its category of UEs (as specified by the PRACH con
figuration index for that category).
[0080] Beneficially, based on the time resource (subframe) in which the base station 5
receives the random access message (preamble sequence), the base station 5 is able to
determine (using its UE category determination module 69) the category of the sending
communication device. Therefore, the base station 5 can also determine whether to
transmit a DCI in the PDCCH CSS (for legacy UEs) or to transmit a DCI in the
EPDCCH CSS (for reduced bandwidth UEs and/or coverage enhanced UEs) in
response to the communication device's random access message.
[0081] In addition, for coverage enhanced UEs, the base station 5 (using its PRACH configuration
module 67) may also perform preamble sequence partitioning (as per option
A above) within the associated PRACH configuration index in time and inform (e.g.
via system broadcast) the communication devices 3 which sequence partition applies to
which coverage level within the associated PRACH time resources (subframes).
[0082]
Figure 5 illustrates another exemplary way in which UE category specific PRACH
configurations can be employed in the system shown in Figure 1. In this example, the
base station 5 employs, for each category of communication devices 3, a respective a s
sociated PRACH configuration using different associated frequency resources (e.g.
PRACH is provided in a different frequency band for each device category) of the
same subframe. Effectively, the resulting PRACH configuration comprises a frequency
division multiplexing (FDM) based PRACH, in which each category of commu
nication device 3 is configured to use a different frequency band during the random
access procedure.
[0083] In this example, the following PRACH configuration is employed:
- FDM region '0' is allocated to legacy UEs;
- FDM region T is allocated to reduced bandwidth (MTC) UEs; and
- FDM region '2' is allocated to coverage enhanced (MTC) UEs.
[0084] It will be appreciated that in FDM region '2' it is also possible to employ additional
sequence partitioning (as per option A) for distinguishing among different levels of
coverage enhancement supported by the mobile communication device transmitting in
that FDM region.
[0085] For example, the base station 5 may broadcast (e.g. in advance and/or in each
subframe) information identifying the respective PRACH configuration (including in
formation identifying the associated frequency band) for each UE category.
[0086] By listening to the information (e.g. SIB2) broadcast by the base station 5, each com
munication device 3 is able to obtain (using its MTC module 45) the applicable
PRACH configuration (PRACH frequency band) for its category. Therefore, whenever
a communication device (e.g. the MTC device 3-2) needs to perform a random access
procedure, its random access module 47 transmits a preamble sequence within the
frequency band configured for its category (e.g. in any of subframes #1, #4, and #7
shown in Figure 5).
[0087] Then, depending on the frequency (and time) resource in which the base station 5
receives the preamble sequence transmission, the base station 5 is able to determine
(using its UE category determination module 69) the category of the sending commu
nication device. Therefore, the base station 5 can also determine whether to transmit a
DCI in the PDCCH CSS (for legacy UEs) or to transmit a DCI in the EPDCCH CSS
(for reduced bandwidth UEs and/or coverage enhanced UEs) in response to the communication
device's random access message.
[0088] In addition, for coverage enhanced UEs, the base station 5 may also perform
preamble sequence partitioning (as per option A above) within the associated PRACH
frequency resource (FDM region) and inform (e.g. via system broadcast) the commu
nication devices 3 which sequence partition applies to which coverage level within the
associated PRACH frequency resource.
[0089]
Figure 6 illustrates yet another exemplary way in which UE category specific
PRACH configurations can be employed in the system shown in Figure 1. In this
example, the base station 5 employs a hybrid time-frequency resource based PRACH
configuration for differentiating among the different categories of communication
devices 3.
[0090] Effectively, option D is a combination of options B and C (and may further be
combined with option A, when appropriate).
[0091] In the example shown in Figure 6, three categories of communication devices are
supported in the cell of the base station 5. The first category of communication devices
includes legacy UEs, the second category includes reduced bandwidth UEs, and the
third category includes coverage enhanced UEs.
[0092] The first category is allocated PRACH resources based on an appropriate PRACH
configuration index (in subframes #1, #4, and #7 as specified by e.g. PRACH index 9
shown in Table 3), whilst the second and third category of communication devices are
allocated FDM based PRACH resources (in subframes #2, #5, and #8), in which each
of the two category of communication devices is configured to use a different
frequency band during the random access procedure.
[0093] In this example, the following frequency division multiplexing is employed:
- FDM region '0' is allocated to coverage enhanced MTC UEs; and
- FDM region T is allocated to reduced bandwidth MTC UEs.
[0094] It will be appreciated that in FDM region '0' it is also possible to employ additional
sequence partitioning (as per option A) for distinguishing among different levels of
coverage enhancement supported by the mobile communication device transmitting in
that FDM region.
[0095] In this example, the base station 5 broadcasts (e.g. in advance and/or in each
subframe) information identifying the respective PRACH configuration (including in
formation identifying the associated frequency band and subframe) for each UE
category.
[0096] By listening to the information (e.g. SIB2) broadcast by the base station 5, each com
munication device 3 is able to obtain (using its MTC module 45) the applicable
PRACH configuration (PRACH frequency band / PRACH configuration index) for its
category. Therefore, whenever a communication device (e.g. the MTC device 3-2)
needs to perform a random access procedure, its random access module 47 transmits a
preamble sequence within the subframe/frequency band configured for its category.
[0097] Then, depending on the frequency band and subframe in which the base station 5
receives the preamble sequence transmission, the base station 5 is able to determine
(using its UE category determination module 69) the category of the sending commu
nication device. Therefore, the base station 5 can also determine whether to transmit a
DCI in the PDCCH CSS (for legacy UEs) or to transmit a DCI in the EPDCCH CSS
(for reduced bandwidth UEs and/or coverage enhanced UEs) in response to the com
munication device's random access message.
[0098]
Detailed embodiments have been described above. As those skilled in the art will ap
preciate, a number of modifications and alternatives can be made to the above em
bodiments whilst still benefiting from the inventions embodied therein.
[0099] In the above embodiments described with reference to Figure 4 to 6, a radio frame
comprises ten subframes (subframes #0 to #9). As those skilled in the art will ap
preciate a radio frame may include any number of subframes.
[0100] 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).
[0101] Furthermore, the applicable PRACH configuration may not be explicitly signalled by
the base station and may instead be determined based upon other information, such as
a cell ID associated with the base station. This has the benefit of reducing the amount
of data that has to be signalled to the communication devices.
[0102] 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.
[0103] In the above embodiments, an LTE telecommunications system was described. As
those skilled in the art will appreciate, the techniques described in the present ap
plication 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.
[0104] In the embodiments described above, the base station and the communication device
each include transceiver circuitry. Typically, this circuitry will be formed by dedicated
hardware circuits. However, in some embodiments, part of the transceiver circuitry
may be implemented as software run by the corresponding controller.
[0105] In the above embodiments, a number of software modules were described. 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.
[0106] In the above embodiments, machine-type communication devices and mobile
telephones are described. However, it will be appreciated that mobile telephones (and
similar user equipment) may also be configured to operate as machine-type commu
nication devices. For example, the mobile telephone 3-1 may include (and/or provide
the functionality of) the MTC module 45.
[0107] 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, Annex B). This list is not exhaustive and is intended to
be indicative of the scope of machine-type communication applications.
[0108]
[Table 4]
Service Area MTC applications
Surveillance systems
Backup for landline
Security
Control of physical access (e.g. to buildings)
Car/driver security
Fleet Management
Order Management
Pay as you drive
Asset Tracking
Tracking & Tracing
Navigation
Traffic information
Road tolling
Road traffic optimisation/steering
Point of sales
Payment Vending machines
Gaming machines
Monitoring vital signs
Supporting the aged or handicapped
Health
Web Access Telemedicine points
Remote diagnostics
Sensors
Lighting
Pumps
Remote Maintenance/Control Valves
Elevator control
Vending machine control
Vehicle diagnostics
Power
Gas
Water
Metering
Heating
Grid control
Industrial metering
Digital photo frame
Consumer Devices Digital camera
eBook
[0109] Various other modifications will be apparent to those skilled in the art and will not be
described in further detail here.
[0110] Some or all of the aforementioned embodiments may be described in the following
supplementary notes. Nevertheless, the present invention is not limited to the following
supplementary notes in any way.
[0111] (Supplementary Note 1)
A communications node operable to allocate resources for potential use by any of a
plurality of user communication devices, including legacy user communication devices
and machine-type communication, (MTC), devices, for communicating with the com
munications node, the communications node comprising:
means for sending, to said plurality of user communication devices, control data
defining communication resources for potential use by any of said plurality of user
communication devices, the control data including information identifying at least;
i) a first physical random access channel, PRACH, resource configuration for
said legacy user communication devices; and
ii) a second PRACH resource configuration for said MTC devices;
means for receiving, from a user communication device of said plurality of user com
munication devices, a random access message conforming to one of said first and
second PRACH resource configurations over communication resources defined by said
control data; and
means for determining, based on the PRACH resource configuration with which said
received random access message conforms, whether said user communication device
comprises a legacy user communication device or comprises an MTC device;
wherein said means for sending is operable to send a random access response (RAR)
mapped to a physical downlink control channel (PDCCH) when said user commu
nication device is determined to comprise a legacy user communication device and to
send a random access response (RAR) mapped to an enhanced physical downlink
control channel (EPDCCH) when said user communication device is determined to
comprise an MTC device.
[01 12] (Supplementary Note 2)
The communications node according Supplementary Note 1, wherein each said
PRACH resource configuration defines an associated preamble sequence and wherein
said random access message includes a prefix and a preamble sequence conforming to
one of said first and second PRACH resource configurations, and wherein said de
termining means is operable to determine whether said first user communication
device comprises a legacy user communication device or comprises an MTC device
based on said preamble sequence included in said random access message.
[0113] (Supplementary Note 3)
The communications node according to Supplementary Note 1 or 2, wherein:
i) said first PRACH resource configuration defines a first set of communication
resources for potential use by said legacy user communication devices; and
ii) said second PRACH resource configuration defines a second set of commu
nication resources, different to said first set, for potential use by said MTC devices;
and
wherein said determining means is operable to determine that:
i) said first user communication device comprises a legacy user communication
device when said receiving means receives said random access message over a com
munication resource that belongs to said first set of communication resources; and
ii) said first user communication device comprises an MTC device when said
receiving means receives said random access message over a communication resource
that belongs to said second set of communication resources.
[01 14] (Supplementary Note 4)
The communications node according to any of Supplementary Notes 1 to 3, wherein
said determining means is operable to determine, when said user communication
device is an MTC device, whether that MTC device comprises a reduced bandwidth
MTC device and/or a coverage enhanced MTC device.
[0115] (Supplementary Note 5)
The communications node according to Supplementary Note 4, wherein said de
termining means is operable to determine, when said user communication device is a
coverage enhanced MTC device, a level of coverage enhancement required by said
coverage enhanced MTC device.
[0116] (Supplementary Note 6)
The communications node according to any of Supplementary Notes 1 to 5, wherein
at least one of said first and said second PRACH resource configurations defines a set
of communication resources comprising no more than six physical resource blocks.
[01 17] (Supplementary Note 7)
The communications node according to any of Supplementary Notes 1 to 6,
comprising a base station.
[0118] (Supplementary Note 8)
The communications node according to Supplementary Note 6 comprising a base
station operating in accordance with the long term evolution, LTE, set of standards.
[01 19] (Supplementary Note 9)
The communications node according to any of Supplementary Notes 1 to 8 wherein
said communication resources are resources provided in accordance with at least one
of a time, a frequency, and a code sequence multiplexing scheme.
[0120] (Supplementary Note 10)
A machine-type communication, (MTC), device for a communication system in which
a communications node allocates resources for potential use by any of a plurality of
user communication devices, including legacy user communication devices and
machine-type communication, (MTC), devices, the MTC communications device
comprising:
means for receiving, from the communications node, control data defining commu
nication resources for potential use by any of said plurality of user communication
devices, the control data including information identifying at least;
i) a first physical random access channel, PRACH, resource configuration for said
legacy user communication devices; and
ii) a second PRACH resource configuration for said MTC devices; and
means for sending, to the communications node, a random access message conforming
to said second PRACH resource configuration over communication resources defined
by said control data;
wherein said means for receiving is operable to receive a random access response
(RAR) mapped to an enhanced physical downlink control channel (EPDCCH) re
sponsive to said random access message.
(Supplementary Note 11)
A method performed by a communications node in a communication system in
which the communications allocates resources for potential use by any of a plurality of
user communication devices, including legacy user communication devices and
machine-type communication, (MTC), devices, for communicating with the commu
nications node, the method comprising:
sending, to said plurality of user communication devices, control data defining com
munication resources for potential use by any of said plurality of user communication
devices, the control data including information identifying at least;
i) a first physical random access channel, PRACH, resource configuration for
said legacy user communication devices; and
ii) a second PRACH resource configuration for said MTC devices;
receiving, from a user communication device of said plurality of user communication
devices, a random access message conforming to one of said first and second PRACH
resource configurations over communication resources defined by said control data;
determining, based on the PRACH resource configuration with which said received
random access message conforms, whether said user communication device comprises
a legacy user communication device or comprises an MTC device;
sending a random access response (RAR) mapped to a physical downlink control
channel (PDCCH) when said user communication device is determined to comprise a
legacy user communication device; and
sending a random access response (RAR) mapped to an enhanced physical downlink
control channel (EPDCCH) when said user communication device is determined to
comprise an MTC device.
[0122] (Supplementary Note 12)
A method performed by a machine-type communication, (MTC), device in a commu
nication system in which a communications node allocates resources for potential use
by any of a plurality of user communication devices, including legacy user commu
nication devices and machine-type communication, (MTC), devices, the method
comprising:
receiving, from the communications node, control data defining communication
resources for potential use by any of said plurality of user communication devices, the
control data including information identifying at least;
i) a first physical random access channel, PRACH, resource configuration for
said legacy user communication devices; and
ii) a second PRACH resource configuration for said MTC devices;
sending, to the communications node, a random access message conforming to said
second PRACH resource configuration over communication resources defined by said
control data; and
receiving a random access response (RAR) mapped to an enhanced physical
downlink control channel (EPDCCH) responsive to said random access message.
[0123] (Supplementary Note 13)
A communication system comprising a communications node according to any of
Supplementary Notes 1 to 8 and an machine-type communication device according to
Supplementary Note 9.
[0124] (Supplementary Note 14)
A computer program product comprising computer implementable instructions for
causing a processing device to perform a method according to Supplementary Note 10
or 11.
[0125] This application is based upon and claims the benefit of priority from United
Kingdom patent application No. 1417068.2, filed on September 26, 2014, the
disclosure of which is incorporated herein in its entirety by reference.

Claims
A communication apparatus which is operable to communicate with at
least one of a first type mobile station and a second type mobile station,
the communication apparatus comprising:
means for transmitting a control signal, where in the control signal
comprises first resource configuration for a first physical random
access channel(PRACH) and second resource configuration for a
second PRACH ; and
means for receiving a random access message based on either one of
the first resource configuration and the second resource configuration.
A communication apparatus according to claim 1, wherein the commu
nication apparatus further comprises means for transmitting a random
access response(RAR),
wherein the RAR is mapped to a physical downlink control
channel(PDCCH) in case the RAR is transmitted to the first type
mobile station,
wherein the RAR is mapped to an enhanced physical downlink control
channel(E-PDCCH) in case the RAR is transmitted to the second type
mobile station.
A communication apparatus according to claim 1 or 2, wherein the
random access message is based on the first resource configuration in
case that first type mobile station transmits the random access message,
wherein the random access message is based on the second resource
configuration in case that second type mobile station transmits the
random access message.
A communication apparatus according to any of claim 1 to 3, wherein
the communication apparatus further comprises means for determining
a type of a mobile station based on a resource to receive the random
access message.
A communication apparatus according to any of claim 1 to 4, wherein
the second type mobile station is machine-type communication(MTC)
device.
A communication apparatus according to any of claim 5, wherein the
MTC device comprises at least one of a reduced bandwidth MTC
device and a coverage enhanced MTC device.
A communication apparatus according to any of claim 1 to 6, wherein
the control signal is broadcasted by SIB.
WO 2016/047106 PCT/JP2015/004712
[Claim 8] A mobile station which is operable to communicate with a commu
nication apparatus, the mobile station comprising:
means for receiving a control signal, where in the control signal
comprises first resource configuration for a first physical random
access channel(PRACH) and second resource configuration for a
second PRACH ; and
means for transmitting a random access message based on the second
resource configuration.
[Claim 9] A mobile station according to claim 8, wherein the second resource
configuration is determined based on a category of the mobile station.
[Claim 10] A mobile station according to claim 8 or 9, wherein the mobile station
is machine-type communication(MTC) device.
[Claim 11] A mobile station according to claim 10, wherein the category comprises
a reduced bandwidth MTC device and a coverage enhanced MTC
device.
[Claim 12] A mobile station according to any of claim 8 to 11, wherein the second
resource configuration is mapped to a coverage level.
[Claim 13] A mobile station according to any of claim 8 to 12, wherein the
coverage level is mapped to the number of repetition of a control
channel transmission.
[Claim 14] A method performed by a communication apparatus which is operable
to communicate with at least one of a first type mobile station and a
second type mobile station, the method comprising:
transmitting a control signal, where in the control signal comprises first
resource configuration for a first physical random access
channel(PRACH) and second resource configuration for a second
PRACH ; and
receiving a random access message based on either one of the first
resource configuration and the second resource configuration.
[Claim 15] A method performed by a mobile station which is operable to com
municate with a communication apparatus, the method comprising:
receiving a control signal, where in the control signal comprises first
resource configuration for a first physical random access
channel(PRACH) and second resource configuration for a second
PRACH ; and
transmitting a random access message based on the second resource
configuration.