COMMUNICATIONS SYSTEM FOR TRANSMITTING AND RECEIVING DATA
Field of the Disclosure
The present disclosure relates t o communications systems for transmitting and receiving
data t o and/or from communications devices and infrastructure equipment, and methods of
communicating data.
Background of the Disclosure
Mobile communications systems continue t o be developed t o provide increased capacity
and expand the number and variety of devices that can be served. Recently, third and fourth
generation mobile telecommunication system, such as those based on 3GPP defined UMTS and Long
Term Evolution (LTE) architectures have been developed to support more sophisticated
communications services t o personal computing and communications devices than simple voice and
messaging services offered by previous generations of mobile telecommunications systems. For
example, with the improved radio interface and enhanced data rates provided by LTE systems, a
user may enjoy high data rate applications such as mobile video streaming and mobile video
conferencing that would previously only have been available via a fixed line data connection. The
demand to deploy third and fourth generation networks is therefore strong and the coverage area of
these networks, i.e. geographic locations where access to the network is possible, is expected to
increase rapidly. More recently it has been recognised that rather than providing high data rate
communications services t o certain types of electronic devices, it is also desirable to provide
communications services t o electronic devices that are simpler and less sophisticated. Expanding the
variety of devices that are served beyond those that require high data rate connections also
significantly increases the number of devices that may potentially be served and therefore the
number of possible revenue streams for telecommunications systems providers. Machine type
communication devices provide an example of these new devices which may be served. MTC devices
may be semi-autonomous and autonomous wireless communication devices which may
communicate small amounts of data on a relatively infrequent basis. Some examples include socalled
smart meters which, for example, are located in house of a customer of a utility provider and
periodically transmit information back to a central MTC server relating to the customer's
consumption of a utility such as gas, water, electricity and so on.
Summary of the Disclosure
According to the present disclosure there is provided a communications system comprising
infrastructure equipment arranged to provide a wireless interface to a communications device. The
communications device comprises a controller and a transceiver configured to transmit and/or
receive signals representing the data to and/or from the infrastructure equipment over the wireless
interface. The transceiver under control of the controller is configured t o transmit a request for
services message to the infrastructure equipment, and to receive a response message to the request
for services message transmitted from the infrastructure equipment. The request for services
message includes a delay period and the infrastructure equipment, in response to receiving the
request for services message, processes the request to form the response message and stores the
response message for transmission to the communications device. The response message is stored
until the expiry of the delay period or transmission of the response message, and the controller is
configured after transmission of the request for services to configure the transceiver to enter a
reduced power state in which the amount of power consumed by the transceiver is reduced and to
exit the reduced power state to receive the response message.
Including a delay period in a request for services message from a communications device t o
infrastructure equipment in a communications system allows the communications device t o have
more accurate knowledge of when a response to the request for services will be transmitted by the
infrastructure equipment. As a result of this knowledge the transceiver of the communications
device is able to enter a reduced-power state for a period of time and exit the reduced power mode
prior to the transmission of the a response t o the request without possibility that it may not receive
the response when the response is transmitted. This therefore allows the communications device to
reduce power consumption whilst still receiving the response. This approach may also be beneficial
when the processing of a request at infrastructure equipment takes a minimum period of time. For
example if it is known that a response may not be transmitted before the end of this minimum
processing period it may be more energy efficient to configure the transceiver to enter a reduced
power sate for at least the minimum processing period so that the transceiver does not attempt to
receive the response before it can possibly be transmitted.
In some embodiments of the present disclosure the controller is configured to control the
transceiver to transmit a random access request message t o the infrastructure equipment
requesting up-link communications resources for transmitting the request for services message. The
infrastructure equipment is configured t o transmit a random access request response to the
communications device granting up-link communications resources in response t o receiving the
random access request, and the communications device is also configured to transmit the request
for services message in the allocated up-link communications resources t o the infrastructure
equipment.
In other embodiments the controller is configured to control the transceiver prior to the
expiry of the delay period to transmit a second random access request message to the infrastructure
equipment requesting up-link communications resources for transmitting a request for a response
message to the infrastructure equipment. The request for a response message requests a response
to the request for services message, and in response t o a granting of the up-link communications
resources from the infrastructure equipment, to transmit the request for response message in the
allocated up-link communications resources to the infrastructure equipment, and to receive a
response message from the infrastructure equipment providing the requested services to the
communications device in response to the request for services message. The infrastructure
equipment is configured t o transmit a random access request response to the communications
device granting up-link communications resources in response to receiving the second random
access request from the transceiver, to receive the request for a response message requesting a
response to the request for services message, and t o transmit a response message to the
communications device providing the requested services to the communications device in response
to the request for services message.
The granting of resources to the communications device to request a response to the
request for services enables the communications device to specify a time when it wishes t o receive
the response to the request for services whilst not having to specify such a time when the request
for services is transmitted. This may overcome synchronisation issues between the communications
device and the infrastructure equipment that may arise when the transceiver of the communications
device is in a reduced power state for a long period of time. The transmission of a request for a
response by the communications device also allows the infrastructure equipment to have processed
the request so that it is available for transmission when the request for a response is received.
Furthermore, the transmission and reception of a request for a response may allow the
infrastructure equipment to schedule the transmission in a conventional manner and may provide
the communications device with flexibility in when it wishes to receive the response to the request
for services.
In a further embodiment the controller is configured to control the transceiver to exit the
reduced power state to receive the response message in response to the expiry of the delay period,
and the infrastructure equipment is configured t o transmit the response message to the transceiver
in response to the expiry of the delay period.
The transmission of the response to the request for services in response to the expiry of the
delay period allows the response to the request for services to the transmitted and received at a
predetermined time without further random access request or requests for a response. This may
therefore allow the transceiver to remain in the reduced power state for a longer period of time and
reduce power consumption at both the communications device and the infrastructure equipment.
In yet another embodiment the random access request message transmitted by the
transceiver to the infrastructure equipment requesting up-link communications resources includes
an identifier identifying the communications device which has transmitted the random access
request message. The transceiver is configured to receive a random access response message from
the infrastructure equipment which provides the granted up-link communications resources for
transmitting the request for services message, the random access response including the
identification number. Prior to the expiry of the delay period the transceiver is configured to
transmit a second random access request message, which includes the identification number to the
infrastructure equipment, and t o receive in response to the second random access request message
a response message from the infrastructure equipment providing the requested services to the
communications device in response to the request for services message. The infrastructure
equipment is also configured to transmit a random access response message providing the granted
up-link communications resources for the transceiver to transmit the request for services message
to the infrastructure equipment, to receive the second random access request message from the
communications device, and t o transmit, in response to the second random access request message,
a response message providing the requested services t o the communications device in response to
the request for services message.
Transmitting and receiving a second random access request including the same identifier
enables the communications device to identify itself to the infrastructure equipment as the device
which transmitted the request for services. A response to the request for services can therefore be
transmitted by the infrastructure equipment and received by the communications device without
the transmission of a request for a response to the request for services in addition to the second
random access request. This may allow the transceiver t o remain in the reduced power state for a
longer period of time and allow the transceiver and infrastructure equipment to transmit fewer
messages, thus reducing power consumption and scheduling complexity.
Various further aspects and embodiments of the present disclosure are provided in the
appended claims, including but not limited to infrastructure equipment arranged to provide a
wireless interface t o a communications device and a method for transmitting and receiving signals
representing data to and/or from infrastructure equipment.
Brief Description of the Drawings
Embodiments of the present disclosure will now be described by way of example only with
reference to the accompanying drawing in which like parts are provided with corresponding
reference numerals and in which:
Figure 1 provides a schematic diagram of an example communications network;
Figure 2 provides a schematic diagram of a structure of an example downlink LTE subframe;
Figure 3 provides a diagram of an example CC connection procedure in an LTE network;
Figure 4 provides a diagram illustrating the power consumption of a receiver operating in
accordance with the procedure of Figure 3;
Figure 5 provides a diagram of an RRC connection procedure in an LTE network in
accordance with an example embodiment of the present disclosure;
Figure 6 provides a diagram illustrating the power consumption of a receiver operating in
accordance the procedure illustrated in Figure 5;
Figure 7 provides a flow diagram of operations at a communications device operating in
accordance with the procedure illustrated in Figure 5;
Figure 8 provides a flow diagram of operations at a base station operating in accordance
with the procedure illustrated in Figure 5;
Figure 9 provides a flow diagram of operations at a communication device operating in
accordance with an example embodiment of the present disclosure;
Figure 10 provides a flow diagram of operations at a base station operating in accordance
with an example embodiment of the present disclosure;
Figure 11 provides a diagram of an RRC connection procedure in an LTE network in
accordance with an example embodiment of the present disclosure;
Figure 12 provides a flow diagram of operations at a communications device operating in
accordance with the procedure illustrated in Figure 11;
Figure 13 provides a flow diagram of operations at a base station operating in accordance
with the procedure illustrated in Figure 11;
Figure 14 provides a diagram of an RRC connection procedure in an LTE network in
accordance with an example embodiment of the present disclosure;
Figure 15 provides a flow diagram of operations at a communications device operating in
accordance with the procedure illustrated in Figure 14;
Figure 16 provides a flow diagram of operations at a base station operating in accordance
with the procedure illustrated in Figure 14;
Figure 17 provides a schematic diagram of a communication device configured to operate in
the network of Figure 1 and in accordance with example embodiments of the present disclosure;
and
Figure 18 provides a schematic diagram of a base station configured to operate in the
network of Figure 1 and in accordance with example embodiments of the present disclosure.
Description of Example Embodiments
Figure 1 provides a schematic diagram illustrating a conventional mobile communications
system. The system includes a plurality of base stations 101 connected t o a core network 102 where
the base stations and core network are arranged t o provide a wireless radio interface. Each of the
plurality of base station provides a service area 103 and serves a plurality of communications devices
104 which are located within the service area 103. Each of the communications devices 104 within a
service area transmits and receives data to and from the base station 101 over a radio uplink and a
radio downlink respectively of the wireless interface. Correspondingly, each base station transmits
and receives data to and from the communications devices that are within its service area over the
radio downlink and radio uplink respectively. Data transmitted to the base stations 101 may be
routed to the core network 102 so that services such as for example voice calling, internet access,
authentication, mobility management and charging and so on may be provided. In some examples
Figure 1 may represent an LTE network and the base stations may be referred t o as enhanced Node
B (eNodeB or eNB) and in other examples the base station and core network may be referred to
infrastructure equipment. In an LTE network the communications devices may also be referred to as
user equipment (UE), which may for example be mobile telephones, tablets, machine type
communications devices etc. However, in other examples the communications devices may be
referred to as mobile terminals and communications devices etc.
Mobile telecommunications networks or systems utilise a wide variety of different radio
interfaces, for example, 3GPP LTE utilises an Orthogonal Frequency Division Multiplexing (OFDM)
radio interface. OFDM operates by dividing the available bandwidth into a plurality of orthogonal
sub carriers and then dividing up this resource to form a predetermined structure which can convey
data t o the communications devices in a system. In the downlink of an LTE system the available
resources are divided temporally into radio frames which last 10ms, with each frame comprising 10
subframes which each last 1ms. The subframes of an LTE signal are then further divided into OFDM
symbols and resource blocks that comprise 12 subcarriers over a period of 0.5ms or 6 or 7 symbols.
These resource blocks form the physical channels of a LTE subframe which are used to carry data on
the downlink and the uplink.
Figure 2 provides a schematic diagram providing a grid which illustrates the structure of an
example of a two downlink LTE subframes. The subframes comprise a predetermined number of
symbols which are transmitted over a 1ms period. Each symbol comprises a predetermined number
of orthogonal sub-carriers distributed across the bandwidth of the downlink radio carrier. The
example sub-frame shown in Figure 2 comprises 14 symbols and 1200 sub-carriers spaced across a
20M Hz bandwidth. The smallest unit on which data can be transmitted in LTE is twelve sub-carriers
transmitted over one sub-frame. For clarity, in Figure 2, each individual resource element is not
shown, but instead each individual box in the sub-frame grid corresponds to twelve sub-carriers
transmitted on one symbol.
Figure 2 shows resource allocations for four communications devices 203, 204, 205, 206. For
example, the resource allocation 203 for a first communications device (UE 1) extends over five
blocks of twelve sub-carriers, the resource allocation 206 for a second communications device (UE2)
extends over six blocks of twelve sub-carriers and so on. Control channel data is transmitted in a
control region 201 of the sub-frame comprising the first n symbols of the sub-frame where n can
vary between one and three symbols for channel bandwidths of 3MHz or greater and where n can
vary between two and four symbols for channel bandwidths of 1.4M Hz. The data transmitted in the
control region 201 includes data transmitted on the physical downlink control channel (PDCCH), the
physical control format indicator channel (PCFICH) and the physical HA Q indicator channel (PH ICH).
The PDCCH contains control data indicating which sub-carriers on which symbols of the subframe
have been allocated to specific communications devices (UEs). Thus, the PDCCH data
transmitted in the control region 201 of the sub-frame shown in Figure 2 would indicate that UE1
has been allocated the first block of resources 203, that UE2 has been allocated the second block of
resources 204, and so on. In subframes where it is transmitted, the PCFICH contains control data
indicating the duration of the control region in that sub-frame (i.e. between one and four symbols)
and the PHICH contains HARQ (Hybrid Automatic Request) data indicating whether or not previously
transmitted uplink data has been successfully received by the network. In certain subframes,
symbols in a central band 202 of the sub-frame are used for the transmission of information
including the primary synchronisation signal (PSS), the secondary synchronisation signal (SSS) and
the physical broadcast channel (PBCH) mentioned above. This central band 202 is typically 72 subcarriers
wide (corresponding t o a transmission bandwidth of 1.08 MHz). The PSS and SSS are
synchronisation signals that once detected allow a communications device 104 t o achieve frame
synchronisation and determine the cell identity of the base station (eNB) transmitting the downlink
signal. The PBCH carries information about the cell, comprising a master information block (MIB)
that includes parameters that the communications devices require t o access the cell. Data
transmitted t o individual communications devices on the physical downlink shared channel (PDSCH)
can be transmitted in the remaining blocks of communications resource elements of the subframe.
Figure 2 also shows a region of PDSCH containing system information and extending over a
bandwidth of R2 . The number of sub-carriers in an LTE channel can vary depending on the
configuration of the transmission network. Typically this variation is from 72 sub carriers contained
within a 1.4M Hz channel bandwidth t o 1200 sub-carriers contained within a 20M Hz channel
bandwidth as shown in Figure 2. As is known in the art, subcarriers carrying data transmitted on the
PDCCH, PCFICH and PHICH are typically distributed across the entire bandwidth of the sub-frame.
Therefore a conventional communications device must be able t o receive the entire bandwidth of
the sub-frame in order t o receive and decode the control region.
During normal operation of a LTE communications device the device will monitor the PDCCH
for information on the resources in has been allocated in the PDSCH and then receive the data that
is present in its allocated resources. The PDSCH of an LTE downlink subframe allocated t o system
information also comprises a number of identifiers or identifying sequences. Theses identifiers are
then included in preambles which are used for random access capabilities for communications
devices not currently current connected t o the base station (RRCJdle). The uplink subframes may
comprise a corresponding physical random access channel (PRACH) over which preambles or other
identifying numbers or sequences may be sent t o initiate a connection with a base station where the
location of the PRACH channel is indicated in the system information. This random access procedure
will be explained in more detail below.
In mobile communication systems, communications devices may have more strict power
constraints than a base station because they are often battery powered. Consequently, in order t o
reduce power consumption at a communications device, a common design criterion is t o minimise
the transmission and reception of control information and data at a communications device. To
achieve power reductions communications devices may disconnect from a network in addition t o
times where the communications device is turned off. When emerging from a disconnected state a
communications device may be required t o initiate a connection with a base station. For example, in
an LTE system when a communications device is first switched on or is otherwise not connected t o a
base station, in order t o send and receive data the communications device is first required t o
connect t o a base station.
Figure 3 provides a diagram illustrating the process by which a communications device may
connect t o a base station in an LTE network and therefore transition between RRCJdle t o
RRC_Connected. Initially the communications device is not synchronised with the OFDM frames and
therefore the communications device first detects primary synchronisation and secondary
synchronisations signals. These signals are utilised by the communications device t o synchronise
with downlink frames transmitted by the base station. Once synchronised with the downlink frames
the communications device is able to receive the control information on the PDCCH and PBCH and
subsequently receive the system information which conveys the identifiers for the preambles and
PRACH location which are used for an uplink random access procedure. Once an identifier has been
received it is transmitted in a preamble over the PRACH channel t o the base station in a random
access request message illustrated by the communication 301 in Figure 3. The transmission of the
random access request message to the base station indicates that the communications device
requires resources in the up-link and possibly the downlink to be allocated. In response to receiving
the random access request message the base station allocates resources t o the communications
device and transmits a random access request response message 302 to the communications device.
The random access response 302 indicates t o the communications device the resources which have
been allocated to it and allows the communications device to synchronise with the uplink frames of
the base station so that a further random access procedure is not required and timing advance can
be implemented.
In response to receiving the random access response 302 and being synchronised with the
uplink frames of the base station, the communications device may transmit a radio resource control
(RRC) connection request 303 to the base station over the up-link resources allocated to the
communications device in the random access response 302. This RRC connection request represents
a request t o the communications network t o establish a radio communications bearer for
transmitting data to and/or from the communications device and the communications network or
base station, however, it may also be a request for other types of service from the base station.
When the RRC connection request message 303 has been received by the base station the base
station acknowledges the correct receipt of the request by transmitting an acknowledgment 304 t o
the communications device. The acknowledgment 304 does not represent a successful connection
but simply the correct reception of the data within the RRC connection request. The correct
reception of the request may be assessed via the use of a cyclic redundancy check (CRC) or similar
error detection methods. A further request confirming an RRC connection setup 306 is required to
be transmitted and received by the base station and communications device respectively. In a
mobile communication system such as that depicted in Figure 1, when a connection or other request
is made by a communications device this request may be required to be passed onto a subsequent
entity in the core network, for example an eNB may pass a request onto an MMEor SGW.
Consequently, the processing time associated with an RRC connection request may be variable and a
response to a RRC connection request may not be transmitted by the base station t o a
communications device immediately. In order take account of this situation, in an LTE system the
communications device attempts t o receive a response to the RRC connection request in a window
of a predetermined duration. In response t o the sending of the RRC connection request the
communications device commences a wait timer 305 during which the communications device
attempts to receive a response t o the RRC connection request. For example, in an LTE system the
device sets a wait timer to a one of a plurality of predetermined values specified by a timer T300
that is broadcast by the eNB in the system information block, where the timer may have a value of
up to 2000ms. Once the RRC connection request has been processed and the connection is
confirmed, a RRC connection setup message 306 is transmitted to the communications device and
received by the communications device if it is transmitted before expiry of the wait timer at the
communications device. Once the communications device has received the RRC connection setup
the communications device transmits an acknowledgement 307 to the base station in order to
acknowledge the safe receipt of the RRC connection setup message. If an acknowledgment is not
received by the base station, the base station may retransmit the RRC connection setup message.
During the period the timer at the communication device is running, the communications
device attempts to receive the RRC connection setup communication. To do this the
communications device monitors the PDCCH which indicates to the communications device whether
the RRC connection setup message will be transmitted in the forthcoming PDSCH channel resource
blocks. However, because transmission time of the response to the RRC connection request is
unknown, the communications device has t o receive the control information in every PDDCH until it
receives the PDDCH that specifies the location of the RRC connection setup message or until the
timer expires. The communications device may therefore be in receiving mode for a substantial
period of time even though useful data is neither being received or transmitted.
Figure 4 illustrates the operation of a communications device t o receive a RRC connection
setup message during a 10ms radio frame. Throughout the radio frame, each PDCCH transmission
401 is received until the RRC connection setup is received. Therefore the controller within the
communications device powers up the transceiver or receiver, as shown by the UE receiver power
402 plot in Figure 4, in order to establish whether the communications device has been allocated
resources in the subsequent PDSCH 403. Consequently, the only PDCCH instance which is received
that conveys useful data is PDCCH 404.
In communications devices which have strict power constraints, such as MTC devices, these
periods of PDCCH reception may represent a significant drain on the communications devices
resources. Consequently, it may be beneficial if the reception period defined by the timer is avoided
such that the communications device reduces the power consumed by the transceiver during
periods that it is not possible that the RRC connection setup message will be transmitted, for
examples, because of a minimum processing time of the request by the communications network.
Although the response timer and reception procedure outlined above has been described
with reference to an LTE system, this issue of redundant reception is not restricted to LTE systems.
For example, in any communication system where a request for services is made and a response is
required (in addition to an acknowledgment) but the timing of the transmission of the response is
not certain, a similar technical problem may occur. Thus embodiments of the present technique can
apply t o different message exchanges where a request is made and a response is provided, for
instance, a device which is an a connected state with a system may transmit a request to the system
which takes a period of time t o process and fulfil e.g. retrieving data, preforming analysis of data or
requesting a service. Embodiments of the present technique therefore can reduce power
consumption of communications devices in respect of a transceiver's attempt t o receive a response
from the system for an extended period of time commencing with the transmission or
acknowledgment of the reception of the request. Furthermore, although in the above discussed
scenarios the communications device is preforming the request, the request may be transmitted by
any entity in a system as long as any substantive response (i.e. not simple CRC acknowledgment etc.)
to the request is not able t o be transmitted immediately or it is not certain when a response to the
request will be available for transmission. It may also not be required that a random access
procedure be performed before any request because the power consumption issues are related t o
the substantive request and the procedure for receiving a response to the substantive request.
In LTE networks a reception technique termed discontinuous reception (DRX) may partially
mitigate some of the problems outlined above. However, DRX has a number of shortcomings which
limit its application. DRX is a cyclic or period process that is negotiated between the communications
device and the base station prior t o the commencement of DRX. A single negotiation defines a
plurality of periods that the receiver in the communications device will turn-on and attempt to
receive control information from the base station. However, it is likely that a request from a
communications device as described above will be a one-off or aperiodic and therefore attempting
to use DRX would result in significant overheads because it will check control instances even when
there is no useful data to be received. A receiver performing DRX may operate in a similar manner t o
that illustrated in Figure 4, but will receive instances of control information less frequently, for
example, every three frames. However, although power consumption may be reduced by DRX,
control information may still be received even when there is no guarantee there will be data in the
subsequent PDSCH. Consequently, inefficiencies in the reception of responses t o requests may
remain even with the use of DRX.
Figure 5 illustrates a procedure in accordance with a first example embodiment of the
present disclosure. The procedure illustrated in Figure 5 is with reference to an RRC connection
request in LTE system described above but may be applied t o any request for services and response
procedure t o the request where the timing of processing and transmission of a response to a
request may be unknown. The steps and messages 301 t o 302 are substantially similar to those
described with reference to Figure 3, however, the RRC connection request 501 additionally contains
an indication of a defined delay period or transmission wait timer which defines a period relative to
the transmission of the RRC connection request. This delay period may then be used to define the
desired transmission time of a response to the RRC connection request and the point in time at
which the communications device attempts to receive a response. The delay period may be defined
by the communications device, the communications network or the base station. For example, the
communications device may in a system information block receive an indication of a delay period
that should be used or receive a set of delay period from which it chooses an appropriate one. When
the RRC connection request 501 has been received, the base station acknowledges the correct
reception of the data contained with the RRC request 501 with an acknowledgment 502. Upon
receiving the RRC request 501, the base station extracts the delay period from the RRC request and
commences a timer 503 at the base station or elsewhere in the base station side of the system
which monitors the elapsed time since transmission of the request relative to the delay period.
During the delay period the request received by the base station is processed and an appropriate
response composed. This processing may require communication with other entities in the system
or core network and therefore may take an extended period of time. Once the RRC connection has
been processed and confirmed, and the response composed 504, the response is stored or buffered
505 in a memory at the base station until the delay period expires such that the storage of the
response is dependent on the delay period. Once the delay period has expired the base station
transmits the RCC connection setup message 506 such that the transmission of the response is
dependent on the delay period. Once the response has been transmitted, the base station awaits an
acknowledgment from the communications device to indicate the correct reception of the RRC
connection set up message.
At the communications device, prior to the transmission of the RRC connection request
message 501 a controller in the communications device may determine an appropriate delay period
to be conveyed along with the RRC connection request. The delay period may be generated by the
communications device controller or the controller may select a value from a predetermined set of
timer values transmitted in the system information in a similar manner to existing T-timers such as
T300, T302 etc. In response t o transmitting the RRC connection request 501 the controller of the
communications device or other controlling means initiates a timer with the delay period and
commences the timer. After the transmission of the request the communications device awaits an
acknowledgment of the RRC connection request and once this has been received the controller may
configure the transceiver t o enter a reduced-power mode or state during which it does not transmit
or attempt to receive any transmission from the base station. However, the controller may configure
the transceiver to enter the reduced power or sleep mode in response to the transmission of the
RRC request. The reduced-power state overcomes the power consumption associated with cycling of
the transceiver or receiver depicted in Figure 4 by 402 because it does not attempt to receive any
information during this period. The transceiver remains in the reduced-power state until the delay
period expires and then enters a receiving mode to receive the PDCCH. It is assumed that the delay
period at the communications device and the base station are approximately synchronised so that
when the communications device exits the reduced power state the base station soon after
transmits the response t o the RRC connection request which has been buffered at the base station.
In this way the communications device may receive substantially fewer instances of scheduling
information on the PDCCH before receiving a response to the RRC connection request. Furthermore
data relevant to the communications device will be transmitted whilst the transceiver is awake
unlike DRX where a receiver awakes without knowledge of whether there is data t o be transmitted.
This procedure is further differentiated for DRX because the transceiver is only required t o turn-on
once and the procedure is not cyclic but dependent on when a request is required t o be transmitted.
In some instances congestion in the downlink may result in transmission of the RRC
connection setup or response 506 being delayed until resources are available to transmit the
response. Consequently, in some examples of the present embodiment there may be a reception
window which commences with the expiry of the delay period and within which the base station
may transmit and the communications device may receive a response to the RRC connection
request. This window may either be specified in the RRC connection request or may be a
predetermined window length which is common to all requests where a delay period is specified and
the base station buffers a response and the communications device's transceiver enter a low power
mode, respectively. Although the use of a reception window may increase a time for which a
communications device attempts t o receive a response, the duration of the window is likely t o be
significantly less than the window described in Figure 3 and therefore energy saving will still be
achieved. As well as easing problems related to congestion and scheduling, the utilisation of a
window after the delay period, may also overcome any small synchronisation problems resulting
from clock drift between the communications device and the base station.
In order to maintain approximate synchronisation between the delay periods at the
communications device and the base station, account of the propagation delay and data extraction
delay at the base station is required. For instance, when using a timer to time the delay period, at
the communications device, the timer commences when the RRC request is transmitted but an
equivalent timer at the base station commences once the RRC request has been received, the delay
period extracted and the timer started. Consequently, when initiating the timer at the base station
compensation may be introduced into the delay period in order to take account of the
aforementioned delays associated reception of the request and commencement of the timer. This
compensation may help ensure that the communications device does not exit the reduced power
mode before the transmission of the RRC connections setup message and therefore does not
unnecessarily receive redundant control information in the PDCCH.
In order for advantages of the above described procedure to be fully exploited it is
important that an appropriate delay period is determined. A key consideration that determines the
minimum delay period is the minimum period of time it will take to process and composes a
response to the request at the base station. For instance, a delay period should exceed the minimum
possible time before a response is ready for transmission. If this is not the case the communications
device may attempt to receive the response when it cannot be transmitted, thus wasting energy.
The determination of the delay period may also take into account a number of other factors, for
example, the time by which the communications device requires a response, the period the
communications device wishes to remain in reduced-power mode, tolerance t o delay and mobility
issues, and periods specified by the communications network. For example, when considering
mobility issues it may be required that the communications device remains within the range of the
base station that it submitted the request for the duration of the delay period in order that it can
receive the response from the base station at the appropriate time. If the communications device
were mobile and the delay period was set at too long a duration, the communications device may
have moved out of range of the base station t o which it originally made the request. In these
circumstances the communications device may not receive the response or additional mobility
management and timer management procedures will be required by the core network in order t o
ensure that the response is transmitted to the communications device at the correct time. In
addition to constraints at the communications device there may also be system constraints on the
delay period. For instance, there may be a set of delay periods from which an appropriate delay
period can be chosen or there may be a maximum delay period that can be specified in order to
avoid problems which may occur as a result of clock drift between the communications device and
the base station. Furthermore, there may be one or more sets of delay periods stored at the
communications device, each set providing a range of delay periods for a request of a certain type
each differing types of request may have differing processing times associated with them at a base
station. Also, when considering legacy devices in an LTE network they may be configured to use a
maximum delay period length if they are unable to select individual delay periods.
The units in which delay periods are defined may vary, for instance the delay period may be
defined by a period in time such as milliseconds or a number of frames or subframes. The delay
period may be defined as a subframe number at which the response is to be transmitted or the
number of elapsed subframes until transmission/reception should occur.
Figure 6 illustrates an example power consumption plot 601 of a receiver or transceiver in a
communications device which operates is accordance with the procedure outlined above. As can be
seen the delay period expires and controller configures the transceiver to exit the reduced power
state, the transceiver then receives the PDCCH 602 in order to identify where in the PDSCH 603 the
C connection setup message is located and then receives the RCC connection setup message.
When comparing Figures 4 and 6 it can be seen that the power consumption of the receiver is
reduced as fewer PDCCH instances are required to be received before the RCC connection setup
message is transmitted. In some examples it may not be necessary to receive any control
information prior to receiving the response to the RRC connection request message because the
location of the response may have been predetermined.
As mentioned above, the present procedure may be beneficial t o MTC devices because of
their extremely low power consumption. In one example an MTC device may for the majority of time
be in a sleep mode but during off peak periods it may wake-up in order to transmit data on utility
consumption to a central server. In this scenario the communications device may transmit an RRC
connection request and specify a delay period such that when the delay period expires the MTC
device has gathered and processed the data so that it is ready t o transmit and can transmit once the
delay period expires. In such scenarios the time which the communications device and/or
transceiver is awake may be reduced compared to when the data gathering and processing is
performed prior to the C connection request.
Figure 7 provides a flow diagram summarising the steps taken at a communications device in
an LTE system when implementing the process which has been described above with reference t o
Figures 5 and 6. Figure 7 and the later flow diagrams are not exhaustive nor are all steps essential,
for example steps including synchronisation have not been included and the transceiver may not be
in a reduced power state prior to transmitting a request.
S701: Exit a reduced-power state at the transceiver
S702: Transmit a random access request message t o an eNB in a PRACH.
S703: Receive a random access response message from an eNB granting a PUSCH
resource.
S704: Determine at a controller of the communications device a delay period appropriate
for a Radio Resource Control (RRC) connection request processing time and the communications
device's requirements.
S705: Transmit a Radio Resource Control (RRC) connection request message including the
delay period t o the eNB in the granted PUSCH resource.
S706: Set a timer to the delay period and commence the timer.
S707: Receive an acknowledgment of reception of the RRC connection request from the
eNB.
S708: Enter the reduced-power state at the transceiver.
S709: Exit from the reduced-power state at the transceiver upon expiry of the delay
period.
S710: Receive an RRC connection request response message from the eNB.
S711: Transmit an acknowledgement of reception of the RRC connection response to the
eNB.
Figure 8 provides a flow diagram summarising the steps taken at a base station when
implementing the procedure described above with reference to Figures 5 and 6 in an LTE system.
S801: Receive a random access request message in a PRACH from a communications
device.
S802: Transmit a random access response message to the communications device granting
a PUSCH resource.
S803: Receive a Radio Resource Control (RRC) connection request message including a
delay period from the communications device in the granted PUSCH resource.
S804: Set a timer to the delay period and commence the timer.
S805: Transmit an acknowledgment of reception of the RRC connection request to the
communications device.
S806: Process the RRC connection request and buffer the response message to be
transmitted t o the communications device.
S807: Transmit the buffered RRC connection request response message to the
communications device when delay period expires.
S808: Receive an acknowledgement of reception of the RRC connection request response
from the communications device.
Figure 9 provides a flow diagram summarising a generalised approach at a communications
device t o the use of the proposed delay periods when transmitting a request to a base station in a
mobile communications system.
S901: Transmit a request for services including a delay period t o a base station.
S902: Set a timer to the delay period and commence the timer.
S903: Enter a reduced-power state at the transceiver.
S904: Exit the reduced-power state at the transceiver when the delay period expires.
S905: Receive a response t o the request for services from the base station.
Figure 10 provides a flow diagram summarising a generalised approach at a base station to
the use of the proposed delay periods when receiving a request in a mobile communications system.
S1001: Receive a request for services message including a delay period from a
communications device.
S1002: Set a timer t o the delay period and commence the timer.
S1003: Process the request for services and buffer the response message to be transmitted
to the communications device.
S1004: Transmit the buffered response message to the communications device when delay
period expires.
Although in Figures 7 t o 10 possible alternatives or additions to the procedures described
with reference to Figures 5 and 6 have not been included, these alternations may be in introduced.
For example, the eNBor base station may introduce compensation into the delay period in order to
take account of the propagation delay and extraction delay when receiving the request and
acknowledgments may not be required.
In a procedure in accordance with a second example embodiment of the present disclosure,
a response to a request for services is buffered at the base station until it is requested by the
communications device. As one can see in Figure 11, the initial steps in such a procedure are
substantially similar t o those in the first examples embodiment, where a random access request is
made 1101 by the communications device, a response message t o the random access request is
transmitted by the base station 1102 and a RRC connection request including a delay period 1103 is
transmitted by the communications device to the base station and this is acknowledged by the base
station 1104. However, in contrast t o the first example embodiment, the response t o the RRC
connection request is buffered 1105 either until it is requested and successfully received by the
communications device or the delay period and/or its associated timer 1106 at the base station
expires. Therefore the delay period may also be referred to as a time out period and the timer as a
time out timer with respect to the base station. After the communications device receives an
acknowledgment of the RRC connection request its controller configures the transceiver to enter a
reduced power state where it does transmit or receive. The controller may configure the transceiver
to exit the reduced power state either because it wishes to receive the response, the delay period
timer has expired or because the elapsed time since the commencement of the timer reaches a
predetermined fraction of the delay period. Once the transceiver has exited the reduced power
state, the random access procedure previous utilised (1101, 1102) begins and a subsequent or
second RRC connection request 1107 is transmitted which does not include a delay period. When
the base station receives this second RRC connection request message the buffered RRC connection
request response 1108 may be immediately transmitted to the communications device because
there has been sufficient time for the request to have been processed and a response formed since
the initial RRC connection request 1103. Once the RRC connection setup message is received at the
communications device it may transmit an acknowledgment 1109 to the base station which then
removes the buffered response. Although in Figure 11 a delay period timer is not shown on the
communications device side, in some example embodiments a delay period timer will be started
after the RRC connection request message 1103 and the transceiver will enter the reduced power
state after receipt of the acknowledgment 1104 or transmission of the RRC request message. The
transceiver may then exit the reduced power state dependent upon the delay period timer. For
instance the transceiver, under control of the controller, may exit the reduced power state a set
proportion through the delay period or a set period before the end of the delay period.
Figure 12 provides a flow diagram summarising the procedure described above at the
communications device. The steps refer to the steps which may be taken in an LTE system.
S1201: Exit a reduced-power state at the transceiver.
S1202: Transmit a random access request message t o an eNB in a PRACH.
S1203: Receive a random access response from the eNB granting a PUSCH resource.
S1204: Determine at a controller a delay period appropriate for a Radio Resource Control
(RRC) connection request processing time and the communications device's requirements.
S1205: Transmit a Radio Resource Control (RRC) connection request including the delay
period to the eNB in the granted PUSCH resource.
S1206: Receive an acknowledgment of reception of the RRC connection request from the
eNB.
S1207: Enter the reduced-power state at the transceiver.
S1208: Exit the reduced-power state at the transceiver.
S1209: Transmit a random access request in a PRACH to the eNB.
S1210: Receive a random access response message from the eNB granting a PUSCH
resource.
S1211: Transmit a second Radio Resource Control (RRC) connection request message to the
eNB in the granted PUSCH resource.
S1212: Receive a RRC connection request response from the eNB
S1213: Transmit an acknowledgement of reception of the RRC connection request response
to the eNB.
Figure 13 provides a flow diagram summarising the procedure described above at the base
station. The steps refer to the steps which may be taken in an LTE system.
S1301: Receive a random access request message in a PRACH from a communications
device.
S1302: Transmit a random access response message to the communications device granting
a PUSCH resource.
S1303: Receive a Radio Resource Control (RRC) connection request message including a
delay period from the communications device in the granted PUSCH resource.
S1304: Set a timer to the delay period and commence the timer.
S1305: Transmit an acknowledgement of reception of the second RRC connection request
message to the communications device.
S1306: Process the RRC connection request and buffer the response to be transmitted to
the communications device until the expiry of the timer or successful transmission of the response.
S1307: Receive a random access request in a PRACH from the communications device.
S1308: Transmit a random access response to the communications device granting a PUSCH
resource.
S1309: Receive a second Radio Resource Control (RRC) connection request message from
the communications device in the granted PUSCH resource.
S1310: Transmit the buffered RRC connection request response to the communications
device.
S1311: Receive an acknowledgement of reception of the RRC connection request response
from the communications device.
In a similar manner to Figures 9 and 10 the steps set out in Figure 12 and 13 may be adapted
for use in a system where no random access procedure is required and the request may be of any
sort which requires processing such that the response cannot be transmitted to the communications
device immediately. Furthermore, the steps set out in Figures 12 and 13 maybe adapted by the
addition and removal of steps previously described, such as the commencement of a timer at the
communications device at Step 1205 upon which transmission of the second request is dependent ,
delay period compensation at the eNB, and removal of the acknowledgment steps.
In a further embodiment in accordance with an example of the present disclosure, a
subsequent or second random access request is utilised to signal to the base station that the
communications device wishes to receive a response to its request. Figure 14 illustrates this
procedure in an LTE network. The steps in this procedure are substantially similar to those described
with reference to Figure 11 to 13. However instead of performing a full random access procedure
when the transceiver at the communications device exits the reduced power state, the
communications device performs the first step of the random access procedure to initiate the
transmission of the RRC connection setup message. As previously described, when a
communications device preforms a random access request t o return from an RCCJdle mode the
communications device sends one of a fixed number of identifiers in a preamble to the base station,
where the identifiers are advertised in one of the system information blocks in the downlink. In the
embodiment shown in Figure 14, the communications device sends the same identifier in the
preamble at 1405 as sent in the preamble at 1401. Consequently, the base station can recognise that
it is the same communications device which transmitted the RRC connection request with the delay
period and can transmit the buffered RCC connection setup message upon reception of the
preamble at 1405. This procedure reduces the number of steps and transmission which have to be
performed relative to the procedure illustrated in Figure 11 to 13 and therefore may reduce
complexity and power consumption at both the communications device and the base station.
However, unless the identifier allocations are fixed it is possible that during the period in which the
transceiver at the communications device is in the reduced power mode, another communications
device may have randomly chosen the same identifier in order to connect to the base station and
therefore may transmit a random access request with the same identifier. This may then lead to the
response to the RRC connection request being wrongly transmitted. If the response is wrongly
transmitted it will not be acknowledged by the second communications device or the intended
communications device and therefore the response will remain buffered until the response is
transmitted and an acknowledgment received from the intended communications device, or the
delay period expires. Although this may overcome the problems associated with randomly selected
preamble identifiers, it may contribute towards congestion because unnecessary messages may be
transmitted over the communications network.
The procedure illustrated in Figure 14 is described by the flow diagram of Figure 15, where
the steps are those taken at the communications device in an LTE system.
S1501: Exit a reduced-power state at the transceiver.
S1502: Transmit a random access request message including an identifier to an eNB in a
PRACH.
S1503: Receive a random access response from the eNBgranting a PUSCH resource.
S1504: Determine at a controller a delay period appropriate for a Radio Resource Control
(RRC) connection request processing time and the communications device's requirements.
S1505: Transmit a Radio Resource Control (RRC) connection request including the delay
period to the eNB in the granted PUSCH resource.
S1506: Receive an acknowledgment of reception of the RRC connection request from the
eNB.
S1507: Enter a reduced-power state at the transceiver.
S1508: Exit the reduced-power state at the transceiver.
S1509: Transmit a second random access request including the same identifier in a PRACH
to the eNB.
S1510: Receive an RRC connection request response message from the eNB.
S1511: Transmit an acknowledgement of reception of the RRC connection request response
to the eNB.
The procedure illustrated in Figure 14 is described by the flow diagram of Figure 16, where
the steps are those taken at the base station of an LTE system.
S1601: Receive a random access request message including an identifier in a PRACH from a
communications device.
S1602: Transmit a random access response message to the communications device granting
a PUSCH resource.
S1603: Receive a Radio Resource Control (RRC) connection request including a delay period
from the communications device in the granted PUSCH resource.
S1604: Set a timer to the delay period and commence the timer.
S1605: Transmit an acknowledgement of reception of the RRC connection request to the
communications device.
S1606: Process the RRC connection request and buffer the response message to be
transmitted t o the communications device until the expiry of the timer or transmission of the
response.
S1607: Receive a second random access request in a PRACH from the communications
device including the same identifier.
S1608: Transmit the buffered RRC connection response message to the communications
device.
S1609: Receive an acknowledgement of reception of the RRC connection request response
from the communications device.
As previously mentioned, although the procedures above have been described with
reference to an LTE system they may be applied to a wide range of systems where the request are
transmitted and a response to the request may not be transmitted immediately because of the
processing time associated with the request. Accordingly, although Figure 14 to 16 a preamble
including an identifier for a random access request is used t o initiate the transmission of the
buffered response, any value or feature which is able to identify the requesting communications
device may be used to initiate the transmission of the response to the request. For instance, the
actual identity of the communications device may be used. Furthermore, the steps set out in Figures
15 and 16 maybe adapted by the addition and removal of steps previously described, such as the
commencement of a timer at the communications device at Step 1505 upon which transmission of
the second random access request is dependent, delay period compensation at the eNB, and
removal of the acknowledgment steps.
Figure 17 provides a schematic diagram of a communications device which may operate in
accordance with the hereinbefore described embodiments. The communications device 104 includes
a transceiver 1701 operable to transmit and t o receive data from a base station where the
transceiver is controlled by a controller 1702 and may be configured or controlled by the controller
to transmit messages and enter and exit a reduced power state as set out in the procedures
described above. The communications device may also comprise a timer which may be initiated with
a delay period and record the elapsed time from a point defined by the controller and/or count
down a time period from a point defined by the controller. For example, the controller may
configure the timer to record the elapsed time since the transmission of a request by the transceiver
and compare this with a specified delay period.
Figure 18 provides a schematic diagram of a base station or infrastructure equipment which
may operate in accordance with the hereinbefore described embodiments. The base station 101
includes a transceiver 1801 operable to transmit and to receive data from a plurality of
communications devices where the transceiver is controlled by a controller 1802. The base station
also comprises a timer 1803 which may be initiated with a delay period received in data received by
the transceiver and record the elapsed time from a point defined by the controller and count down a
time period from a point defined by the controller. For example, the controller may configure the
timer t o record the elapsed time since the reception of a request by the transceiver and compare
this with a specified delay period. The base station also includes a buffer which may be configured to
store messages which are to be transmitted. For example, the buffer may store a response t o a
request for services received from a communications device and be emptied when a delay timer
delay period expires the stored response is successfully transmitted. The controller may process
received requests and also coordinate communications between the base station and the core
network 102, for instance coordinating the communications of a request received by the base
station t o the core network.
In some examples in accordance with embodiments of the present disclosure a
communications device for transmitting and receiving data to and from infrastructure equipment
forming part of a communications network is provided. The communications device comprises a
controller and a transceiver configured to transmit and/or receive signals representing the data t o
and/or from the infrastructure equipment. The transceiver is configured under the control of the
controller to transmit a request for services message to the infrastructure equipment, and to receive
a response message to the request for services message from the infrastructure equipment. The
request for services message includes a delay period, and the controller is configured after
transmission of the request for services message t o configure the transceiver to enter a reduced
power state in which an amount of power consumed by the transceiver is reduced for the delay
period. The controller is also configured, after the delay period has expired, to configure the
transceiver to exit the reduced power state in order to receive the response message from the
infrastructure equipment.
Including a delay period in a request for services message from a communications device t o
infrastructure equipment in a communications network allows the communications device t o have
more accurate knowledge of when a response to the request will be transmitted by the
infrastructure equipment. As a result of this knowledge the transceiver of the communications
device is able to enter a reduced-power state for a period of time and exit the reduced power mode
prior to the transmission of the a response t o the request without possibility that it may not receive
the response when the response is transmitted. This therefore allows the communications device to
reduce power consumption whilst still receiving the response. This approach may also be beneficial
when the processing of a request at infrastructure equipment takes a minimum period of time. For
example if it is known that a response may not be transmitted before the end of this minimum
processing it may be more energy efficient to configure the transceiver to enter a reduced power
sate for at least the minimum processing period so that the transceiver does not attempt t o receive
the response before it can possibly be transmitted.
Various aspects and features of the present technique are defined in the following
numbered clauses:
1. A communications system comprising infrastructure equipment arranged t o provide a
wireless interface t o a communications device, the communications device comprising a controller
and a transceiver configured t o transmit and/or receive signals representing the data to and/or from
the infrastructure equipment over the wireless interface, and the transceiver under control of the
controller is configured
to transmit a request for services message to the infrastructure equipment, and
to receive a response message t o the request for services message transmitted from the
infrastructure equipment, wherein the request for services message includes a delay period and the
infrastructure equipment, in response to receiving the request for services message, processes the
request to form the response message and stores the response message for transmission to the
communications device, the response message being stored until the expiry of the delay period or
transmission of the response message, and the controller is configured after transmission of the
request for services to configure the transceiver to enter a reduced power state in which the amount
of power consumed by the transceiver is reduced and t o exit the reduced power state t o receive the
response message.
2. A communications system according to clause 1, wherein the controller is configured to
control the transceiver
to transmit a random access request message t o the infrastructure equipment requesting
up-link communications resources for transmitting the request for services message and the
infrastructure equipment is configured
to transmit a random access request response to the communications device granting up
link communications resources in response to receiving the random access request, and the
communications device is configured
to transmit the request for services message in the allocated up-link communications
resources to the infrastructure equipment.
3. A communications system according t o clause 2, wherein the controller is configured to
control the transceiver prior t o the expiry of the delay period
to transmit a second random access request message to the infrastructure equipment
requesting up-link communications resources for transmitting a request for a response message t o
the infrastructure equipment, the request for a response message requesting a response to the
request for services message, and in response to a granting of the up-link communications resources
from the infrastructure equipment,
to transmit the request for response message in the allocated up-link communications
resources to the infrastructure equipment, and
to receive a response message from the infrastructure equipment providing the requested
services to the communications device in response to the request for services message, and
the infrastructure equipment is configured
to transmit a random access request response to the communications device granting up
link communications resources in response to receiving the second random access request from the
transceiver,
to receive the request for a response message requesting a response to the request for
services message, and
to transmit a response message to the communications device providing the requested
services to the communications device in response to the request for services message.
4. A communications system according to clause 2, wherein the controller is configured to
control the transceiver to exit the reduced power state to receive the response message in response
to the expiry of the delay period, and the infrastructure equipment is configured to transmit the
response message to the transceiver in response to the expiry of the delay period.
5. A communications system according to clause 2, wherein the random access request
message transmitted by the transceiver to the infrastructure equipment requesting up-link
communications resources includes an identifier identifying the communications device which has
transmitted the random access request message and the transceiver is configured
to receive a random access response message from the infrastructure equipment which
provides the granted up-link communications resources for transmitting the request for services
message, the random access response including the identification number, and prior t o the expiry of
the delay period the transceiver is configured
to transmit a second random access request message, which includes the identification
number to the infrastructure equipment, and
to receive in response to the second random access request message a response message
from the infrastructure equipment providing the requested services t o the communications device
in response to the request for services message; and the infrastructure equipment is configured
to transmit a random access response message providing the granted up-link
communications resources for the transceiver t o transmit the request for services message to the
infrastructure equipment,
to receive the second random access request message from the communications device, and
to transmit, in response t o the second random access request message, a response message
providing the requested services to the communications device in response to the request for
services message.
6. A communications system according to any of the preceding clauses, wherein the request
for services message represents a request for a radio resources connection request t o the
communications network to establish a radio communications bearer for transmitting data t o and/or
from the communications network.
7. A communications system according to any of the preceding clauses, wherein the
infrastructure equipment transmits an indication of the delay period and the controller is configured
with the transceiver unit to receive the indication of the delay period from the communications
network and to store the indication in data store.
8. A communications system according to any of the preceding clauses, wherein the delay
period exceeds the time taken to process the request for services message and form the response
message at the infrastructure equipment.
9. The communications system according to any of the preceding clauses, wherein the
communications network is a 3GPP LTE mobile network and the request for services message is a
Radio Resource Control request and the response to the request for services message is a Radio
Resource Control Setup response.
10. Infrastructure equipment arranged t o provide a wireless interface to a communications
device forming part a communications network, the infrastructure equipment configured to transmit
and/or receive signals representing data to and/or from the communications device over the
wireless interface, and the infrastructure equipment is configured
to receive a request for services message from the communications device,
to transmit a response message to the request for services message to the communications
device, wherein the request for services includes a delay period and the infrastructure equipment, in
response to receiving the request for services message, processes the request t o form the response
message and stores the response message for transmission to the communications device, the
response message being stored until expiry of the delay period or transmission of the response
message.
11. Infrastructure equipment according to clause 10, wherein the infrastructure is configured
to receive a random access request message from the communications device requesting
up-link communications resources for transmitting the request for services message,
to transmit a random access request response to the communications device
granting up-link communications resources in response t o receiving the random access request
message, and
to receive the request for services message in the granted up-link resources from the
communications device.
12. Infrastructure equipment according to clause 11, wherein the infrastructure equipment is
configured
to store the response to the request for services until the expiry of the delay period or
transmission of the response message,
to receive a second random access request message requesting uplink communications
resources for transmitting a request for a response message from the communications device,
to transmit a random access request response to the communications device granting up
link communications resources in response to receiving the second random access request message
from the communications device,
to receive the request for a response message requesting a response to the request for
services message, and
to transmit the response message to the communications device providing the requested
services to the communications device in response to the request for services message.
13. Infrastructure equipment according to clause 10 or 11, wherein the infrastructure
equipment is configured to transmit the response message to the communications device in
response to the expiry of the delay period.
14. Infrastructure equipment according to clause 12, wherein the random access request
message transmitted by the communications device to the infrastructure equipment requesting up
link communications resources includes an identifier identifying the communications device which
has transmitted the random access request message and the infrastructure equipment is configured
to transmit a random access response message to the communications device which
provides the granted up-link communications resources for transmitting the request for services
message, the random access response including the identification number
to receive a second random access request message from the communications device, which
includes the identification number,
to transmits in response to the second random access request message a response message
to the communications device providing the requested services t o the communications device in
response to the request for services message.
15. Infrastructure equipment according to any of clauses 10 to 14, wherein the request for
services message represents a request for a radio resources connection request to the
communications network to establish a radio communications bearer for transmitting data t o and/or
from the communications network.
16. Infrastructure equipment according to any of clauses 10 to 15, wherein the delay period
exceeds the time taken to process the request for services message at the infrastructure equipment.
17. Infrastructure equipment according to any of clauses 10 to 16, wherein the communications
network is a 3GPP LTE mobile network and the request for services message is a Radio Resource
Control request and the response to the request for services message is a Radio Resource Control
Setup response.
18. A method for transmitting and receiving signals representing data t o and/or from
infrastructure equipment forming part of a communications network to and/or from a
communications device, the method comprising
receiving a request for services from the communications device,
transmitting a response message to the request for services to the communications device,
wherein the request for services message includes a delay period and the infrastructure equipment,
in response to receiving the request for services,
processing the request for services and
storing the response message for transmission t o the communications device, the response
message being stored until the expiry of the delay period or transmission of the response message,
and the controller is configured after transmission of the request for services to configure the
transceiver to enter a reduced power state in which the amount of power consumed by the
transceiver is reduced and to exit the reduced power state t o receive the response message.

Claims
1. A communications system comprising infrastructure equipment arranged t o provide a
wireless interface t o a communications device, the communications device comprising a controller
and a transceiver configured t o transmit and/or receive signals representing the data to and/or from
the infrastructure equipment over the wireless interface, and the transceiver under control of the
controller is configured
to transmit a request for services message to the infrastructure equipment, and
to receive a response message t o the request for services message transmitted from the
infrastructure equipment, wherein the request for services message includes a delay period and the
infrastructure equipment, in response to receiving the request for services message, processes the
request to form the response message and stores the response message for transmission to the
communications device, the response message being stored until the expiry of the delay period or
transmission of the response message, and the controller is configured after transmission of the
request for services to configure the transceiver to enter a reduced power state in which the amount
of power consumed by the transceiver is reduced and t o exit the reduced power state t o receive the
response message.
2. A communications system as claimed in Claim 1, wherein the controller is configured to
control the transceiver
to transmit a random access request message t o the infrastructure equipment requesting
up-link communications resources for transmitting the request for services message and the
infrastructure equipment is configured
to transmit a random access request response to the communications device granting up
link communications resources in response to receiving the random access request, and the
communications device is configured
to transmit the request for services message in the allocated up-link communications
resources to the infrastructure equipment.
3. A communications system as claimed in Claim 2, wherein the controller is configured to
control the transceiver prior t o the expiry of the delay period
to transmit a second random access request message to the infrastructure equipment
requesting up-link communications resources for transmitting a request for a response message t o
the infrastructure equipment, the request for a response message requesting a response t o the
request for services message, and in response to a granting of the up-link communications resources
from the infrastructure equipment,
to transmit the request for response message in the allocated up-link communications
resources to the infrastructure equipment, and
to receive a response message from the infrastructure equipment providing the requested
services to the communications device in response to the request for services message, and
the infrastructure equipment is configured
to transmit a random access request response to the communications device granting up
link communications resources in response to receiving the second random access request from the
transceiver,
to receive the request for a response message requesting a response to the request for
services message, and
to transmit a response message to the communications device providing the requested
services to the communications device in response to the request for services message.
4. A communications system as claimed in Claim 2, wherein the controller is configured to
control the transceiver to exit the reduced power state to receive the response message in response
to the expiry of the delay period, and the infrastructure equipment is configured to transmit the
response message to the transceiver in response t o the expiry of the delay period.
5. A communications system as claimed in Claim 2, wherein the random access request
message transmitted by the transceiver to the infrastructure equipment requesting up-link
communications resources includes an identifier identifying the communications device which has
transmitted the random access request message and the transceiver is configured
to receive a random access response message from the infrastructure equipment which
provides the granted up-link communications resources for transmitting the request for services
message, the random access response including the identification number, and prior t o the expiry of
the delay period the transceiver is configured
to transmit a second random access request message, which includes the identification
number to the infrastructure equipment, and
to receive in response to the second random access request message a response message
from the infrastructure equipment providing the requested services t o the communications device
in response to the request for services message; and the infrastructure equipment is configured
to transmit a random access response message providing the granted up-link
communications resources for the transceiver t o transmit the request for services message to the
infrastructure equipment,
to receive the second random access request message from the communications device, and
to transmit, in response t o the second random access request message, a response message
providing the requested services to the communications device in response to the request for
services message.
6. A communications system as claimed in claim 1, wherein the request for services message
represents a request for a radio resources connection request to the communications network t o
establish a radio communications bearer for transmitting data t o and/or from the communications
network.
7. A communications system as claimed in claim 1, wherein the infrastructure equipment
transmits an indication of the delay period and the controller is configured with the transceiver unit
to receive the indication of the delay period from the communications network and to store the
indication in data store.
8. A communications system as claimed in claim 1, wherein the delay period exceeds the time
taken to process the request for services message and form the response message at the
infrastructure equipment.
9. The communications system as claimed in claim 1, wherein the communications network is a
3GPP LTE mobile network and the request for services message is a Radio Resource Control request
and the response to the request for services message is a Radio Resource Control Setup response.
10. Infrastructure equipment arranged t o provide a wireless interface to a communications
device forming part a communications network, the infrastructure equipment configured to transmit
and/or receive signals representing data to and/or from the communications device over the
wireless interface, and the infrastructure equipment is configured
to receive a request for services message from the communications device,
to transmit a response message to the request for services message to the communications
device, wherein the request for services includes a delay period and the infrastructure equipment, in
response to receiving the request for services message, processes the request t o form the response
message and stores the response message for transmission to the communications device, the
response message being stored until expiry of the delay period or transmission of the response
message.
11. Infrastructure equipment as claimed in Claim 10, wherein the infrastructure is configured
to receive a random access request message from the communications device requesting
up-link communications resources for transmitting the request for services message,
to transmit a random access request response to the communications device
granting up-link communications resources in response t o receiving the random access request
message, and
to receive the request for services message in the granted up-link resources from the
communications device.
12. Infrastructure equipment as claimed in Claim 11, wherein the infrastructure equipment is
configured
to store the response to the request for services until the expiry of the delay period or
transmission of the response message,
to receive a second random access request message requesting uplink communications
resources for transmitting a request for a response message from the communications device,
to transmit a random access request response to the communications device granting up
link communications resources in response to receiving the second random access request message
from the communications device,
to receive the request for a response message requesting a response to the request for
services message, and
to transmit the response message to the communications device providing the requested
services to the communications device in response to the request for services message.
13. Infrastructure equipment as claimed in Claim 10, wherein the infrastructure equipment is
configured to transmit the response message t o the communications device in response to the
expiry of the delay period.
14. Infrastructure equipment as claimed in Claim 12, wherein the random access request
message transmitted by the communications device to the infrastructure equipment requesting uplink
communications resources includes an identifier identifying the communications device which
has transmitted the random access request message and the infrastructure equipment is configured
to transmit a random access response message to the communications device which
provides the granted up-link communications resources for transmitting the request for services
message, the random access response including the identification number
to receive a second random access request message from the communications device, which
includes the identification number,
to transmits in response to the second random access request message a response message
to the communications device providing the requested services to the communications device in
response to the request for services message.
15. Infrastructure equipment as claimed in Claim 10, wherein the request for services message
represents a request for a radio resources connection request to the communications network t o
establish a radio communications bearer for transmitting data t o and/or from the communications
network.
16. Infrastructure equipment as claimed in Claim 10, wherein the delay period exceeds the time
taken to process the request for services message at the infrastructure equipment.
17. Infrastructure equipment as claimed in Claim 10, wherein the communications network is a
3GPP LTE mobile network and the request for services message is a Radio Resource Control request
and the response to the request for services message is a Radio Resource Control Setup response.
18. A method for transmitting and receiving signals representing data t o and/or from
infrastructure equipment forming part of a communications network to and/or from a
communications device, the method comprising
receiving a request for services from the communications device,
transmitting a response message to the request for services to the communications device,
wherein the request for services message includes a delay period and the infrastructure equipment,
in response to receiving the request for services,
processing the request for services and
storing the response message for transmission to the communications device, the response
message being stored until the expiry of the delay period or transmission of the response message,
and the controller is configured after transmission of the request for services t o configure the
transceiver to enter a reduced power state in which the amount of power consumed by the
transceiver is reduced and to exit the reduced power state t o receive the response message.
19. A communications network substantially as hereinbefore described with reference to the
drawings.
20. Infrastructure equipment substantially as hereinbefore described with reference to the
drawings.
21. A method for transmitting signals representing data as hereinbefore described with
reference to the drawings.