TECHNICAL FIELD OF THE DISCLOSURE
The present disclosure relates to communications devices and methods for communicating
data using communications devices, and also to communications apparatus which operate as relay
nodes and methods for communicating via a relay node. The present disclosure also relates to
infrastructure equipment, which forms part of a mobile communications network and methods of
communicating using infrastructure equipment.
BACKGROUND OF THE DISCLOSURE
The "background" description provided herein is for the purpose of generally presenting the
context of the disclosure. Work of the presently named inventors, to the extent it is described in this
background section, as well as aspects of the description which may not otherwise qualify as prior art
at the time of filing, are neither expressly or impliedly admitted as prior art against the present
invention.
Third and fourth generation mobile telecommunication systems, such as those based on the
3GPP defined UMTS and Long Term Evolution (LTE) architecture are able to support more
sophisticated services than simple voice and messaging services offered by previous generations of
mobile telecommunication systems. For example, with the improved radio interface and enhanced
data rates provided by LTE systems, a user is able to 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 networks
is possible, is expected to increase rapidly.
The anticipated widespread deployment of third and fourth generation networks has led to the
parallel development of a class of devices and applications which, rather than taking advantage of the
high data rates available, instead take advantage of the robust radio interface and increasing ubiquity
of the coverage area. Examples include so-called machine type communication (MTC) applications,
which are typified by semi-autonomous or autonomous wireless communication devices (i.e. MTC
devices) communicating small amounts of data on a relatively infrequent basis. Examples include socalled
smart meters which, for example, are located in a customer's house and periodically transmit
information back to a central MTC server data relating to the customers consumption of a utility such
as gas, water, electricity and so on. Other examples include medical devices which are continuously
or intermittently transmitting data such as for example measurements or readings from monitors via a
communications network to a server, and automotive applications in which measurement data is
gathered from sensors on a vehicle and transmitted via a mobile communications network to a server
attached to the network.
Whilst it can be convenient for a terminal such as an MTC type terminal to take advantage of
the wide coverage area provided by a third or fourth generation mobile telecommunication network,
there are at present disadvantages and challenges to successful deployment. Unlike a conventional
third or fourth generation communications device such as a smartphone, an MTC-type terminal is
preferably relatively simple and inexpensive, having a reduced capability. In addition MTC-devices
are often deployed in situations that do not afford easy access for direct maintenance or replacement,
so that reliable and efficient operation can be crucial. Furthermore, while the type of functions
performed by the MTC-type terminal (e.g. collecting and reporting back data) do not require
particularly complex processing to perform, third and fourth generation mobile telecommunication
networks typically employ advanced data modulation techniques (such as 16QAM or 64QAM) on the
radio interface which can require more complex and expensive radio transceivers to implement.
It is usually justified to include such complex transceivers in a smartphone as a smartphone
will typically require a powerful processor to perform typical smartphone type functions. However, as
indicated above, there is now a desire to use relatively inexpensive and less complex devices to
communicate using LTE type networks. Accordingly such devices may be low power or battery
operated and therefore have a reduced transmission power capability compared with more
conventional devices. Such MTC devices may also be deployed in remote locations where radio
propagation conditions may be poor so that radio signals transmitted by the MTC device may be less
likely to be receivable by a base station.
SUMMARY OF THE DISCLOSURE
According to an example embodiment of the present technique there is provided an
infrastructure equipment, which forms part of a mobile communications network for transmitting data
to communications devices or receiving data from communications devices. The infrastructure
equipment comprises a transmitter configured to transmit signals representing data to the
communications devices via a wireless access interface, a receiver configured to receive signals from
the communications devices via the wireless access interface, and a controller for controlling the
transmitter and the receiver to receive an indication that data is to be transmitted to one of the
communications devices, and in response to transmit a first paging message to the communications
device to indicate that the communications device is to receive the data via the wireless access
interface. If a response to the transmitted first paging message is not received within a predetermined
time, then if the infrastructure is able to use a power boosting mode, to transmit the first paging
message with a boosted power, or if the infrastructure equipment is not able to use a power boosted
mode for transmitting, to transmit a second paging message to one or more communications apparatus
which can operate as a relay node for the communications device. The second paging message
identifies the relay node and the communications device for which the infrastructure equipment is to
transmit the data.
Embodiments of the present technique can provide an arrangement in which an infrastructure
equipment which forms part of a mobile communications network and comprises a transmitter for
transmitting signals to communications devices via a wireless access interface, and a receiver for
receiving signals from the one or more communications devices via the wireless access interface and a
controller. The controller is configured to determine that data is to be transmitted to one of the
communications devices, to detect that the communications device is one of the predetermined type of
communications devices, such as an MTC device, to transmit a paging message to the
communications device to indicate that the communications device is to receive the data via the
wireless access interface (on the downlink). If the controller in combination with the receiver does
not receive a response to the transmitted paging message within a predetermined time the controller
determines whether the infrastructure equipment is able to transmit the paging message with a boosted
transmission power and if the infrastructure equipment is able to transmit the paging message with a
booster transmission power to increase the transmission power of the transmitted paging message or if
the infrastructure equipment cannot increase the transmission power in accordance with the boosted
power level or if the controller in combination with the receiver does not receive a response to the
paging message transmitted with the boosted transmission power from the communications device to
transmit a second paging message to one or more communications apparatus which can operate as a
relay node for the communications device to the effect of informing the communications apparatus
that it is to transmit the second paging message to the communications device.
The embodiments of the technique can provide an arrangement for transmitting data to a
communications device on the downlink where that communications device is a predetermined type
of limited mobility or capability to receive downlink signals. According to the present technique after
the infrastructure equipment has attempted to transmit a paging message to the communications
device and has not received a response from the communications device within a predetermined time,
having determined that the communications device is of the predetermined type, the infrastructure
equipment then attempts to transmit the paging message with an increased power in accordance with a
boosted power node. This is in contrast to a conventional arrangement in which if the
communications device is not of the predetermined type then the infrastructure would arrange for the
paging message to be transmitted by other infrastructure equipment within a tracking area. However
the infrastructure equipment itself may not be able to perform a boosted power transmission because
of various reasons such as the infrastructure equipment does not have the capability to perform the
boosted power transmission or the boosted power transmission is not available at a certain time of the
day. However, even after transmitting the paging message with a boosted power the communications
device may not be able to receive the boosted power transmission message at its location. This may
be because the communications device is a device of reduced capability, but this may apply to
conventional communications devices. Accordingly, after attempting to transmit the paging message
with the boosted power which has not been received for a predetermined time or if the infrastructure
equipment is not able to transmit the paging message with a boosted power then the infrastructure
equipment transmits a second paging message to one or more communications apparatus which can
act as a relay node within a coverage area provided by the infrastructure equipment.
The infrastructure equipment may comprise a base station with a transmitter and receiver and
a mobility manager or mobility management entity, which contains the information, which contains
the type of the communications device. In one example the infrastructure equipment provides a
plurality of base stations each of which may be able to transmit the paging message with a boosted
power mode or not and in accordance with the capability of the base station to transmit the paging
message with a booster power the mobility management entity may control the transmission of the
paging message to reflect the power transmission.
Accordingly, the embodiments of the present technique can provide an optimised
arrangement for transmitting a downlink message to contact a communications device where that
communications device may not be able to receive the downlink transmission. In one example the
device of the predetermined type may be an MTC type device.
Various further aspects and features of the present technique are defined in the appended
claims.
The foregoing paragraphs have been provided by way of general introduction, and are not
intended to limit the scope of the following claims. The described embodiments, together with further
advantages, will be best understood by reference to the following detailed description taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the disclosure and many of the attendant advantages thereof
will be readily obtained as the same becomes better understood by reference to the following detailed
description when considered in connection with the accompanying drawings wherein like reference
numerals designate identical or corresponding parts throughout the several views, and wherein:
Figure 1 provides a schematic diagram of a mobile communications system according to an
example of an LTE standard;
Figure 2a provides a schematic diagram of a communications device (UE) communicating
with a mobile communications network via a communications apparatus operating as a relay node, in
which uplink assistance is provided by the relay node; Figure 2b is a schematic block diagram
illustrating different scenarios in which a relay nodes provides assistance for transmitting on the
uplink only, the downlink as well as the uplink;
Figure 3 is a schematic representation of a downlink of a wireless access interface which
incorporates a virtual carrier;
Figure 4 is a graphical representation illustrating power boosting for certain subcarriers of
resource blocks in a power spectral density boosting mode;
Figure 5 is an example flow diagram illustrating an operation of a mobility management
entity (MME) in which a relay node is discovered by maintaining a list of available relay nodes within
a tracking area;
Figure 6 is an example flow diagram illustrating the operation of a mobility management
entity (MME) for an example in which a common paging identifier is used;
Figure 7 is a flow diagram illustrating an example operation of a base station (eNB) for
example in which the eNB receives a list of available relay nodes within a coverage area;
Figure 8 is an example flow diagram illustrating an example operation of a base station (eNB)
in which relay nodes are discovered using a common paging identifier;
Figure 9 is an example flow diagram illustrating an example operation of a relay node in
which relay nodes are discovered using a list of available relay nodes maintained at a base station
(eNB);
Figure 10 is an example flow diagram illustrating an operation of a relay node in which the
relay node has been disclosed using a common paging identifier;
Figure 11 is an example flow diagram illustrating the operation of a communications device
in accordance with the present technique.
DESCRIPTION OF EXAMPLE EMBODIMENTS
Hereinafter preferred embodiments of the present technique will be described in detail with
reference to the appended drawings. Note that, in this specification and appended drawings, structural
elements that have substantially the same function and structure are denoted with the same reference
numerals, and repeated explanation of these structural elements is omitted.
Example Communications System
Figure 1 provides a schematic diagram illustrating some basic functionality of a conventional
mobile telecommunications network, using for example a 3GPP defined UMTS and/or Long Term
Evolution (LTE) architecture. The mobile telecommunications network / system 100 of Figure 1
operates in accordance with LTE principles and which may be adapted to implement embodiments of
the disclosure as described further below. Various elements of Figure 1 and their respective modes of
operation are well-known and defined in the relevant standards administered by the 3GPP (RTM)
body, and also described in many books on the subject, for example, Holma H. and Toskala A [1]. It
will be appreciated that operational aspects of the telecommunications network which are not
specifically described below may be implemented in accordance with any known techniques, for
example according to the relevant standards.
As can be seen in Figure 1, the network includes a plurality of base stations 101 connected to
a core network, which includes in the present example a serving gateway (S-GW) 102 which is
connected to each of the base stations (eNodeBs (eNBs)), a packet data gateway (P-GW) 106 and a
mobility management entity (MME) 110. As those acquainted with LTE will appreciate, the packet
data gateway 106 acts as a gateway with an external network 108. Each base station provides a
coverage area 103 (i.e. a cell) within which data can be communicated to and from communications
devices (also referred to as mobile terminals, MT or User Equipment, (UE) 104. Data is transmitted
from base stations 101 to communications devices 104 within their respective coverage areas 103 via
a radio downlink. Data is transmitted from communications devices 104 to the base stations 101 via a
radio uplink. The serving gateway 102 routes data to and from the communications devices 104 via
the respective base stations 101 from and to the packet data gateway 106. The mobility management
entity 110 controls operations and functions to support the mobility of the communications devices
104 communicating via the mobile communications network. The packet data gateway 106 provides
functions such as authentication, charging and so on.
Mobile telecommunications systems such as those arranged in accordance with the 3GPP
defined Long Term Evolution (LTE) architecture use an orthogonal frequency division multiplex
(OFDM) based interface for the radio downlink (so-called OFDMA) and the radio uplink (so-called
SC-FDMA).
The base stations 101 of Figure 1 may be realised as any type of evolved Node B (eNodeB)
such as a macro eNodeB and a small eNodeB. The small eNodeB may be an eNodeB such as a pico
eNodeB, a micro eNodeB, and a home (femto) eNodeB that covers a cell smaller than a macro cell.
Instead, the base station 101 may be realized as any other types of base stations such as a NodeB and
a base transceiver station (BTS). The base station 101 may include a main body (that is also referred
to as a base station apparatus) configured to control radio communication, and one or more remote
radio heads (RRH) disposed in a different place from the main body. In addition, various types of
terminals, which will be described below, may each operate as the base station 101 by temporarily or
semi-persistently executing a base station function.
Any of the communications devices 104 may be realized as a mobile terminal such as a
smartphone, a tablet personal computer (PC), a notebook PC, a portable game terminal, a
portable/dongle type mobile router, and a digital camera, or an in-vehicle terminal such as a car
navigation apparatus. The communications device 104 may also be realized as a terminal (that is also
referred to as a machine type communication (MTC) terminal) that performs machine-to-machine
(M2M) communication. Furthermore, the terminal apparatus 104 may be a radio communication
module (such as an integrated circuit module including a single die) mounted on each of the terminals
Relay Technologies
Relay technologies are known generally to provide an arrangement for receiving signals from
a base station and for retransmitting the received signals to a UE in a mobile communications
network, or to receive signals transmitted from a UE for re-transmission to a base station of a mobile
communications network. As a result of such an arrangement a radio coverage area provided by an
mobile communications network can be extended by a relay node to reach communications devices
which would otherwise be out of range of the mobile communications network.
As explained above, it is desirable to extend the normal coverage of eNodeBs for machine
type communications (MTC) UEs that are typically located in locations where they experience
significant penetration losses. For example, electric and gas meters are often installed in locations
where they suffer from poor network coverage, such as in the basements of residential buildings,
beneath the staircase or even underground (below a manhole cover). To ensure MTC applications in
such challenging locations, 3GPP initially identified the need for 20dB improvement in coverage for
low-cost MTC devices in comparison to defined LTE cell coverage footprint at the beginning of its
study item, however finally settled on a lower value of 15dB. For MTC coverage extension, power
spectral density (PSD) boosting has been studied extensively along with other approaches such as
repetition coding and it is noted that MTC UEs in extreme coverage scenarios might have
characteristics such as very low data rate, greater delay tolerance and no mobility.
As disclosed in our co-pending European patent application EP14170122.7, a multi-RAT
uplink relay assisted transmission arrangement can be provided in which a relay node is used to assist
a UE in relaying uplink transmission by receiving signals from a UE and re-transmitting the signals to
an eNodeB, as if the relay node were a UE (the content of which are incorporated herein by
reference). In this concept the MTC UE is able to receive downlink physical channels from the
eNodeB but needs a relay node to relay its uplink transmissions to the eNodeB. In the downlink,
coverage extension techniques, such as power boosting, may be employed so that a UE can receive
the downlink signals from the eNodeB with sufficient signal strength. Accordingly the down-link
follows LTE signalling protocols. However, on the uplink the UE is not able to reach or chooses not
to reach the eNodeB so that there is no direct connection between the MTC UE and the eNodeB. In
this regard, relay nodes (relay nodes) are deployed to facilitate the communication for two main
reasons:
• Energy saving due to less transmitting used by the MTC devices;
· Coverage extension for those MTC devices in hostile radio environment.
If the MTC devices cannot establish LTE uplink connection with the eNodeB, they can
communicate with the eNodeB via one or multiple relay nodes using radio interface technologies that
are potentially different from LTE, e.g. WiFi, LTE-U etc. An arrangement can therefore be provided
in which communications devices which are out of coverage range of an eNodeB for uplink and
downlink transmissions at least can discover relay nodes which are either fixed relay nodes or ad hoc
relay nodes. A communications device can discover one or more relay nodes within a vicinity
through which radio communications are possible via a radio access interface which is different to a
radio access interface which it would use to communicate with a base station of a mobile
communications network. The communications device then transmits a relay assist request assistance
message to the relay node which responds by performing a random access procedure as if the relay
node was a communications device operating in accordance with a first wireless access interface of
the mobile communications network. Following a successful random access procedure, the relay
node then performs a radio resource connection establishment procedure in which it identifies the
communications device for which relay assisted communications has been requested and acquires an
identity of a base station. The relay node then transmits to the communications device the identity of
the base station so that communications device and the base station can communicate in accordance
with a first wireless access interface using the relay node which transmits and receives signals to the
UE via a second wireless access interface.
Figures 2a and 2b provide example scenarios in which a communications device 204 forms an
ad-hoc relay node to facilitate communication of radio signals to communications devices (UEs) 104.
In some examples the UEs may be MTC-UEs. As shown in Figure 2a a base station or eNodeB 101
transmits downlink transmissions 201 via an LTE-type wireless access interface to UEs 104 which as
already mentioned may be MTC type UEs. The base station or eNodeB 101 includes a transmitter
101.tx, a receiver 101.rx and a controller or scheduler 101.ct. Correspondingly the UEs 104 includes
a transmitter 104.tx, a receiver 104.rx and a controller 104.ct.
As mentioned above, MTC type UEs may be disposed in a remote location such as a
basement of a house or within a car and therefore radio transmission and reception from the UEs may
be difficult. Furthermore, MTC-UEs themselves are likely to be low power devices and therefore, for
example, may be battery powered. As such, the UEs 104 may be limited in their transmission power
in addition to being disposed in a location, which makes radio communications difficult. However,
the eNodeB 101 is not as limited in transmission power and therefore the downlink transmission
signals 201 are more likely to be receivable by the UEs 104 in situations in which up-link
transmissions from the MTC-UE may not reach the eNodeB 101. This scenario is shown in Figure 2a
in which a communications apparatus may operate as a relay node 204 provides uplink assistance only
for the UE 104 and so receives signals 206 from the UE 104 and retransmit the signals from the relay
node 204 to the base station 101 represented by an arrow 208.
The examples shown in Figure 2b provide an illustration of a mixture of scenarios. A first
UE 104.1 does not require assistance for either the uplink or the downlink transmissions 210, 211. A
second UE 104.2 is provided with assistance for uplink transmissions only using a relay node 204 and
so corresponds to the example provided in Figure 2a. A third UE 104.3 requires assistance for both
downlink and uplink transmissions and so for the downlink the communications apparatus 204
receives the downlink transmissions 214 and retransmits the downlink signals received from the eNB
101 to the UE 104.3 via signals 216. Thus Figure 2b presents a more realistic scenario in which UEs
are deployed within a cell and therefore may either require no assistance for the uplink or the
downlink, assistance for the uplink only or assistance for the uplink and the downlink depending on
radio communications conditions.
For downlink transmissions, for scenarios in which an MTC-UE is not under the coverage of
the eNB directly, the 20dB coverage extension target can be achieved using power spectral density
(PSD) boosting the narrow band virtual (by offloading the resource blocks used by normal LTE
usage) [4]; hence this idea has been vigorously followed for PDSCH as well as PBCH and PDCCH
(including VC-PDCCH). An illustration of PSD boosting is provided by the example embodiments
shown in Figures 3 and 4.
As an example, the structure of a downlink shared channel for MTC devices, which is
known as a Virtual Carrier (VC-PDSCH) is presented in Figure 3. The term "virtual carrier"
corresponds in essence to a narrowband carrier for MTC-type devices within a host carrier for an
OFDM-based radio access technology (such as WiMAX or LTE). The virtual carrier concept is
described in a number of co-pending patent applications (including GB 1101970.0 [7], GB 1101981.7
[8], GB 1101966.8 [9], GB 1101983.3 [10], GB 1101853.8 [11], GB 1101982.5 [12], GB 1101980.9
[13] and GB 1101972.6 [14]), the contents of which are incorporated herein by reference.
Figure 3 provides a simplified example of the downlink of the wireless access interface when
provided by OFDM in accordance with LTE. Each subframe 301 is 1ms in duration and may be
further divided into two slots of 0.5ms duration. The subframes 301 may be grouped together into
frames which are formed from ten subframes. Each subframe 301 may include user plane and control
plane data, where control plane data may for example be conveyed across a physical downlink control
channel (PDCCH) 301 and user plane data conveyed across a physical downlink shared channel
(PDSCH) 304. Resources of the subframes are allocated to different UEs such that data intended for a
UE is transmitted in resources allocated to the UE, and an indication of the allocation is provided in
the control channel PDCCH 201. As shown in Figure 3, a region 306 comprising a central six
resource blocks (RBs), which are the equivalent of 1.4MHz) of the available bandwidth, provides a
reserved set of resources for a VC-PDSCH 308 and a VC-PDCCH 310. As such MTC devices which
are reduced capability devices can communicate via an LTE-like wireless access interface using a
transmitter and receiver, which is limited in frequency to that of the central region 306.
Figure 4 provides a graphical representation of OFDM sub-carriers 401, which represented as
power with respect to frequency. As represented by a region 404 and an arrow 406, PSD boosting is
applied to VC-PDSCH by unloading some resource blocks from either sides of central 1.4 MHz as
illustrated in Figure 4 wherein it is shown that six resource blocks are unloaded to provide 3dB
boost to VC-PDSCH.
The power of MTC PDSCH is boosted according to the value determined from:
where M and N denote the number of resource blocks allocated to the MTC PDSCH and
number of unloaded resource blocks, respectively.
The PSD boosting is an effective approach for downlink coverage improvement when extra
time-frequency (TF) resource blocks are available for power aggregation; an ideal implementation
scenario is during the night when the traffic in the network is significantly reduced.
Therefore, the downlink PSD boosting transmission could be scheduled in such a specific, quieter
time period, which does make sense for MTC services that operate on a delay non- sensitive basis.
However, in some cases there may not be enough time and frequency resource blocks available in a
cell, and in some specific scenarios for example fire alarm, earthquake warning, etc.,
communications may be preferably done without significant delay. Downlink relay assisted
transmission is an alternative for those scenarios. Then the main question is how and when the
connection switches between the two approaches.
As a starting proposition, downlink relay assisted transmission would only be used
when PSD boosting is not possible. However, the paging of the UE is not straightforward when
it cannot read the downlink common channels. In the current LTE paging procedure the MME 110
in the core network knows the location of a UE at the accuracy of Tracking Area (TA), and
paging starts in the tracking area where the UE last registered to the network. After the eNBs under
the tracking area being paged have sent a paging message in all the cells, the UE is expected to start
Random Access procedure in order to establish radio link connection. If within a certain time (set
by timers at MME) the UE fails to respond to the page, a new paging message is sent to the
tracking area and eventually the UE will be paged in neighbouring tracking areas. The help of
Relay Nodes that can connect to the UE with a different, non-3GPP RAT, can greatly facilitate the
reduction in paging messages.
Due to the significantly different impact on the radio interface usage (from the occupied
resources and period), the availability of PSD boosting can be judged independently depending
on:
• The viability of PSD boosting PBCH.
• The viability of PSD boosting PDSCH/PDCCH.
In the uplink-only relay assisted transmission (as per Figure 2), where the direct link between
the MTC-UE and eNB has been assumed (i.e. PSD boosting) extra round-trip delay is introduced
only from uplink MTC UE-to-RN link. However, when the downlink direct link is unavailable, the
RN-to- MTC UE link introduces additional delay (as per Figure 2).
Discovering a relay node 214 which is available to transmit data to a UE 214 on the DL is a
technical problem addressed by the present technique.
As will be appreciated from the above explanation, discovering relay nodes 204, which are
available to assist in downlink communications to a UE 104.3 represents a technical problem which is
addressed by embodiments of the present technique.
Adaptive Protocol for Paging MTC Devices
Example embodiments of the present technique will now be described in which four separate
procedures relating to downlink relay assisted transmission are presented, namely, the procedure at
the MME, the procedure at the eNB, the procedure at the relay node and the procedure at the MTCUE,
respectively. A timer (Tpaging) and an indicator (Npaging) are defined in the MME (see Figure
5). These are defined as:
· timer Tpaging- when Tp a ging and the paging still unsuccessful, the PSD boosting or relay
node assistance will be applied (second stage of paging).
• indicator Npaging - the exchange signal between the MME and eNBs in the tracking area
of the MTC-UE, when Npaging=0, normal paging will be applied at the eNB. While
Npaging=l, the PSD boosting or relay node assistance will be applied.
In the first instance ( Tpaging) arises with PSD boosting for paging and/or relay node discovery triggered by the
eNB. This approach has an advantage that this would avoid every time activating all the eNBs
sending PSD boosted physical channels in all the cells or connecting with multiple relay nodes in the
first instance.
As will be explained below Figures 7 to 10 include four branches. Two branches are defined
at the first stage for procedures at the eNB, the relay node and the UE, depending on the device that
acts upon the normal LTE paging message. Branch 1 is defined for the scenario where the MTCUE
(and normal UE) is at a good location, so that the channel condition is strong enough to
facilitate LTE downlink and uplink communications directly between the eNB and the UE (without
any uplink or downlink relay support).
In branch 2, the downlink and uplink transmission cannot be achieved directly between UE
and eNB without relay node support. However, any MTC-UE will sooner or later have something
to transmit or it will have to do periodical Tracking Area Updates (TAU). The relay nodes that assist
UEs in the cell would have a table of UE identifiers listing the UEs which they have already
assisted or may have discovered. When the MME sends a paging request to the eNBs in the tracking
area, the paging message sent in a cell is read by all the UEs and also by the relay node. Then the
relay node assisted transmission could be triggered by the relay node itself.
Branches 1 and 2 belong to a category where PSD boosting and random relay node
discovery (by eNB) are not considered in the first instance of paging (Npaging=0), which avoids
unnecessary resource block PSD boosting and signal exchanging. However, for UEs that are
located in poor propagation conditions and have no relay node response on their behalf either, the
normal LTE paging on the tracking areas will fail. Eventually, the second paging stage will be
triggered by setting the indicator Npaging.= 1 -
Embodiments of the present technique can provide an arrangement in which an indication
flag Npaging the MME is provided, which guides the eNB on whether to use PSD boosted
paging or relay node assisted transmission. This indication flag is exchanged over, for example,
the SI interface between the MME and the eNB. In the first stage Npaging=0, while after the
predefined timer is out of date, Npaging=l, its value will be sent to the eNBs along with the paging
information to trigger the use PSD boosting or random relay node discovery, which are branches 3
and 4, respectively.
When the eNB receives the paging indicator flag Npaging=^, it will try to find the MTCUE
by either PSD boosting or the relay node discovery process. Cells where PSD boosting is
available will page the MTC-UE directly, while the eNB without PSD boosting resources will
implement the relay node discovery for the MTC-UE. Depending on the different relay discovery
schemes, two cases are considered in the second stage, namely, relay node discovery case 1 and relay
node discovery case 2, which are presented in the following sections:
Rely Node Discovery case 1:
A list of relay node identifiers that are linked to a specific eNB will be retained by the MME.
When Npaging =1, the MME will request the eNBs to page the relay nodes on the list depending on
whether the PSD boosting indicator from the eNB is set or not (Np d-paging, see the procedure at
MME). Only the eNBs without PSD boosting resources available for paging (Npsd-paging = 0) will
receive the relay node identifier list along with the MTC-UE discovery request. This would be
different from normal paging in that the MME only sends the paging request to a specific eNB and
not all of them under the tracking area. Once a radio link connection with relay nodes is
established, each relay node will be provided with a request to find and connect to the MTC UE
whose identifier is provided by the core network.
All the eNBs with PSD boosting resources available will provide the PSD boosting
indicator set (Npsd-paging=l) to the MME, and the paging of the MTC-UE occurs in normal fashion
in the cell with PSD boosting assistance.
Relay Node Discovery case 2 :
A common paging identifier is established which, when present, makes all the Relay Nodes
read the paging record and the appended MTC-UE identifier. When Npaging =1, such a common
paging identifier will be sent through the eNBs in the tracking area where the cells cannot provide
PSD boosting {Np d-paging = 0)· relay nodes that have been pre-configured to detect the common
paging identifier will respond, extract the appended MTC UE identifier and try to connect to the
respective MTC-UE.
In the following description of example embodiments of the present technique, procedures at
the eNB, the relay node and the UE are presented in four respective sections corresponding to the
four cases mentioned above, which each refer to the respective branches 1, 2, 3, 4 where this is
appropriate.
Embodiments of the present technique can provide an arrangement in which a
communications device can discover communications apparatus, which can act as relay nodes. The
communications apparatus may be predesignated or deployed or fixed relay nodes or may be
communications devices themselves which are for example provided with a plurality of radio access
technologies and so can form an ad-hoc relay node. Ad hoc relay nodes are comprised of
communications devices which are provided with more than one radio access technology and are
configured to act as relay nodes because they are able to communicate with other communications
devices and also a base station (eNodeB) or the mobile radio network. Thus the communications
apparatus may itself be a mobile communications device, smart phone or wireless router. The mobile
device to relay node communication may therefore be a device-to-device communication as disclosed
in our co-pending European patent applications 14153010.5, 14153540.1, 14157187.7, 14154396.7,
14161202.8, 14161201.0, 14161181.4, the contents of which are incorporated herein by reference. A
relay node discovery may be performed in accordance with a process disclosed in EP14170122.7, the
content of which is incorporated herein by reference.
MME Procedure
An example procedure at the MME is shown in Figure 5 for the relay node discovery case
1 and Figure 6 for the relay node discovery case 2. When the MME receives downlink data
notification from the serving gateway (S- GW), a timer will be initialized to t=0, and it sends paging
message to all eNBs in the tracking area (tracking areas) where the UE last registered.
Then two cases arise depending on the relay node discovery schemes for the cells without
available PSD boosting resource. Figure 5 corresponds to the relay node discovery case 1 while
Figure 6 is for the relay node discovery case 2 described above.
Relay Node Discovery case 1:
Figure 5 illustrates the operation of an MME in accordance with relay discovery case 1 in
which a list of available relay nodes is provided to each of one or more base stations where the UE
may be reached. Figure 5 is summarised as follows:
SO: The MME firstly receives a notification from the serving gateway (S-GW) that downlink
data is available to be transmitted to an MTC type UE. Accordingly, a timer t is set to zero.
SI: At decision point SI the timer is compared to a paging time Tpaging and if the time exceeds
the paging time then processing proceeds to step S4, otherwise processing proceeds to step S2.
S2: The MME sends paging information to all the eNB's in a tracking area within which the
UE has been registered by the MME. The Npag g flag is equal to zero to indicate that enhanced paging
conditions are not yet applied.
S3: At decision point S3 the MME determines whether the UE has established an RRC
connection or not. If no RRC connection has been established then processing proceeds to step SI. If
an RRC connection has been established then processing proceeds to step S9.
S4: If the timer has exceeded the Tpaging time then processing proceeds to step S4 in which the
MME sends the MTC UE identifier and sets the Npaging flag to be equal to 1 to all the eNB's within the
tracking area indicating whether or not they can apply PSD boosting.
S5: The MME then receives the NpsD-pagmg from all the eNB's in the tracking area.
S6: At decision point S6 the MME determines for each of the eNB's within the tracking area
whether the PSD paging flag NP SD-paging is equal to 1 or not. If the paging NP SD-paging flag is set to be
equal to 1 then processing proceeds to step S7. Alternatively processing proceeds to step S8.
S7: The MME sends the MTC UE identifier to the eNB concerned for paging with PSD
boosting and after processing proceeds to step S3 for confirmation that the UE has established an
RRC connection.
S8: If the PSD paging flag NP SD-paging does not equal 1, then the MME sends the relay node
paging identifier list and the MTC UE identifier to the eNB in question for paging. Processing then
proceeds to step S3 to determine whether a UE has established an RRC connection.
S9: After establishing an RRC connection the relevant bearers are established and the tS-GW
will forward the data to the eNB with which the UE has established an RRC connection. Processing
then ends at step S10 and t is set to zero.
As will be understood from the flow diagram presented in Figure 5, when the eNBs in the
tracking areas receive the indicator Npaging-^ from MME, they will feed back an indicator
Npsd -paging to the MME (step S5 in Figure 5), where:
• When Npsd -paging=l: the PSD boosting resources for paging the MTC - UE are
available
· When Npsd -paging =0: the PSD boosting resources for paging the MTC - UE are
unavailable
Based on the received value of Npsd -paging from each specific eNB in the tracking areas,
two options are listed in the step S 6 of Figure 5. For the eNBs feeding back Npsd paging=l
(have PSD boosting paging resources), the MTC - UE identifier will be sent to the eNBs to page
directly (step S7). For the eNBs feeding back Npsd -paging =0, a list of the relay node identifiers
will be sent to the eNBs (do not have PSD boosting paging resources) along with the MTC -
UE identifier for relay node discovery. The MME maintains an RN identifier list that links relay
nodes to the eNBs under which they have registered, and these relay nodes will be paged
independently.
Relay Discovery Case 2 :
A common paging identifier is established which, when present, makes all the Relay Nodes
read the paging record and the appended MTC UE identifier. The common paging procedure
includes the delivery of at least the following information from the MME:
• a common paging identifier that makes all the configured relay nodes reachable with
one paging message
• explicit or implicit identification of the MTC-UE that the MME intends to page
The common paging identifier should be understood by all of the configured relay nodes
that an MTC-UE out of the eNB physical channel coverage is being paged by the MME. The explicit
or implicit MTC-UE identification extracted from the common paging information could be, for
example, the MTC-UE' s IMSI (International mobile subscriber identity) or any other type
of identification that can be mapped to the intended MTC-UE uniquely during the RN-to-MTC- UE
connection.
The MME will send the common paging identifier along with the MTC-UE identifier to all of
the eNBs in the tracking areas. The eNBs that can provide PSD boosting for paging (Npsdpaging=
l) will page the MTC-UE directly and overlook the common paging identifier, while the
others (Npsd-paging=0) will page the common identifier and expect to receive response from the
relay nodes that have been configured with capability to read the common paging.
Figure 6 is a flow diagram which represents the operation of the MME when relay node
discovery case 2 is performed in which relay discovery is determined using a common paging
identifier. Steps performed in Figure 6 correspond substantially to those in Figure 5 and so they are
the same step references. However, Figure 6 differs from this procedure in Figure 5 by step S14
which replaces steps S4 to S8 in Figure 5. In step S14 the MME sends a common paging identifier
and MTC UE paging identifier to the eNBs in the tracking area and sets the paging flag to be equal to
1. In this case the eNBs proceed to page the MTC UE using the common paging identifier and the
MTC's UE paging identifier via the eNB's in the tracking area.
eNB Procedure
The flowchart of the eNB procedure is depicted in Figure 7 and Figure 8, where the relay
node discovery cases 1 and 2 are separately depicted. Because branches 1, 2 and 4 are identical in the
two procedures, only branch 3 is depicted in Figure 8.
Figure 7 provides an example flow diagram illustrating the operation of an eNB for the
example in which the relay node discovery case 1 is performed. The MME communicates a list of
relay nodes which are available within each of the coverage areas of base stations of a tracking area
where the UE may be located. Figure 7 is summarised as follows:
TO: In step TO the eNB receives paging information from MME.
Tl: The eNB at decision point Tl determines whether the paging flag for the MTC UE has
been set. If a paging flag has been set for the MTC UE then processing proceeds to decision point
Til. Otherwise processing proceeds to step T2.
T2: Step T2 the eNB proceeds to page the MTC UE.
T3: In step T3 the eNB determines whether a response has been received from the UE or a
relay node. If no response is received then processing proceeds to terminate in step T21.
T4: If the UE responds to the paging message then processing corresponds to a normal
random access procedure in accordance with, for example, an LTE Standard.
T5: If a relay node responds to the paging message then in step T5 the relay node performs a
random access procedure with the eNB to establish a connection with the eNB.
T6: In response to the random access procedure the relay node transmits a relay request for
the UE identifier and performs a hybrid automatic repeat request (HARQ) process adjusted in
accordance with a transmission time interval from the relay node as according to for example our co
pending European patent application no. 14170122.7.
T7: For an example in which power boosting is available then the eNB sends a power
boosting indicator to the relay node.
T8: At decision point T8 the eNB determines whether power boosting is available to the eNB
through the PDCCH and PDSCH.
T9: If power boosting is not available then the eNB receives the HARQ adjustment TTI from
the relay node.
T10: The relevant bearers are then established and the S-GW forwards data to the eNB which
consequently sends the data to the MTC UE via this relay node.
Til: At decision point Til, if the eNB determines that PSD boosting is available for the
paging messages, then processing proceeds to step T18. Otherwise processing proceeds to step T12.
T12: If PSD boosting for the paging message is not available then the eNB sends the Npag in i
flag equal to zero to the MME and receives the identifier for the relay nodes and the MTC UE
identifier.
T13: The eNB then pages the relay node according to the relay nodes paging list received
from the MME.
T14: The relay node then performs a random access process to set up a connection with the
eNB.
T15: The eNB then sends the MTC UE identifier information to the relay node and indicates
to the relay node to connect the MTC UE identifier and wait for hybrid ARQ adjustment time.
T16: At decision point T16 it is determined whether the MTC UE has made a connection via
the relay node with the eNB or not. If not then processing proceeds to step T21 and terminates. If the
MTC UE has established a connection via the relay node to the eNB then processing proceeds to step
T7. If PSD boosting is available to the eNB then the eNB sends the NP sD-paging flag to 1 to the MME
and receives the MTC UE identifier.
T19: The eNB then transmits the paging message with PSD boosting to the MTC UE
identifier.
T20: Relay assisted random access is then performed with the eNB.
As will be appreciated from Figure 7, the procedure is initialized by a paging request from
the MME for the MTC-UE arriving at the eNB. Depending on the status of the Npaging flag from
the MME, the eNB has three types of response expected (step T3 in Figure 7):
• It sends a normal paging message to the MTC-UE, or
• It sends the paging message utilizing PSD boosting, or
• It discovers a relay node connected to the UE and transmits the paging message via this
relay node.
As shown in Figure 7, depending on the availability of the PSD boosting for PBCH at
eNB, two branches follow from step T4. Each of the branches shown in Figure 7 is explained in the
following sections:
Branch 1
Branch 1 corresponds to a MTC-UE that is located at good propagation conditions with
sufficiently strong channel to support the direct uplink and downlink communications between the
eNB and the MTC-UE. Clearly, branch 1 will be successfully executed in the first stage (and
therefore, no stage 2 in the following) by the normal LTE paging and PDCCH/PDSCH
transmission.
Branch 2
However, there is a possibility that the normal LTE paging (Npaging=0) signal cannot reach
the MTC-UE directly. When the MME sends a paging request to the eNBs in the tracking area, the
paging message sent in a cell is read by all the UEs and also by the relay node. The relay node will
check its lookup list to find out whether the MTC-UE that is being paged is on a list with which it
was previously able to communicate (see relay node procedure section for details). Should the relay
node successfully match the MTC-UE identifier with one of its lookup identifiers, it may respond to
the eNB after verifying that the MTC-UE is reachable by this relay node.
In the step T5 of Figure 7, the relay assisted random access will be operated between the
eNB and the UE. As described in [6], the relay request on behalf of MTC-UE and the MTC-UE
identifier will be exchanged between eNB and relay node. Different from the relay assisted random
access in [6], where uplink-only assistance is considered and a HARQ timeline adjustment is
based on the extra delay caused by uplink relay, in the invention, two cases of HARQ timeline
adjustment:
• Uplink-only relay assisted transmission (Figure 7)
• Both uplink and downlink are relay assisted by the relay node (Figure 8) are
considered, depending on the PSD boosting availability.
When PSD boosting can be done for both paging and data transmission stages, then uplinkonly
relay assisted transmission will be applied and the relay assisted random access will be
similar to [6]. However, two HARQ timeline adjustment TTIs will be calculated at UE/relay node
and received by the eNB in case of PSD boosting is unavailable.
When the MTC-UE/relay node is connected to the eNB, the eNB will make another judgment
in step T8 before sending the data to the target UE/relay node. The judgment result will be sent to
relay node/MTC-UE indicated by the new defined indicator Npsd :
Npsd = 1 indicate the PSD boosting is available
Npsd =0 : indicate the PSD boosting is unavailable
The reason that we make PSD boosting judgment separately on paging and following
data/control signal is because paging may occupy much less resources during PSD boosting
compared with the following data/control signal. For example the extra PSD boosting resource
blocks available for paging do not imply more resource blocks can be reserved for following data and
signal transmission to the MTC-UE.
If the extra PSD boosting resource is available for that UE, the downlink transmission will
be done directly to the MTC-UE (step T10). In this case, the timeline should be adjusted by eNB
since now it will be degraded to the uplink-only relay assisted transmission, where the direct
downlink has been reached by PSD boosting.
However, when the result of the judgment is negative, which implies extra resource block
for PSD boosting is unavailable and a relay is necessary to bridge the downlink transmission, the
(Npsd = 0) indicator would be forwarded to the MTC-UE from the relay node for confirmation.
The delay and HARQ timeline adjustment will be set to reflect the fact that both uplink and
downlink are relayed by the relay node.
Branch 3
The failures of the direct transmission (branch 1) and relay node initialized response of the
normal paging on the behalf of UE (branch 2) will trigger the repeat of paging in the tracking area
or nearby tracking areas along with the indicator Npaging=0 to the eNB. Once >Tp aging, the
indicator Npaging will be set to 1 and triggers PSD boosting for paging or causes the eNB to find a
relay node for the MTC-UE actively. With the setting of the Npaging flag the procedure will go to
the step Til (branch 3). Depending on the availability of the PSD boosting resource blocks for the
paging, two extra branches (branch 3 and 4) are introduced.
Branch 3 is the case that the PSD boosting for paging is unavailable, where eNBs will
initialize the relay node discovery in the tracking areas. However, depending on the relay node
discovery schemes, two cases are considered in Figures 7 and Figure 8, respectively.
In the relay node discovery case 1 in Figure 7 , all of the eNBs in the tracking areas
will first send the availability of the PSD boosting for paging by the indicator Npsd-paging back to
MME in step T12. Multiple relay nodes in the MME paging list will be paged via the eNB and
requested to search for the MTC-UE. The procedure is as follows: all the relay nodes in the list
receiving the page will start random access (step T14) and will set up an RRC connection. After this
the eNB will send MTC-UE identifier to all the relay nodes (step T15) and requests them to find the
MTC -UE. The eNB will expect one relay node assisted random access on behalf of the UE and
receive the HARQ timeline adjustment TTI (step T15). There is a possibility that multiple relay
nodes will try to connect to the same MTC-UE and only one (also in the case that the PSD
boosting for paging from other cells are failure) should succeed and be selected as the relay. A
successful relay node discovery for the MTC-UE will lead to step T7, and then later steps will be
shared with branch 2.
Branch 4
Branch 4 differs from branch 3, because the availability of the PSD boosting for
paging will lead the procedure to branch 4. The availability of sufficient resource blocks drives
the direct downlink transmission between the MTC-UE and eNB, only uplink relay node assistance
is needed, in step T6, the eNB will follow the same judgment as in branches 2 and 3.
Note that branch 3 and branch 4 may be implemented simultaneously in different cells
under a tracking area (some cells with PSD boosting will perform branch 4, while other perform
branch 3). However, the UE will establish radio link connection and set up the radio bearers only via
one eNB. These two cases are summarised as follows:
1) There is direct downlink from eNB through PSD boosting
Here the UE will know the cell identifier of the serving cell, and would only select a relay
node to assist in the uplink if that relay node is connected to the same cell. There is a likelihood that
the UE is contacted by a relay node that is camping under a different cell (whilst searching for the
paged UE), but is able to reach the UE. The priority would clearly be that the UE would not select
that relay node since it is not under the serving cell. Thus there will be no possibility of selecting a
different eNB from the downlink one.
2 ) There is no direct downlink from eNB because of lack of PSD boosting
Here there is a likelihood that e.g. two relay nodes that camp under different cells are both
able to discover the UE and connect to it. Again, the UE would only choose one, probably
determining based on the radio link characteristics of the interface between it and the relay node.
In the relay node discovery case 1, there is a relay node identifier list maintained at the
MME which links eNB identifier and relay node identifier. The list could be updated
periodically/non-periodically according to the last record of which relay nodes had camped in the
eNB in the tracking areas.
An illustration of an operation of the eNB in a situation where the common paging identifier
is used to discover relay nodes in accordance with relay node discovery case 2 is represented in Figure
8 which corresponds to branch 3 showing in Figure 7. Figure 8 is summarised as follows:
Rll: At decision point Rll the eNB determines whether PSD boosting is available for the
paging message or not. If this is not available then processing proceeds to step R12. If PSD boosting
is available then processing proceeds to step T18 showing in Figure 7.
R12: According to relay node discovery case 2, the relay node is paged using the common
paging identifier for the MTC UE's.
R13: The relay node then performs a random access procedure in order to set up a connection
with the eNB.
R14: The eNB then waits for confirmation that a connection has been made with relay node
so that a connection between a relay node and MTC UE has been established for which a H ARQ
process can be performed with an adjusted transmission time interval.
R15: At decision point R15 it is determined whether a connection has been established via the
relay node with the UE or not. If a connection has been established then processing proceeds to step
T7. Otherwise processing proceeds to step T21 and processing terminates.
As will be appreciated for the example shown in Figure 8, the operation of the eNB for relay
node discovery case 2 is similar to the case for case 1 shown in Figure 7, so we have considered only
branch 3 is depicted since the other branches are identical to those in Figure 7. This case is different
in step T12 where the common paging scheme (relay node discovery case 2) is employed. In this
case, the paging message shall include a common paging identifier which can be read and reacted
upon by pre-configured relay nodes, along with an MTC-UE identifier which can map the MTC-UE
uniquely. As long as the eNB received the common paging information along with Npaging=l, the
cells without PSD boosting for paging resources will perform the relay node paging using the
common paging identifier. The random access procedure follows in step T13 and the relay node
will try to connect to the MTC-UE according to the common paging information. As opposed to
case 1 in Figure 7 , there is no need for the network to send a request to the relay node asking
for the MTC-UE t o search. Again, only one relay node should eventually be successful in
connecting to the MTC-UE (in the case that the PSD boosting for paging from other cells are a
failure). A successful relay node discovery for the MTC-UE will lead to step T7, and then later steps
will be shared with branch 2.
Relay Node Procedure
Only three branches (from the four branches for the eNB procedure presented in Figure 7 and
8) are present in the relay node procedure, since branch 1 does not use the relay node at all. Any relay
node which has been selected for uplink relay assistance on behalf of an MTC-UE will maintain a UE
identifier lookup table (see Table 1). The relay node adds the UE identifier of the MTC-UE to this
table (there would be an expiry timer after which an identifier is considered stale and discarded). It
is clear that only relay nodes that have previously assisted a UE would have its identifier in the
table. When the MME sends a paging request to the eNBs in the tracking area, the paging
message sent in a cell is read by all the UEs and also by the relay node.
The flow diagrams in Figures 9 and 10 illustrate the operation of a relay node for relay node
discovery case 1 and relay node discovery case 2 respectively. Each of the branches 2, 3 and 4 shown
in Figures 9 and 10 are explained in the following sections:
Branch 3
Two cases will arise corresponding to the two relay node discovery cases in branch 3. Starting
from the step U0 of relay node discovery case 1 (Figure 9), where the relay node(s) receive the paging
message from eNB. A relay node will not only check whether its own identifier is included in the
paging record but it does the same for all the UEs whose identifier are in the list held at the relay node.
In either case, the relay node(s) will start a normal random access in the step 2. Following the random
access procedure and RRC connection, the relay node will receive a signal (for example one-bit) from
the eNB to indicate whether the forthcoming data in the PSDCH is:
• Data for the relay node (e.g. one-bit indicator Ndata= 0)
· MTC UE identifier to be discovered (e.g. one-bit indicator Ndata= 1)
The indicator N ata (also could be explained as a relay request when the eNB target to
another MTC-UE) will map its value to the above mentioned two options. Obviously, the
conventional downlink transmission will be performed (step U4) when the data is for the relay
node itself (Ndata= 0).

CLAIMS
1. An infrastructure equipment for forming a base station of a mobile communications
network for transmitting data to communications devices or receiving data from communications
devices, the infrastructure equipment comprising
a transmitter configured to transmit signals representing data to the communications devices
via a wireless access interface,
a receiver configured to receive signals from the communications devices via the wireless
access interface, and
a controller for controlling the transmitter and the receiver
to receive a paging request from a mobility management entity of the mobile communications
network for transmission to one of the communications devices,
in response to transmit a first paging message to the communications device to indicate that
the communications device is to receive the data via the wireless access interface, and
if a response to the transmitted first paging message is not received within a predetermined
time, then
if the infrastructure is able to use a power boosting mode, to transmit the first paging message
with a boosted power, or
if the infrastructure equipment is not able to use a power boosted mode for transmitting,
to transmit a second paging message to one or more communications apparatus which can
operate as a relay node for the communications device, the second paging message identifying the
relay node and the communications device for which the infrastructure equipment is to transmit the
data.
2. An infrastructure equipment as claimed in Claim 1, wherein the controller in
combination with the transmitter
to receive an indication from the mobility management entity to transmit the first paging
message with a boosted power, and
in response to the indication to transmit the first paging message with the boosted power.
3. An infrastructure equipment as claimed in Claim 1, wherein the controller is
configured
to receive from the mobility management entity of the communications network an indication
of one or more communications apparatus which are able to act as a relay node for the
communications device, and the controller is configured in combination with the transmitter and the
receiver
to transmit the second paging message to the communications apparatus to act as the relay
node for the communications device to receive the data from the infrastructure equipment, which is
identified by the indication received from the mobility manager.
4. An infrastructure equipment as claimed in Claim 2, wherein
if the infrastructure equipment is not able to use a power boosted mode for transmitting, then
the controller is configured to provide an indication to the mobility management entity that it cannot
use the power boosted mode for transmitting in response to a request from the mobility manager.
5. An infrastructure equipment as claimed in Claim 4, wherein the controller is
configured to receive a second paging request from the mobility management entity, if the
infrastructure equipment is not able to use the power boosted mode, and in response to transmit the
second paging message to the one or more communications apparatus which can operate as a relay
node for the communications device.
6. A method of transmitting data to a communications device from an infrastructure
equipment forming a base station of a mobile communications network, the method comprising
receiving a paging request from a mobility management entity of the mobile communications
network for transmission to one of the communications devices,
in response transmitting a first paging message to the communications device to indicate that
the communications device is to receive the data via the wireless access interface, and
if a response to the transmitted first paging message is not received from the communications
device within a predetermined time, then
if the infrastructure is able to use a power boosting mode, transmitting the first paging
message with a boosted power, or
if the infrastructure equipment is not able to use a power boosted mode for transmitting,
transmitting a second paging message to one or more communications apparatus which can
operate as a relay node for the communications device, the second paging message identifying the
relay node and the communications device for which the infrastructure equipment is to transmit the
data.
7. An infrastructure equipment forming a mobility management entity of a mobile
communications network, the infrastructure equipment comprising
a communications interface for connecting the infrastructure equipment to one or more base
stations within a tracking area of the mobile communications network, and
a controller configured in response to receiving an indication that data is to be transmitted to a
communications device,
to transmit via the communications interface a paging request to one or more of the base
stations in the tracking area to transmit a first paging message to the communications device indicated
in the paging request, and
if a response to the transmitted first paging message is not received within a predetermined
time, then
to transmit via the communications interface a second paging request to the one or more base
stations within the tracking area either to transmit the first paging message with a boosted power, if
the base station is able to use a power boosting mode, or
if the base station is not able to use a power boosted mode for transmitting,
to transmit via the communications interface a second paging message to one or more
communications apparatus which can operate as a relay node for the communications device, the
second paging message identifying the relay node and the communications device for which the base
station is to transmit the data.
8. An infrastructure equipment as claimed in Claim 7, wherein the controller in
combination with the communications interface are configured
to transmit a request to each of the one or more base stations within the tracking area for an
indication as to whether the base station can transmit using the power boosted mode,
to receive an indication from the base station as to whether the base station can transmit using
the power boosted mode, and if the base station can transmit using the power boosted mode, and if the
base station can transmit using the power boosted mode,
to transmit a request to the base station to transmit the first paging message with the power
boosted mode, if a response to the transmitted first paging message is not received within the
predetermined time, or if the base station cannot transmit using the power boosted mode,
to transmit a request to the base station via the communications interface to transmit the
second paging message to the one or more communications apparatus which can operate as the relay
node for the communications device.
9. An infrastructure equipment as claimed in Claim 7, comprising a data store, wherein
the controller is configured to store in the data store an indication for each of the one or more base
stations within the tracking area of one or more communications apparatus which can act as relay
nodes for communications devices, and to transmit to the base stations, which cannot operate with the
power boosted mode, a second paging request with an indication of the one or more communications
apparatus which can act as relay nodes for the communications device.
10. An infrastructure equipment as claimed in Claim 7, wherein the second paging
request includes an indication of a common paging identifier, which can be recognized by each of the
communications apparatus which can act as a relay node for the communications device to receive the
data from the base station, and an indication of the communications device which is to receive the
data from the infrastructure equipment.
11. An infrastructure equipment as claimed in Claim 7, comprising a data store, wherein
the controller is configured
to detect if a communications apparatus has acted as a relay node for one or more
communications devices, which have transmitted data to a serving base station or received data from
the serving base station via the relay node,
to store in the data store an indication of the one or more communications apparatus which
have acted as a relay node, in association with an indication of their serving base station, and
to identify from the indication from the base station on whether it can use power boosting
which communications apparatus which has acted as a relay node for the communications device will
be requested to act as the relay node for the communications device, and
to transmit the second paging message to the communications apparatus to act as the relay
node for the communications device to receive the data from the identified serving base station, which
is identified by the indication stored in the data store.
12. An infrastructure equipment as claimed in Claim 11, wherein the second paging
message comprises a common paging identifier for detection by one or more communications
apparatus which can act as a relay node for the communications device to receive the data via the
wireless access interface, and an indication of the communications device.
13. A method of controlling transmission of data to a communications device from a base
station of a mobile communications network, the method comprising
transmitting via a communications interface a paging request to one or more of the base
stations in a tracking area to transmit a first paging message to the communications device indicated
in the paging request, and
if a response to the transmitted first paging message is not received within a predetermined
time, then
transmitting via the communications interface a second paging request to the one of more
base stations within the tracking area either to transmit the first paging message with a boosted power,
if the base station is able to use a power boosting mode, or
if the base station is not able to use a power boosted mode for transmitting,
to transmit via the communications interface a second paging message to one or more
communications apparatus which can operate as a relay node for the communications device, the
second paging message identifying the relay node and the communications device for which the base
station is to transmit the data.
14. Electronic circuitry for a base station of a mobile communications network for
transmitting data to communications devices or receiving data from communications devices, the
electronic circuitry comprising
transmitter circuitry configured to transmit signals representing data to the communications
devices via a wireless access interface,
receiver circuitry configured to receive signals from the communications devices via the
wireless access interface, and
controller circuitry for controlling the transmitter and the receiver
to receive a paging request from a mobility management entity of the mobile communications
network for transmission to one of the communications devices,
in response to transmit a first paging message to the communications device to indicate that
the communications device is to receive the data via the wireless access interface, and
if a response to the transmitted first paging message is not received within a predetermined
time, then
if the infrastructure is able to use a power boosting mode, to transmit the first paging message
with a boosted power, or
if the infrastructure equipment is not able to use a power boosted mode for transmitting,
to transmit a second paging message to one or more communications apparatus which can
operate as a relay node for the communications device, the second paging message identifying the
relay node and the communications device for which the infrastructure equipment is to transmit the
data.
15. Electronic circuitry for a mobility management entity of a mobile communications
network, the electronic circuitry comprising
communications interface circuitry for connecting the infrastructure equipment to one or more
base stations within a tracking area of the mobile communications network, and
controller circuitry configured in response to receiving an indication that data is to be
transmitted to a communications device,
to transmit via the communications interface a paging request to one or more of the base
stations in the tracking area to transmit a first paging message to the communications device indicated
in the paging request, and
if a response to the transmitted first paging message is not received within a predetermined
time, then
to transmit via the communications interface a second paging request to the one or more base
stations within the tracking area either to transmit the first paging message with a boosted power, if
the base station is able to use a power boosting mode, or
if the base station is not able to use a power boosted mode for transmitting,
to transmit via the communications interface a second paging message to one or more
communications apparatus which can operate as a relay node for the communications device, the
second paging message identifying the relay node and the communications device for which the base
station is to transmit the data.