GB2487780A

GB2487780A - Resource allocation messages employing short Radio Network Temporary Identifiers (RNTI)

Info

Publication number: GB2487780A
Application number: GB1101966.8A
Authority: GB
Inventors: Darren Phillip Mcnamara; Andrew Lillie; Peter Darwood; Martin Beale
Original assignee: Wireless Technology Solutions LLC
Current assignee: Wireless Technology Solutions LLC
Priority date: 2011-02-04
Filing date: 2011-02-04
Publication date: 2012-08-08
Anticipated expiration: 2031-02-04
Also published as: GB2487780B; GB201101966D0

Abstract

An infrastructure equipment provides a wireless access interface for communicating data to and/or from mobile terminals in a mobile communications system. The wireless access interface provides a down-link frequency channel for communicating data to the mobile terminals and a shared control channel for communicating resource allocation messages to the mobile terminals. The resource allocation message include an identification number, such as a Radio Network Temporary Identifier (RNTI), allocated to one of the mobile terminals for indicating an allocation of one of the units of communications resource of the wireless access interface, and each of a plurality of the mobile terminals is divided into a plurality of different groups. The infrastructure equipment is adapted to form super-frames 104 comprising a plurality of the units of communications resource of the down-link channel, to transmit in a super-frame control information providing for each of the plurality of mobile terminals in a first of the groups of devices a short identification number in association with the identification number allocated to the mobile terminal by the infrastructure equipment for use in allocating the units of communications resource to the mobile terminal for the first super-frame, and to transmit in a second of the super-frames control information for the second group.

Description

I

INFRASTRUCTURE EQUIPMENT AND METHOD

Field of the lnventi

The present invention relates to mobile communications systems for communicating data to and/or from mobile communications devices, infrastructure equipment, mobile communications devices and methods for communicating data packets. q

Mobile communication systems have evolved over the past ten years or so from the GSM System (Global System for Mobiles) to the 3G system and now include packet data communications as well as circuit switched communications. The third generation project partnership (3GPP) has now began to develop a mobile communication system referred to as Long Term Evolution (LIE) in which a core network part has been evolved to form a more simplified architecture based on a merging of components of earlier mobile communications network architectures and a radio access interface which is based on Orthogonal Frequency Division Multiplexing (OFDM) on the downlink and Single Carrier Frequency Division Multiple Access (SC-FDMA) on the uplink. The core network components are arranged to communicate data packets in accordance with an enhanced packet communications system.

At present mobile communications services are dominated by human to human (H2H) communications, that is, data which is transmitted by a human to another human or at least data that is transmitted for presentation to a human being. It is now recognised that there is a desire to cater for communications to and/or from machines which are referred to generally as machine type communications (MIC) or machine to machine (M2M) communications.

MTC communications can be characterised as communicating data which has been generated from a source automatically, for example in response to some other stimulus, or event reporting some attribute of the machine, or some monitored parameter, or so-called smart metering. Thus whilst human communications such as voice can be characterised as being communications requiring a communications session of some minutes with data being generated in bursts of several millisecond with pauses there between or video can be characterised as streaming data at a substantially constant bit rate, MTC communications can generally be characterised as sporadically communicating small quantities of data although it would be appreciated that there is also a wide variety of possible MTC communications.

As will be appreciated it is generally desirable to provide a mobile communications system and network which can operate efficiently, particularly although not exclusively in respect of the challenges presented by communicating data packets generated by MTC communications devices.

Su mmary ohe Invention According to the present invention there is provided an infrastructure equipment of a mobile communications system for communicating data to and/or from mobile terminals. The infrastructure equipment comprises a transmitter and a receiver which are arranged in operation to provide a wireless access interface for communicating the data to and/or from the mobile terminals, and a scheduler for allocating communications resources of the wireless access interface to the mobile terminals for communicating the data. The wireless access interface provides a down-link frequency channel for communicating data to the mobile terminals, the down-link frequency channel being divided in time into different units of communications resource which are allocated by the scheduler of the infrastructure equipment to the mobile terminals, and a shared control channel for communicating resource allocation messages to the mobile terminals, each resource allocation message including an identification number allocated to one of the mobile terminals for indicating an allocation of one of the units of communications resource of the wireless access interface, and each of a plurality of the mobile terminals is divided into a plurality of different groups. The infrastructure equipment is adapted to form super-frames comprising a plurality of the units of communications resource of the down-link channel, to transmit in a first of the super-frames control information providing for each of the plurality of mobile terminals in a first of the groups of devices a short identification number in association with the identification number allocated to the mobile terminal by the infrastructure equipment for use in allocating the units of communications resource to the mobile terminal for the first super-frame, to transmit in a second of the super-frames control information providing for each of the plurality of mobile terminals in a second of the groups of terminals a short identification number in association with the identification number allocated to the mobile terminal by the infrastructure equipment for use in allocating the units of communications resource to the mobile terminal for the second super-frame. The infrastructure equipment is further arranged to adapt each of the resource allocation messages to include a plurality of the short identification numbers when allocating the units of communications resources to a plurality of the mobile terminals in the first or the second super-frames.

S

Embodiments of the present invention can provide a mobile communications system in which an arrangement is provided for reducing the size of resource allocation messages, which allocate resources of a shared channel to mobile communications devices for communicating data. As a result, the number of allocation messages which can be communicated via a shared down-link control channel can be increased which, in turn, increases a rate at which resources can be allocated for transmitting data to terminals. The reduction in the size of the resource allocation messages is achieved by allocating shortened identifiers to mobile terminals on a basis of a super-frame. The mobile terminals are divided into different groups and for each super-frame a short identifier is allocated to each of the mobile terminals of one of the groups in association with an identification number which is conventionally used and allocated to the mobile terminals for allocating resources. Thus for the duration of the super-frame the short identifiers can be used to allocate resources to the mobile terminals of the group. In the next frame the short identifiers are allocated to a different group of mobile terminals. Thus the same short identifier can be used between super frames but allocated to different mobile terminals, so that the short identifier can be a small quantity of data such as a few bits and smaller than the identification number. In one example the different groups are mutually exclusive so that one mobile terminal is allocated to one group only, but in other examples a mobile terminal may be allocated to more than one group.

The super-frame is comprised of a plurality of units of resource, which are formed by dividing a repeating frame in time, which may be equal time divisions. In one example, the units are sub-frames of a frame, so that the super-frame is formed from a repeating set of sub-frames, which may be greater than the frame.

As will be appreciated, if a mobile terminal belongs to a group which has not been allocated a short identifier for the current super-frame then it may have to wait longer before communications resources can be allocated to it. However, the base station may have some time critical data to be communicated to that mobile terminal. Accordingly, in some examples, the base station may communicate a resource allocation message to a mobile terminal via the shared control channel, when the mobile terminal has not been allocated a short identifier for a current super frame, in which the resource allocation message includes an identification number of the mobile terminal.

According to some embodiments the identification number which is replaced by the short identifier in the resource allocation messages is a radio network temporary identifier or the like.

Further aspects and features of the present invention are defined in the appended claims and include an infra-structure element and methods.

t5c_P_ 9Ltk!tflP Example embodiments of the present invention will now be described with reference to the accompanying drawings in which like parts have the same designated references and in which: Figure 1 is a schematic block diagram of a mobile communications network and mobile communications devices forming a communication system which operates in accordance with the 3GPP Long Term Evolution (LTE) standard; Figure 2 is a schematic representation of a down-link frequency carrier comprising sub-frames; Figure 3 is a schematic representation of a mobile network with up-link and down-link communications; Figure 4 is a schematic representation of a downlink frame comprising 6 sub-frames; Figure 5 is a simplified call-flow showing the RNT1 allocation during an RRC connection setup; Figure 6 is a schematic representation of a super-frame according to an embodiment of the invention; Figure 7 is a schematic representation of two super-frames according to another embodiment of the invention; Figures Ba to Bc are examples of mapping or correspondence between RNTIs and short-lOs; Figure 9 is a schematic representation of a downlink message translation process from RNTI to Short-ID; Figure 10 is an example of a super-frame comprising 3 sub-frames according to a further embodiment of the invention.

Description of Example Embodiments

Embodiments of the present invention will now be described with reference to an implementation which uses a mobile communications network operating in accordance with the 3GPP Long Term Evolution (LTE) standard. Figure 1 provides the example architecture of an LTE network. As shown in Figure 1 and as with a conventional mobile communications network, mobile communications devices (also called UEs or terminals) I are arranged to communicate data to and from base stations 2 which are referred to in LIE as enhanced Nodel3s (e-NodeB). For transmitting and receiving data via the wireless access interface the communications devices I each include a transmitter/receiver unit 3.

The base stations or e-NodeB's 2 are connected to a serving gateway S-OW 6 which is arranged to perform routing and management of mobile communications services to the communications devices I as they roam throughout the mobile communications network. In order to maintain mobility management and connectivity, a mobility management entity (MME) 8 manages the enhanced packet service (EPS) connections with the communications devices I using subscriber information stored in a home subscriber server (HSS) 10. Other core network components include the policy charging and resource function (PCRF) 12 a packet data gateway (P-OW) 14 which connects to an internet network 16 and finally to an external server 20. More information may be gathered for the LTE architecture from the book entitled "LTE for UMTS OPDM and SC-FDMA based radio access", HoLma H. and Toskala A. page 25 ft In the following description LIE/SAE terminology and names are used. However embodiments of the present technique can be applied to other mobile communications systems such as UMIS and GERAN with the GSM/GPRS core network.

LTE and RFjfl.ejlocation According to the LTE standard, communications are arranged in packet switched form in that a physical channel on the up-link and the down-link is not allocated to a communications device. Communications resources on both the up-link and the down-link for transmitting data are shared amongst all of the communications devices. On the up-link data is transmitted in physical up-link shared channels (PUSCH) whereas the down-link data is transmitted to the mobile communications devices on physical down-link shared channels (PDSCH). The allocation of resources on the up-and down-link shared channels is managed by the eNode B using a physical down-link control channel (PDCCH). If data is to be transmitted to a particular mobile communications device then the eNode B transmits a message on the down-link shared control channel which all of the mobile communications devices listen to. The mobile communications device to which the data is to be transmitted is identified using an identifier called Radio Network Temporary Identifier (RNTI). There are various types of RNTI allocated to mobile communications devices in accordance with a relative phase of a communication session in which data is communicated to or from the mobile communications device. Thus the eNode B transmits a message in the physical down-link control channel providing the RNTI of the mobile communications device (or devices) which is to receive data on the down-link and an indication of the down-link communications resources that have been allocated on the down-link shared channel to the mobile communications device(s). In LTE, RNTIs either uniquely identify a mobile communications device within a cell, like a C-RNTI which is used for example to send downlink data to one specific mobile communications device only, or they identify all the mobile communications devices in the cell. For example, a Sl-RNTI is used to send downlink data to all the mobile communications devices in the cell.

An example of a down-link arrangement of the physical down-link shared channels and the physical down-link control channel is shown in Figure 2. As explained above mobile communications devices are arranged to communicate via a base station or e-NodeB 2, using up-link and down-link shared communications resources. Thus, as shown in Figure 3, a plurality of mobile communications devices I communicate via an e-NodeB 2. Thus Figure 3 provides a simplified representation of a group of mobile communications devices which are operating within a cell served by the e-NodeB 2. As will be appreciated therefore the mobile communications devices must be allocated resources on the down-link shared channels in order to receive data from the base station.

As will be appreciated the down-link channel illustration provided by Figure 2 is in a somewhat simplified form. According to the LTE standard, a physical down-link frame is illustrated in Figure 4. Likewise, Figure 4 is a somewhat simplified form, for example a LTE frame usually includes 10 sub-frames but only 6 sub-frames have been represented for the downlink frame of Figure 4. In Figure 4 the PDCCH is shown which occupies some time and frequency resources within a resource zone that stretches across the entire frequency band and across I to 3 symbols, where the time and frequency resources are usually distributed within that zone based on a random or pseudo-random algorithm. In contrast the Physical Down-link Shared CHannel (PDSCH) is comprised of a plurality of time and frequency resources which are allocated via the PDCCH. In effect, the PDCCH provides the mobile communications devices with the resource allocations and the corresponding RNTI. A mobile communications device can therefore, based on the RNTI, know which resource allocations it should decode to receive its data. The data may be either data for this mobile communications device only or for all mobile communications devices in the cell.

A message sequence flow showing an exchange of messages which are required in order to allocate resources on the down-link as well as the up-link as shown in Figure 5. In Figure 5 a terminal I is shown communicating messages to and receive messages from an e-NodeB 2 when setting up a connection with the e-NodeB 2. The first message Ml is a message from the terminal I to the e-WodeB 2 which comprises RACH message including a RACH preamble. From the RACH preamble, a RA-RNTI ("Random Access RNTI") can be S identified. The e-NodeB 2 then responds to the terminal 1 with message M2, sent to the RA-RNTI identified from the RACH preamble and comprising in particular a T-RWTI (Temporary RNTI') and an uplink resource allocation.

The terminal 1 sends message M3 using the uplink resource allocated indicated in message M2, where the message is a RRC connection request sent as coming from the terminal with the T-RNT1 indicated in message M2. The e-NodeB 2 responds to message MS with a RRC connection setup message M4. M4 is sent to the T-RNTI of messages M2 and M3 and comprise the C-RNTI that the terminal I will use for the duration of the RRC connection. In effect, the C-RNTI is usually the same as the T-RNTI. In other words, once the RRC connection setup is successfully completed, the T-RNTI becomes the CRNTl.

The usually way for a terminal I to receive data once the RRC connection has been successfully established is shown with in Figure 5. The terminal I will receive a downlink data on a downlink shared frequency channel of the type shown in Figure 4, i.e. including a PDCCH and a PDSCH. The PDCCH will indicate in particular the resource allocation in the PDSCH using the RNTI. For example the CRNTl x is given the resources allocation A, the C-RNTI y is given the resource allocation A and the Sl-RNTI (for sending system information to the entire cell) is given the resource allocation A31. Then, based on the RNTIs in the PDCCH, the terminal I knows which resource elements to decode in the PDSCH. If for example the terminal I has the CRNTl x, terminal I then decodes the data that has been allocated A (which is transmitted for this terminal only) and the data that has been allocated A3, (which is transmitted for all terminals in the cell). Terminal I will for example not decode the data that has been allocated A because the CRNTl y does not indicate that the data is for terminal 1. As can be seen in this example, the terminal I may decode data for several RNTIs, in this case C-RNTI x and Sl-RNTI. In another example, the terminal I may have more than one C-RNTI identifying it. For example, the data in allocation A and A may be for the same terminal I if terminal I can be identified as CRNTI x and C-RNTI y. for information, various examples of RNTI types are provided in a table in the appended Annex.

Using this RNTI identification system, a downlink carrier can easily be shared amongst several terminals where each terminal knows where to find its data based on the RNTI associated with this data.

As will be appreciated from the above explanation in order to receive an allocation of resource then a mobile communications device must be explicitly identified using one of its RNTIs. In an MTC or dedicated messaging network, terminals which are operating as MTC type devices may be required to communicate a plurality of signalling messages in order to transmit a data message. In one example, in order to transmit for example a meter reading, a terminal will be required to exchange a series of messages via and/or to the base station which may include: -RRC connection -Authentication via a remote authentication server -Session start with meter reading server -Meter reading data transfer which may also inckide an exchange of messages associated with the data transmission -Session with meter reading server tear down -RRC connection tear down.

In an LTE Network these messages are scheduled in the down-link using the PDCCH which communicates an allocation message to the terminals. The LTE standard defines that the PDCCH is to be sent in the control region at the beginning of each sub-frame, where the control portion is between I and 3 symbols long. The size of the control region is limited, thereby limiting the resources that can be allocated to PDCCH messages. Thus, when there are many small messages to be transmitted such as for example, short signalling messages, system capacity may be limited by the amount of available signalling resource which would be the number of PDCCHs available for an LTE network. Therefore the amount of data that can be transmitted to terminals is not in that case limited by the actual down-link capacity (e.g. the number of PDSCH), but by the capacity to signal those PDSCHs using PDCCHs.

According to the present technique an arrangement is provided for reducing the size of the allocation message to mobile communications devices for communicating data. As a result, the number of allocation messages which can be communicated via for example a PDCCH can be increased which, in turn, increases the resources allocated for transmitting data to terminals. In other words the number of PDCCHs per sub-frame can thereby be increased.

Super-frame form1 According to the present technique there is provided a super-frame structure, the super-frame comprising a plurality of down-link sub-frames, where some terminals are provided with a short identifier which can be used within the super-frame, for example for allocating communications resources on a downlink shared channel.

In one example, the super-frame could be the duration of an LTE frame which is ten sub-frames or ten milliseconds or, in another example, it might be a multiple of the LTE frame duration. Figure 6 provides an example arrangement of a down-link frame structure illustrating a super-frame, where the super-frame is 10 sub-frames long. In Figure 6, a first frame structure 101 is shown to be comprised of a plurality of sub-frames 102. In an expanded form of a super-frame 104, it can be seen that the super-frame is comprised of a number of sub-frames. Each sub-frame includes a PDCCH5 as well as a PDSCHS where the PDCCH5 can be found in the PDCCH region and the PDSCHs in the PDSCH region.

In accordance with the present technique, a mapping of RNTI and short-identifiers (or "short-IDs") is provided to the terminals in a sub-frame of the super-frame. In the example of Figure 6, the super-frame 104 consists of one frame in a time-dimension, and the correlation or correspondence 106 between a set of RNTIs and a set of short-IDs is communicated in the first sub-frame of the super-frame. Examples of such correspondence are given in Figures Ba to 8c, which are further discussed below, in this and the next sub-frames of the super-frame, the terminals can identify their down-link resource allocation using their short- ID. The terminals can also still use the longer RNTI, but it is advantageous to use the short-lDs, if possible, because it reduces the amount of resources to be used for allocation messages, e.g. PDCCHs, as explained below.

In LIE, the RNTI is conventionally used to mask a cyclic redundancy check code (CRC) of the PDCCI-I transmission, where the RNTI and the PDCCH CRC are both 16 bits long. This is done by scrambling the PDCCH CRC with the RNTI. In accordance, if a PDCCH-like allocation message is to be sent, the short-iD which may for example be 8 bits could be used to mask a shorter CRC for example which may also be 8 bits or the short IDs of a plurality of terminals may be jointly coded within a PDCCH which allocates resources to a plurality of terminals where the 16 bit CRC is used for the PDCCH with a conventional format. Therefore, shorter allocation messages may be used and, because the number of short-ID to be used is lower than the number of possible RNTIs as provided by the LTE standard (216 possible RNTIs), the short-ID can be chosen to be much shorter than the RNTI, for example 4 bits. In this example situation, the allocation message can be reduced by 12 bits thereby providing a reduction in size.

A further example is illustrated in Figure 10 with a three sub-frame super-frame 104.

The first sub-frame includes a table of correspondence 106 between three C-RNII corresponding to three different terminals and short-lOs. In this example, this message is sent like any other downlink data, that is, in a Physical Down-link Shared Channel (PDSCH- 1) to which a PDCCH points. In another example, the correspondence information may be communicated in a different manner, for example within the PBCR. In Figure 10, the PDCCH allocating PDSCH-1 contains the Sl-RNTI such that all terminals within the cell decode the correspondence information 106. The same sub-frame also includes PDSCH-2 with data for the terminal with the G-RNTI "61465" (UE61465), where PDSCH-2 is allocated with a PDCCH or PDCGH-Iike message using the short ID "1", according to the information 106. In use, UE61465 would receive the first sub-frame; decode PDSCH-1 (like all terminals within the cell) such that it knows that short-ID "1" refers to its own C-RNTI; identify that PDSCH-2 is for UE61465 as well with the PDCCH for short-ID 1; and decode PDSCH-2. As is now apparent, the allocation messages, for example PDCCH and PDCCH-like messages, can be substantially reduced in size by using short-IDs within a super-frame. Therefore, more allocation messages can be included within the PDCGH region and more PDSCH can therefore be allocated, if necessary.

As shown in Figure 10, in the next and second sub-frame, both newly-introduced shortIDs and legacy RNTIs may be used in the same sub-frame. In this example UE61465 identifies that PDSCH-1 has to be decoded based on its C-RNTI "61465", and that PDSCH-2 has to be decoded based on its short-ID "1". Therefore, backward compatibility with traditional LTE is ensured, while shorter allocation messages using short-ID may be used.

The last sub-frame of the super-frame in Figure 10 shows an example where only short-IDs are used within a sub-frame. The super-frame could also be arranged to only include allocations based on short-IDs in every of its sub-frames.

For example and as shown schematically in Figure 7, the e-NodeB 2 is transmitting down-link data in two super-frames each of which includes correspondence information 106 transmitted in the example on the first sub-frame of each super-frame, where the data in each of the super-frame is only for terminals listed in the correspondence information 106.

As shown in Figure 7 a first group 110 is comprised of four communications devices and receives data in the first super-frame whereas a second group 112 is comprised of five terminals and receives data in the second super-frame. For ease of representation, the two groups have been represented as two completely distinct groups even though some terminals may be in both groups.

When and if forming groups, there are various ways of assigning terminals to groups which include: -By a type of device, for example smart meters are divided into a separate group whereas vending machines may be divided into a different group.

-By RNTI, for example the most significant "N" bits of the RNTI could define the group identity while the "1 6-n" least significant bits define the identity of terminals within the group.

-By an explicit assignment to a group, for example at call setup the base station could assign terminals to a particular group. This assignment could be fairly disparate, for example there could be a mix of RNTI's and device types within the group.

-By a pre-determineci Group ID, for example provided within the terminal's profile in the HLR/HSS.

-By an expected amount and/or type of traffic from the terminal.

Generally, similar criteria may be used to decide which RNTI should be given a short ID within the correspondence information 106. Also, as the correspondence information matches a RNTI with a short-ID, it is possible to have correlated or uncorrelated to the matched RNTI and terminals. For example, one terminal may have two C-RNTIs but it may be decided that only one RNTI will be given a short-ID, if for example it is considered to be the only relevant RNTI to be given a short-ID. In another example, it may be decided that if one terminal-specific RNTI is given a short-ID, then all other terminal-specific RNTI identifying the same terminal are also given a short-ID, which can be the same as or different to the first short-ID it has been given.

Also any suitable combination of RNTIs and short-ID may be provided, a few of which are illustrated in particular in Figure 8c. in this example, UE61465 and UE00237 have been given the same short-ID "1" such that any data transmitted to the short-ID "t' will be decoded by both terminals. This can be useful if for example a new price list is to be sent to several vending machines. The vending machines in the same cell can be given the same short-ID such that they will all receive the new price list with one message sent to this short-ID. Using the table of Figure Sc may not only help increase the number of PDCCI-T or PDCCH-like messages that can be sent in a sub-frames, it also increase the resources available for PDSCH data, as the same data may be sent to a ii terminals with only one PDSCH, rather than sending n PDSCH (and vi corresponding long or short PDCCH).

Any RNTI may be assigned a short-ID and thus, particular RNTIs may also be assigned a short-ID. For example, in Figure Sc, RNT1 65535 has been given a short-ID, where this particular RNTI value corresponds in LTE to the SI-RNTI. If for example it is anticipated that the e-NodeB will be required to send several system information messages to all terminals in the cell in the next sub-frames, it can then be advantageous to have a short-ID corresponding to the Sl-RNTI in order to reduce the size of allocation messages for system information messages which are expected to be sent in the next sub-frames.

Figures 8a and Sb also show that the allocation may be an explicit allocation (Figure 8a) or an implicit allocation (Figure Sb) using for example the position of a RNTI in a list to infer the corresponding short-ID. Such an implicit allocation may for example helps reducing the size of the correspondence information 106 by simply sending the list of RNTI that have been given a short-ID.

Figure 9 provides an illustrative representation of the operation of the terminals and the mobile radio network which implements communication using the super-frame structure and the short ID's explained above. In Figure 9 three terminals UE61465, 1JE10983 and tiE00237 are shown to be communicating with an e-Node8 2. Also shown is a serving gateway 6. The e-NodeB 2 receives from the serving gateway 6 a message to be communicated to the terminal UE61465. If a super-frame is being provided on the down-link or if it has been decided to provide one, the e-NodeB translate the RNTI 61465 into the short-ID "1" and insert a short allocation message with the short-ID within a downlink sub-frame of the super-frame, rather than insert a full-size PDCCH with the full-size C-RNTI.

The length of a super-frame may vary on super-frame by super-frame basis. For example a first super-frame may be 10 sub-frames long when the next one is B sub-frames long. Also the short-ID are intended to be allocated for the duration of a super-frame when a super-frame is of fixed duration. Even though the super-frame is initially intended to be used for short periods of time, possibly on a regular bases, the super-frame may also be provided for an undetermined length, on the assumption that the super-frame will be provided until it is not needed anymore. In such a case, the correspondence information may be updated one or more times whilst the super-frame is provided. Such updates provides flexibility to ensure the short-IDs utilization can be adjusted to better correspond to the current use of the down-link and the terminals can then maintain the correspondence between RNTIs and short-los up-to-date when receiving the updates.

Various further aspects and features of the present invention are defined in the appended claims. Various modifications may be made to the embodiments described above without departing from the scope of the present invention. For example, embodiment of the present invention finds application with other types of mobile communications networks providing downlink communications and is not limited to LIE or 3GPP networks. Annex

Identifier Name To usage P-RNTI Paging RNTI All UEs in the if a PDCCH (allocation message) with cell this RNTI is received, then all UEs read some PDSCH resource that has been allocated by the PDCCH. That PDSCH resource will then contain paging messages.

Sl-RNTl System All UEs in the If a PDCCH (allocation message) with Information cell this RNTI is received, then all UEs read RNTI some PDSCH resource that has been allocated by the PDCCH. That PDSCH resource will then contain system information for the cell.

RA-RNTI Random access One specific UE When a UE performs a RACH, it chooses RNTI a time-frequency resource (quasi-randomly) to use for the RACH. The time-frequency resource is mapped on a one-to-one basis with a RA-RNTI. The RA-RNTI is used to respond to the RACH.

C-RNTI -Cell RNTI One specific UE Used to schedule tiEs with PDSCH resource during normal operation. The PDCCH that allocates a UE has its CRC bits scrambled with the C-RNTI. The C-RNTI is inherited from the T-RNTI.

The C-RNTI is re-allocated during the handover procedure.

Temporary-T-RNTI One specific tiE Allocated during the random access RNTI response. The UE uses this T-RNTI until the contention resolution process is complete. Once contention resolution is complete, the T-RNTI becomes the C-RNTI.

SPS-RNTI Semi-persistent One specific UE scheduling RNTI TPC-Transport power One specific UE PUSCH-control of

RWTI PUSCH RNTI

TPC-Transmit power One specific UE PUCCH-control for

RNTI PUCCH RNTI

Claims

CLAIMS1. An infrastructure equipment of a mobile communications system for communicating data to and/or from mobile terminals, the infrastructure equipment comprising a transmitter and a receiver which are arranged in operation to provide a wireless access interface for communicating the data to and/or from the mobile terminals, and a scheduler for allocating communications resources of the wireless access interface to the mobile terminals for communicating the data, wher&n the wireless access interface provides a down-link frequency channel for communicating data to the mobile terminals, the down-link frequency channel being divided in time into different units of communications resource which are allocated by the scheduler of the infrastructure equipment to the mobile terminals, and a shared control channel for communicating resource allocation messages to the mobile terminals, each resource allocation message including an idenlification number allocated to one of the mobile terminals for indicating an allocation of one of the units of communications resource of the wireless access interface, and each of a plurality of the mobile terminals is divided into a plurality of different groups, and the infrastructure equipment is adapted to form super-frames comprising a plurality of the units of communications resource of the down-link channel, to transmit in a first of the super-frames control information providing for each of the plurality of mobile terminals in a first of the groups of devices a short identification number in association with the identification number allocated to the mobile terminal by the infrastructure equipment for use in allocating the units of communications resource to the mobile terminal for the first super-frame, and to transmit in a second of the super-frames control information providing for each of the plurality of mobile terminals in a second of the groups of terminals a short identification number in association with the identification number allocated to the mobile terminal by the infrastructure equipment for use in allocating the units of communications resource to the mobile terminal for the second super-frame1 and to adapt each of the resource allocation messages to include a plurality of the short identification numbers when allocating the units of communications resources to a plurality of the mobile terminals in the first or the second super-frames.
2. An infrastructure equipment as claimed in Claim 1, wherein one of the short identification numbers in the first super-frame is allocated to identify a different mobile terminal from the second group of devices in the second frame.
3. An infrastructure equipment as claimed in Claim I or 2, wherein the control information comprises an indication of the units comprised in the super-frame.
4. An infrastructure equipment of claim 3, wherein the indication provides a number of subsequent units in the super-frame and indicates the first unit of the super-frame.
5. An infrastructure equipment of claim 2, wherein the indication comprises a list of units comprised in the super-frame.
6. An infrastructure equipment of claim 1, wherein the infrastructure equipment is operable to transmit a resource allocation message to one of the mobile terminals of the second group which is not a member of the first of the groups of mobile terminals in the first super frame, the resource allocation message including the identification number of the mobile terminal.
7. An infrastructure equipment as claimed in any preceding Claim7 the mobile communications system is arrange to select the identification numbers based on at least a profile of the one or more terminals corresponding to the identifier.
8. An infrastructure equipment as claimed in Claim 7, wherein the selecting the identification numbers includes selecting the identification numbers for the mobile terminals based on at least an expected traffic amount and/or type from the one or more terminals corresponding to the identifier,
9. An infrastructure equipment of any preceding Claim, wherein the identification number is a Radio Network Temporary Identifier.
10. A method of operating an infrastructure equipment in a mobile S communications network for communicating data to and/or from mobile terminals, the method comprising providing a wireless access interface from the infrastructure equipment for communicating the data to and/or from the mobile terminals, and allocating communications resources of the wireless access interface to the mobile terminals for communicating the data, wherein the providing the wireless access interface includes providing a down-link frequency channel for communicating data to the mobile terminals, the down-link frequency channel being divided in time into different units of communications resource which are allocated by the infrastructure equipment to the mobile terminals, and providing a shared control channel for communicating resource allocation messages to the mobile terminals, each resource allocation message including an identification number allocated to one of the mobile terminals for indicating an allocation of one of the units of communications resource of the wireless access interface, and the allocating the communications resources of the wireless access interface to the mobile terminals includes dividing each of a plurality of the mobile terminals into a plurality of different groups, forming a super-frame comprising a plurality of the units of communications resource of the down-link channel, transmitting in a first of the super-frames control information providing for each of the plurality of mobile terminals in a first of the groups of devices a short identification number in association with the identification number allocated to the mobile terminal by the infrastructure equipment for use in allocating the units of communications resource to the mobile terminal for the first super-frame, and transmitting in a second of the super-frames control information providing for each of the plurality of mobile terminals in a second of the groups of terminals a short identification number in association with the identification number allocated to the mobile terminal by the infrastructure equipment for use in allocating the units of communications resource to the mobile terminal for the second super-frame, and adapting each of the resource aflocation messages to include a plurality of the short identification numbers when allocating the units of communications resources to a plurality of the mobile terminals in the first or the second super-frames.
11. A method as claimed in Claim lot wherein one of the short identification numbers in the first super-frame is allocated to identify a different mobile terminal from the second group of devices in the second frame.
12. A method as claimed in Claim 10 or 11, wherein the control information comprises an indication of the units comprised in the super-frame.
13. A method of claim 12, wherein the indication provides a number of subsequent units in the super-frame and indicates the first unit of the super-frame.
14. A method of claim 12, wherein the indication comprises a list of units comprised in the super-frame.
15. A method of claim 10, the method comprising transmitting a resource allocation message to one of the mobile terminals of the second group which is not a member of the first of the groups of mobile terminals in the first super frame, the resource allocation message including the identification number the mobile terminal.
16. A method of any of claims 10 to 16, the method comprising selecting the identification numbers based on at least a profile of the one or more terminals corresponding to the identifier number.
17. A method of as claimed in Claim 16, wherein the s&ecting the identification numbers includes selecting the identification numbers for the mobile terminals based on at least an expected traffic amount and/or type from the one or more terminals corresponding to the identifier.
18. A method of any of Claims 8 to 13, wherein the identification number is a Radio Network Temporary Identifier,
19. A infrastructure equipment substantially as herein before described with reference to the accompanying drawings.20: A method for communicating data to terminals for use in a network element substantially as herein before described with reference to the accompanying drawings.