GB2493128A - Assigning identifiers to user equipment - Google Patents

Abstract

A network (12,14, Figure 4) assigns to a first user equipment UE (10, Figure 4) and to a second UE (11, Figure 4) the same temporary identifier for use at least while the first and the second UEs are simultaneously in a connected state in the same cell. Individual control channel transmissions utilizing the temporary identifier are selectively associated to only one of the first and the second UEs according to a predetermined time domain division. In various embodiments the time domain division comprises discontinuous reception DRX periods having mutually exclusive reception time periods; or mutually exclusive radio frame or sub-frame groups assigned to the first and second UEs for at least downlink control channel transmissions. The temporary identifier may be a Cell Radio Network Temporary Identifier (C-RNTI). The re-use of the same shared identifier for two or more devices in a cell which are distinguished in the time domain (i.e. having particular frames/sub-frames allocated to each device) allows a solution to the problem of having a finite number of temporary identifiers available to allocate by a particular enodeB.

Description

METHOD, APPARATUS AND COMPUTER PROGRAM

FOR ASSIGNING IDENTIFIERS TO USER EOLJIIPMENT

Technical Ficld The present invention relates to a method, apparatus and computer program for assigning identifiers to user equipment.

Exemplary and non-limiting embodimcnts of this invention relate gcnerally to wireless communication systems, methods, devices and computer programs, and more specifically relate to allocating the same identifier to multiple uscr equipmcnt in a Cell.

Background

The following abbreviations used in thc spccification and/or thc drawings are defined as follows: 3GPP third generation partnership project ACK acknowledgement C-RNTI cell radio network temporary identifier DL downlink (network towards UE) DL-CCH downlink control channel DL-SCH downlink shared channel DRX discontinuous reception eNodeB base station of a LTE/LTE-A system E-IJFRAN evolved univcrsal terrestrial radio access network (LTE) HARQ hybrid automatic repeat request LTE long term evolution (of the E-UTRAN system) MAC medium access control MME mobility management entity NACK negative acknowledgement PDCCI-I physical downlink control channel S-OW serving gateway RRC radio resource control UE user equipment IJL uplink (UE towards network) UL-CCH uplink control channel UL-SCH uplink shared channel In the E-UTRAN system as well as many other radio access technologies, users are assigned a temporary identifier for use while in a cell. As smartphones and other portable intcrnct appliances that enable mobile email, navigation and browsing have become more commonplace, many cells manage a radio environment in which there is a high number of concurrent users transferring relatively small amounts of data. Adding to this number of low volume users are smartphones which have applications such as social networking services running in the background that routinely set up a wireless connection to exchange data even without active user input.

In the LTE system, such devices are in the RRC-CONNECTED state with the network access node in the cell, which assigns or otherwise allocates a C-RNTI to each mobile device as its temporary identifier. Since these C-RNTIs are used to distinguish one device in the cell from all others, each (-RNTI uniquely identifies the devices operating in the ccli. Much research has gone into increasing the sheer data capacity of such radio systems but in the above scenario a limit of unique C-RNTIs available in the cell is often reached before any limit on data throughput. It is altogether possible that a newly entering device can potentially be denied connection in a cell for lack of any C-RINTIs available to allocate to it.

Embodiments of the teachings herein mitigate the above problem.

Summary

According to a first aspect of the present invention, there is provided apparatus for assigning identifiers to user equipment, the apparatus comprising a processing system arranged to: assign to a first user equipment and to a second user equipment the same temporary identifier for use at least while the first and the second user equipment are simultaneously in a connected state in the same ecU; and selectively associate individual control channel transmissions utilising the temporary identifier to only one of the first and the second user equipment according to a predetermined time domain division.

The processing system may comprise at least one processor and a memory storing a set of computer instructions.

According to a second aspect of the prcsent invention, there is provided a method of assigning identifiers to user equipment, the method comprising: assigning to a first user equipment and to a sccond user equipment thc same temporary idcntifier for use at least while the first and the second user equipment are simultaneously in a coimeeted state in the same cell; and selectively associating individual control channel transmissions utilising the temporary identifier to only one of the first and the second user equipment according to a predetermined time domain division.

According to a third aspect of the present invention, there is provided a computer program for use in apparatus for assigning identifiers to user equipment, the computer program comprising: code for assigning to a first user equipment and to a second user equipment the same temporary identifier for use at least while the first and the second user equipment are simultaneously in a connected state in the same cell; and code for selectively associating individual control channel transmissions utilising the temporary identifier to only one of the first and the second user equipment according to a predetermined time domain division.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 shows a timing diagram showing interrelationships among transmissions on different downlink logical channels as context for exemplary embodiments of the teachings herein; Figure 2 is similar to Figure 1 but for uplink logical channels; Figure 3 shows a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with exemplary embodiments of the present invention; and Figure 4 shows a simplified block diagram of various network devices and a TIE similar to those shown at Figure 1, which are exemplary electronic devices suitable for use in practising exemplary embodiments of the present invention

Detailed Description

While the exemplary embodiments of the invention detailed below are in the context of the C-RNTI which is used in the LTE system, these are simply examples and not limiting to the broader teachings herein. Various other systems use differently named temporary identifiers to distinguish mobile user devices operating in a cell and these teachings can be used to extend the number of users that a fixed number of such temporary identifiers can service. Such other systems are not limited to only cellular-type systems as such and certain embodiments of the invention can also apply for wireless local area networks and other non-cellular radio access technologies, which might for example cover a limited geographical area.

One possible way to solve the C-RNTI limitation discussed above in the background section is to increase the number of C-RNTIs available in a cell. A similar approach was done in the past to increase the possible number of globally unique identifiers associated with the network access nodes themselves. In the past, hexadecimal numbers replaced previous base-10 digits to increase the number of available identifiers, but also the number of bits allocated for a given identifier can be increased to allow for expanding the number of available identifiers. This is seen as somewhat difficult to implement since legacy equipment is often unable to be adapted S by a simple software download to the newer system and also the old and new numbering system must be able to exist side by side for some transition period.

The present teachings take a different approach to resolve or at least mitigate the problem, namely by re-using the same temporary identifier value for two or more user devices (more generally liEs) in the cell and distinguish them from one another in the time domain, such as by use of discontinuous reception periods assigned to the two liEs having mutually exclusive reception time periods or by appropriate usc of radio frame or subframe numbers.

As a brief overview, assume a first and a second UF are each allocated the same C-RNTI #x. Both of those liEs are in a RRC-CONINECTED state with the same cell at the same time. When the network sends control signalling such as a radio resource allocation schedule PDCCH to the first liE, it will send it in a radio frame or subframc associated with the first liE. The first liE will interpret the C-RNTI #x sent on the PDCCH as its own identity only if that PDCCH is sent in a radio frame/subframe associated with the first UE. The second UE will not be looking for a PDCCI-1 addressed to it during those times since the time division of these two liEs is mutually exclusive on the control channel.

The network can enforce this time division quite easily, such as for example when assigning discontinuous reception DRX periods to these UEs. Other examples for imp'ementing this time domain separation are detafled further below, such as the system frame number and subframe number satisfying certain criteria such as frame/subframe groupings where the different groups are associated with the different first and second liEs. Such framc/subframe groups can be configured together with the C-RNTI, at least at the time when the same C-RNTI is assigned to the later-coming UE.

As a prelude to discussing the specific examples in detail, Figures I and 2 show a general relation among logical channels in a system in which channel or radio resource allocations on a shared channel are sent on a downlink control channel, and ACKs and NACKs for the data on the shared channel are sent also on a control channel. This general structure is present in E-LJTRAN/LTF systems as well as others, and thc high data throughput capacity of LTE indicatcs similar channel structures might bc adopted in future systems also. Regardless of the specific radio access technology, Figures 1 and 2 illustrate an exemplary environment in which embodiments of the invention maybe practised to advantage.

Figures 1 and 2 illustrate the logical DL-CCH and LTL-CCH as independent channels although in the LTF system at least they are physically located on the same carriers with the data channels DL-SCI-l and UL-SCH. The names of the logical channels in Figures 1 and 2 can be mapped to conesponding channels in various radio access technology systems to show applicability of these teachings.

Figures 1 and 2 show frame numbers recited linearly along the top of those drawings; other systems may use a hierarchical frame numbering system. For example, the radio frames of 10 ms are numbered linearly in Figures 1 and 2 but each radio frame may also include multiple subframes (e.g. 10 subframes indexed as 0 through 9 per radio frame in LTE). Other systems may use a different frame/slot/subframe numbering regimen to which the examples illustrated in Figures I and 2 may be reasonably adapted for implementations in other types of radio systems.

As noted above, the DL-CCH is used for allocating the DL-SCH resources for a certain liE. The UE identifier is transmitted in some form on the DL-CCI-1 to indicate the specific UE to which the allocation on the DL-SCI-1 is granted. This is the liE's temporary cell identifier noted above. For example, the liE identifier may be transmitted explicitly in the DL-CCH, it may be encoded, the scheduling grant in the DL-CCH may be encrypted or otherwise encoded with a key which is the liE identifier or which is a function of the liE identifier, or the DL-CCH itself that is directed to the particular liE can be channel coded using the UE identifier as one of several coding parameters. There are many other options available, but the point is that the liE identifier is used in some manner so that only the liE to which the DL-CCH is directed can read the relevant contents. More generally, the liE identifier is transmitted explicitly or implicitly in a specific frame of the DL-CCH.

In many cellular systems, the UE identifier is assigned to the UE upon the liE becoming established in thc cdl, upon the liE becoming connected in a non-idlc state, after a random access procedure, after a handovcr from an adjacent cell, or by other means. In any event, it is the network which assigns the liE its temporary identifier for usc in the cell.

Transmission of data according to Figure 1 is conducted as follows. First the liE checks the DL-CCH sent by the network to check whether its identifier is transmitted in one of the frames. The reception of the DL-CCI-1 may be discontinuous if the liE knows from its DRX configuration or from any other source that its identifier is not going to be transmitted in some frames. The liE identifier in LTE in this context is the C-RNTI.

When the tiE detects its identifier and a channel allocation on the DL-CCH (point A in Figure 1), it receives a piece of data on the DL-SCH according to the channel allocation information (point B). There may be a delay between A and B. TypicaHy this delay is fixed in the radio system and may also be zero, that is the channel allocation and the data reception are in the same frame.

The liE then transmits an ACK or NACK on the UL-CCH depending on the success of the data reception. In the cxampk in Figure 1 the liE transmits a NACK

S

after the first reception (point C) since it is assumed the data at point B was not properly received/decoded. This ACK or NACK usually happens at a fixed or preconfigured delay, so the network knows where to expect the UE feedback transmission. The ACK or NACK may also contain the UE identifier. The UE then receives on the DL-SCH retransmissions of the original data (at points D and F) until the data is received correctly (point F) at which point finally the TIE transmits an ACK (point 0).

In the above chain of transmissions, no new channel allocations via the DL-CCH are needed in some systems such as LTE, because the NACKs (points C and E) implicitly act as an agreement that the same channel is used for the retransmissions at fixed or preconfigured delays. The retransmissions arc usually implemented with HARQ, but different radio systems may use different retransmission methods and still take advantage of the teachings herein.

There may be several chains of data retransmissions present in parallel. Figure I shows this in that the transmissions represented by PQRTU constitute one chain and the transmissions represented by HJK another; and transmissions VW partially represent a third chain. The number of retransmissions varies. Note that each transmission chain is initiated by a TIE identifier and channel allocation message on the DL-CCH. These transmission chains arc independent of each other and they may belong to the same UE or different LIEs. The use of the channels for data transmission depends on the specific channel allocation procedures of the network and the radio access technology it employs.

Figure 2 illustrates the operation of the uplink data transmission. Many of the principles used in the DL data transmissions continue in the UL data transmission chain and so only the differences are detailed for Figure 2. In the case of Figure 2, the DL-CCH (point A) allocates radio resources on the UL-SCH (point B). The delay between the network's transmission of the UE identifier and the channel allocation on the DL-CCI-1 and the TIE's data transmission on the allocated radio resource on the IJL-SCH is typically longer. In LTE the reason for this is that the size of the transport block on the TJL-SCH is not known before the UE receives the channel aflocation on the DL-CCH, so the UE carries out the channel coding for the transmission only after receiving the channel allocation. The delays in general between these different logical channel transmissions are either fixed or preconfigured in the radio system.

The feedback for retransmissions (points C and E) is sent on the DL-CCH, i.e. the same channel as the channel allocations (point A). Retransmission at point D which results in thc ACKINACK feedback at point E assumes the feedback from the network at point C was a NACK. Typically the network will transmit the TiE identifier along with the NACK (point C) as well as with the ACK (point E) responses to the TiE's UL data (points B and D respectively).

Another transmission chain in Figure 2 has an UL allocation sent with the UE identifier at P, UL data sent at point Q, the network's NACK with the TiE identifier at R, the UE's re-transmission of its data at T, and finally the network's ACIC with the UE identifier at V. The remaining UL data transmission chain shows the Ut channel allocation and UE identifier sent by the network at H, UL data sent by the TiE at J, and the network's ACK along with the LiE identifier at K. In certain practical network implementations, Figures 1 and 2 are actually describing the same channels and they are laid over each other to form a single system. Both uplink and downlink channel allocations may be transmitted together to the UE if there is data waiting to be transmitted in both directions at the same time, but logically the uplink and downlink procedures maybe considered as separate and logically independent.

In view of the interrelationships among logical channels for both UL and DL data transmissions as detailed for Figures 1 and 2, it is seen that the UE identifier (the C-RNTI in LTE) plays an important role in the transmission procedures. Without additional arrangements, each LiE must have a unique identifier in the cell else the resource/channel allocations on the DL-CCH and feedback signalling on the DL-CCH or the UL-CCH (as the ease may be) would be ambiguous.

The number of unique identifiers which any given cdl has for use among its UEs is usually limited and designed so that adjacent cells are not using the same ones.

As noted in the background section above, the radio environment is changing so that this limited number of UE identifiers per cell may become a limiting factor.

Exemplary embodiments of these teachings provide a method to use the same UE identifier for more than one TIE in a cell and still avoid the signalling of Figures 1 and 2 becoming ambiguous as to which TiE such signalling is directed to or from which TIE it originated. Below are also presented some variants of the core concepts as expanding but non-limiting examples with reference to Figure 3.

First, Figure 3 begins with the broader aspects of these teachings as recited from the perspective of the network access node, such as an cNodeB operating in an E-TJTRAN system having first and second UEs under its control. At block 302 the access node assigns to a fir st UE and to a second UE the same temporary identifier for use at least while the first and the second UEs are simultaneously in a connected state in the same cell. This does not imply that the UEs must be in a connected state at the time when the network first assigns these identifiers; only that the identifiers, once assigned, are for usc while those TiEs arc in the connected state in the cell (and possibly also for use while they are in the idle state). At block 304 the access node then selectively associates individual control channel transmissions utilising the temporary identifier to only onc of the first and the second liEs according to a predetermined time domain division. The explicitly defined rules by which to do this may be stored in the eNodeB's local mcmory, and various examples are given below.

Various embodiments of the control channel transmissions "utilising" the identifier are given above, with both explicit and implicit utilisations detailed. Below arc given various exemplary but non-limiting embodiments of how the eNodcB might enforce or otherwise purposefully bring about the predetermined time domain division so it can selectively associate different individual control channel transmissions (either or both of DL and TilL control channel transmissions) with only one or the other of the first and second yEs.

At block 306, the predetermined time domain division comprises discontinuous reception DRX periods assigned to the first and to the second UEs in which those DRX periods have mutually exclusive reception time periods. In this manner, while the first L[E has a listening slot and checks the DL-CCH for its assigned (same) identifier, the second UE is in a dc-powered state to reduce its power consumption. Sincc the DRX periods arc mutually exclusive in thcir reception time periods then, when the second UE has an active listening slot, the first TiE is in a powcr saving mode and not listening on the DL-CCI-1.

The further examples at Figure 3 have the predetermined time domain division as mutually exclusive radio frame or subframe groups assigned to the first and second UEs for at least DL control channel transmissions, as stated generally at block 308.

One particular embodiment of block 308 is detailed at block 310; the mutually exclusive radio frame or subframc groups are even and odd numbered radio frame or subframe groups. In this example, there are only two TiEs sharing the same temporary cell identifier so there only needs to be two groups, even and odd frames in this case (or equivalently even and odd subframes without regard to frame number).

The first UE configured with the same identifier and odd frames/subframes would then use the identifier, but would be allowed to receive and transmit the identifier only in odd frames/subframcs. The second TiE can then use the same identifier, but only in the even frames/subframes. Note that both UEs could in principle use any frames in the UL-SCH and DL-SCH since those logical channels are not used to carry the identifier information, but the time domain restriction applies on the even or odd frames on the UL-CCH and the DL-CCH.

The grouping of the frame numbers could in practice use more complicated methods so that the same identifier can potentially be used with more than only two UEs. In principle any mathematical %rmula could be used to derive grouping of the frames and/or subframes, as long as the fbrmula produces an unambiguous group identifier from the frame and/or subframe numbers. Put another way, the different groupings have mutually exclusive sets of either frames and/or of subframes.

Different rules must usually be applied on different channels. Referring to Figure 1, there is always a 5-frame offiet between the channel allocation on the DL-CCH and the feedback on the UL-CCH. Thereibre, an offiet would typically be used if the rules of the frame number grouping are done at the granularity of single frames.

As an example of this, the radio frames in LIE which are numbered with the SFN are divided into 10 subframes. The HARQ process cycle is 8 subframes. One way to conveniently to divide the subframes into 8 groups is with the lbrmula: Ciroupid = (10 * SF14 + subFN + offset) mod 8.

In this fbrnmla, SFN is the system frame number, subFN is the subframe number ranging between 0. ..9, and offset is the channel-specific offset that is needed to handle the timing differences of different channels in the manner noted above ibr the LIE system (or in a different manner fbr other systems). If instead there is needed only 4 or 2 groups, the modulo operation can be changed from mod 8 to mod 4 or mod 2 respectively. This fbrmula is particularly useful when the data rates are rather high and the delay requirements are stringent.

Block 312 of Figure 3 gives a generic!brm of the above lbrmula ibr generating such mutually exclusive groupings. Each of the mutually exclusive radio frame or subframe groups is given by the fbrmula: Group id=(l0*SFN+subFN+offset)modX; in which SFN, subFN and offset are defined above and X is selected from the group 2, 4 and 8. These values for X provide the best performance, but other v&ues of X can also be used so more generally X can be any integer greater than one.

This next example shows a coarser frame grouping and defines the groups by the following formula: Group_id = (SEN div OS) mod ON Tn this formula, SFN is again thc system frame number, OS is thc group size, and GN is the number of groups. Consider an example in which the frames of the system are 10 ms long, the OS value is set to 6 and the ON value is set to 10. The result would be a scheduling where each liE would have 60 ms active time in every 600 ms. The individual liE would be aflowed to receive and transmit its ID during the active period only, which is mutuaLly exclusive of the 60 ms active period of any of the other UPs (up to 9 others since GN=1 0) sharing this same UE identifIer in the cell. This is shown at block 314 of Figure 3.

Where completion of the (HARQ) re-transmission chain as detailed in Figures 1 and 2 requires the use of the UE identifier, the network must take this into account in the scheduling and not allocate the channel to any liE near the end of its active period, or potentially have to abort some re-transmission chain (which might be acceptable in certain circumstances or systems). The following formula for defining the frame and/or subframe groups alleviates this problem somewhat: Groupid = ((SN * SFN + subFN + offset) div OS) mod ON Meanings of these terms are all detailed above, and this formula is shown at block 316 of Figure 3. This formula achieves the same configuration as above by setting OS = 6 * SN, GN = 0, offset = 0 for the DL-CCH and offset = -5 for the IJL-CCH, assuming SN subframes in the radio frames which are numbered with the SFNs.

This variant is more advantageous in cases where the liEs sharing the same identifier are not anticipated to need urgent data transmission and the amount of data is low. It is also necessary that there are other UEs in the cell that are not configured with any frame division, because this embodiment does not use the shared channels efficiently. But this is a moderate requirement, because it is very probable that in a practical deployment the UBs using this frame division technique will constitute a minority in terms of data volumes although they might form the majority of liEs in the cell (e.g. those liEs consuming the cell's identifier pooi which in LTE is the C-RNTI pool).

Figure 3 detailed above shows a logic flow diagram which describes the above exemplary embodiments from the perspective of the network access node. Figure 3 represents results from executing a computer program or an implementing algorithm stored in the local memory of the access node, as well as illustrating the operation of a method and a specific manner in which the processor and memory with computer program/algorithm are configured to cause that access node (or one or more components thereof) to operate. The various blocks shown in Figure 3 may also be considered as a plurality of coupled logic circuit elements constructed to carry out the associated fiinction(s, or specific result or function of strings of computer program code stored in a computer readable memory.

Such blocks and the fhnctions they represent are non-limiting examples, and may be practised in various components such as integrated circuit chips and modules, and that the exemplary embodiments of this invention may be realised in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this invention.

Reference is now made to Figure 4 for illustrating a simplified block diagram S of various electronic devices and apparatus that are suitable for use in practising the exemplary embodiments of this invention. In Figure 4, a serving cell or network access node 12 is adapted for communication over a wireless link with a mobile apparatus, such as a mobile terminal or UF 10. The access node 12 may be a macro eNodeB, a remote radio head or relay station, or other type of base station/cellular network access node.

The first LiE 10 includes processing means such as at least one data processor (DP) bA, storing means such as at least one computer-readable memory (MEM) lOB storing at least one computer program (PROG) 1 OC, and also communicating means such as a transmitter TX I OD and a receiver RX I OE for bidirectional wireless communications with the network access node 12 via one or more antennas IOF.

The network access node 12 similarly includes processing means such as at least one data processor (DP) 12A, storing means such as at least one computer-readable memory (MEM) 12B storing at least one computer program (PROG) 12C, and communicating means such as a transmitter TX 12D and a receiver RX 12E for bidirectional wireless communications with the UE 10 via one or more antennas 12F.

There is a data and/or control path, shown in Figure 4 as a control link which in the LTE system may be implemented as an SI interface, coupling the network access node 12 with the serving gateway S-OW/mobility management entity MME I 4 (or more generally a higher network node). The network access node 12 stores at 120 an association of each LiE 10,11, which share the same temporary cell identifier, with the radio frames or other time division means which the access node uses to distinguish which control channel transmission is associated with which of those UEs 10,11 as detailed above.

Similarly, the S-GW/MME 14 includes processing means such as at least one data processor (DP) 14A, storing means such as at least one computer-readable memory (MEM) 14B storing at least one computer program (PROG) 14C, and communicating means such as a modem 14H for bidirectional communication with the network access node 12 via the control link. While not particularly illustrated for the TJE 10 or network access node 12, those devices are also assumed to include as part of their wireless communicating means a modem which may be inbuilt on a radiofrequency RF front end chip within those devices 10,12 and which chip also carries the TX 1OD!12D and the RX IOE!12E.

For completeness also is shown the second liE 11 which includes its own proccssing mcans such as at Icast onc data processor (DP) 1 1A, storing means such as at least one computer-readable memory (MEM) 1 lB storing at least one computer program (PROG) 11 C, and communicating means such as a transmitter TX lID and a receiver RX I 1E for bidirectional wireless communications with the access node 12 via one or more antennas I iF.

At least one of the PROGs 12C in the access node 12 is assumed to include program instructions that, when executed by the associated DP 12A, enable the device to operate as discussed above. In this regard, the exemplary embodiments may be implemented at least in part by computer software stored on the MEM 12B which is executable by the DP 12A of the access node 12, or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware). Electronic devices implementing these aspects of the invention need not be the entire devices as depicted at Figure 4, but exemplary embodiments may be implemented by one or more components of same such as the above described tangibly stored software, hardware, firmware and DP, or a system on a chip SOC or an application specific integrated circuit ASIC.

Various embodiments of the computer readable MEMs lOB, IIB, l2B and 14B include any data storage technology type which is suitable to the local technical environment, induding but not limited to semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, removable memory, disc memory, flash memory, DRAM. SRAM, BEPROM and the like. Various embodiments of the DPs IOA, hA, 12A and 14A include but are not limited to general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and multi-core processors.

The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invcntion are envisaged. It is to bc understood that any feature dcscribed in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be emp'oyed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims (1)

1. <claim-text>SCLAIMS1. Apparatus for assigning identifiers to user equipment, the apparatus comprising: a processing system arranged to: assign to a fir st user equipment and to a second user equipment the same temporary identifier for use at least while the first and the second user equipment are simultaneously in a connected state in the same cell; and selectively associate individual control channel transmissions utilising the temporary identifier to only one of the first and thc second user equipmdnt according to a predetermined time domain division.</claim-text> <claim-text>2. Apparatus according to claim 1, in which the predetermined time domain division comprises discontinuous reception periods assigned to the first and to the second user equipment which have mutually exclusive reception time periods.</claim-text> <claim-text>3. Apparatus according to claim 1, in which the predetermined time domain division comprises mutually exclusive radio frame or subframe groups assigned to the first and second user equipment for at least downlink control channel transmissions.</claim-text> <claim-text>4. Apparatus according to claim 3, in which the mutually cxclusivc radio frame or subframe groups are even and odd numbered radio frame or subframe groups.</claim-text> <claim-text>5. Apparatus according to claim 3, in which each of thc mutually exclusivc radio frame or subframe groups is given by the formula: Groupid = (10 * SEN -I-subFN + offset) mod X in which SFN is a system frame number; subFN is a subframe number; offset is a timing offset between a control channel and a data channel; and X is an integer greater than one.</claim-text> <claim-text>6. Apparatus according to claim 3, in which each of the mutually exclusive radio frame or subframe groups is given by the formula: Group_id = (SFN div GS) mod GN; in which SFN is a system frame number; GS is a group size; and GN is a number of groups.</claim-text> <claim-text>7. Apparatus according to claim 3, in which each of the mutually exclusive radio frame or subframe groups is given by thc formula: Group_id = ((SN * SFN + subFN + offset) div GS) mod GN; in which SFN is a system frame number; subFN is a subframc number; offset is a timing offset between a control channel and a data channel; GS is a group size; and GN is a number of groups.</claim-text> <claim-text>8. Apparatus according to any of claims I to 7, in which the apparatus comprises a network access node.</claim-text> <claim-text>9. Apparatus according to claim 8, in which the network access node comprises an eNodeB operating in an E-UTRAN system and the same temporary identifier is a C-RNTI.</claim-text> <claim-text>10. A method of assigning identifiers to user equipment, the method comprising: assigning to a first user equipment and to a second user equipment the same temporary identifier for use at least while the first and the second user equipment are simultaneously in a connected state in the same cell; and selectively associating individual control channel transmissions utilising the temporary identifier to only one of the first and the second user equipment according to a predetermined time domain division.</claim-text> <claim-text>11. A method according to claim 10, in which the predetermined time domain division comprises discontinuous reception periods assigned to the first and to the second user equipment which have mutually exclusive reception time periods.</claim-text> <claim-text>12. A method according to claim 10, in which the predetermined time domain division comprises mutually exclusive radio frame or subframe groups assigned to the first and second user equipment for at least downlink control channel transmissions.</claim-text> <claim-text>13. A method according to claim 12, in which the mutually exclusive radio frame or subframe groups are even and odd numbered radio frame or subframe groups.</claim-text> <claim-text>14. A method according to claim 12, in which each of thc mutually exclusive radio frame or subframe groups is given by the formula: Groupid = (10 tSFN + subFN ÷ offset) mod X; in which SFN is a system frame number; subFN is a subframe number; ofikct is a timing offset between a control channel and a data channel; and X is an integer greater than one.</claim-text> <claim-text>15. A method according to claim 12, in which each of the mutually exclusive radio frame or subframe groups is given by the formula: Groupid = (SFN div OS) mod ON; in which SFN is a system frame number; OS is a group size; and ON is a number of groups.</claim-text> <claim-text>16. A method according to claim 12, in which each of the mutually exclusive radio frame or subframe groups is given by the formula: GmupJd = ((SN * SFN + subFN + offset) div OS) mod ON; in which SFN is a system frame number; subFN is a subframc number; offset is a timing offtct between a control channel and a data channel; OS is a group size; and ON is a number of groups.</claim-text> <claim-text>17. A method according to any of claims 10 to 16, in which the method is executed by a network access node.</claim-text> <claim-text>18. A computer program for use in apparatus for assigning identifiers to user equipment, the computer program comprising: code for assigning to a first user equipment and to a second user equipment the same temporary identifier for use at least while the first and the second user equipment are simultaneously in a connected state in the same cell; and code for selectively associating individual control channel transmissions utilising the temporary identifier to only one of the first and the second user equipment according to a predetermined time domain division.</claim-text> <claim-text>19. A computer program according to claim 18, in which the predetermined time domain division comprises discontinuous reception periods assigned to the first and to thc sccond user equipment which have mutually exclusive reception time periods.</claim-text> <claim-text>20. A computer program according to claim 18, in which the predetermined time domain division comprises mutually exclusive radio frame or subframe groups assigned to the first and second user equipment for at least downlink control channel transmissions.</claim-text> <claim-text>21. A computer program according to claim 19, in which the mutually exclusive radio frame or subframe groups are even and odd numbered radio frame or subframe groups.</claim-text> <claim-text>22. A computer program according to claim 19, in which each of the mutually exclusive radio frame or subframe groups is given by one of: the formula Group id = (10 * SFN + subFN + offset) mod X; or the formula Group_id = (SFN div GS) mod GN; or the formula Group_id = ((SN * SEN + subFN -F offset) div GS) mod GN; in which SEN is a system frame number; subEN is a subframc number; offset is a timing offset between a control channel and a data channel; X is an integer greater than one; CS is a group size; and ON is a number of groups.</claim-text> <claim-text>23. Apparatus for assigning identifiers to user equipment, substantially in accordance with any of the examples as described herein with reference to the accompanying drawings.</claim-text> <claim-text>24. A method of assigning identifiers to user equipment, substantially in accordance with any of the examples as described herein with reference to the accompanying drawings.</claim-text>