Method for signaling in a cellular telecommunications network

Abstract

A signaling method for implementation by a base station controlling at least one cell of a network attached to at least one terminal, uniquely identified on this cell by a dedicated temporary network identifier, is provided. It may comprise allocating an open temporary network identifier to an interferer terminal identified by the base station as being capable of interfering with at least one communication established by another terminal attached to this cell or a neighbor cell, publishing this open temporary network identifier and sending a first physical control channel according to a predetermined format to the interferer terminal comprising a condensed representation of the open identifier, this first channel coded using the dedicated temporary network identifier of the interferer terminal. The method may comprise sending a second physical control channel to the interferer terminal allocating it transmission resources over the cellular network, coded using the open temporary network identifier.

Claims

1. A signaling method for implementation by a base station of a cellular telecommunications network, this base station controlling at least one cell of the network to which is attached at least one terminal uniquely identified on this cell by a dedicated temporary network identifier, the signaling method comprising: allocating an open temporary network identifier, to an interferer terminal identified by the base station from among said at least one terminal attached to the cell as being capable of interfering with at least one communication established by another terminal attached to this cell or to a neighbor cell of this cell; publishing this open temporary network identifier; sending a first physical control channel according to a predetermined format to the interferer terminal comprising a condensed representation of the open temporary network identifier allocated to the interferer terminal, this first physical channel being coded using the dedicated temporary network identifier of the interferer terminal; and sending a second physical control channel to the interferer terminal allocating it transmission resources over the cellular network, this second channel being coded using the open temporary network identifier.

2. The signaling method according to claim 1, wherein the process of publishing the open temporary network identifier comprises broadcasting this identifier to the terminals attached to said cell and/or to the terminals attached to at least one other cell controlled by the base station and neighbor of said cell.

3. The signaling method according to claim 1, wherein the publishing of the open temporary network identifier comprises broadcasting this identifier to at least one other base station controlling a neighbor cell of the cell.

4. The signaling method according to claim 1, further comprising broadcasting a message on said cell comprising a correspondence between the open temporary network identifier and its condensed representation.

5. The signaling method according to claim 1, further comprising sending a dedicated signaling message to the interferer terminal managed by a radio resource management layer, this dedicated signaling message comprising a correspondence between the open temporary network identifier and its condensed representation.

6. The signaling method according to claim 1, wherein the format of the first physical control channel comprises a field containing a sequence of predetermined bits.

7. The signaling method according to claim 1, wherein the format of the first physical control channel comprises a number of bits less than a format of the second physical control channel.

8. The signaling method according to claim 1, wherein the cellular telecommunications network is an LTE (Long Term Evolution) network and: the open temporary network identifier and the dedicated temporary network identifier allocated to the interferer terminal are identifiers of RNTI (Radio Network Temporary Identifier) type; and the first and the second physical control channel are PDCCH channels (Physical Downlink Control CHannel).

9. The signaling method according to claim 5, wherein the dedicated signaling message is an RRC (Radio Resource Control) signaling message.

10. A computer having stored thereon instructions which, when executed by the computer, cause the computer to perform the signaling method of claim 1.

11. A non-transitory data storage medium readable by a computer on which is stored a computer program comprising instructions for executing the steps of the signaling method according to claim 1.

12. A base station of a cellular telecommunications network, controlling at least one cell of the network to which is attached at least one terminal uniquely identified on this cell by a dedicated temporary network identifier, this base station comprising a processor and a memory, wherein the processor: allocates an open temporary network identifier to an interferer terminal identified from among said at least one terminal attached to the cell as being capable of interfering with at least one communication established by another terminal attached to this cell or to a neighbor cell; publishes this open temporary network identifier; sends a first physical control channel according to a predetermined format to the interferer terminal, comprising a condensed representation of this open temporary identifier, such that said first physical channel can be coded using the dedicated temporary network identifier of the interferer terminal; and sends a second physical control channel to the interferer terminal allocating it transmission resources over the cellular network, such that said second physical channel can be coded using the open temporary network identifier allocated to the interferer terminal.

13. A communication method for implementation by an interferer terminal attached to a cell of a cellular telecommunications network and uniquely identified in this cell by a dedicated temporary network identifier, said cell being controlled by a base station, and the interferer terminal being capable of interfering with at least one communication established by another terminal of said cell or of a neighbor cell to this cell, the communication method comprising: decoding a first physical control channel using the dedicated temporary network identifier, this first physical control channel having a predetermined format and comprising a condensed representation of a open temporary network identifier allocated to the interferer terminal by the base station and published or intended to be published by the latter; on detection of the predetermined format of the first physical control channel: determining the open temporary network identifier allocated to the interferer terminal from said condensed representation contained in the first physical channel; and decoding a second physical control channel using the open temporary network identifier thus determined, this second physical control channel allocating transmission resources for transmission over the cellular network to the interferer terminal; and using the transmission resources allocated in this second channel to communicate over the cellular network.

14. A terminal attached to a cell of a cellular telecommunications network and uniquely identified on this cell by a dedicated temporary network identifier, said cell being controlled by a base station and said interferer terminal being capable of interfering with at least one communication established by another terminal attached to said cell and/or to a neighbor cell to said cell, said terminal comprising a processor and a memory, wherein the processor: decodes a first physical control channel using the dedicated temporary network identifier, this first physical control channel having a predetermined format and comprising a condensed representation of an open temporary network identifier allocated to the interferer terminal by the base station, and published or intended to be published by the latter; on detection of the predetermined format of the first physical control channel, determines the open temporary network identifier from the condensed representation contained in the first physical control channel; on detection of the predetermined format of the first physical control channel, decodes a second physical control channel using the determined open temporary network identifier, this second physical control channel allocating transmission resources over the cellular network to the interferer terminal; and uses the transmission resources allocated in this second channel for communicating over the cellular network.

15. A system of a cellular telecommunications network comprising: a base station according to claim 12 controlling at least one cell of the cellular telecommunications network; an interferer terminal according to claim 14 attached to said cell; and a terminal interfered on by said interferer terminal, said interfered terminal being attached to the cell of the interferer terminal or to a neighbor cell of the network, and able to implement an interference cancellation technique using the open temporary network identifier allocated to the interferer terminal and published by the base station.

16. The signaling method according to claim 1, wherein the dedicated temporary network identifier is reserved to the interferer terminal and uniquely identifies the interferer terminal on the cell controlled by the base station.

17. The base station according to claim 12, wherein the dedicated temporary network identifier is reserved to the interferer terminal and uniquely identifies the interferer terminal on the cell controlled by the base station.

18. The communication method according to claim 13, wherein the dedicated temporary network identifier is reserved to the interferer terminal and uniquely identifies the interferer terminal on the cell controlled by the base station.

19. The terminal according to claim 14, wherein the dedicated temporary network identifier is reserved to the interferer terminal and uniquely identifies the interferer terminal on the cell controlled by the base station.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages of the present invention will become apparent from the description given below, with reference to the appended drawings which illustrate embodiments thereof which are in no way limiting in nature. In the figures:

(2) FIG. 1 schematically represents a system of a telecommunications network, a base station and a terminal in accordance with the invention, in a particular embodiment;

(3) FIGS. 2 and 3 schematically represent the hardware architecture of the base station and the terminal illustrated in FIG. 1;

(4) FIG. 4 represents, in the form of a block diagram, the main steps of a signaling method in accordance with the invention in a particular embodiment wherein it is implemented by the base station in FIG. 1;

(5) FIG. 5 represents, in the form of a block diagram, the main steps of a communication method in accordance with the invention in a particular embodiment wherein it is implemented by the base station in FIG. 1; and

(6) FIGS. 6A and 6B present examples of predetermined formats of the physical control channel which can be used in the context of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(7) FIG. 1 shows, in its environment, a system 1 of a cellular telecommunications network NW, in accordance with the invention, in a particular embodiment.

(8) In this particular embodiment, the cellular telecommunications network NW is an LTE mobile network, as defined by 3GPP. Each cell of the network NW is controlled by a base station (or eNodeB) serving the various terminals (or UEs for User Equipments) attached to the cell.

(9) By way of illustration, two cells C1 and C2 of the cell network NW are represented in FIG. 1, the cell C1 being controlled by the base station BS1 and the cell C2 being controlled by the base station BS2. Each base station serves one or more terminals present in the cell(s) that it controls. Thus, in FIG. 1, it is considered that a terminal T1 and a terminal T1 are attached to the cell C1 and served by the base station BS1, and that a terminal T2 is attached to the cell C2 and served by the base station BS2.

(10) Of course no limitation is attached to the number of base stations under consideration, nor to the number of cells managed by a base station, nor even to the number of terminals attached to each cell.

(11) In accordance with the LTE standard, each terminal attached to a cell is allocated a temporary network identifier known as RNTI by the base station controlling this cell, in order to communicate over the network NW. In a manner known to those skilled in the art, this RNTI identifier is a dedicated identifier, i.e. reserved to the terminal and which identifies it uniquely on the cell to which it is attached. Thus, in the example presently considered here, the base station BS1 allocates a dedicated temporary network identifier RNTI1 to the terminal T1 and a dedicated temporary network identifier RNTI1 to the terminal T1, and the base station BS2 allocates a dedicated temporary network identifier RNTI2 to the terminal T2.

(12) To better illustrate the invention, it is assumed here that the terminal T1 is capable of interfering with communications on the network NW of the terminal T1 attached to the same cell as it, i.e. the cell C1 (by creating MU-MIMO interference for example), as well as with communications over the network NW of the terminal T2 attached to the cell C2 (intercellular interference). In other words, the terminal T1 and the terminal T2 are the victims of interference generated by the transmissions originating from the base station BS1 and intended for terminal T1.

(13) Of course, these assumptions are not limiting per se, as a terminal can be an interferer terminal for certain terminals (i.e. the transmissions from the network toward this interferer terminal constitute interference for the communications established by these terminals), and undergo interference (i.e. be interfered on) generated by other terminals (i.e. by the transmissions from the network toward these other terminals).

(14) In accordance with the invention, the system 1 comprises: at least one base station in accordance with the invention controlling at least one cell of the cellular telecommunications network. This base station is in the example presently considered here the base station BS1 that controls the cell C1; at least one interferer terminal attached to this cell, namely, in the example considered in FIG. 1, the terminal T1; and at least one terminal interfered on by this interferer terminal, and attached to the cell of the interferer terminal or to a neighbor cell of the network: in this case here, two interfered terminals are considered, namely terminals T1 and T2.

(15) No limit is however attached to the numbers of interferer and interfered terminals in consideration, nor to the type of interference created by the interferer terminal. Thus the invention can apply as well in the presence of MU-MIMO interference generated within one and the same cell as described previously, and/or in the presence of intercellular interference between signals intended for terminals attached to neighbor cells,

(16) The terminals T1, T1 and T2 can be terminals of any kind capable of communicating over the LTE network NW, such as for example mobile phones, smartphones, laptop computers etc.

(17) In the embodiment described here, for the sake of simplicity, the terminals T1, T1 and T2 are all LTE terminals in accordance with the invention, each being equipped with a non-linear receiver of MMSE-SIC type, or in other words with a non-linear receiver employing a successive interference cancellation technique. Such receivers are known per se and will not be further described here: thus, by way of example, they may be non-linear receivers employing hard decision channel decoding, or non-linear receivers employing soft decision turbo (or iterative) channel decoding, as notably described in the contribution R1-090232, 3GPP TSG RAN WG1, of January 2009 entitled Comparing performance, complexity and latency of SC-FDMA SIC and OFDM MLD.

(18) In the embodiment described here,these terminals have the hardware architecture of a computer, as illustrated in FIG. 2.

(19) More specifically, each terminal notably comprises a processor 3, a read-only memory 4, a random-access memory 5, a non-volatile memory 6 and means 7 for communicating over the LTE telecommunications network NW, known per se.

(20) The read-only memory 4 of each terminal forms a storage medium in accordance with the invention, readable by the processor 3 and on which is stored a computer program including instructions for executing the steps of a communication method in accordance with the invention, the steps of which will be described later with reference to FIG. 5 in a particular embodiment.

(21) This computer program defines, in an equivalent way, software and functional modules of the terminals T1, T1 and T2 capable of executing the various steps of the method of communication and of interacting with the components of the terminals described previously with reference to FIG. 2, such as notably a module for decoding a first physical control channel (in this case a first PDCCH channel for an LTE network) having a format predetermined using the dedicated temporary network identifier of the terminal in consideration, a module for determining an open temporary network identifier from a condensed representation contained in the first physical control channel, a module for decoding a second physical control channel allocating resources to the terminal using this open temporary network identifier and a module for using the transmission resources allocated in the second channel to communicate over the network.

(22) Note that it is not necessary for the implementation of the invention that all terminals able to communicate over the network NW implement a nonlinear receiver using an interference cancellation technique.

(23) Similarly, all terminals able to communicate over the network NW are not necessarily in accordance with the invention, in other words, configured so as to be able to decode the open temporary identifiers allocated by their respective base station in order to allow the other terminals to cancel the interference that they generate. Thus, in the example presently considered, it suffices that T1 is in accordance with the invention, and that the terminals T1 and T2 are able to decode a PDCCH channel coded using an open temporary identifier allocated by the base station BS1 to terminal T1, and to apply an interference cancellation method to the interfering signals emitted by the base station BS1 and intended for the terminal T1 using the transmission parameters obtained by decoding the PDCCH channel emitted by the base station BS1 over the cell C1.

(24) As mentioned previously, the base station BS1 is in accordance with the invention.

(25) In the embodiment described here, it possesses the hardware architecture of a computer, as illustrated in FIG. 3, and notably comprises a processor 8, a read-only memory 9, a random-access memory 10, a nonvolatile memory 11 and means 12 for communicating over the LTE telecommunications network NW, known per se. These communication means 12 in particular allow it to communicate first with the terminals attached to the cell C1 and where applicable, to other neighbor cells of the cell C1 controlled by the base station BS1, and secondly with the base stations of the neighbor cells, such as for example with the base station BS2 of the cell C2.

(26) The read-only memory 9 of the base station BS1 forms a storage medium in accordance with the invention, readable by the processor 8 and on which is stored a computer program including instructions for executing the steps of a signaling method in accordance with the invention, the steps of which will be described later with reference to FIG. 4 in a particular embodiment.

(27) This computer program defines, in an equivalent way, software and functional modules of the base station capable of executing the various steps of the method of signaling and of interacting with the components of the base station BS1 described previously with reference to FIG. 3. These software modules are in particular a module for allocating an open temporary network identifier RNTI to an interferer terminal (e.g. T1), a module for publishing this open temporary network identifier to the terminals of the cell C1 and/or neighbor cells of C1 controlled by the base station BS1, and/or to other base stations than station BS1 controlling neighbor cells of C1 (e.g. BS2), a module for sending a first physical control channel (PDCCH) according to a predetermined format to the interferer terminal comprising a condensed representation of the open temporary identifier and coded using the temporary identifier dedicated to the interferer terminal, and a module for sending a second physical control channel allocating transmission resources on the cellular network to the interferer terminal, this second channel being coded using the open temporary identifier allocated to the interferer terminal.

(28) We will now describe with reference to FIGS. 4 and 5, the main steps of a method for signaling and a method for communicating in accordance with the invention, in a particular embodiment wherein these steps are implemented respectively by the base station BS1 and by the terminal T1 in FIG. 1.

(29) As mentioned previously, it is assumed that the terminal T1 is an interferer terminal, in other words that it is capable by the intermediary of its communications with the base station BS1 of interfering with the communications established by other terminals over the network NW.

(30) For the sake of simplicity, we will limit the description to an intercellular interference generated by the transmissions from the base station BS1 toward the terminal T1 attached to the cell C1 on the communications of the terminal T2 attached to the cell C1. The processing of MU-MIMO type interference capable of being generated by the transmissions intended for terminal T1 on the communications of the terminal T1 attached to the cell C1 is addressed later.

(31) It is assumed that in a preliminary step, the base station BS1 selects, from among all the RNTI temporary identifiers available for the cell C1, a subset of so-called open RNTI identifiers, intended to be published to the neighbor cells and the terminals of cell C1 (step E10 in FIG. 4).

(32) In the embodiment described here, the selected subset corresponds to a range comprising a limited number P of contiguous RNTI identifiers, for example 1, 4, 8 or 16 identifiers.

(33) In accordance with the invention, each open temporary identifier RNTIoi, i=1, . . . P, is represented in condensed (i.e. shortened, digest) form by a code COD1, . . . , CODP respectively.

(34) This code corresponds for example to a binary representation of the rank occupied by each temporary identifier in the list of open identifiers selected by the base station BS1. For example here, if this list comprises P=8 elements, COD1=001 means that the open identifier in question is the first identifier of this list.

(35) In a variant, other types of condensed representation can be considered as long as they make it possible to establish a unique correspondence with an open temporary identifier selected by the base BS1, and that they make it possible to limit the resources necessary for the representation of the open identifiers compared to these identifiers themselves (in other word for an RNTI identifier of 16 bits, a condensed representation of this identifier uses less than 16 bits).

(36) In the embodiment described here, the base station BS1 broadcasts a message over the cell C1 (for example over a shared channel PDSCH) comprising the list of selected open identifiers RNTIoi, i=1, . . . P in correspondence with their condensed representations COD1, . . . . CODP.

(37) This message is received by the set of terminals attached to the cell C1, and in particular by the terminals T1 and T1. In this embodiment, by way of this message, the base station BS1 not only publishes the list of the open identifiers to the terminals of cell C1, but also informs these terminals (and particularly terminal T1) of the correspondence between the open identifiers and their condensed representations.

(38) In the embodiment described here, the base station BS1 moreover publishes (i.e. broadcasts) the open RNTI identifiers selected to the base stations of the neighbor cells of the cell C1 and particularly to the base station BS2 (step E20).

(39) As mentioned previously the term publication is understood to mean the fact of bearing the open RNTI temporary identifier to the knowledge of the other terminals, in other words to make them public, so as to facilitate the decoding by these other terminals of the PDCCH physical channels associated with these identifiers (in other words, coded with these identifiers), and thus determine the transmission parameters allocated to the terminals to which these open temporary network identifiers are allocated, in order to suppress the interference generated by them.

(40) This publication is done here by the base station BS1 via the sending of a signaling message containing the list of selected open RNTI identifiers.

(41) This signaling message can be emitted by the base station BS1 to the base stations of the neighbor cells over the interface X2 of the LTE network NW, given the definition of a new appropriate message. The interface X2 is known to those skilled in the art: its role is to allow the transport of data packets and items of control information between the base stations of the network NW. It is particularly described in the 3GPP document 36.423.

(42) In a variant, the base station BS1 can emit the signaling message containing the list of selected open RNTI identifiers, over a connection of fiber point-to-point type established with the base stations of the neighbor cells (and in particular with the base station BS2).

(43) In another embodiment wherein the base station BS1 controls several separate cells (including cell C1), the base station BS1 transmits a signaling message containing the list of open RNTI identifiers of the cell C1 to the terminals of the cells that it controls and which are neighbors of the cell C1. For this purpose, the base station BS1 relies for example on the signaling managed by the RRC layer for managing the radio resources of the network. This RRC layer is notably defined in document 3GPP TS 36.331 entitled Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol Specification, Release 11, December 2012.

(44) The signaling message then sent by the base station BS1 can be a system information message emitted independently to each cell controlled by the base station BS1 over a shared physical channel PDSCH. In this way, no network interface is needed for this signaling.

(45) Note that the selection of a range of contiguous open RNTI identifiers allows more spectrally efficient signaling. Specifically, to signal the list of open RNTI identifiers selected by the base station BS1, it suffices that the signaling message emitted by the base station BS1 contains a number indicating the number of the first open RNTI identifier of the range, and of a number indicating the number of open RNTI identifiers selected by the base station BS1.

(46) In a variant, the signaling message emitted by the base station BS1 to the base stations of the neighbor cells contains each open RNTI identifier selected by the base station BS1 and coded on 16 bits.

(47) The list of open RNTI identifiers selected by the base station BS1 is received by the base stations of the neighbor cells, and notably by the base station BS2.

(48) The base station BS2 (as well as the other base stations) then publishes in turn the list of open RNTI identifiers selected by the base station BS1, to the terminals attached to the cell C2, for example in a signaling message. This signaling message is for example a system information message emitted by the base station BS2 over a shared physical channel PDSCH.

(49) Note that in the example considered here, we are limited to the cancellation of intercellular interference so that the open RNTI identifiers are signaled by the base station BS1 only to the base stations of the neighbor cells. When cancellation of MU-MIMO type interference generated within the cell C1 is also considered, the base station BS1 also publishes the selected open RNTI identifiers to the mobile terminals of its cell C1, for example by sending an RRC signaling message.

(50) As described previously, in accordance with the LTE standard, the base station BS1 also allocates a dedicated temporary RNTI identifier to each terminal attached to its cell C1, making it possible to uniquely identify this terminal on the cell C1 (step E30). Thus, in the example considered here, it allocates the dedicated temporary identifier RNTI1 to the terminal T1. This identifier RNTI1 is, unlike the open RNTI identifiers selected in step E10, reserved for the terminal T1. It is chosen from among the RNTI identifiers available for the cell that have not been selected as open RNTI identifiers during step E10.

(51) This dedicated identifier RNTI1 sent by the base station BS1 to the terminal T1 in a dedicated RRC signaling message (configuration message), in a manner known to those skilled in the art, and is received by the latter (step F10 in FIG. 5).

(52) From that point: the base station BS1 can send to the terminal T1 physical channels PDCCH coded using this identifier RNTI1, particularly to signal to it the parameters and the transmission resources that it has allocated to it (including notably the allocated modulation and coding scheme, physical resource blocks PRB, dedicated DMRS pilot sequence), and the terminal TI monitors the search space defined by this identifier RNTI1, and can perform a valid decoding of the physical channels PDCCH that are intended for it and which are (en)coded using this identifier RNTI1 and use the transmission resources allocated in these PDCCH channels to communicate over the network NW.

(53) The coding and decoding of the PDCCH physical channels using an RNTI identifier as well as the allocation of the parameters and transmission resources by the base station BS1 to the terminal T1 for an LTE network are described in more detail in the document TS 36.212 entitled Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding, v11.1.0, Release 11, December 2012 and the document TS 36.213 previously mentioned and will not be further described here.

(54) We will now assume that the base station BS1 determines that the terminal T1 is capable of creating interference toward neighbor cells (i.e. the transmissions from the base station BS1 towards the terminal T1 are capable of interfering with the communications of the terminals of the neighbor cells) and particularly toward the terminals of the cell BS2 (step E40), for example because the terminal T1 requests a radio resource-consuming service over a fairly long time period (e.g. stream broadcasting service) and will therefore occupy a wide bandwidth over a long time. In other words, it detects that the terminal T1 is an interferer terminal in accordance with the invention.

(55) In a variant, other criteria can be considered at the base station BS1 for detecting that a terminal is capable of interfering with the communications of the terminals of the neighbor cells of cell C1 (or even of cell C1) such as for example the fact that the terminal is at the edge of the cell, etc. Such criteria are described in the document WO 2010/108136.

(56) In a variant, the base station BS1 can detect that a terminal is capable of interfering with the communications of the terminals of the neighbor cells of the cell C1 using an exchange of information with the base stations controlling these neighbor cells. This detection can be carried out in each TTI when for example the base stations communicate over a connection of point-to-point fiber type. For example, the neighbor base station BS2 can then inform the base station BS1 of the planned use of certain radio resources by the terminal T2 in a future TTI, so that the base station BS1 knows that if it uses these resources for the terminal T1 in this future TTI, the transmission to the terminal T1 is capable of creating intercellular interference for the terminal T2.

(57) Following this detection, the base station BS1 allocates to the terminal T1 an open RNTI identifier, denoted RNTIo1, chosen from among the open RNTI identifiers selected in step E10, and broadcast to the base stations of the neighbor cells to cell C1 and to the terminals attached to the other cells that it controls (step E50).

(58) This identifier RNTIo1 is allocated to the terminal T1 along with its dedicated temporary identifier RNTI1. It is associated as previously described with a condensed representation, denoted COD1 (for example COD1=001).

(59) To signal to the terminal T1 that the open temporary identifier RNTIo1 has been allocated to it the base station BS1 emits, in accordance with the invention, within a given transmission time interval or TTI, a first PDCCH physical channel, denoted PDCCH1, coded with the dedicated temporary identifier RNTI1 of the terminal T1 (step E60).

(60) This first channel PDCCH1 advantageously has a particular predetermined DCI format, denoted by DCIo, which in itself expresses the fact that an open temporary identifier is allocated in this channel to the interferer terminal whose dedicated temporary identifier has been used to encode this channel.

(61) For example, in this particular DCI format DCIo, the N first bits of this format DCIo of the first channel PDCCH1 are set to 1, N being a predetermined integer number chosen so as to avoid any ambiguity concerning the interpretation of this first channel.

(62) The format DCIo of the first channel PDCCH1 further comprises a field, known as Chp RNTIo, carried for example by the M bits following the N first bits set to 1, in which is found the condensed representation of the open temporary identifier associated with the interferer terminal to which the first channel PDCCH1 is intended.

(63) An example of such a format DCIo is illustrated in FIG. 6A, for the interferer terminal T1.

(64) In accordance with this example, the format DCIo of the channel PDCCH1 contains N first bits set to 1 corresponding to a predetermined sequence Seq, followed by M=3 bits corresponding to the condensed representation COD1=001 of the open temporary identifier RNTIo1 allocated to the terminal T1 by the base station BS1, this condensed representation being contained in the field Chp RNTIo.

(65) In the embodiment described here, the format DCIo of the first channel PDCCH1 comprises the same number of bits as a format described in the standard 3GPP LTE for signaling the resources allocated to a terminal in an LTE network, so as to facilitate its decoding by the interferer terminal T1. For example, it comprises the some number of bits as a format 1A as defined in the document TS 36.212.

(66) In another embodiment, the DCI format of the first channel PDCCH1 comprises a number of bits less than that of the DCI formats defined in the document TS 36.212 of the 3GPP.

(67) An example of such a format denoted DCIo is illustrated in FIG. 6B. It comprises a reduced number L of bits, chosen so as to be sufficient to be able to include the condensed representation of the open temporary identifiers allocated to the interferer terminals (in this case L=3 suffices in the examples considered previously).

(68) The terminal T1, meanwhile, monitors in a conventional manner (i.e. as defined in the standard 3GPP LTE), at each transmission time interval (TTI), the search space corresponding to its dedicated temporary identifier RNTI1.

(69) Thus, on reception of the control channel PDCCH1 on the research space corresponding to the dedicated identifier RNTI1, the terminal T1 decodes the channel PDCCH1 using this identifier RNTI1, in a manner known per se (step F20).

(70) It then verifies if the DCI format of the channel PDCCH1 thus decoded coincides with the format DCIo expressing the fact that an open temporary identifier is allocated to the terminal T1 in this channel PDCCH1, and prompting it to decode another PDCCH channel using this open temporary identifier in this same TTI (test step F30).

(71) If the DCI format of the channel PDCCH1 does not coincide with the format DCIo (reply no to the test step F30), but with a DCI format defined in the 3GPP LTE standard, this means that the channel PDCCH1 is not intended to allocate an open temporary identifier to the terminal T1 but concerns transmission parameters allocated to it (step F40). The terminal T1 then uses these transmission parameters in a manner known per se to communicate over the network NW.

(72) On the other hand, if the terminal T1 detects that the DCI format of the channel PDCCH1 coincides with the predetermined format DCIo (reply yes in the test step F30), this is interpreted by the terminal T1 as an order to decode another PDCCH channel transmitted in the same TTI using the open identifier signaled in the Chp RNTIo field of the channel PDCCH1, by way of its condensed representation COD1.

(73) The terminal T1 extracts the condensed representation COD1 from the decoded channel PDCCH1.

(74) It then determines from this condensed representation the open temporary identifier RNTIo1 that is allocated to it (step F50).

(75) For this purposes, in the embodiment described here, it uses the correspondence signaled by the base station BS1 in step E10.

(76) In another embodiment of the invention, this correspondence between the open identifiers and their condensed representations, and a fortiori between the identifier RNTIo1 and its condensed representation COD1, can be signaled by the base station BS1 to the terminal T1 in a dedicated RRC signaling message.

(77) In yet another embodiment, this correspondence between the open identifiers and their condensed representations, and a fortiori between the identifier RNTIo1 and its condensed representation COD1, can be deduced by the terminal T1 from a signaling message (such as for example by a signaling message emitted over a shared channel PDSCH) containing the list of open identifiers and emitted by the base station BS1 towards the terminals attached to its cell (for example when the condensed representation of an open temporary identifier corresponds to its ranking in the list).

(78) In the same transmission time interval as the channel PDCCH1, the base station BS1 emits a second physical control channel PDCCH2 allocating parameters and transmission resources (notably one or more modulation and coding schemes MCS and PRB blocks) to the interferer terminal T1. The way in which these resources are allocated properly speaking to the terminal T1 is known per se and is in accordance with the practices defined in the 3GPP standard for the LTE network.

(79) The DCI format of the second physical control channel PDCCH2 is one of the formats defined in the 3GPP standard, for example any one of the DCI formats 2, 2A, 2B, 2C or 2D defined in the document 3GPP TS 36.212.

(80) In accordance with the invention, this second channel PDCCH2 is coded using the open temporary identifier RNTIo1 allocated to terminal T1 (step E70 in FIG. 4).

(81) Note that the PDCCH channels associated with the open RNTI identifiers, being intended to be decoded by interfered terminals (for example by terminal T2) in poor radio conditions from the point of view of the cell C1 (since they are served by another cell C2), generally need strong protection. This results in the use of a high aggregation factor to form these channels, i.e. each PDCCH channel intended for an open RNTI identifier is preferentially formed with a high number of elements or CCE (for Control Channel Element) (in an LTE network, according to the considered level of protection of the PDCCH, a PDCCH channel can generally be formed by 1, 2, 4 or 8 CCE). The number of combinations of candidate resources to be tested during the search for PDCCH channels by the terminal T2, which depends on this aggregation factor, will thus be relatively small. The additional complexity related to the invention can consequently be limited.

(82) It is also possible to deliberately reduce the number of DCI formats eligible to be transmitted using an open RNT1 identifier, in order to limit the complexity of the search of the PDCCH channels performed by the interfered terminals. A slight increase in the search complexity can however by tolerated for terminals capable of carrying out a MMSE-SIC reception, because the latter will be provided with greater computational capacity. In order for this increase in complexity to avoid harming other terminals notwithstanding, it is possible to use open RNTI identifiers only for terminals capable of implementing interference cancellation using an MMSE-SIC technique.

(83) Following the decoding of the channel PDCCH1, the terminal T1 conventionally monitors (i.e. as defined in the 3GPP standard), for the transmission time interval in progress, the search space corresponding to the open temporary identifier RNTIo1 allocated by the base station BS1 in the channel PDCCH1.

(84) Thus, on receiving the control channel PDCCH2 on the search space corresponding to the open identifier RNTIo1, the terminal T1 decodes the channel PDCCH2 using the open identifier RNTIo1, in a manner known per se (step F60 in FIG. 5).

(85) It then extracts the transmission parameters contained in this channel, then from that point uses, over the transmission time interval in progress, the resources designated by these transmission parameters when communicating over the network NW (step F70).

(86) It is assumed that in the same time (i.e. in the same TTI), the cell C2 serves the terminal T2, able to employ a MMSE-SIC receiver as described previously.

(87) The terminal T2 has moreover been informed by the base station BS2 of the list of open identifiers (containing in particular the open identifier RNTIo1) selected by the base station BS1 and intended for the interferer terminals of the cell C1 capable of interfering with the communications of other terminals (including those of cell C2 in particular).

(88) The terminal T2 decodes, using its dedicated temporary identifier RNTI2 (allocated by the base station BS2 in a manner known per se), the PDCCH channels that are transmitted to it in this TTI over the search space associated with this identifier. While detecting that data are intended to it in this TTI, the terminal T2 attempts to decode the PDCCH channels potentially transmitted by the base station BS1 over the search spaces corresponding to the open identifiers which it was informed, and in particular over the search space corresponding to the identifier RNTIo1.

(89) Where applicable (i.e. if it detects and decodes a PDCCH channel associated with the open identifier RNTIo1, such as for example the channel PDCCH2), this decoding advantageously allows the terminal T2 to identify the transmission parameters allocated to the terminal T1 on this TTI, and to determine if the resources used by the terminal T1 to communicate over the network NW deduced from these parameters coincide or correspond (in part only or totally), with the resources that it uses itself to communicate. This decoding allows the terminal T2 to determine whether or not the terminal T1 is an interferer and if it must attempt to cancel the interference generated by T1 using its MMSE-SIC receiver, taking into account the transmission parameters allocated to the terminal T1 for this same TTI.

(90) Where applicable, the terminal T2 can then, using the knowledge of these transmission parameters, decode the interfering signal of the terminal T1 with success then cancel the corresponding interference which makes it possible to improve the quality of its radio link for the detection of the useful signal that is intended for it.

(91) In other words, the invention facilitates the application of interference cancellation techniques in the case where an intercellular interference exists between two terminals, and this on condition of reasonable complexity in terms of signaling.

(92) Note that the DCI format of the channel PDCCH1 has no effect on the terminal T2 since this channel is encoded using the dedicated identifier RNTI1 of the terminal T1 and not using the open identifier RNTIo1.

(93) Moreover, in order to improve the performance of the system 1 and the interference cancellation, it is possible to employ prior coordination between the base stations BS1 and BS2 to ensure that the coding and modulation scheme of the terminal T1 is decodable by the terminal T2 (during the application of the interference cancellation method), and that the data rate offered to the terminal T2 takes into account the improved performance of the terminal T2 due to the interference cancellation via the knowledge of the transmission parameters allocated to T1 easily allowed by the invention. The terminal T2 can thus receive a better instantaneous data rate in this TTI than if it had only employed one linear receiver.

(94) Note that all the terminals of the cell C1 do not necessarily consume enough resources to generate interference damaging to the communications of terminal T2, and that therefore needs cancelling. Indeed, if the terminal T2 is served on a high number of PRB resource blocks (for example 25) but is interfered on by the transmission of one PRB resource block of the cell C1 to the terminal T1, this interference causes few damages and does not necessarily require the application of an MMSE-SIC receiver to reduce it. The terminals that do not need to receive a PDCCH channel decodable by other terminals can be constantly served on their dedicated RNTI identifier. These terminals can be advantageously configured to not have to search their PDCCH channel according to a predefined format indicating an open temporary network identifier, which makes it possible to save on their battery consumption.

(95) As mentioned previously, the example illustrated with reference to FIGS. 1-6 concerns the cancellation of intercellular interference between two terminals T1 and T2 served by base stations BS1 and BS2 controlling separate neighbor cells C1 and C2. However, the invention is also applicable in a context in which one seeks to cancel an interference of MU-MIMO type generated within one and the same cell (for example by the communications from the terminal Ti on the communications of the terminal T1). Similar steps to those described previously for the cancellation of intercellular interference can then be employed, on condition of the publication of the list of open RNTI identifiers to the terminals attached to the cell C1 (such as for example to the terminal T1).

(96) Similarly, the invention is also applicable in a context in which both intercellular interference and MU-MIMO interference must be cancelled.