WO2018220301A1

WO2018220301A1 - Method of direct communication between terminals

Info

Publication number: WO2018220301A1
Application number: PCT/FR2018/050923
Authority: WO
Inventors: Hicham ANOUAR
Original assignee: Phanteq
Priority date: 2017-06-01
Filing date: 2018-04-12
Publication date: 2018-12-06
Also published as: FR3067210A1; FR3067210B1

Abstract

The invention relates to a method of direct communication between at least two terminals of a mobile network, on a set of blocks of radio resources defined according to one or more dimensions, organized frame-wise, the method being implemented by a sender terminal and comprising the following steps: -test transmission (40), to at least one receiver terminal, of at least one signalling message dependent on a first subset of blocks of radio resources; and -as a function of at least one acknowledgement message received in response to the test transmission, transmission (44), to the at least one receiver terminal, of data on the first subset of blocks.

Description

METHOD OF DIRECT COMMUNICATION BETWEEN TERMINALS

FIELD OF THE INVENTION

The invention is in the field of telecommunications. It concerns in particular the direct communications between terminals, standardized by the LTE (for Long Term Evolution) standard from the release 12 under the name of "Sidelink communications" and standardized in the IEEE 802.1 standard. BACKGROUND OF THE INVENTION

In general, a mobile telephone network allows the simultaneous use of mobile equipment (eg mobile phones and digital tablets equipped with SIM cards) for communicating by radio with a terrestrial infrastructure including base stations (typically having antennas) covering a specific geographic extent (cell), as well as a core network to manage the delivery of mobile communications.

These elements (including antennas, SIM cards and mobile devices) can come from various manufacturers. It is therefore necessary to respect certain technical specifications, and to apply the same rules to allow these elements of various origins to be able to interact, for example for the establishment and routing of communications.

It is to face this problem that the ETSI (European Telecommunications Standards Institute) cooperates since the end of the 90s, particularly with its American and Asian counterparts on a partnership project called 3GPP (for 3rd Generation Partnership Project). This cooperation led to the development and publication of technical specifications for mobile networks from the 3 ^rd generation (3G).

To meet growing needs in speed due to the democratization of video streaming and mobile applications, 4G was born with LTE (for Long Term Evolution), optimized to carry data.

The 3GPP working groups are also developing 5G which aims to address the increased needs of complex applications requiring very high speed and high reliability, for example cloud computing and big data, home automation or communications involving vehicles. autonomous (without driver).

In addition to traditional uplink (from mobile equipment to network) and downlink (network to mobile equipment) communications in mobile networks, the LTE standard (from Release 12) provides for the implementation of direct sidelink (SL) communications between neighboring mobile devices, ie without going through the network infrastructure. For example, D2D (for Device to Device) communications between terminals are known, but also V2V (for Vehicle to Vehicle) communications between intelligent vehicles, for example autonomous (without drivers).

This new type of communication is possible thanks in particular to a specific PC5 radio interface which makes it possible to create a wireless local area network (WLAN) between neighboring mobile devices.

Regarding the allocation of resources for SL communications, two modes are provided in the LTE (Release 13) standard. In the first mode called "scheduled mode", the allocation of resources is managed by the base station and indicated to the terminals via a signaling message. In the second mode called "autonomous mode", the allocation of resources is managed by the terminals themselves (ie directly communicating terminals), choosing the resources of their choice from a preconfigured set of resources. .

The second mode allows a greater autonomy of the terminals and a better use of the resources. Indeed, each terminal is free to choose the resources that it wishes to be or not within the scope of a base station and it is thus possible to meet the needs of different services including throughput.

In order to make data transmission more reliable and to reduce the number of collisions due to the fact that the terminals do not know which resources will be chosen by other neighboring terminals for their own data transmissions, repetition and frequency hopping mechanisms are put in place. implemented.

However, these mechanisms do not make it possible to achieve good spectral efficiency (that is to say a good orthogonal frequency distribution and more generally radio resources between neighboring terminals) nor to offer quality of service guarantees. .

In general, the LTE standard, in particular the specification ETSI TS 136 213 V14.2.0 (2017-04), does not provide an effective mechanism to reduce the risk of collisions without affecting the spectral efficiency or the quality of service. There is therefore a need to propose such a mechanism.

In the IEEE 802.1 1 standard, access to the radio channel is random and distributed according to the DCF (Distributed Coordination Function) mechanism. This mechanism is based on a prior listening of the radio channel CS (for "Carrier Sensing") and a random retention called "Random Backoff" before access audit channel. To avoid the well-known hidden terminal problem, an RTS / CTS message exchange mechanism is used after listening to the channel. However, this mechanism remains inefficient in the case of extended topology networks. Indeed, the CTS signaling can be masked by the data transmission or by other signaling messages. This is because the signaling messages and the data share the radio resources of the channel without orthogonalization in time (asynchronous network) or in frequency. Here too, an efficient channel access mechanism regardless of network topology is needed. SUMMARY OF THE INVENTION

The present invention thus aims to overcome at least one of these disadvantages.

In this context, a first aspect of the invention concerns a method of direct communication between at least two terminals of a mobile network, on a set of radio resource blocks defined in one or more dimensions, organized in a frame, the method being implemented by a transmitting terminal and comprising the following steps:

- transmitting, to at least one receiving terminal, at least one signaling message according to a first subset of radio resource blocks; and

according to at least one acknowledgment message received in response to the test transmission, transmission to the at least one receiver terminal of data on the first subset of blocks.

Advantageously, the risk of collision is drastically reduced since the data transmission is actually performed or completed after a test phase to confirm that the resources chosen are not in conflict.

In addition, the spectral efficiency is improved since repetition is not necessary.

Correlatively, a second aspect of the invention relates to a communication device according to the LTE / IEEE 802.1 1 standard and implementing the aforementioned method.

The advantages, aims and special features of this device are similar to those of the aforementioned method. Other features of the method and device according to embodiments of the invention are described in the dependent claims.

The acknowledgment message may be a function of the receive radio quality by the receiving terminal and / or the modulation and coding scheme (MCS) used for the test transmission. For example, when the quality is too poor, the receiving terminal may decide not to return an acknowledgment, or indicate in this acknowledgment that the quality of reception is bad. In another example, the acknowledgment may indicate the new MCS to be used for transmitting the data on the first subset of blocks.

In particular embodiments, the frame comprises a plurality of predefined radio resource block configurations and the first subset is a predefined configuration of radio resource blocks.

In particular embodiments, the frame comprises at least one control part and the at least one signaling message is transmitted on a radio resource block of the at least one control part associated with the predefined configuration corresponding to the first sub-part. set of blocks, thereby enabling identification of the first subset of blocks.

This signaling message indicates for example that the data will be transmitted on the first subset of blocks.

The frame may also include one or more portions reserved for data transmission.

When the frame is organized into patterns, in some embodiments, there may be a unique match between resources in the control portion and each configuration of the data portion. This facilitates the identification of the configuration (s) of the data portion (s) concerned by the signaling messages sent on the control part.

In particular embodiments, the test transmission includes a test data transmission on a second subset of radio resource blocks representative of the first subset of radio resource blocks.

In this case, the acknowledgment message may indicate good reception of the test data on the second subset.

Typically, these test data may consist of a sample of the data to be transmitted on the first subset of blocks.

Depending on the mode, the test data can be transmitted in the control part of the frame or in the data part. In particular embodiments, the test transmission is performed on a first frame while the transmission of the data is performed on a second frame comprising the first subset of radio resource blocks, the second frame being different from the first frame.

In particular embodiments, the radio resource blocks located between the radio resource blocks used for the test transmission and the reception of the acknowledgment message (s) are reserved to transmit DSSL short direct data and / or transmit or receive data. other acknowledgment or acknowledgment messages.

In particular embodiments, the frame may comprise a plurality of control portions.

In particular embodiments, the test transmission and the reception of the at least one acknowledgment message in response to the test transmission are performed on the same control part of the frame.

In particular embodiments, the radio resource blocks used for the test transmission are also used by the transmitting terminal for the transmission of data, whether it is spread over one or more frames.

In particular embodiments, the method comprises receiving another acknowledgment message on predefined control portions of the frame, in response to the data transmitted on the first subset of blocks, the other acknowledgment message. notifying the transmitting terminal of a change in an MCS modulation and coding scheme employed by the at least one receiving terminal and / or acknowledging the data received so far.

In particular embodiments, the method comprises receiving a reservation message of a third subset of radio resource blocks of the current frame or of a future frame.

In particular embodiments, the method comprises transmitting another signaling message to the at least one receiving terminal, indicating at least one block of radio resources in use on the current frame by the transmitting terminal.

In particular embodiments, the method comprises receiving connection quality measurements between the transmitting terminal and each receiving terminal of a plurality of receiving terminals, the method further comprising a step of selecting at least one relay terminal. among the plurality of receiver terminals according to the quality measurements, an identifier of the at least one terminal relay being indicated in a header message transmitted with the data on the first subset of blocks.

In particular embodiments, the method comprises receiving quality measurements of the connection between the two terminals of a plurality of pairs of terminals, the method further comprising a step of calculating a multicast broadcast graph from quality measures received.

In particular embodiments, the method further comprises the following steps:

receiving a reservation message from a subset of blocks of radio resources sent by a terminal of the mobile network to another terminal different from the transmitter;

- measurement of the reception quality of the reservation message; and

- depending on the result of the comparison of the measured reception quality with a threshold value, reservation or not of said subset of radio resource blocks.

In particular embodiments, the reservation message indicates a quality level of reception of messages by said terminal of the mobile network.

In particular embodiments, the reservation of the subset of radio resource blocks is also a function of the result of the comparison of the reception quality indicated in the reservation message with a threshold value.

In particular embodiments, the future frame is separated from the current frame by a predefined duration according to at least one block of radio resources dedicated to the reservation message and / or indicated in the reservation message.

In particular embodiments, at least one first block of radio resources is dedicated to the at least one signaling message and at least one second block of radio resources is dedicated to the at least one acknowledgment message. at least a first block and the at least one second block being spaced apart by a predefined duration at least equal to the time necessary for decoding the at least one acknowledgment message.

In particular embodiments, at least a third radio resource block is dedicated to the reservation message, the at least one first block and the at least one third block being spaced apart by a predefined duration at least equal to the time required. decoding the reservation message. In particular embodiments, the third subset of reserved radio resource blocks corresponds to the first subset of blocks.

In particular embodiments, the at least one signaling message indicates reservation information, this reservation information comprising all the radio resources and identifying at least one future frame that at least one terminal of the mobile network other than the sending terminal has reserved.

In particular embodiments, the reservation information is associated with a time-limited validity period starting with the transmission of the at least one signaling message.

In particular embodiments, the method further comprises the following steps:

calculating a probability of success of the test transmission as a function of a number of signaling messages received from other terminals of the mobile network and indicating the first set of radio resource blocks and a total number of signaling messages received from other terminals of the mobile network since the test transmission; and

- depending on the probability of success calculated, transmission or not data on the first subset of blocks.

In practice, the total number of signaling messages also includes the signaling messages received which do not indicate the first set of radio resource blocks.

In particular embodiments, the at least one signaling message indicates a priority index associated with each future transmission and the calculation step takes into account this priority index.

In particular embodiments, radio resource blocks dedicated to the signaling and / or acknowledgment messages are smaller in size than the other radio resource blocks of the frame or have different dimensions compared to the other resource blocks. radio of the frame.

In particular embodiments, the various steps of the aforementioned methods are determined by instructions of computer programs.

Consequently, the invention also relates to a computer program on an information medium, this program being capable of being implemented by a microprocessor, this program comprising instructions adapted to the implementation of the steps of the method such as than mentioned above. This program can use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code, such as in a partially compiled form, or in any other form desirable shape.

The aforementioned information carrier and computer program have characteristics and advantages similar to the method they implement.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will become apparent in the description below, illustrated by the accompanying figures which illustrate embodiments having no limiting character. In the figures:

- Figure 1 illustrates the direction of downlink and uplink communications between a terminal and the mobile network and sidelink communications between two terminals;

- Figure 2 illustrates a block of resources;

FIG. 3 illustrates an exemplary frame format for the management of sidelink communications;

FIG. 4 represents, in flowchart form, the main steps of a method of direct communication between terminals according to embodiments of the invention;

FIG. 5 illustrates a first example of SL transmission in accordance with the implementation of the method of FIG. 4;

FIG. 6 illustrates a second example of SL transmission in accordance with the implementation of the method of FIG. 4;

FIG. 7 illustrates a third example of SL transmission in accordance with the implementation of the method of FIG. 4;

FIG. 8 illustrates an example of unicast transmission SL spread over several frames with free choice of the resources of the DP (Open DSP);

FIGS. 9a and 9b illustrate an example of distribution of resources dedicated to DCH (FIG. 9a) and signaling messages (FIG. 9b) of an SC-

Period SL;

FIG. 9c illustrates an example of SL unicast transmission spread over several frames whose resources are organized in accordance with FIGS. 9a and 9b (Closed DSP); FIG. 10 illustrates an example of SL unicast transmission on a single frame with free choice of the resources of the DP (Open DSP);

FIG. 11 illustrates an example of SL unicast transmission on a single frame with a choice limited to the configurations of the DP (Closed DSP);

FIG. 12 illustrates an example of unicast SL transmission spread over several frames with a choice limited to the configurations of the DP (Closed DSP) without test data;

FIG. 13 illustrates an example of transmission SL on a frame comprising several control parts SP;

FIG. 14 represents an example of a multicast communication link in a multicast group;

FIG. 15 illustrates an example of multicast SL communication establishment on frames composed of a certain number of SP control parts.

FIG. 16a illustrates an example of a frame with predefined configuration of the radio resources in an asynchronous network;

FIG. 16b illustrates an example of unicast SL communication establishment on the frame of FIG. 16a;

FIG. 16c illustrates an example of multicast SL communication establishment on the frame of FIG. 16a.

DETAILED DESCRIPTION OF THE INVENTION

In general, the present invention makes it possible to control access to a set of radio resource blocks of a sidelink communications management frame. Typically, the method is implemented by a transmitting node and comprises a first phase comprising a test transmission of the quality of the radio link during which a signaling message function of a first subset of radio resource blocks of the frame and possibly test data is transmitted to at least one receiving node. In practice, the test data constitutes a sample (a first part) of the data that the sending node wishes to send.

Then, the transmitting node waits to receive one or more acknowledgment messages meaning that the test transmission went well or not.

Once this acknowledgment message has been received, a second phase starts, during which a conventional transmission of data takes place to the receiving node on the first subset of radio resource blocks. In case a sample of this data (test data) has already been sent during the test phase, the conventional transmission is to send the rest of the data.

This second phase only takes place with the proviso that the first (test) phase has ended with the receipt of one (or more) acknowledgment message (s) attesting to the good progress of the test.

Thus, the risk of collisions due to the fact that sending nodes have chosen the same blocks of radio resources are avoided.

Examples will now be described.

FIG. 1 illustrates the direction of the downlink and uplink communications between a terminal 10 and the mobile network (antenna 12) as well as the sidelink communications between two terminals 10 and 14.

Such terminals are typically mobile phones or tablets equipped with USIM cards, or any other UE user equipment as defined by the LTE standard. The present invention is not limited to this standard and can be applied in other contexts.

Figure 2 illustrates a Resource Block (RB).

The basic transmission unit is the RB. An RB has a duration corresponding to a number Nsym of transmission symbols and is defined on a number Nsc of subcarriers. An RB (or a set of RBs) carries either signaling messages (GIS) or data packets (DATA). The size of the information carried by a set of RBs is defined according to the modulation and coding scheme (MCS) employed (e.g. SC-FDMA, RSMA).

In this example, the radio resources are represented in two-dimensional time / frequency RB. However, a different number of dimensions and / or dimensions of different nature than time and frequency can be envisaged. For example, RBs could be three-dimensional (e.g., time, frequency and code) or one-dimensional (time).

Also, in the remainder of the description, the RBs considered will be of the same size and of identical nature. However, the invention is not limited to this and the RB can also be of different sizes (eg small RB for signaling and larger for data) or even of different nature (eg data transmission by SC-FDMA on RB time / frequency and transmission of RSMA signaling on time / frequency / code RBs).

Figure 3 illustrates an example of a frame format for managing sidelink communications. The LTE standard has defined a frame for SL communications management called SC-Period. A SC-Period is composed of a ^part 1 of control or signaling SP (Signaling for Pool) followed by a 2 ^nd portion DP data (for Data Pool). The SP is used for the transmission of the SCIO signaling message also called SA (Scheduling Assignment). This message is sent by a sending terminal subsequently called "source node", "sending node" or "transmitter" to one or more receiving terminals subsequently called "destination nodes", "receiving nodes" or "receivers". This message carries the necessary information to enable the recipient (s) to identify themselves and identify the source, and to decode the data transmission that takes place in the DP. DP and SP are composed of RB as shown in the figure.

As will be seen later, in certain embodiments of the present invention, the SC-Period frame is used as known from the LTE standard, that is to say with a temporal separation between the parts. SP control and DP data (see for example Figures 5 to 12). In other embodiments, a modified SC-Period frame is used in which the control portions SP and DP data are not time separated so that communications can be initiated at different locations in the frame (see, for example, FIG. 13).

In both cases (SP and DP separated temporally or not), it is here proposed to partition the DP data portion of each frame into several sub-parts denoted DSP (for Data Sub-Pool). A DSP subpart differs from the LTE standard T-RPT in that repetition of data across multiple DSPs is not required. In addition, the resources chosen for a transmission can be identical on all the DSPs of the frame (no frequency hopping between several DSPs).

FIG. 4 illustrates the general principle of access control performed during the direct communication between terminals according to embodiments of the invention.

During a step 40, a test transmission is performed by a transmitter to one or more receivers. According to the invention, this test transmission is a function of a first subset of radio resource blocks on which data will be transmitted thereafter.

Thus, this test transmission consists in particular in transmitting a SCIO signaling message also called SA (for Scheduling Assignment) on a block of the control part SP of the frame. This SA message typically indicates the identity of the targeted receptors. It also indicates the first subset of resource blocks on which it intends to transmit data.

For example, this first subset of resource blocks is a freely chosen set of RBs (called "Open DSP") by the sender in a DSP.

Alternatively, the radio resource blocks of the DP data portion of the frame may be organized into a plurality of predefined resource configurations denoted DCH (for Data CHannel). In this case, the first subset of resource blocks is a DCH selected from the set of available configurations (a situation called "Closed DSP"). In this case, it may be sufficient to indicate the identifier of the DCH in the SA message.

According to a particular embodiment, the control part SP of the frame may comprise resources dedicated to SA messages by DCH. In other words, a unique match is provided between each DCH and each resource block dedicated to SA messages. In this case, it is not necessary to indicate the identifier of the DCH in the message SA because the receiver will be able to identify the corresponding DCH according to the resource used to send the message SA.

In embodiments, the test transmission also includes the transmission of test data that typically consists of a sample (i.e., a first portion) of data that would be sent during a conventional transmission. These test data are typically transmitted over a second subset (T-DSP) of radio resource blocks representative of the first subset of blocks.

According to particular embodiments, this second subset is located in the control part SP of the frame.

According to other particular embodiments, the test data are sent in the data part DP of a first frame, thus reserved for the test. These embodiments are particularly advantageous when the transmission spreads over several frames

During a step 42, the transmitter monitors the reception of an acknowledgment message of the test transmission. This acknowledgment message attests whether or not the test transmission is successful.

According to embodiments, the acknowledgment message may be received on the control part SP of the same frame on which the test transmission was performed. In this case, this acknowledgment message is for example SAA (for Scheduling Assignaient Acknowledgment). Alternatively, the acknowledgment message may be received on the control part SP of a next frame. In this case, this acknowledgment message is for example denoted ARM (for Acknowledgment Reservation MCS).

The acknowledgment message further indicates the modulation and coding scheme (MCS) to be used subsequently for the transmission of the data.

Other acknowledgment messages fulfilling additional functions could be used.

Returning to our example, if an acknowledgment message is received and this message testifies to the good progress of the test transmission, the real data transmission can take place on the first subset of radio resource blocks during a step 44.

If an acknowledgment message is received but indicates a test transmission problem or if no acknowledgment message is received at the resources dedicated to the acknowledgment messages, the transmission is interrupted during a step 46 and the sending of the data does not take place.

The example described can be adapted to multicast or multicast case (multiple receivers forming a group). In this particular case, a positive acknowledgment can be expected from each member of the multicast group, otherwise the test transmission can not be a success. Thus, for example, if the transmitter only receives a given number of positive acknowledgments while the message SA is aimed at a multicast group comprising more receivers, these acknowledgments may not be sufficient to validate the test transmission and the communication may be abandoned.

Thus, in general, depending on the number of acknowledgments received and their nature (positive or negative acknowledgments), the issuer can conclude that a test transmission has been successful or not, and decide whether or not to continue transmitting the data accordingly. .

Advantageously, the proposed solution makes it possible to manage both unicast communications and multicast communications.

Examples of the SC-Period frame will now be described with reference to FIGS. 5, 6 and 7. FIGS. 5 and 6 relate to examples in which the test transmission is carried out on the control part SP of a frame and the transmission of the data. which follows is performed on the data part DP of the same frame. Figure 7 relates to a variant in which the test transmission is performed on a first frame and the acknowledgment and the transmission of data are performed on another frame. In the following figures, the data (test or not) are denoted DATA, as opposed to the signaling messages.

In FIG. 5, a signaling message SA is transmitted on the control part SP of the frame. In this example, the sending node is free to choose the resources on which it wishes to transmit the data, among the resources of the sub-parts DSP (situation called "Open DSP").

After a sufficient lapse of time for the SA message to be decoded by the relevant receiving nodes, test data (here constituting a first part of the data to be transmitted) are transmitted to the receiver (s) targeted by the SA message, on a dedicated sub-block of resources (second subset) noted T-DSP (for Test Data Sub-Pool). After sufficient time for the test data to be decoded by the relevant receiving nodes, an acknowledgment message SAA is received by the transmitting node. In this example, it is assumed that this SAA acknowledgment is positive in that it attests to the good reception of the test data on the T-DSP. The transmission of the rest of the data can therefore take place on the data part DP of the frame. In this example, it is noted that the time-frequency pattern used for the test data in the T-DSP is identical to the pattern used for transmission of data on the DSP sub-parts of the DP.

In FIG. 6, a signaling message SA is transmitted on the control part SP of the frame.

In this example, DCH (Data Channel) resource configurations are predefined in each DSP. The sending node is free to choose the configuration of its choice on which it wishes to transmit the data (situation called "Closed DSP"). In this case, it is assumed that there is a unique match between the resource used to send the SA message and a given configuration of the DP part.

Thus, sending the SA message to this dedicated resource allows the receiver (s) to identify the configuration (DCH) chosen by the sender for future data transmission. In this example, the test transmission is mainly constituted by the sending of the signaling message SA.

After a sufficient period of time for the message SA to be decoded by the relevant receiving nodes, an acknowledgment message SAA is received by the transmitting node.

In this example, it is assumed that this SAA acknowledgment is positive in that it attests to the good reception of the SA message. Data transmission can therefore take place on the data part DP of the frame, in particular on the configuration DCH corresponding to the message SA.

In Figure 7, the data transmission is spread over several frames.

A signaling message SA is transmitted on the control part SP of a first SC-Period frame.

After a sufficient period of time for the message SA to be decoded by the relevant receiving nodes, test data are transmitted to the receiver (s) targeted by the message SA, on a sub-block of resources of the DP part. . These test data consist of a first part of the data that the transmitter wants to transmit to the receiver (s).

During a future SC-Period frame, for example the next frame, an ARM acknowledgment message is received by the transmitting node. In this example, it is assumed that this acknowledgment ARM is positive in that it attests to the good reception of the test data sent on the previous frame. The transmission of the rest of the data can therefore take place on the data part DP of the new frame. Thus, the transmission of the first part of the data performed on the previous frame serves as a test transmission for the future frame. In this example, the time-frequency pattern used for the test data in the first frame is identical to the pattern used for the transmission of data on the DSP sub-blocks of the next frame.

These three examples described with reference to Figures 5, 6 and 7 are only simplified examples to illustrate the principle underlying the invention.

More detailed examples will now be described with reference to the following figures.

FIG. 8 illustrates an example of transmission SL spread over several SC-Period frames with free choice of the resources of the DP (Open DP).

In FIG. 8, only a few frames are represented, in particular the first two and the last frame. However, the invention is not limited to this representation. In some embodiments, transmissions are implemented on a plurality of consecutive frames or alternatively spaced apart in time.

In general, the transmission is spread over several frames when the volume of the data to be sent is large and / or in case of real-time or periodic traffic.

In this example, the transmitter transmits a signaling message SA in the control part SP of a first frame.

The transmitter chooses the radio resources on which it transmits the message SA. In practice, this selection can be random (after or without Backoff) among the resources dedicated to SA messages. Alternatively, the SA resources can be pre-allocated to the nodes.

If a backoff mechanism is employed then the backoff counter is stopped or decremented upon detection or not of an acknowledgment message (eg ARM message).

In this example, the choice of resources for data transmission in the DSP is free (Open-DSP). In other words, the sender can choose the resources he will use to transmit the data.

Thus, in the SA signaling message, the transmitter explicitly indicates the resources chosen in the DSP and the information necessary for their decoding. This is called a "reservation" of resources.

If the transmission must continue on a future frame then the transmitter signals the identifier of this future frame either in the message SA or in conjunction with the data. As will be seen later, according to embodiments of the invention, this reservation can be accepted or refused by the receiver or receivers of the message SA, depending on conflicts existing with other resource reservations or depending on the quality of the radio link or other criteria.

Then, the transmitter transmits data on the resources selected in the data portion DP of this first frame. This transmission serves as a test of the quality of the radio link between the transmitter and the receiver (s).

In response to the test transmission, the transmitter receives an ARM acknowledgment message in the control part SP of the next frame.

In practice, the receiver chooses the radio resources on which it transmits the message ARM to the issuer of the message SA. This selection can be random among resources dedicated to ARM messages or indicated by the issuer in his SA message. The latter solution is useful in the case of a multicast transmission (multiple receivers) because the transmitter can indicate separate resources for different receivers. Another possible solution is to provide a predefined correspondence between the resources used for the transmission of the SA message and the resources to be used for the transmission of the ARM message. Alternatively, the dedicated resources for the ARM messages are pre-allocated to the nodes.

Returning to our example, the ARM message attests to the good reception of the test data by the receiver (s) referred to in the SA message. This acknowledgment allows the transmitter to know the status of the previous transmission. If the transmission is not successful, the message ARM indicates a negative response or it is not sent and the transmitter abandons the transmission of the data that it intended to follow following the reception of the message ARM (case not represented on the Figure 8).

In the opposite case (shown in FIG. 8), the ARM message can identify the frame where the future transmission will take place and indicates the MCS modulation and coding scheme that the transmitter could use during this future transmission.

Advantageously, the transmitter has every interest in using the MCS indicated in the ARM message because it is representative of the quality of the current radio link between the transmitter and the receiver. Indeed, the indicated MCS is based on a recent measurement of the quality of the radio link between the transmitter and the receiver that will be noted RLQI (for Radio Link Quality Indication).

For example, this measurement takes into account the RSRP (for Receive Power Signal Reference) which makes it possible to obtain an average value of the power received from a reference signal per resource block, the RSSI (for Reference Signal Strength Indicator) which provides an average value of the received power of a reference signal over the entire frequency band and / or the SINR (for Signal-to-Interference-plus-Noise Ratio).

In a particular embodiment, the signaling message SA indicates a threshold MCS below which the transmission can not be done. When the MCS measured by the receiver which should be used for transmission of the data by the transmitter is lower than the threshold MCS indicated in the SA message, the receiver sends a negative ARM acknowledgment so that the transmission stops.

In a particular embodiment, the ARM message may also indicate PC power control (Power Control), Timing Advance (TA) commands provided in the LTE standard, or any other useful information.

In practice, the frame and the resources to be reserved for the future transmission of data are indicated by the issuer in his SA message or in conjunction with the data. When the receiver detects that this frame (to be reserved) or these resources are in conflict with its own reservations, the latter may refuse the reservation, for example by negatively acknowledging the test transmission (negative ARM message).

Indeed, in a particular embodiment, the receiver can also reserve resources to protect its reception, for example by using the message ARM acknowledgment. To do this, he can indicate in the ARM message the identifier of the future frame as well as the radio resources to be reserved in this future frame. In this case, another terminal, different from the transmitter, located in the vicinity of the receiver, can succeed in decoding the ARM message transmitted by the receiver. This neighbor terminal can then measure the quality of the reception of this ARM message, denoted RLQIRX. When the quality of the RLQIRX reception is good enough (this criterion being evaluated according to the implementation), this means that the neighboring terminal can not use the reserved resources without hindering the communication between the receiver and the transmitter. Therefore, this neighbor terminal abstains from using reserved radio resources during the future frame indicated in the ARM message. This avoids conflicts of access between neighboring terminals of the receiver.

In a variant of this particular embodiment, the message ARM can also indicate a measurement of the quality of the radio link with the transmitter denoted RLQISIG, based on the reception of the test data (ie the data transmitted in the previous frame here). and / or SA message. In this case, the abovementioned neighbor terminal takes this measure into account in order to determine whether it can use the reserved resources without hindering the communication between the receiver and the transmitter or whether it should instead refrain from using the radio resources reserved during the future frame indicated in the ARM message.

In case of reservation by the receiver to protect the reception of the data, the ARM message must be able to be decoded before the occurrence of a resource dedicated to SA messages of the reserved frame. In practice, it is the organization of resources dedicated to signaling messages in the frame that allows it. This allows the receiver's neighbors time to consider the reservation before attempting to access the frame's resources.

In practice, following a reservation by ARM message, a communication can be established on the reserved frame either by transmitting a new SA message on the control part SP of the reserved frame, or by proceeding directly to the transmission of the data on the part DP data of the reserved frame.

In this example, the ARM message used to acknowledge the test transmission is used as a reservation message. However, the invention is not limited to this and another reservation message, for example independent of the acknowledgment, could be used.

Back to our example, after a certain period of time necessary for the decoding of the ARM message here positive, the transmitter transmits a signaling message SA in the control part SP of the second frame then starts the transmission of the other data in the data part DP of this frame.

In this example, this transmission is performed on the same radio resources RB than the previous one, that is to say on the resources used for the test transmission in the first frame. In fact, the test transmission has been successfully done on these resources and the ARM message has made it possible to warn the receiver's neighbors of the future use of these resources.

Sending an SA message on each reserved frame may be useful for example to change the MCS to take into account a change in radio conditions. Typically, such a change in radio conditions can be observed following a modification of the topology of the network (for example displacement of the nodes). In this case, the sending node can proceed directly to the transmission of the data in the DP with the new MCS.

Also, sending an SA message on each reserved frame may be useful in the case of point-to-multipoint transmission, that is, from one sender to a plurality of receivers in a group given called "multicast group", where multicast group members change during communication. Indeed, the message SA indicates the identity of the targeted receivers.

Back to our example, the transmitter receives, following the last transmission, an acknowledgment message ACK signifying the good reception of all the data (from the first to the last frame).

As for the ARM message, the receiver chooses the radio resources on which it transmits the ACK message to the issuer of the SA message. This selection can be random among resources dedicated to ARM / ACK messages or indicated by the issuer in its SA message. The latter solution is useful in the case of a multicast transmission (multiple receivers forming a group) because the transmitter can indicate separate resources for different receivers. Another possible solution is to provide a predefined correspondence between the resources used for the transmission of the SA message and the resources to be used for the transmission of the ARM / ACK messages. Alternatively, the dedicated resources for the ARM / ACK messages are pre-allocated to the nodes.

Thus, while the acknowledgment message ARM relates to the test data, the acknowledgment message ACK relates to all the data transmitted during the communication. Alternatively, the ARM message may also act as an ACK message. In this case, it is sent without indication of future reservation or MCS.

Advantageously, the mechanisms for acknowledging the test data according to the invention make it possible to activate rapid FEC (for Forward Error Correction) error control schemes at the level of the various layers (in particular RLC / MAC / PHY) of the terminals and to make communications more reliable.

In some embodiments, the SP control portion of the frames can be used to introduce any type of signaling messages (SA, ARM, ACK, etc.) or even of short data service without signaling such as for example message discovery. neighborhood, routing signaling messages or application signaling, or to broadcast traffic (broadcast).

In the control part SP, resources can be dedicated to each type of signaling messages. Alternatively, several types of signaling messages may share the same resources.

In practice, the different signaling messages can be transmitted on resources of different sizes. Also or alternatively, the size of the resources to which the signaling messages are sent and the size of the resources dedicated to the data may be different. By way of illustration, ARM messages can be transmitted on sub-carrier reduced size RBs or on 3 time / frequency / code dimensions.

In a particular embodiment, the resources of the control part SP can be used for sending ACK-REQ acknowledgment request messages and the reception of the corresponding ACK-RSP response messages.

The ACK-REQ acknowledgment request message is typically sent by the transmitter following one or more data transmissions already made but for which it has not received ACK messages, or because the system does not provide a message. ACK either because it failed to decode it correctly (radio loss). The acknowledgment request message ACK-REQ may be for a single receiver and correspond to one or more data transmissions. As a variant, it may be intended for several receivers and correspond to one or more common (multicast) or distinct (unicast) data transmissions.

In practice, the transmitter chooses the radio resources on which it transmits the acknowledgment request message ACK-REQ. This selection can be random among resources dedicated to ACK-REQ messages or depending on the selection of resources for sending the SA message. The ACK-RSP response message is typically sent by a receiver in response to an ACK-REQ acknowledgment request message. It can therefore correspond to one or more data transmissions already made. Alternatively, a receiver may respond to several ACK-REQ messages from the same or different transmitters in the same ACK-RSP message.

In practice, the receiver chooses the radio resources on which it transmits the ACK-RSP response message. This selection can be random among the resources dedicated to the ACK-RSP messages or indicated by the transmitter in its ACK-REQ acknowledgment request message, or else be dependent on the selection of the resources dedicated to the ARM or ACK or ACK messages. REQ.

The resources of the control part SP can be used also for short direct data transmission DSSL (for Direct Short Side Link) with prior sending of message SA. The resources dedicated to this type of transmission are denoted DSSLP (for DSSL Pool).

In general, the organization of the resources of the SP control and DP data components, that is to say the resources dedicated to the different types of messages, is either signaled by the network (RRC message for example in the context of the standard LTE) is preconfigured in the terminals.

FIG. 9a illustrates an example of distribution of the resources dedicated to the different DCH (Closed DSP) configurations in the DP part for unicast SL transmission spread over several frames.

Thus, unlike the example described with reference to FIG. 8, the choice of resources for data transmission in the DP is not free here but is limited to a finite number of predefined DCH configurations.

In this example, each DSP of the DP part is organized into two configurations denoted DCH # 1 and DCH # 2.

Thus, the sender can only choose the pre-defined configuration that he will use to transmit the data, but not the resources that compose it.

In practice, a DCH can be shared between the terminals or alternatively be pre-allocated to a subset of terminals.

FIG. 9b illustrates an example of distribution of the resources dedicated to the different types of signaling messages (and possibly to DSSL data) in the SP part of the frame.

In this example, the SP portion contains DCH dedicated resources (DCH # 1 and DCH # 2 of FIG. 9a) to ARM messages, ACK acknowledgments, and SA messages. In addition, it contains dedicated resources for short direct DSSL data.

Advantageously, when there is a unique correspondence between the resources dedicated to messages SA, ARM and ACK and the different DCHs, the resource chosen for the transmission of one of these messages allows the receiver to identify the concerned DCH. It is therefore not necessary to indicate the identifier of the DCH chosen in the message SA, ARM or ACK.

In a variant (not shown), the resources dedicated to the different types of signaling messages, in particular messages SA, ARM and ACK, could be shared between several DCHs. In this case, the message should explicitly indicate the identifier of the concerned DCH in order to allow the message receiver to identify the concerned DCH.

Of course, all the resources dedicated to these messages / data are not necessarily actually used during a transmission. For example, even if there are two RBs dedicated to DCH # 1 SA messages and two dedicated DCH # 2 SA RBs, only a dedicated RB can actually be used to send a SA message for a given DCH. as will be seen in the transmission example of FIG. 9c.

Figure 9c illustrates an example of multi-frame unicast SL transmission with limited choice to DSP (Closed DSP) configurations.

In this example, each frame is organized as illustrated in the figures

9a and 9b.

Then, the transmitter transmits a first part of the data which serves as a test of the radio link on the chosen DCH configuration in the data portion DP of this first frame.

In response to transmission of the test data, the transmitter receives an ARM acknowledgment message in the control part SP of the next frame.

As in the previous example, this ARM message attests to the good reception of the test data by a receiver referred to in the SA message. This acknowledgment allows the transmitter to know the status of the transmission.

If the transmission is not successful, the ARM message is not sent by the receiver or else it indicates a negative response and the transmitter abandons the transmission of the data that he intended to do following receipt of the ARM message (case not shown in FIG. 9c).

In the opposite case (represented in FIG. 9c), the message ARM identifies the frame where the future transmission will take place and the modulation and coding scheme MCS that the transmitter could use during this future transmission.

In a particular embodiment, the receiver can also reserve the resources to protect its future reception, for example by using the acknowledgment message ARM.

In this case, as well as for resources dedicated to SA messages, if the resources dedicated to the ARM messages are shared between the different DCHs, the receiver must indicate the identifier of the reserved DCH in the ARM message.

On the other hand, if there is correspondence between the resources dedicated to the ARM messages and the DCHs, the resource chosen for the transmission of the ARM message makes it possible to identify the reserved DCH. It is therefore not necessary to indicate the identifier of the DCH selected in the ARM message.

Advantageously, thanks to the unique correspondence between the resources dedicated to the ARM messages and the DCHs, even if the ARM message is not correctly decoded by a terminal neighbor of the receiver other than the transmitter, this neighboring terminal can measure the quality of the RLQIRX reception of the ARM message and determine whether it can use the identified DCH (thanks to the resource on which the ARM message is transmitted) without interfering with the communication between the receiver and the transmitter. In this case, the neighboring terminal abstains from using the reserved DCH during the future frame. This avoids conflicts of reservations between neighboring terminals.

In practice, in order to allow a neighbor terminal of the receiver to determine the future frame reserved by an ARM message without necessarily decoding it correctly in order to extract the content, each set of resources dedicated to the ARM messages and corresponding to a DCH can be divided into a number of subsets of resources. Each subset of resources thus constituted makes it possible to transport one or more ARM messages and corresponds to a request for reservation on a future frame distant by a certain predefined time from the frame where the ARM message has been sent. As mentioned previously, an ARM message may possibly make it possible to reserve the corresponding DCH in a future frame. However, this is not always the case because an ARM message can simply be used to acknowledge the good reception of the data. Preferably, in a half-duplex transmission / reception (HD) mode, a node which is in transmission on a slot containing resources dedicated to the ARM messages is prohibited from accessing all the DCHs that may be reserved by ARM messages on this slot during future frames that these ARM messages might reserve. One possible solution to overcome this constraint is to group resources dedicated to the ARM messages of different DCHs corresponding to the same future frame on the same slot or slots.

The examples described with reference to FIGS. 8 and 9 relate more particularly to transmissions spread over several frames. As mentioned, conflicts over access to resources in such situations are avoided by using transmission over a previous frame as a means of testing whether the selected radio resources will be conflicting or not on the next frame. The ARM message reservation mechanism avoids new conflicts during future transmissions.

The examples described with reference to FIGS. 10, 11 and 12 more particularly make it possible to avoid conflicts even before accessing for the first time the data portion DP of a frame.

To do this, it is proposed to carry out a test transmission directly in the control part SP of the frame and to provide dedicated resources for the acknowledgment messages (such as the SAA message for Scheduling Assignment Acknowledgment). In a first embodiment, specific resources denoted T-DSP (for DSP Test) are dedicated to sending a first portion of the data serving as test data (FIGS. 10 and 11). In a second embodiment, resources dedicated to SA signaling messages by DCH are provided (FIG. 12).

Figure 10 illustrates an example of SL unicast transmission on a single frame with free choice of DSP (Open DSP) resources.

This example differs from that described with reference to FIG. 8 in that the test transmission and the acknowledgment are performed in the SP portion of the frame and the subsequent data transmission is performed in the same frame.

In this example, the transmitter transmits a signaling message SA in the control part SP of the frame.

If a backoff mechanism is used then the backoff counter is stopped or decremented on detection or not of an acknowledgment message (eg SAA message).

In this example, the choice of resources for data transmission in DSPs is free (Open-DSP). In other words, the sender can choose the resources he will use to transmit the data in case of a positive test.

Thus, in the SA signaling message, the transmitter explicitly indicates the resources selected as well as the information necessary for their decoding.

Then, the transmitter transmits test data on dedicated T-DSP resources.

The receiver decodes the SA message intended for it, proceeds to decode the test data transmitted in the T-DSP and sends a SAA acknowledgment message to the transmitter on the dedicated resource in the control part SP of the frame.

In practice, the receiver chooses the radio resources on which it transmits the SAA message. This selection can be random among the resources dedicated to the SAA messages or indicated by the issuer in his SA message. Another possible solution is that there is a predefined correspondence between the resources used for the transmission of the SA message and the resources to be used for the transmission of the SAA message. In a variant, the resources dedicated to SAA messages are pre-allocated to the nodes.

In general, the resources dedicated to the SAA messages are separated from those of the T-DSP by a time "Tp" allowing on the one hand the decoding of the test data sent on the T-DSP and on the other hand the coding of the message SAA by the receiver. As an illustration, in the current LTE standard, "Tp" is 4ms.

This SAA message attests to the good reception of the test data by the receiver (s) referred to in the SA message. This acknowledgment allows the transmitter to know the status of the transmission.

If the test transmission is not successful, the SAA message is not sent or else it indicates a negative response and the sender abandons the transmission of the data that he intended to follow following receipt of the SAA message (case not shown in Figure 10). In the opposite case (shown in FIG. 10), after a certain period of time necessary for the decoding of the SAA message positive here, the transmitter starts the data transmission in the DP part of this frame.

In this example, the time-frequency pattern of the RB resources used to send the data to the DSPs is the same as the time-frequency pattern of the resources that are used to send the test data to the T-DSP.

Finally, at the beginning of the next frame, the transmitter receives an acknowledgment message ACK signifying the good reception of all the data.

Figure 11 illustrates another example of unicast SL transmission on a single frame with choice of DSP (Closed DSP) configurations.

This example differs from that described with reference to FIG. 9 in that the test transmission and the acknowledgment are performed in the SP portion of the frame and the subsequent data transmission is performed in the same frame.

In addition, unlike the example described with reference to FIG. 10, the choice of resources for the transmission of data in the DSPs is not free here (Closed-DSP) but is limited to a finite number of predefined DCH configurations. . Each DSP is for example organized as illustrated in Figure 9a. In general, a DCH may have different resource configurations in each DSP of the frame.

Thus, the transmitter can only choose the predefined configuration that it will use to transmit the data in case of positive test, but not the resources that compose it.

Then, the transmitter transmits test data on dedicated T-DSP resources. It is recalled that this test data constitutes part of the "useful" data that the transmitter wishes to transmit to the receiver (s) indicated in the SA message.

In this Closed-DSP scheme, the size of the T-DSP can be reduced compared to the Open-DSP. Indeed, it suffices that each DCH is represented in the T-DSP by at least one RB.

The receiver decodes the SA message intended for it, proceeds to decode the test data transmitted in the T-DSP and sends a SAA acknowledgment message to the transmitter on the dedicated resource in the control part SP of the frame. If the test transmission is not successful, the SAA message indicates a negative response or is not sent and the transmitter abandons the transmission of the other data that it intended to follow following receipt of the SAA message (case not shown on Figure 1 1).

In the opposite case (represented in FIG. 11), after a certain period of time necessary for the decoding of the SAA message positive here, the transmitter starts the transmission of data in the DP part of this frame.

In this example, the time-frequency pattern of the RB resources used to send the data to the DSPs corresponds to the DCH configurations in these DSPs and may be different from the time-frequency pattern of the resources that are used to send the test data. in the T-DSP. This is because it suffices that each DCH is represented by at least one RB in the T-DSP.

In this example, the transmitter receives an ARM acknowledgment message at the beginning of the next frame, acknowledging on the one hand the reception of all the data on the previous frame and on the other hand as a reservation message for a frame future, as explained previously with reference to FIG. 9.

In this example, following the ARM message, a new test transmission takes place on the reserved future frame. The various messages and data mentioned in this example (SA, test data on the T-DSP, SAA, data) are exchanged again on the frame reserved by the ARM message.

Figure 12 illustrates an example of multi-frame unicast SL transmission with limited choice to DSP (Closed DSP) configurations.

In this example, the transmitter transmits a signaling message SA in the control part SP of the frame. This transmission constitutes the test transmission. Indeed, in this example, there is a unique correspondence between the resources dedicated to the messages SA and the DCHs, and the message SA is used to both signal and test the quality of the radio link between the transmitter and the receiver on the DCH chosen. Thus, unlike the example described with reference to FIG. 11, during the test transmission, no data is sent in addition to the message SA.

It is important to note that the SA message must be transmitted on all dedicated DCH SA resources. In this case, in this example, only one RB is dedicated by DCH so only one SA message is needed. However, if two (or more) RBs were dedicated to SA messages, so many SA messages would have to be sent. Advantageously, it is not necessary to indicate the identifier of the DCH in the message SA because the receiver will be able to identify the corresponding DCH according to the resource used to send the message SA.

The receiver decodes the message SA which is intended for it and sends a message of acknowledgment SAA to the transmitter on the dedicated resource in the control part SP of the frame to indicate that it has correctly received the message SA.

The SAA message may indicate the MCS to be used later in data transmission, power control or advance control or other useful information.

If the sender correctly receives the SAA message, data transmission may take place on the DCH corresponding to the resource on which the SA message was received. A transmitter that does not receive a SAA message does not transmit data.

In this example, the transmitter receives an ARM acknowledgment message at the beginning of the next frame, acknowledging on the one hand the reception of all the data on the previous frame and on the other hand as a reservation message for a frame future, as explained above.

In this example, following the ARM message, a new test transmission takes place on the reserved future frame. In practice, this test transmission comprises sending an SA message on the reserved frame. The various messages and data mentioned in this example (SA, SAA, data) are exchanged again on the frame reserved by the message ARM.

In embodiments, a frame may contain DSPs of different sizes. In case of Open-DSP, a T-DSP corresponding to each type of DSP can be provided in the SP part. In case of Closed-DSP, a T-DSP where each DCH is represented or a resource dedicated to the SA message corresponding to each DCH can be provided in the SP part.

Resources dedicated to signaling messages can be shared between different types of DSPs or divided into fixed configurations where each is dedicated to one type of DSP. If resources dedicated to SA messages are shared between different types of DSPs, the SA message explicitly identifies the DSP used.

Fig. 13 illustrates an exemplary SL transmission on a frame comprising a plurality of SP control portions so that communications can be initiated and terminated at different locations in the frame. Such a configuration allows several terminals to access the radio resources of the same SC-Period frame successively and while avoiding conflicts. Indeed, thanks to the plurality of parts SP, a communication can be initiated at several points in the frame.

An SP part may contain resources dedicated to signaling but also data (Open-DSP or Closed-DSP). In some cases, the same RB can be shared between signaling and data.

Preferably, a part SP which contains resources dedicated to the messages SA contains resources dedicated to the corresponding SAA messages. In this case, the part SP must be sufficiently long in time to allow the establishment of a communication, that is to say to allow the sending by a transmitter of a message SA and possibly test data. (usually consisting of some of the "useful" data to be sent), receiving the SAA response, and decoding that response.

The frame may optionally comprise a DP portion only dedicated to the data, composed of DSP and / or DCH.

In general, the resources dedicated to the SA messages, to the test data where appropriate and to the SAA messages, can be arranged anywhere in the SP parts. However, the resources dedicated to the SA and SAA messages used for the establishment of a call must be sufficiently spaced in time to allow the decoding of the SA message, the decoding of any test data and the decoding of the SAA message before the call. the occurrence of a new resource dedicated to SA messages.

In the example illustrated in FIG. 13, the frame consists of three parts SP and there is no part DP. Each part SP consists of a slot dedicated to the SA messages (first column of RB) then of a first DSP followed by a T-DSP then of a second DSP, then of a slot dedicated to the messages of acknowledgment (SAA ACK) then a last DSP. The resources for the transmission of data are freely chosen by the issuer {Open-DSP).

As visible in FIG. 13, in a first part SP, a terminal A transmits to a terminal B a message SA and then test data on a first part of the dedicated resources in the T-DSP. The terminal B decodes the SA message from the terminal A as well as the test data and transmits a SAA acknowledgment to the terminal A in order to allow the transmission of data. This data transmission takes place on the corresponding resources of the DSPs and T-DSPs of the subsequent SPs of the frame. Note that the time-frequency pattern is identical on PS DSPs and T-DSPs next and on the T-DSP of the first part SP where the test transmission from A to B was carried out.

In this example, a terminal C adjacent to the terminal B also receives the SAA acknowledgment transmitted by the terminal B and thus detects that it is too close to it to use the same resources for its own transmissions.

Thus, in the second part SP, the terminal C transmits to a terminal D an SA message indicating resources different from those used by B to receive data from A.

The terminal C also transmits test data on a second part of the dedicated resources in the T-DSP. The terminal D decodes the SA message from the terminal C as well as the test data and sends a SAA acknowledgment to the terminal C in order to authorize the transmission of data on the corresponding resources. This data transmission takes place on the corresponding resources of the DSP and T-DSP of the following SP part. Note that the time-frequency pattern is identical on the DSP and T-DSP of the next SP part and on the T-DSP of the second part SP where the test transmission from C to D.

These embodiments thus make it possible to reduce conflicts between neighboring terminals, while allowing optimal use of radio resources.

Although the example described with reference to FIG. 13 concerns an Open-DSP case, those skilled in the art can easily transpose the teachings to the Closed-DSP case where data configurations are predefined so that the transmitter It is not possible to choose RB resources individually.

In general, embodiments allow communication initiated in a part SP to continue after receipt of the SAA acknowledgment on all subsequent DSPs / DCHs of the frame, whether in SP parts or in DP parts.

Thus, when the sender can choose the {Open-DSP} resources when establishing a call to a certain SP # i of the frame, the T-DSPs of the subsequent SPs are used as regular data DSPs. This allows the communications that will be established to the next SPs to take into account the presence of communications already established on the resources of the frame.

When there is a unique correspondence between the resources dedicated to the SA messages and the DCHs (Closed-DSP), the SA message must be transmitted on the resources corresponding to the DCH chosen for the transmission of data. Once a communication is established, resources dedicated to SA messages and DCH are used by this communication. This also allows neighboring terminals to take into account the communications already established on the DCH of the frame.

In a particular embodiment, the SAA acknowledgment message may indicate the resources or the DCH reserved by the SA message. Another terminal, different from the transmitter, located in the vicinity of the receiver, can succeed in decoding this SAA acknowledgment message and can then measure the quality of the RLQIRX reception of this message. When the quality of the RLQIRX reception is good enough (this criterion being evaluated according to the implementation), this means that the neighboring terminal can not use the resources or the reserved DCH without hindering the communication between the receiver and the transmitter. Therefore, this neighbor terminal abstains from using the radio resources / DCH reserved by the SA message. This avoids conflicts of reservations between neighboring terminals.

In a variant of this particular embodiment, the SAA message may also indicate a measurement of the quality of the radio link with the transmitter rated RLQISIG, based on the receipt of the SA message and / or test data if there is any. at. In this case, the above-mentioned neighbor terminal takes this measure into account in order to determine whether it can use the reserved resources or DCH without hindering the communication between the receiver and the transmitter or whether it should instead refrain from using the radio resources / DCH reserved by the SA message.

Advantageously, in case of a single correspondence between the resources dedicated to the SAA messages and the DCHs, even if the SAA message is not correctly decoded to extract the content from a neighbor terminal of the receiver other than the transmitter, this neighboring terminal may measuring the quality of the RLQIRX reception of the SAA message and determining whether it can use the identified DCH (thanks to the resource on which the SAA message is transmitted) without hindering the communication between the receiver and the transmitter. In this case, the neighboring terminal abstains from using the reserved DCH during the remainder of the frame.

Thus, the SAA message makes it possible to protect a communication established on a frame and to prevent neighboring terminals from establishing a communication on the resources used.

Preferably, in a half-duplex transmission / reception (HD) mode, a node which is in transmission on a slot containing resources dedicated to the SAA messages is prohibited from accessing all the resources / DCHs likely to be reserved by SAA messages on this slot during the current frame. Banning the neighbors of a receiver, through the SAA message, to access the resources used by this receiver solves the well-known problem of the hidden terminal.

It is recalled that the problem of the hidden terminal arises when a terminal A is in the vicinity of a terminal B itself in the vicinity of a terminal C, the terminals A and C not being in the vicinity of the terminal. one of the other. Thus, the terminal A is a hidden terminal for the terminal C and vice versa. This problem has the consequence that if the terminal A transmits towards the terminal B, the terminal C does not see it and can therefore decide to send to the terminal B, in which case there will be collision (and the terminal A does not will not report).

Embodiments in which the resources dedicated to the SAA messages are not shared with other signaling messages or with data also make it possible to solve the well-known problems of the masked terminal and the exposed terminal, which allows spatial reuse. maximum radio resources.

It is recalled that the problem of the masked terminal arises when a terminal A transmits to a terminal B adjacent to a terminal C and a terminal D adjacent to the terminal C is already transmitting to a terminal E. The terminal C is a masked terminal for B because the signaling messages transmitted by the B are masked by the transmission of D. This situation is frequent in the topologies with several radio hops and degrades the performance in terms of bit rate.

It is also recalled that the problem of the exposed terminal arises when a terminal B transmits to a terminal A and the terminal B is close to a terminal C that the terminal A does not see. The terminal C is prohibited from transmitting to another neighboring terminal D because it hears that B is transmitting (to the terminal A), so it is exposed to B, while it could quite send to the terminal D without hindering the communication from B to A.

It is pointed out that the problem of the masked terminal is solved even if the SAA message is not received when there is a correspondence between the resource used to send the SAA and a DCH (Closed-DSP) since the detection of a transmission on a resource dedicated to SAA messages alone allows to protect the reception on the DCH in question until the end of the frame.

In general, the provision of resources dedicated to SA messages across multiple SPs allows, with a minimum of resources, multiple communication links that are not mutually conflicting to be established throughout. of the frame. The solution thus presented makes it possible to achieve maximum spatial reuse of radio resources with a minimum of resources dedicated to SA messages.

According to particular embodiments, the SAA message could be sent after the establishment of the call. This is optional and could be advantageous in a variety of situations, for example when changing MCS.

In a particular embodiment, the receiver sends several SAA messages, for example at regular intervals, over several predefined SP parts of the frame. This makes it possible, for example, to update the MCS used and to acknowledge the data previously received.

Indeed, the fact that communications can initiate and terminate at any SP portion of a frame can cause changes in the radio quality of the established communications. A change of the MCS used is desirable in this case to adapt to possible changes in the quality of the radio link.

Advantageously, a new SAA message being sent during communication (that is to say after the test phase), it makes it possible to use fast FEC error control schemes, for example of the H-ARQ type ( for Hybrid Automatic Repeat reQuest) at the different layers (including RLC / MAC / PHY).

According to a particular embodiment, the new SAA message can also be used to protect the reception radio resources on a frame. In this case, the new SAA message protects the receiving resources until the next occurrence after a predefined interval of a resource dedicated to the SAA messages in the frame where the forwarding is provided or if necessary until the end of the frame .

This scheme has the advantage of releasing nodes that could not access protected (ie, in-use) resources during transmission as a result of changes in their radio link quality to the receiver .

If a reservation scheme by SAA message is used and a receiver wishes to make a reservation of the same resources for a future frame then the SAA message is sent on each resource dedicated to the SAA messages of the frame where the forwarding is provided even if the data transmission stops before the end of the frame.

In a half-duplex transmit / receive mode, a node on a slot containing resources dedicated to SAA messages (or any other reservation message) is prohibited from accessing all the data resources that the SAA messages (or any other booking message) of this slot could reserve until the occurrence of the next resources dedicated to the SAA messages in the frame where the return is provided or if necessary until the end of the frame.

In particular embodiments, it may be advantageous to establish bidirectional SL communication on the same frame.

In this case, the transmitter initiating a bidirectional communication (hereinafter referred to as "first transmitter" or "second receiver") indicates in its message SA the radio resources / DCH on which it is already transmitting or receiving in the current frame. It then indicates, together with the data, any change of resources / DCH that it uses while waiting for the receiver (hereinafter referred to as "first receiver" or "second transmitter") to establish communication in the other direction. .

In the case of two-way Half-Duplex transmission / reception, the first receiver establishes the communication towards the first transmitter by choosing resources for the transmission of the message SA and the data which are not on slots on which the first transmitter is in emission and which are not already used in reception by this first transmitter.

To enable the establishment of a bi-SL communication, control SP 1 ^st part of the frame containing an SAA SA signs must contain resources for carrying two SA messages on two separate slots, as well as to transport two messages SAA on two separate slots. In case of reservation of a future frame by ARM message, the first control part SP of this frame must also contain resources for two messages SA and SAA.

Similarly, the frame must contain resources for transporting two ACK and ARM messages on two separate slots, if they are used.

In practice, the first receiver (i.e. the second transmitter) can indicate in its SA message the resources it will use for the transmission of ACK and ARM messages. Similarly, the transmitter (i.e. the second receiver) may indicate in its SAA message the resources it will use for transmitting ACK and ARM messages. Also, the first transmitter and the first receiver can indicate in their ARM messages the resources they will use in the future frame reserved for the transmission of their SA and SAA messages.

Note that for bi-directional traffic that is fast or has asymmetry in the volume of data exchanged in the different directions (SIP signaling, TCP session, http, etc.), it is preferable to establish bidirectional SL communication in the same frame. In particular embodiments, it may be advantageous to establish communication between two terminals using a multiplicity of SL communications established between relays located between these terminals.

In this case the communication is relayed by one or more relay terminals on one or more radio hops. The choice of relays is made on the basis of a certain knowledge of the state of the links between terminals, but generally without any relation taking into account existing communications which can lead to conflicts in terms of access to the resource.

In order to solve this problem, it is proposed to use the test transmission to obtain path quality measurements between the remote terminals (called source node and destination node) passing through different relays.

To do this, it is proposed to address the SA message to the various possible relays. A source node having the choice between a number k of potential relays to its final destination which is at a number B of radio hop sends a message SA containing the identification information of these relays and the identifier of the destination node.

Each relay k decodes the SA message and measures the quality of the RLQIRX reception of the SA message and / or test data if any. It then calculates an indication of the quality of the paths between the source node and the destination node passing through it, denoted PQlE2N (k) (for Path Quality Indication). This indication may be, for example, an average of the expected bit rates on all or a selection of the possible paths between the source node and the destination node passing through the relay. Relay k then sends a response SAA message. This SAA message contains, among other information, the MCS between the relay and the source node and the PQlE2N (k).

The sending node can thus, from the SAA messages and in particular the different PQlE2N (k) received, choose one of the relays. It indicates the identifier of this relay in a header message transmitted with the data.

Then, a relay that correctly decodes this header and is designated as a relay continues receiving data. If the decoding of the header fails or if the source node does not select, the relay abandons the reception of the data.

In some cases, it is possible that the bit rate between the source node and the destination node is less than the accumulated bit rate between the source node and the relay on the one hand and secondly between the relay and the destination node. In this case, it may be advantageous to go through this relay even if the source node and the destination node are in range of one another and can communicate directly.

In a particular embodiment, the source node may indicate in the SA message a THPQI threshold such that when a relay k only responds with a SAA message if the quality indication of the paths PQlE2N (k) is greater than this threshold. .

Also, the source node may indicate in the SA message the number of radio hops max that the computation of the quality indication of the paths PQlE2N (k) must take into account.

The source node may indicate in the SA message a threshold RLQIMIN on the

RLQI such that only paths with an RLQI greater than this threshold are taken into account in the calculation of the indication PQIE2N by the relays.

In particular embodiments, a point-to-multipoint transmission, i.e., of a transmitter to a plurality of receivers of a given group called "multicast group", may be established. Such transmissions are used for example in the context of public security services.

In this example, consider a multicast group consisting of N (N≥ 2) nodes whose K (1 <k <N) are potential transmitters PT (for Potential Transmitters). Multiple multicast groups rated MG (Multicast Group) share system radio resources and one node may belong to multiple MGs.

The SA message sent during the test transmission identifies the target MG and MCS that the transmitter intends to use for data transmission.

In order to be able to adapt the MCS used to the radio conditions between the transmitter and the receivers, the MCS indicated in the SA message is only used on the first slots containing resources chosen by the transmitter.

Based on the number of SAA messages received and the information they contain, the sender may decide whether to transmit the data or not.

In the first case, it sends a header message, transmitted exclusively or in conjunction with the data, on the first slots containing resources it has chosen, indicating the MCS that will be used for further transmission. The first slots must be sufficient to carry the header message and give the receivers the necessary time to decode it. This number can be reported in the SA message or preconfigured in the system.

The nodes of one MG may not all be within radio range of each other. A node can indicate in its SAA message the RLQI of its radio links with all or a selection of MG nodes. A selection can be made by a threshold on the RLQI, for example signaled in the SA message or preconfigured. On the basis of the information received in the SAA messages, the transmitter decides which MCS to use for transmission, calculates a broadcast graph in the group and designates a list of relays as well as a list of the nodes to which each relay should relay the transmission, directly and possibly via other relays.

This information is also transmitted in the data header message. A relay k with a transmission to be relayed to a part of the nodes of the MG proceeds in the same way as the source node with the exception of the identity of the destination nodes and subsequent relays. An emitter can also indicate in the header message on which frame and which radio resources (for the signaling and the data) its relays can establish the communications for the relaying of the data.

A relay can inform the relay that precedes it or the source node of the state of its own transmission (establishment or not, identity of its actual receivers, resources used, MCS employee, ...) via messages SAA, ARM, or ACK.

In multicast multicast communication, a transmitter may indicate the change of destination node and relay information. This indication can be made via the SA message or in conjunction with the data via a header message. A change can occur in case of mobility nodes for example.

A node that receives multiple SA messages to join the same multicast communication may decide to join the best radio quality or distance to the source node in the number of radio hops.

In practice, sufficient resources are provided for SAA messages. In particular, the SAA resources can be on small-sized RBs (in time and / or frequency, for example) relative to the other RBs of the frame. They can also be on RBs having an extra dimension compared to the other RBs of the frame.

Fig. 14 shows an example of a multicast communication link in a multicast group MG. Other MGs can share radio resources with this MG but are not represented. In this example, the MG is composed of 8 nodes (A, B, C, D, E, F, G and H). Transmission from node A to the group requires relaying of node E to nodes F, G and H.

Fig. 15 illustrates an example of establishing multicast SL communication over frames composed of a number of SPs. Resources dedicated to SAA signaling are pre-allocated to each node of the MG or signaled by the sending node in the SA message. The resources dedicated to SAA signaling are on smaller RBs corresponding to half the size of a regular RB in terms of subcarrier. During a first frame, the node A passed the test transmission to B, C, D, and E. On the following frame, the node E, designated by A, relay this transmission to F, G and H.

In particular embodiments, it may be advantageous to establish a broadcast type of communication between a transmitter and any receiver within the range of the transmitter. In this case, the targeted receivers do not belong to a given group as for multicast.

A difficulty that arises then is that the transmitter does not know the number of acknowledgments that it is supposed to receive following the test transmission since it does not target a specific receiver during this transmission test.

To overcome this difficulty, it is possible to provide an implicit acknowledgment, especially when broadcast communication is spread over several frames.

In practice, the sender signals the future frame on which he wishes to transmit data in his SA message sent during the test transmission. In this embodiment, the test transmission is performed for example on the same set of resources as that desired for the transmission of data.

Each node receiving the SA message and decoding its content can identify and then memorize all the radio resources that will be used in future frames. Thus, when it wishes to establish itself a communication, the node can indicate this information (ie the list of resources that will be used by the issuer, and other transmitters if there are any) in his own message HER. For example, the information may be associated with a validity period limited in time.

When the time of the data transmission desired by the initial sender comes, that can calculate a ratio between the number of SA messages indicating the resources he has reserved himself and the total number of SA messages received since the transmission test. (also including SA messages that do not indicate the resources it has reserved). The initial transmitter may decide to perform the desired transmission according to the calculated ratio. The closer it is to 1, the greater the probability that the test transmission was successful for all the nodes in range. Thus, each transmission serves as a test for the next transmission and SA messages sent by the nodes located in its vicinity and indicating the resources reserved by the initial transmitter allows it to know that the transmission test went well to less for a certain proportion of the nodes. In this sense, these SA messages constitute (implicit) acknowledgments of the test transmission.

This mechanism can also be applied to cases of unicast or multicast communications where resources dedicated to acknowledgment messages (SAA,

ARM) are not available in the frame.

In a particular embodiment, the SA message also indicates a priority index associated with each future transmission and the calculated report takes into account this priority index.

The foregoing examples are only embodiments of the invention which is not limited thereto.

The present invention can also be used in the case of an asynchronous network. FIG. 16a illustrates an exemplary frame in such an asynchronous network.

In this example, which is not limiting, only one predefined configuration (DCH) is represented.

It is recalled that the radio resources (RB) are generally in two dimensions (time / frequency), other dimensions (for example code) can also be used.

In the case where the network is asynchronous, the frame (SC-period) is not organized in the time domain into a plurality of predefined configurations (DCH). On the other hand, it is possible to provide such an organization (DCH) in the other dimensions of the frame, for example in frequency. In other words, if the radio resources are common in the time domain, they can be separated in the frequency domain for example. Thus, some radio resources (or configurations) can be dedicated, in the frequency domain, to the transport of the signaling messages while others (in the frequency domain) can be devoted to the transport of the data.

In this case, the test transmission and the reception of the acknowledgment are preferably performed on predefined configurations dedicated to SA, SAA, and / or ARM signaling messages.

In the example of FIG. 16a, each DCH configuration is associated with a frequency channel dedicated to the ACK messages, two channels dedicated to the SAA messages. and a dedicated channel for SA messages. The channel dedicated to the SA messages is part of the corresponding DCH and therefore serves both the transmission of the SA message and therefore the channel test, and the transmission of data once communication is established.

In the case of an IEEE 802.1 1 network, for example, the SA SAA ACK messages correspond respectively to the RTS / CTS / ACK messages.

Figure 16b illustrates an example of unicast communication on the frame shown in Figure 16a.

Figure 16c is an example of multicast communication with four receivers. Here again, the choice of the channel reserved for the SAA acknowledgment message and the choice of the transmission time order by each receiver is either predefined or indicated in the SA message.

In a particular situation, a first node wishing to transmit on the radio channel can detect (with a reception level greater than a predefined threshold) a transmission of SA message or data, by a second node, on a channel reserved for sending of SA messages. In this case, the backoff counter of the first node is blocked until the next scheduled receipt of a SAA acknowledgment message from a third node in response to the SA message or the data of the second node (and not up to the second node). end of the data transmission by the second node). The duration of the blocking is thus limited until the expected reception of the SAA acknowledgment message and equal at most to a predefined value "Tsaa".

By listening to the channel reserved for the SAA acknowledgment and depending on the level of reception of this message and other information in this message, the first node may decide to reserve the channel or not. It can therefore forbid access to the radio channel (by blocking its Backoff counter for example) for at least the "Tsaa" period while awaiting the next scheduled transmission of the SAA message or the end of the transmission of the data. It can then update its network allocation vector NAV (for "Network Allocation Vector") in this way.

Thus, by providing separate channels for the SAA acknowledgment messages and the data, the well-known problem of the masked terminal is solved as well as that of the hidden terminal. Moreover, by not blocking a node until detection of a SAA message, the problem of the exposed terminal is also solved.

Claims

1. Method of direct communication between at least two terminals of a mobile network, on a set of radio resource blocks defined in one or more dimensions, organized in a frame (SC-Period), the method being implemented by a terminal transmitter and comprising the following steps:

- test transmission (40) to at least one receiving terminal of at least one signaling message (SA) according to a first subset (DSP; DCH) of radio resource blocks; and

- according to at least one acknowledgment message (SAA; ARM) received in response to the test transmission, transmission (44), to said at least one receiving terminal, data on said first subset of blocks.

The method of claim 1, wherein the frame comprises a plurality of predefined radio resource block (DCH) configurations and said first subset is a predefined configuration of radio resource blocks.

The method according to claim 2, wherein said frame comprises at least one control part (SP) and the at least one signaling message (SA) is transmitted on a radio resource block of said at least one control part (SP). ) associated with and forming part of the predefined configuration corresponding to the first subset of blocks, thereby enabling identification of the first subset of blocks.

The method according to claim 3, wherein an acknowledgment message (SAA, ARM) is received on a block of radio resources of said at least one control portion (SP) associated with the predefined configuration corresponding to the first subset of blocks, thus enabling identification and acknowledgment of the test transmission on the first subset of blocks.

The method of any one of claims 1 to 4, wherein said signaling message (SA) indicates at least one block of radio resources to be used for sending said acknowledgment message (SAA, ARM).

The method according to any one of claims 2 to 4, wherein a predefined configuration of said plurality is reserved for the transport of said acknowledgment message (SAA, ARM).

The method of claim 1 or 2, wherein the test transmission comprises a data transmission on a second subset (T-DSP) of radio resource blocks representative of the first subset of radio resource blocks.

The method according to any of claims 1 to 7, wherein the test transmission is performed on a first frame while the data transmission is performed on a second frame comprising said first subset (DSP; DCH) of blocks. radio resources, the second frame being different from the first frame.

The method according to any one of claims 1 to 8, wherein the radio resource blocks located between the radio resource blocks used for the test transmission and the reception of the acknowledgment message (s) are reserved for transmitting direct data. Short (DSSL) and / or transmit or receive other Acknowledgment Messages (ACK / ACK-RSP) or Acknowledgment Request (ACK-REQ).

The method of any one of claims 1 to 9, wherein said frame comprises a plurality of control portions (SP).

11. The method of claim 9, wherein the test transmission and reception of said at least one acknowledgment message in response to the transmission test are performed on the same control part (SP) of the frame.

The method according to any one of claims 1 to 11, wherein the radio resource blocks used for the test transmission are also used by the transmitting terminal for said data transmission, whether it is spread over one or more frames. .

The method of any one of claims 1 to 12, comprising receiving another acknowledgment message (SAA) on radio resources of one or more control portions (SP) of the frame in response to the data. transmitted on said first subset of blocks, said other acknowledgment message (SAA) notifying the transmitting terminal of a modulation and coding scheme (MCS) supported by said at least one receiving terminal and / or acknowledging the received data until there.

The method of any one of claims 1 to 13, comprising receiving a reservation indicating message (SAA, ARM) of the first subset of radio resource blocks of the current frame or a future frame.

The method according to any one of claims 1 to 14, comprising transmitting another signaling message (SA) to said at least one receiving terminal, indicating at least one block of radio resources in use on the frame current by the transmitting terminal.

A method according to any one of claims 1 to 15, comprising receiving connection quality measurements between the transmitting terminal and each receiving terminal of a plurality of receiving terminals, the method further comprising a step of selecting at least one relay terminal among the receiver terminals of said plurality as a function of the quality measurements, an identifier of said at least one relay terminal being indicated in a header message transmitted with said data on said first subset of blocks.

17. A method according to any one of claims 1 to 16, comprising receiving quality measurements of the connection between the two terminals of a plurality of pairs of terminals, the method further comprising a step of calculating a graph. Multicast broadcast from the quality metrics received.

The method of claim 16 or 17, wherein the connection quality measurements are received in said signaling message (SAA, ARM).

The method of any one of claims 1 to 18, further comprising the steps of:

receiving or detecting a message indicating a reservation (SAA, ARM) of a subset of radio resource blocks sent by a terminal of the mobile network to another terminal different from the transmitter;

measuring the quality of reception of said reservation message (RLQIRX); and

- depending on the result of the comparison of the measured reception quality with a threshold value, prohibition of transmission or not on said subset of radio resource blocks until the expected receipt of another message indicating a reservation of this subset of radio resource blocks.

20. The method of claim 19, wherein said reservation message indicates a quality level of reception of messages (RLQISIG) by said terminal of the mobile network.

21. The method of claim 20, wherein said reservation of said subset of radio resource blocks is also a function of the result of the comparison of the reception quality indicated in the reservation message (RLQISIG) with a threshold value.

The method of any one of claims 1 to 21, wherein an acknowledgment and / or reservation message according to the first subset of radio resources is spaced in time from another signaling message (SA). function of the first subset of radio resources with a predefined duration of at least equal to the time necessary for the decoding of the at least one acknowledgment and / or reservation message.

23. The method of claim 14, wherein said future frame is separated from the current frame by a predefined duration function of at least one block of radio resources dedicated to said reservation message and / or reported in said reservation message.

24. A method according to any one of claims 1 to 23, wherein at least a first block of radio resources is dedicated to said at least one signaling message (SA) and at least a second block of radio resources is dedicated to said at least one an acknowledgment message (SAA; ARM), said at least one first block and at least one second block being spaced by a predefined duration at least equal to the time necessary for decoding said at least one signaling message (SA).

The method of any one of claims 1 to 24, further comprising the steps of:

receiving or detecting a message (SA) indicating the establishment of a transmission on a subset of blocks of radio resources sent by a terminal of the mobile network to another terminal different from the transmitter;

prohibiting transmission on said subset of radio resource blocks, until the next scheduled reception of another message acknowledging a communication (SAA ARM) on said subset of radio resource blocks.

The method according to claim 1 or 2, wherein said at least one signaling message (SA) indicates reservation information, said reservation information comprising all the radio resources and identifying at least one future frame at least a network terminal has reserved.

The method of claim 26, wherein said reservation information is associated with a time-limited validity period beginning with the transmission of said at least one signaling message.

The method of claim 1, 2, 26 or 27, further comprising the steps of:

calculating a probability of success of the test transmission as a function of a number of signaling messages (SA) received from other terminals of the mobile network and indicating said first set of radio resource blocks and a total number of signaling messages (SA) received from other terminals of the mobile network since the test transmission; and according to the probability of success calculated, transmission or not of said data on said first subset of blocks.

29. The method of claim 28, wherein said at least one signaling message (SA) indicates a priority index associated with each future transmission and said calculating step takes into account said priority index.

30. A method according to any one of claims 1 to 29, wherein radio resource blocks dedicated to the signaling (SA) and / or acknowledgment (SAA, ACK, ARM) messages are of reduced size compared to the others. radio resource blocks of the frame or have different dimensions compared to other blocks of radio resources of the frame.

31. Communication device implementing a method according to any one of claims 1 to 30 for communicating with another communication device.