EP2517389A1

EP2517389A1 - Payload processing synchronization

Info

Publication number: EP2517389A1
Application number: EP10812865A
Authority: EP
Inventors: Marc Mouffron; Manuel Henry
Original assignee: Cassidian SAS
Current assignee: Airbus DS SAS
Priority date: 2009-12-22
Filing date: 2010-12-21
Publication date: 2012-10-31
Also published as: FR2954643A1; FR2954643B1; WO2011083211A1

Abstract

The invention relates to payload processing synchronization, which is applied to a data stream (FD) transmitted between a transmitter (EM) and a receiver (RE). In the transmitter, a means (GF) forms the data stream structured into blocks of K data frames, each comprising informative data and a first synchronization vector (VS_i) associated with a first item of synchronization information (IS_i) in dependence on a previous processing of the data. In the receiver, a means (AF) analyzes K first received data frames, comprising a payload and a second synchronization vector (VSr_m) including value coordinates identical to the coordinates of the first synchronization vector (VS_i). A means (AS) determines a second item of synchronization information (ISr_i) which is similar to the first item of information, on the basis of the second synchronization vector. A means (TD2) synchronizes the processing to be applied to the received payload on the basis of the second item of information.

Description

Synchronization of useful data processing

The present invention relates to a fast synchronization and constant delay conveyed in the useful band of a transmission channel and implemented in a communication system comprising at least two terminal equipment.

It finds its applications in digital communication systems dealing with all types of communication such as cellular or mobile radiocommunications or fixed communications. The planned communications may be individual communications between two terminals or group communications, such as those implemented in professional digital radio systems such as the Terrestrial Trunked Radio (TETRA) system, the TETRAPOL system or the system. P25.

A communication system comprises a set of terminal equipment communicating with each other via a communications network that may or may not be radio, mobile or fixed. A first terminal of the communication system initiates individual, group or data communication to other terminals of the system and transmits a useful data stream and synchronization information relating to the established communication. To access the payload each other terminal in the system synchronizes with the current communication using the received synchronization information.

In general, the transmission of synchronization information from the initiator terminal of the communication to other terminals of the communication system is performed outside the useful data transmission band, or on another transmission channel, such as a signaling channel, that is in a frequency band other than the frequency band dedicated to the flow of useful data. Such transmission of synchronization information has the drawback of causing a delay long and often variable synchronization. In addition, the addition of an additional signaling channel is not feasible in a communication system comprising a single open communication channel, this channel being in this case dedicated to the transmission of the communication flow and not to information synchronization.

Methods for transmitting synchronization information within the useful data stream are defined in state-of-the-art documents such as international patent application WO 200104892 and GB patent 2414145 which relate to cellular communication system protocol. These methods are based in particular on a "flight" of data frame which is replaced by a synchronization frame. This has the disadvantage of impacting the quality of the transmission of useful data, especially for phonic data. In addition, this type of synchronization restricts the possibility of late entry of a terminal into a communication since it has to wait for the next synchronization frame thereby inducing a variable synchronization time.

In the prior art, there are also other specific solutions for managing an encrypted synchronization, in particular in the international patent applications WO 2007 101956 and WO 01/35572 A2, which however concern only an encryption synchronization at irregular intervals that does not allow for an encrypted synchronization. get a fast synchronization at any time of the communication and obviously not in constant time.

The aim of the invention is to overcome the drawbacks mentioned above by setting up a fast and constant delay synchronization method implemented in a communication system between at least two terminal equipments within the useful band of transmission without impact. useful data. To achieve this objective, a synchronization method applied to a data stream comprising useful data and transmitted from a transmitter of a first terminal equipment to at least one receiver of a second terminal equipment, is characterized in that it comprises the following steps:

forming, in the transmitter, the structured data stream in blocks of K successive data frames, each block of K frames comprising useful data and a first synchronization vector associated with a first synchronization information item depending on a previously processed process applied to the payload, and a transmission of each data frame once formed from the transmitter to the receiver,

receiving and analyzing, in the receiver, K first data frames received from the received data stream, the K received data frames having received payload data and a second synchronization vector having coordinates of values identical to the coordinates of the first synchronization vector,

determining a second synchronization information similar to the first synchronization information according to the second synchronization vector, and

a synchronization of the processing to be applied to the useful data received in the receiver as a function of the second synchronization information determined.

This invention makes it possible, during a late entry of the receiver into the communication initiated and established by the transmitter, to synchronize the processing of the useful data received in the receiver with the processing of the useful data transmitted by the transmitter, after a a constant delay comprising the reception and analysis time of K first received data frames comprising inter alia the second synchronization vector. The data processing can be for example a decryption of the data received in the receiver, the data having been encrypted in the transmitter. According to an embodiment of the invention, the transmitted data stream comprises blocks of K data frames each comprising useful data and signaling variables, the K coordinates of the first synchronization vector being respectively introduced into the signaling variables of each of the K data frames.

Such a synchronization does not impact the useful data to be transmitted since the synchronization information to be transmitted from the transmitter to the receiver in the form of a synchronization vector is introduced into predicted signaling variables of the data stream. Thus, each of the K coordinates of the synchronization vector is successively introduced into the signaling variables of the K data frames of each block and repeatedly in all the blocks.

According to an embodiment of the invention, before the step of forming the data stream in the transmitter, the method comprises a determination of the first synchronization vector according to the first synchronization information among a plurality of synchronization vectors respectively paired to a plurality of different synchronization information, each of said vectors having at least one of K coordinates of different value from the coordinates of the other synchronization vectors. According to one embodiment of the invention, the K first received data frames comprise received received data and K received coordinates forming the second synchronization vector, each of the K coordinates corresponding bijectively, according to at least one permutation, to a coordinate of the first synchronization vector. The synchronization coordinates of the first and second synchronization vectors are of identical values but can be ordered in different ways.

According to another embodiment of the invention, the second synchronization information is determined from a plurality of different synchronization information, by comparing the second synchronization vector with a set of different synchronization vectors. paired with the second synchronization information, each of the K coordinates of one of said matched synchronization vectors corresponding bijectively, according to at least one permutation, to a coordinate of the first synchronization vector. Thus, the second synchronization information can be determined from an equivalence table matching synchronization information respectively to a set of synchronization vectors, each of the K coordinates of one of the synchronization vectors of the corresponding set bijectively a synchronization coordinate of the other synchronization vectors of the set matched to the same synchronization information, and comprises: a comparison of the second synchronization vector with each synchronization vector of the equivalence table, and

a reading in the equivalence table of the second synchronization information matched to a synchronization vector identical to the second synchronization vector.

The synchronization coordinates of the first synchronization vector and the set of timing vectors matched to the second synchronization information are of identical values but are ordered in different ways.

The invention also relates to a transmitter and a receiver for example in a terminal equipment implementing the method of the invention.

The transmitter is able to transmit a data stream comprising useful data to at least one receiver of another terminal equipment, and is characterized in that it comprises:

means for determining a first synchronization vector as a function of a first processing-dependent synchronization information previously applied to the payload, among a plurality of synchronization vectors respectively matched to a plurality of different synchronization information, each said vectors having at at least one of its K coordinates of value different from the coordinates of the other synchronization vectors,

means for forming a structured data stream in blocks of K successive data frames, each block of K frames including useful data and the first synchronization vector, the K coordinates of the first synchronization vector being respectively introduced into signaling variables each of the K frames of data, and

means for transmitting each frame once formed to the receiver of the other terminal equipment.

The receiver is adapted to receive a stream of data transmitted from a transmitter of another terminal equipment and having useful data, and is characterized in that it comprises:

means for receiving and analyzing K first data frames received from the received data stream, the K data frames comprising received received data and K received coordinates forming a second synchronization vector having coordinates of values identical to the coordinates of a first synchronization vector determined in the transmitter and matched to a first synchronization information that depends on a previously applied processing on the payload in the transmitter, a means for determining a second synchronization information, among a plurality of information of different synchronization, by comparing the second synchronization vector with a set of different synchronization vectors paired with the second synchronization information, each of the K coordinates of each synchronization vectors of the set corresponding bijectively, according to at least one permutation, to a coo synchronization data of the first synchronization vector, and

means for synchronizing the receiver according to the determined second timing information. Other characteristics and advantages of the present invention will appear more clearly on reading the following description of several embodiments of the invention given by way of non-limiting examples, with reference to the appended drawings in which:

FIG. 1 is a schematic block diagram of an EM transmitter of a terminal equipment and a receiver RE of another terminal equipment, belonging to a communication system, implementing a synchronization method according to the invention ;

FIG. 2A shows the structure of a data stream formed according to the synchronization method of the invention;

FIGS. 2B and 2C show the structure of part of the data stream received by the receiver according to two embodiments of the invention respectively;

FIGS. 3A and 3B show an equivalence table matching synchronization vectors to synchronization information according to two embodiments of the invention respectively, and

FIGS. 4A and 4B are algorithms of the synchronization method according to the invention, implemented respectively in the EM transmitter and the RE receiver.

A communication system implementing a method according to the invention comprises terminal equipments, such as a mobile terminal or a base station of a terrestrial or aeronautical cellular radio network or by satellites, or else of professional terrestrial radio type. , or a network without special infrastructure such as networks in direct mode type walkie-talkie. The terminal equipment may also be a fixed terminal such as a digital telephone set or installation, a computer or a local area network served by an ISDN or IP type digital network. The terminal equipments, hereafter referred to as terminals, communicate with each other via a group communication or an individual communication to exchange data from one another. initiating terminal of the communication to a closed group consisting of one to several other terminals of the communication system. Each terminal includes a transmitter for transmitting a data stream to other terminals of the system and a receiver for receiving data streams from other terminals of the system.

With reference to FIG. 1, an emitter EM of a first terminal equipment processes useful data DU in a first data processing unit TD1. Useful data is, for example, audio and / or video data, text, images or multimedia data. In the processing unit TD1, the data is processed, for example encrypted and / or compressed, according to specific operating modes notified in synchronization information ISj then supplied to a synchronization management unit GS. The synchronization information may also contain processing-complementary information such as the speaker's identity, a movie title, or the name of the broadcast station. The processed data DUt are introduced into a data flow formation unit GF to form a data stream FD comprising, among other things, the processed useful data DUt and the synchronization coordinates of a synchronization vector VSj determined in the management unit. of the synchronization GS according to the synchronization information ISj. The data stream FD is then transmitted via a transmission channel CT from a communication interface to a receiver RE of another terminal of the communication system. If the CT channel is a radio channel, the communication interface ICe can modulate the data stream before transmitting it.

During reception of the received data stream FDr, a communication interface ICr of the receiver RE acquires each part of the stream, hereinafter referred to as the received frame block description BTr _n , and supplies them successively to a flow analysis unit AF. If the CT channel is a radio channel, the ICr interface can demodulate the received data stream. When analyzing a first block of received frames, the unit AF recovers a part of the useful data to be processed DUtr and all the synchronization coordinates to form a synchronization vector VSr _m . The vector VSr _m formed is supplied to a synchronization analysis unit AS which determines the synchronization information ISn as a function of said vector VSr _m . The determined information ISrj is transmitted to a second data processing unit TD2 which synchronizes with the processing applied in the first processing unit TD1, by implementing the procedures complementary to the operating modes implemented in the unit TD1, for example decryption and specific decompression, indicated in the synchronization information ISrj. Thus, the synchronization of the receiver RE is established as soon as the analysis of a first part of the data stream FDr received, or also called the first block of received frames BTr _n . Once the unit TD2 synchronized, the useful data from each block of frames of the stream analyzed by the AF unit are processed in the unit TD2 as they arrive. The processed data DUf are transmitted to other units of the second terminal to be for example saved in a memory, be displayed on a screen of the terminal or listened to by the user of the terminal via a speaker of the terminal.

The units TD1, GS, GF and ICe of the EM transmitter and the ICr, AF, AS and TD2 units of the receiver RE are represented in the form of functional blocks, most of which provide functions relating to the invention and may correspond to to software and / or hardware modules. These units are respectively included in the transmitter and the receiver of each terminal of the communication system. As a variant, in a communication system, for example an information broadcasting system, at least the transmitter of a terminal comprises the units TD1, GS, GF and ICe and at least the receivers of the other terminals comprise the units ICr, AF, AS and TD2.

Referring now to FIGS. 4A and 4B, the method of synchronizing a terminal equipment in a communication system according to the invention comprises steps E1 to E4 for establishing the synchronization of a communication, implemented in the context of FIG. EM transmitter. A such a method also comprises synchronization steps S1 to S7 to said communication which are implemented in the receiver RE.

In step E1, the first data processing unit TD1 notifies synchronization information ISj as a function of the processing applied to the payload data DU. The processing applied to the useful data may correspond to the type of communication selected by the user of the first terminal, for example an encrypted communication. The synchronization information ISj indicates the processing procedure applied to the payload data DU, such as a specific data compression / decompression operating mode, a specific data encryption / decryption operating mode comprising in particular an indicator corresponding to the the encryption / decryption algorithm used as well as references to the associated encryption / decryption keys. Other procedures relating to data processing may be notified. The synchronization information ISj may indicate several operating modes used during data processing, for example, when the payload data DU is compressed and encrypted by the unit TD1. The information ISj will subsequently be read by the processing unit TD2 of the receiver so that it synchronizes and processes the useful data received. To do this, the synchronization information ISj is transmitted from the transmitter EM to the receiver RE via the synchronization vector VSj associated, included in the data stream FD and which is determined in the management unit of the synchronization GS, to step E2. The unit GS comprises a synchronization table TS which matches each synchronization information ISj to a synchronization vector VSj, with the index i G [1, I]. The synchronization table TS has different synchronization information. They are distinguished by the procedure of treatment of useful data. For example, synchronization information corresponds respectively to one or more different compression / decompression modes depending on the type of useful data (audio, video, text or other). According to another example, synchronization information correspond respectively to one or more modes different encryption / decryption procedures corresponding to different algorithms and keys depending on the degree of confidentiality of the exchanges. Each synchronization vector VSj, comprises K successive synchronization coordinates Vi, v ₂ , v _k , v _K , each having a value defined on a set E _P of P elements such that Ep = {1, 2, P-1, P }.

Each synchronization vector VSj included in the synchronization table TS and paired with synchronization information ISj, comprises at least one synchronization coordinate having a value different from the values of the synchronization coordinates of the other synchronization vectors of the table TS. On reading the table TS, the synchronization management unit GS determines the synchronization vector VSj paired with the synchronization information ISj provided by the unit TD1 and transmits it to the data flow forming unit GF. .

In step E3, the stream forming unit GF forms a data stream FD by introducing the useful data DUt processed by the unit TD1 and repeatedly the synchronization vector VSj. With reference to FIG. 2A, the stream FD comprises U frames of data Ti to Ty. Each data frame T _U , with the index u C [1, U], is a binary sequence comprising, inter alia, a set of signaling variables and a set of _u of data variables. The processed useful data DUt are distributed in each set d _n of data variables of the data frames Ti to Ty. The size of the FD stream varies depending on the amount of data processed DUt. For each frame T _U , some or all of the signaling variables correspond to a synchronization coordinate V | <of the synchronization vector VSj, with the index k C [1, K], K being equal to 3 in the figure 2A. The data stream FD is formed of a succession of BTi to BTN frame blocks, also called parts of the data stream. Each block BT _N , with the index n G [1, N], is formed from a group of K successive data frames T _U to T _u + ki, thus including a part of the useful data to be transmitted from _u to d _{u +} kl and all K coordinates vi to V of the synchronization vector VSj. The last block of BTN frames belonging to the FD data stream comprises at least the last data frame Tu. In the data stream FD, the synchronization vector VSj, more particularly its synchronization coordinates vi to νκ, is repeated every K frames of data. At each formation of a data frame T _u , the training unit GF transmits the frame T _u to the communication interface ICe to transmit it via the data transmission channel CT to the communication interface ICr of the receiver RE, at step E4. If the transmission channel CT is a radio channel, the interface ICe modulates the data stream before transmitting it to the receiver.

The transmission channel CT is a traffic channel transmitting the useful data stream over the useful transmission band. The transmission channel is established with or without a signaling channel in any type of digital communication network such as a terrestrial or aeronautical cellular radio network or by satellites, or of professional terrestrial radio type or a network without particular infrastructure such as networks in direct mode of the walkie-talkie type, or else a digital network of ISDN or IP type.

In step S1, the interface ICr of the receiver receives a first block of frames BTr _n , which is not necessarily the first block BTi of K first frames sent by the transmitter EM since the receiving terminal can enter late in the communication, part of the FD stream is already transmitted to other terminals, for example. Thus, the K first frames received and analyzed by the receiver RE form the first block BTr _n received. With reference to FIG. 2B and according to a first embodiment of the invention, the first K = 3 frames Tr _u + 1, Tr _u + 2 and Tr _u + 3 are received in the same order as the K frames of substantially identical data. T _u + i, T _u + 2 and T _u + 3 transmitted by the emitter EM. With reference to FIG. 2C and according to a second embodiment of the invention, the first K = 3 frames Tr _u + 1, Tr _u + 3 and Tr _u + 2 are received in an order different from K frames T _u + i, T _u +2 and T _u +3 transmitted by the emitter EM, especially because of the specificity and / or the transmission quality of the CT channel. For example, the frames are interlaced in the EM transmitter before being transmitted, or the frames undergo a succession of different buffering routes before being received by the receiver.

The received block BTr _n can be demodulated, if the channel CT is a radio channel, and is transmitted to the flow analysis unit AF which, at each analysis of one of the K received data frames Tr _u , retrieves a coordinate synchronization vrk and useful data dr _u , in step S2. As soon as all the synchronization coordinates are retrieved vrj, the AF flow analysis unit forms a synchronization vector VSr _m successively including all the coordinates vri to vrj, each vrk corresponding bijectively to a coordinate of synchronizations transmitted Vk in the frame block BTr _n . According to the first embodiment of the invention, the synchronization coordinates received vr-1 to n <are ordered in a manner similar to the synchronization coordinates transmitted vi to VK according to a circular permutation close. As a variant, the synchronization coordinates received vn to vr "may be ordered according to a symmetrical permutation close to the synchronization coordinates transmitted vi to v". According to the second embodiment of the invention, the synchronization coordinates received vn to vr "can be ordered in any manner and therefore differently from the synchronization coordinates transmitted vi to v". The AF flow analysis unit transmits the useful data dr _u to dr _U + Ki from the block BTr _n to the processing unit TD2 and the vector VSr _m to the synchronization analysis unit AS. In step S3, the synchronization analysis unit AS determines, according to the vector formed VSr _m, synchronization information ISn similar to the synchronization information Isj notified in the first processing unit TD1. The synchronization analysis unit AS comprises an equivalence table TEq illustrated in FIGS. 3A and 3B respectively according to one of the two embodiments of the invention. The table TEq comprises I synchronization information ISi to IS | and M synchronization vectors VSi to VSM- In the TEq table, each synchronization information ISn, with the index i G [1, I], is matched to a set of G synchronization vectors VS _m to VS _m + Gi, with the index m Θ [1, M]. Each of the K coordinates of synchronization v- | j, V2, i. ■ ··. ^v k, i. ■ ··. ^v K i of one of the synchronization vectors VS _m corresponds bijectively to a synchronization coordinate of the other synchronization vectors VS _m + i to VS _m + Gi of this set paired with the same information ISrj.

According to the first embodiment with reference to FIG. 3A, each synchronization information ISrj of the table TEq is matched to, at most, G = K synchronization vectors VS _m to VS _m + Gi having K synchronization coordinates V-IJ, V2, j, Vkj, v, j respectively identical and circularly permutated in each of G = K synchronization vectors. Thus, by referring to the equivalence table of FIG. 3A, relative to the first information ISrj = i, for synchronization vectors VSi, VS2, VS3 having K = 3 coordinates vi, V2,1 and V3 respectively having their its own value on the set Ep, the K = 3 synchronization vectors having bijectively identical coordinates ordered according to a circular permutation, such that Vsi (vii, V2,1, V31), VS2 (V2,1, V31, vi_i ) and VS3 (V3 ^< \, V1 1, V2, i), are considered paired with the same synchronization information ISn = i.

According to the second embodiment with reference to FIG. 3B, each synchronization information ISrj is matched with as many synchronization vectors as there are possible permutations between the K synchronization coordinates. Thus, with reference to the equivalence table of FIG. 3B, relative to the first synchronization information ISn = i for synchronization vectors VS1, VS2, VS3, VS4, VS5, VSQ comprising K = 3 coordinates V1 1, 2,1 and V3 1 respectively having their own value on the set Ep, the synchronization vectors having bijectively identical coordinates ordered according to all possible permutations, such that Vs ^ -i, V2,1, V3, i), VS2 (V2,1, V3,1, vi, i), Vs3 (V3, i, vi, i, V2, i), Vs4 (vi, i, V3, i, V2, i), Vs5 (v ₂ , i , vi, i, V3, i) and VS6 (V3,1, V2,1, vi, i), are considered to be paired with the same synchronization information ISn = i. The synchronization analysis unit AS successively compares the synchronization vector VSr _m provided by the analysis unit of the flow AF to all the synchronization vectors VSi to S of the equivalence table TEq. As soon as a synchronization vector VS _M is identical to the vector VSr _m , the unit AS determines the associated synchronization information ISn. The unit AS transmits the information ISn to the processing unit TD2. In step S4, the unit TD2 reads the synchronization information ISn and searches, for example, in a memory of the unit the processing algorithms designated by the information ISn The unit TD2 synchronizes with the processes applied in the unit TD1 of the emitter EM by implementing the processing algorithms associated with the information Isn and complementary to the processing algorithms applied in the unit TD1. The synchronization of the processing unit TD2 is effective after a constant delay of reception and analysis of the first K received data frames included in a first block of frames comprising the synchronization vector VSr _m . Once synchronization is established, the unit TD2 processes the useful data dr _u to dr _u + Ki transmitted by the AF flow analysis unit. In the case of a phonic communication, the useful voice data are not processed and are therefore lost. At each reception and analysis of a frame block, without modification of the synchronization vector, the unit TD2 processes the received useful data as before. At each modification of the processing applied in the unit TD1 of the emitter EM, for example during an encryption / decryption key change, the processing unit TD2 resynchronizes after receiving and analyzing the first K frames containing the vector synchronization time VSr _m + i matched to the synchronization information ISn + i different from that previously determined ISn, but similar to the notified information ISj + i by the unit TD1. After each useful data processing dr _u , the processing unit TD2 transmits to the other units of the second terminal the processed data df _u . According to one variant, the synchronization table TS in the synchronization management unit GS is identical to the equivalence table TEq, only the first vector VS _m paired with the information \ S \ provided by the unit TD1 is selected to be repeatedly introduced into the data stream FD.

TS and TEq tables can be previously recorded in the terminals of the communication system. In a variant, the TS and TEq tables are transmitted and / or updated by a terminal equipment, such as an encryption / decryption key management server or a software update management server.

According to another embodiment, the synchronization information ISn is determined in the AS unit by applying the synchronization vector VSr _m to a surjective encoding algorithm. The algorithm determines a unique synchronization information ISn for all synchronization coordinate permutations of a set of K coordinates, inducing different timing vectors.

The method according to the invention finds applications in particular in the field of secure communications using multicast or unicast protocols without signaling channels. A first transmitter initiates an encrypted communication according to a first encryption procedure relating to a first synchronization information. The transmitter transmits the data stream comprising the encrypted data and a synchronization vector repeated every K frames in the stream and matched to the first synchronization information. The receivers synchronize the decryption of the transmitted data after a constant period of analysis of K first received frames, comprising a synchronization vector matched to synchronization information similar to the first synchronization information. During communication, the transmitter can change its encryption mode encryption key change for example. The transmitter transmits the data stream comprising encrypted useful data according to a second operating mode and a synchronization vector repeated every K frames and paired with a second synchronization information corresponding to the second operating mode. Thus, after a constant period of analysis of the K first frames received, the receivers resynchronize to decrypt the useful data received according to the new operating mode. Receiver synchronization is effective in the analysis of K received data frames. The invention finds its applications in all types of networks comprising at least one traffic channel transmitting the useful data stream over the useful transmission band.

Claims

1 - Process synchronization method to be applied to useful data (DU) of a data stream (FD) transmitted from a transmitter (EM) of a first terminal equipment to at least one receiver (RE) of a second terminal equipment, characterized in that it comprises the following steps: a formation (E3), in the transmitter, of the data flow (FD) structured in blocks of K successive data frames (T _U - T _U + KI) , each block of K frames comprising useful data (d _u - d _U + -i) and a first synchronization vector (VSj) determined according to a first synchronization information (ISj) depending on a previously applied processing on the payload (DU), and a transmission (E4) of each data frame once formed from the transmitter to the receiver (RE),

receiving (S1) and analyzing (S2), in the receiver, K first received data frames (Tr _u - Tr _U + Ki) of the received data stream (FD, FDr), the K received data frames comprising received useful data (dr _u - dr _U + K i) ^{and a} second synchronization vector (VSr _m ) having coordinates of values identical to the coordinates of the first synchronization vector (VSj),

a determination (S3) of a second synchronization information

(ISrj) similar to the first synchronization information according to the second synchronization vector, and

a synchronization (S4) of the processing to be applied to the payload received in the receiver (RE) as a function of the determined second synchronization information (ISn).

2 - Process according to claim 1, wherein the data stream comprises blocks of K data frames each comprising useful data (d _u - d _U + Ki) and signaling variables, the K coordinates (v- | - vj <) of the first synchronization vector (VSj) being respectively introduced into the signaling variables of each of the K data frames.

3 - Process according to claim 1 or 2, comprising before the step of forming (E3) the data stream (FD) in the transmitter (EM), a determination (E2) of the first synchronization vector (Vsj) in a function of the first synchronization information (ISj) among a plurality of synchronization vectors respectively matched to a plurality of different synchronization information, each of said vectors having at least one of K coordinates of different value from the coordinates of the other synchronization vectors.

4 - Process according to any one of claims 1 to 3, wherein in the receiver, the K first received data frames (Tr _u + i - Tr _{u +} K) include received useful data (dr _u + i - dr _u + K) and K received coordinates (vri - vn <) forming the second synchronization vector (VSr _m ), each of the K coordinates corresponding bijectively, according to at least one permutation, to a coordinate (i - κ) of the first vector synchronization (VSj).

5 - Process according to any one of claims 1 to 4, wherein the second synchronization information (ISn) is determined from a plurality of different synchronization information, by comparing the second synchronization vector (VSr _m ) with a set of different synchronization vectors paired with the second synchronization information, each of the K coordinates of one of said matched synchronization vectors corresponding bijectively, according to at least one permutation, to a coordinate (i - v ") of the first synchronization vector (Vsj). 6 - Process according to any one of claims 1 to 5, wherein the second synchronization information (Isn) is determined from an equivalence table (TEq) matching synchronization information (ISn - ISn) respectively a set of synchronization vectors (VS _m - VS _{m +} g), each of the K coordinates of one of the synchronization vectors of the set corresponding bijectively to a synchronization coordinate of the other synchronization vectors of the set matched to the same timing information, and includes:

a comparison of the second synchronization vector (VSr _m ) with each synchronization vector (VS- | - VSM) of the equivalence table (TEq), and

a reading in the equivalence table (TEq) of the second synchronization information (ISn) paired with a synchronization vector (VS _m ) identical to the second synchronization vector (VSr _m ).

7 - Process according to any one of claims 1 to 6, wherein the equivalence table (TEq) matches synchronization information (Isn) respectively to at most K different synchronization vectors (VS _m - VS _{m +} K) , wherein each of K coordinates of one of said synchronization vectors corresponds bijectively to a coordinate of the other synchronization vectors matched to the same synchronization information, the K coordinates being ordered according to a circular permutation close. 8 - Process according to any one of claims 1 to 6, wherein each synchronization information (Isn) is matched in the equivalence table (TEq) to as many different synchronization vectors as there are possible permutations between the K coordinates of said vectors, each of the K coordinates of one of the synchronization vectors corresponding bijectively to a coordinate of the other synchronization vectors paired with the same synchronization information, the K coordinates being ordered according to any permutation.

9 - Transmitter (EM) of a terminal equipment capable of transmitting a data flow (FD) comprising useful data (DU) to at least one receiver

(RE) of another terminal equipment, characterized in that it comprises:

means (GS) for determining a first synchronization vector (Vsj) according to a first synchronization information (ISj) dependent on a previously applied processing on the payload (DU), among a plurality of synchronization vectors respectively paired with a plurality of different synchronization information, each of said vectors having at least one of its K coordinates of different value from the coordinates of the other synchronization vectors,

means (GF) for forming a data flow (FD) structured in blocks of K successive data frames (T _U - T _U + KI), each block of K frames including useful data (d _u - d _U + K i ) and the first synchronization vector (VSj), the K coordinates (vi - v ") of the first synchronization vector (VSj) being respectively introduced into signaling variables of each of the K data frames, and

means (ICr) for transmitting (E4) each frame once formed to the receiver (RE) of the other terminal equipment.

10 - Receiver (RE) of a terminal equipment able to receive a data stream (FD) transmitted from a transmitter (EM) of another terminal equipment and comprising useful data (DU), characterized in that it comprises :

means (ICr - AF) for receiving and analyzing K first frames of received data (Tr _u - Tr _U + K ₊ i) of the received data stream (FD - FDr), the K frames of data comprising received useful data ( dr _u - dr _U + K + i) and K received coordinates (vr-ι - νΓκ) forming a second synchronization vector (VSr _m ) having coordinates of values identical to the coordinates of a first synchronization vector (VSj) determined in the transmitter and matched to a first synchronization information (ISj) which depends on a previously applied processing on the payload data (DU) in the transmitter (EM),

means (AS) for determining a second synchronization information (ISn), among a plurality of different synchronization information, by comparing the second synchronization vector (VSr _m ) with a set of different timing vectors matched to the second information synchronization, each of the K coordinates of each synchronization vector of the set corresponding bijectively, according to at least one permutation, to a synchronization coordinate (vi - νκ) of the first synchronization vector (VSj), and

means (TD2) for synchronizing the processing to be applied to the payload in the receiver (RE) according to the determined second timing information (ISn).