WO2023089123A1 - Method intended to improve radiofrequency communication between a transmitter device and a receiver device, and device implementing said method - Google Patents

Abstract

The invention relates to a method for preparing and a method for processing radiofrequency data. More specifically, the present invention relates to a method for preparing data with a view to the radiofrequency transmission thereof from a transmitter device. Preparing the data involves in particular considering an interleaving of data bits within a data frame SD intended to define the radiofrequency signal. In this regard, the data frame SD is prepared from a data block called an original block. More specifically, the original data block is divided into two sub-blocks, respectively called sub-block S and sub-block D, in order to form a sub-frame Ss and a sub-frame Dd. The sub-frame Ss in particular comprises Ms repetitions of sub-blocks S all of whose bits are interleaved.

Description

Method for improving radiofrequency communication between a transmitter device and a receiver device, and device implementing said method FIELD OF THE INVENTION

The present invention relates to the field of communications systems, and in particular radiofrequency communications. More particularly, the present invention relates to a method for implementing phase and/or frequency synchronization between a transmitter device and a receiver device, in particular with a view to performing synchronized averaging.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

The extension of the communication range between radiofrequency communication devices, as well as the energy consumption are two issues that designers of these devices must face.

In this respect, the extension of the range of communications can be achieved by improving the link budget between devices, and in particular by improving the sensitivity of communication, and more particularly relating to the reception of a radio frequency signal.

To do this, the relative sensitivity to the reception of a radio frequency signal can be improved by manipulating and/or rearranging the data intended to form a radio frequency signal with a view to its transmission.

Thus, in order to respond to this problem, it has been proposed to implement a so-called spread spectrum technique which consists in spreading the radiofrequency signal over a wide frequency band.

This technique makes it possible, by an artificial increase in the width of the spectrum of the transmitted signal, to reduce certain disturbances which are superimposed on the signal during the transmission of a radio frequency signal from a transmitter device to a receiver device. This technique requires in particular to add spectrum spreading and signal coding means at the level of the transmitter device and complex and sophisticated radio frequency signal processing means at the level of the receiver device which make this technique expensive and complex to implement. work.

Alternatively, it is possible to implement a so-called synchronized averaging technique (“Time Synchronous Averaging” or “TSA” according to Anglo-Saxon terminology). This technique makes it possible in particular to process periodic signals having an unfavorable signal-to-noise ratio ("Signal-to-Noise Ratio" or "SNR"). In theory, this technique makes it possible to achieve a significant gain, but nevertheless requires maintaining synchronization, both in terms of frequency and phase, between the transmitter device and the receiver device.

By way of example, document EP 3 127 247 B1 discloses an example of a synchronization method implemented between a transmitter device and a receiver device. This method is based in particular on the transmission from the transmitter device of a block of data comprising a preamble word followed by a data word repeated identically several times. At the level of the receiver, it is based on the detection of the preamble word to synchronize the receiver device with the transmitter device, then on the synchronized averaging of the repetitions of the data word to find the transmitted data. The effectiveness of this technique is limited by the synchronization method implemented.

Document FR3103070A1 proposes another synchronization method implemented between a transmitter device and a receiver device. This method notably proposes constructing a data frame from data blocks carrying the same information and having a permutation which is specific to each of said blocks. In this document, the permutation is implemented to reduce the periodicity of the transmitted signal in order to limit the correlation between the repeated data blocks. This data frame transmitted from the transmitter device is then processed by the receiver device. This processing includes in particular the repetition of an inverse permutation sequence and the correlation between the data blocks.

However, this method is not satisfactory. Indeed, in order to optimize both phase and/or frequency synchronization, it is preferable to consider relatively long frames. This last aspect directly impacts the time and complexity of the processing performed by the receiving device.

Furthermore, the processing of the data frame by the receiver device cannot be executed as long as the entirety of said frame has actually been received by the receiver device. Consequently, the origin of the transmitted data remains unknown until the data frame has been received and processed by the receiving device. This results in a risk of collision between data frames when several transmitting devices are considered.

Reducing the size of the data frames, while solving the aforementioned problems, will harm the reliability of the processing method. Moreover, the reduction of the periodicity by permutation is very difficult to achieve when shorter data frames are considered.

Also known from document US2014/229997 is a process for preparing a data frame. This process provides for a scrambling operation (“scrambling” in the terms of this document) of certain parts of the frame. Such scrambling, and as is well known in the art, aims to provide a frame that has a balanced number of "1s" and "0s", regardless of the starting frame, which ensures the "flat" character of the transmission spectrum. This method also provides for the repetition of the symbols of a data sub-block in the frame to be transmitted, but does not envisage the repetition of this data sub-block itself.

The document US2019/109685 also relates to a method for preparing a data frame with a view to its transmission. This document relates more particularly to the coding of the “header bits” of a block of data.

An object of the present invention is therefore to propose a method for synchronizing a communication system based on the retransmission of data that is more robust than those proposed in the state of the art. In particular, an object of the present invention is to propose a synchronization method which has a complexity and a reduced processing time with regard to the known methods of the state of the art. Another object of the present invention is to propose a synchronization method which makes it possible to consider longer data frames without however penalizing the synchronization duration.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a method for preparing an SD data frame to be transmitted as a radio frequency signal from a transmitter device to a receiver device, the preparation method comprising the following steps:

a) group the digital data in the form of a block of data, called the original block, having a determined size in bits;

b) dividing the original block into two sub-blocks called, respectively, sub-block S and sub-block D;

c) generating a sub-frame Ss, said sub-frame Ss being generated from Ms repetitions of the sub-block S, Ms being strictly greater than 1, the generation of the sub-frame Ss also comprising the execution of a interleaving all the bits of all the sub-blocks S,

d) generating a Dd subframe, said Dd subframe comprising Md repetitions of the D subframe;

e) constructing an SD data frame formed in the order of the Ss subframe and the Dd subframe, the data frame being intended to define the radio frequency signal to be transmitted.

According to one mode of implementation, the sub-block S forms a block called a preamble block capable of being stored in the memory of the receiver device intended to receive the data frame in the form of a radiofrequency signal.

According to one mode of implementation, the size in bits Bs of the sub-block S is less than the size in bits Bd of the sub-block D.

According to one mode of implementation, Ms is greater than Md, advantageously Md is equal to 1.

According to one mode of implementation, the interleaving of step c) is carried out so as to construct from the repetition of Ms sub-blocks S of m bits, a sub-frame Ss of Ms*m interleaved bits and so that the subframe Ss is formed by a succession of Ms groups of m bits and that at least one of these groups of m bits comprises a set of bits different from the other groups, advantageously each group of m bits comprises a set of bits different from all the other groups.

The invention also relates to a method for processing a radiofrequency signal received by a receiver device, the radiofrequency signal being defined by a data frame SD which comprises in order a subframe Ss and a subframe Dd, the sub-frame Ss being formed from the interleaving of the data bits of Ms sub-blocks S, and the sub-frame Dd being formed from Md sub-blocks D of data, the interleaving of the bits having been obtained according to a determined algorithm and parameters, the concatenation, in order, of a sub-block S and a sub-block D forming a data block called the original block, the processing method comprising the following steps:

a) sampling the received radio frequency signal at an oversampling frequency defined by the receiving device;

b) progressively record the samples, resulting from the sampling carried out in step a), in a buffer memory of the receiving device;

c) among a series of samples recorded in the buffer memory and having a size in bits at least equal to the size of the subframe Ss multiplied by an assumed number of samples per bit chosen from a set comprising a corresponding nominal value at oversampling frequency, at least one value below nominal and at least one value above nominal:

i. select a sequence of samples from a given sample and at regular intervals of size equal to the assumed number of samples per bit;

ii. generating an S-1 subframe by interleaving the sequence of samples, said interleaving corresponding to the inverse interleaving having made it possible to form the Ss subframe from the Ms S sub-blocks;

iii. splitting the subframe S-1 into a number Ms of test sub-blocks St;

iv. processing the Ms St test sub-blocks, the processing of the Ms St test sub-blocks comprising calculating at least one average sub-block and a correlation measure based on the at least one average sub-block ;

v. save the at least one correlation measure calculated in iv, by associating said correlation measure with an index of the sample from which the selection was made and with the presumed number of samples per bit;

vi. repeat steps i to v from at least one other sample from which the previous selection was made;

d) determining, among the saved correlation measures, the correlation measure corresponding to a greater correlation, and retrieving the index of the sample and the assumed number of samples per bit associated with this correlation measure;

e) identifying the sequence of samples selected from the index of the sample associated with the correlation measurement determined during step d), as corresponding to the subframe Ss and from which the frame of SD data has been built.

According to one mode of implementation, said method further comprises a step d1) executed between steps c) and d), step d1) comprising, for at least one other value of the presumed number of samples per bit chosen from the set comprising a nominal value corresponding to a nominal oversampling frequency of the receiver, at least one value lower than said nominal value and at least one value higher than said nominal value, executing step c) again, so as to save the calculated correlation measurements, by associating each correlation measurement with the index of the sample from which the selection was made and with the presumed number of samples per bit considered.

The invention also relates to a method for processing a radiofrequency signal received by a receiver device, the radiofrequency signal being defined by a data frame SD which comprises in order a subframe Ss and a subframe Dd, the subframe Ss being formed from the interleaving of the data bits of Ms sub-block S, and the sub-frame Dd being formed from Md sub-block D of data, Ms and Md being integers, the interleaving of the bits having been obtained according to a determined algorithm and parameters, the concatenation, in order, of a sub-block S and of a sub-block D forming a data block called the original block, the method process comprising the following steps:

a) sampling the received radio frequency signal at an oversampling frequency defined by the receiving device;

b) progressively record the samples, resulting from the sampling carried out in step a), in a buffer memory of the receiving device;

c) among a series of samples recorded in the buffer memory and having a size in bits at least equal to the size of the subframe Ss multiplied by an assumed number of samples per bit chosen from a set comprising a corresponding nominal value at oversampling frequency, at least one value below nominal and at least one value above nominal:

i. select a sequence of samples from a given sample and at regular intervals of size equal to the assumed number of samples per bit;

ii. generating an S-1 subframe by interleaving the sequence of samples, said interleaving corresponding to the inverse interleaving having made it possible to form the Ss subframe from the Ms S sub-blocks;

iii. splitting the subframe S-1 into a number Ms of test sub-blocks St;

iv. processing the Ms St test sub-blocks, the processing of the Ms St test sub-blocks comprising calculating at least one average sub-block and a correlation measure based on the at least one average block;

v. save the at least one correlation measurement calculated in iv, by associating said correlation measurement with an index of the sample from which the selection was made and with the presumed number of samples per bit

vi. comparing the calculated correlation measure with a predetermined threshold value;

If the correlation measurement is greater than the threshold value, perform the following steps:

- associate the correlation measure with an index of the sample from which the selection was made and the assumed number of samples per bit;

- consider these two values as the timing references for phase and frequency synchronization;

if the correlation measure is less than the threshold value, then performing steps i again. see you from at least one other sample than the sample from which the previous selection was made.

According to one mode of implementation, said method comprises a step d1) comprising, for at least one other value of the presumed number of samples per bit chosen from the set comprising a nominal value corresponding to a nominal oversampling frequency of the receiver device, at least one value lower than said nominal value and at least one value higher than said nominal value, the execution of step c) again, so as to save the calculated correlation measurements, by associating each correlation measurement to the index of the sample from which the selection was made and to the presumed number of samples per bit considered.

According to one mode of implementation, the processing step iv) comprises in order:

- a distribution of the test sub-blocks St into two groups;

- for each group, the calculation of an average sub-block;

- the calculation of a measure of correlation between the pair of average sub-blocks calculated previously.

According to one mode of implementation, the sub-block S is a block called a preamble block which is also stored in a memory of the receiver device, and in which the processing step iv) comprises in order:

- the calculation of an average sub-block from all the test sub-blocks St

- the calculation of a measure of correlation between the mean sub-block previously calculated and the preamble block stored in the memory of the receiver device.

According to one mode of implementation, said given sample is initially the first sample recorded in the buffer memory.

According to one mode of implementation, step c) is restarted from a sample following the sample from which steps i to vi were previously restarted.

According to one mode of implementation, step e) is followed by a step of determining the digital data by averaging.

The invention also relates to a computer program which when implemented on a computer executes the steps of the preparation method according to the present invention.

The invention also relates to a computer program which when implemented on a computer executes the steps of the processing method according to the present invention.

The invention also relates to a transmitter device configured to implement the method of preparation according to the present invention.

The invention also relates to a receiver device configured to implement the processing method according to the present invention.

The invention also relates to a communication system which comprises the transmitter device and the receiver device according to the present invention.

Other characteristics and advantages of the invention will emerge from the detailed description which follows with reference to the appended figures in which:

There is a schematic representation of a radiofrequency communication system capable of being implemented within the scope of the present invention, more particularly, the radiofrequency system comprises a transmitter device and a receiver device;

There represents a flowchart reproducing the steps implemented for the execution of a data preparation method by a transmitter device of a communication system according to one aspect of the present invention, more particularly, the preparation method represented in comprises all the steps making it possible to prepare a data frame with a view to its transmission in the form of a radiofrequency signal to a receiver device of the communication system;

There is a schematic illustration of the process for preparing a data frame with a view to its transmission in the form of a radiofrequency signal according to the terms of the present invention;

There represents a flowchart reproducing the steps implemented for the execution, according to a first embodiment, of a data processing method by a receiver device of a communication system according to the present invention, more particularly, the method of treatment shown in comprises all the steps making it possible to process a data frame received in the form of a radiofrequency signal by a receiver device of the communication system;

There schematically represents the stages of analog-digital conversion and recording of the signal received by the receiver;

There presents in part and schematically the processing of a sample sequence implemented according to a first variant of the processing method executed according to the first and a second embodiment;

There presents in part and schematically the processing of a sample sequence implemented according to a second variant of the processing method executed according to the first and a second embodiment;

There represents a flowchart reproducing the steps implemented for the execution, according to a second embodiment, of the data processing method by a receiver device of a communication system according to the present invention, more particularly, the processing method represented to the comprises all the steps making it possible to process a data frame received in the form of a radiofrequency signal by a receiver device of the communication system;

There is a schematic representation of the steps implemented for the interleaving of bits, and in particular of all the bits of Ms sub-blocks S;

There is a matrix representation of Ms repetitions of a sub-block S;

There is a 4-repeat matrix representation of an S sub-block that includes 7 bits.

DETAILED DESCRIPTION OF THE INVENTION

A data preparation method and a radio frequency data processing method are disclosed. More particularly, the present invention relates to a method for preparing data with a view to their transmission in the form of a radio frequency signal from a transmitter device. The preparation of the data notably involves the consideration of an interleaving of data bits within an SD data frame intended to define the radio frequency signal. In this respect, the SD data frame is prepared, within the transmitter device, from a data block called the original block. More particularly, the original data block is divided into two sub-blocks called respectively sub-block S and sub-block D, in order to form a sub-frame Ss and a sub-frame Dd which when concatenated form the frame SD data. In particular, the sub-frame Ss comprises Ms repetitions of sub-blocks S of which all the bits are interleaved, while the sub-frame Dd comprises Md repetitions of the sub-blocks D.

The invention also relates to a method for processing a radiofrequency signal received by a receiver device. The radiofrequency signal is notably defined by the data frame SD which comprises in order the subframe Ss and the subframe Dd, the subframe Ss being formed from the interleaving of the data bits of Ms under -blocks S, and the sub-frame Dd being formed from Md sub-blocks D of data. The interleaving of the bits was obtained in particular according to a determined algorithm and parameters. The processing method makes it possible in particular to synchronize in phase and/or in frequency the receiver device and the transmitter device.

“Over-sampling” means the process of sampling a radio frequency signal at a sampling frequency significantly higher than the Nyquist rate. Theoretically, a bandwidth-limited signal can be perfectly reconstructed if sampled at Nyquist speed or above. The Nyquist rate is defined as twice the highest frequency component of the signal to be reconstructed.

There is a schematic representation of a communication system 1 formed by a transmitter device 2 and a receiver device 3. More particularly, the transmitter device 2 is configured to transmit a radiofrequency signal intended to be received by the receiver device 3. In this respect , before the transmission of the radio frequency signal, the transmitter device 2 implements a method for preparing an SD data frame to be transmitted in the form of a radio frequency signal. For its part, the receiver device 3 is configured to process said radiofrequency signal.

There illustrates all of the steps executed for the implementation of the method 100 for preparing an SD data frame, from digital data, intended to be transmitted in the form of a radiofrequency signal from the transmitter device 2 to the device receiver 3.

The digital data to be transmitted are, prior to their transmission, converted into an analog signal by a digital-analog converter of the transmitter device 2.

The process 100 for preparing the SD data frame comprises in particular the grouping 110 of the digital data in the form of a data block, called the original block 10 ( ). The original block 10 has in this respect a predetermined bit size which may be dependent on the targeted applications. In particular, the size in bits can be between 64 bits and 1024 bits, advantageously between 64 bits and 128 bits.

The preparation method 100 also comprises the execution of a division 120 of the original block 10 into two sub-blocks called, respectively, sub-block S and sub-block D. It is understood, without it being necessary to specify that the original block 10 corresponds to the concatenation, in order, of the sub-block S and the sub-block D ( ).

The preparation method 100 also comprises the generation 130 of a sub-frame Ss from the sub-block S. More particularly, the sub-frame Ss is constructed initially by Ms repetitions 140 of the sub-block S and in a second time by the interleaving 150 of the bits of the set of Ms sub-blocks S.

In this regard, the transmitter device 1 may include interleaving means, such as a computer or a microprocessor, configured to implement a predetermined interleaving algorithm involving a certain number of parameters. More particularly, the interleaving algorithm can be designed to prevent any correlation between the interleaved sub-blocks S within the sub-frame Ss.

In particular, the interleaving according to the terms of the present invention is executed so as to mix all the bits of the Ms sub-blocks S. The interleaving according to the present invention differs from the permutation in that the mixing of the bits is performed between the S sub-blocks. The interleaving does not modify the number of "1"s and "0"s present in the frame formed by the Ms S-sub-blocks, but simply their order. This interleaving therefore does not lead to spreading the transmission spectrum, as is the case with a scrambling operation, this is not its function.

Thus, as considered in the present invention and illustrated in , the original block 10 is formed by the concatenation, in order, of a sub-block S and a sub-block D. The sub-block S comprises a series of m bits named S1, S2, …., Sm, while the sub-block D comprises a series of k bits named D1, D2, …., Dk. It is understood that the sum of m and k is equal to the number of bits n of the original block 10.

The interleaving according to the present invention comprises, initially, Ms repetitions of the sub-block S. This repetition can in particular be represented in matrix form ( ). According to this matrix representation for any bit S _xy , x represents a repetition index of the sub-block S and y represents the position of the bit in the sub-block S.

In other words, each row of this matrix represents a repetition of the original sub-block S. Therefore, the bits in a column are identical.

The implementation of an interleaving algorithm according to the terms of the present invention by the transmitter device 2 makes it possible to construct a sub-frame Ss of Ms interleaved sub-blocks S. The subframe Ss notably has a length, in bits, corresponding to the product of m by Ms ( ).

The interleaving algorithm according to the present invention implements a plurality of IP routines making it possible to analyze each of the lines. In particular, an IP routine begins with the selection of data from a data line (or bits) in a specified order in order to position them in a sequence called an interlaced sequence SE and intended to form the subframe Ss. According to the present invention, an IP routine is executed in turn on each of the rows of the matrix representation of the .

As soon as an IP routine has been implemented on all the rows of the matrix representation, another IP routine is implemented. This other IP routine, during its execution, selects data, not selected during the execution of the previous IP routine(s).

Moreover, each IP routine, when it is implemented, can analyze the lines according to a predefined and therefore known order.

In addition, each IP routine selects a number of bits (called "SB number") greater than or equal to 1. Note, however, that the SB number can vary from one IP routine to another.

Furthermore, it is also understood that a given routine can be characterized by a plurality of numbers SB. In particular, the number of bits selected from one line to another can vary for a given IP routine. In particular, a routine IPi (i for i ^th routine IP) can be characterized by a set of numbers SBj (j being between 1 and Ms).

Also, when an IP routine parses a given row of the matrix of the , it can be agreed that it can only select certain bits. In particular, a bit S _(i+1)k , of a line i+1, cannot be selected by a given routine IP if said routine has already selected the bit S _ik of line i.

Furthermore, when an IP routine parses a given row of the matrix of the , it can be agreed that said routine cannot select bits S _(i+1)(k+1) and/or S _(i+1)(k-1) of a line i+1, if said routine has already selected bit S _ik of line i. This limitation is named in the remainder of the description “Minimum distance required between indices” or “DMI”. In the above statement, the DMI is equal to 1, but those skilled in the art may consider DMIs greater than or equal to 2.

In order to illustrate this aspect with in particular a DMI equal to 1, it is possible to consider a routine IPj parameterized to analyze the rows of the matrix of the one by one. This routine IPj is configured to select only one bit per line (in other words the routine IPj is characterized by a single number SB=1).

Thus, if routine IPj selects bit S _ik of row i of the matrix of the , said routine IPj can select any bit S _(i+1)l of row i+1 of the matrix of the as long as the absolute value of the difference between l and k is at least equal to 2.

In view of the above, an IP routine can be characterized by a plurality of parameters including:

- the SB number for each of the lines analyzed by the IP routine;

- the first row selected (named 1st SRi);

- the first selected bit (named 1st SB) in the first selected row;

- EMR;

- the order (named OR) in which all the lines are analyzed by the considered IP routine.

The routine IPi depending on these parameters can then be written: IP _i = ( [SB _i,1 , SB _i,2 ,..., SB _i,Mth ], 1 ^st SR _i , 1 ^st SB _i , MRID, OR _i ).

Thus, for example, a given IPi routine can analyze the lines in an ORi order from the first to the last line. In other words, the routine IPi analyzes in order line 1, line 2,…, line Ms, so that ORi=[1, 2, 3,…, Ms].

According to another example, the routine IPi can analyze firstly, and in their ranking order, the odd lines, and secondly, and in their ranking order, the even lines.

The number SB, for a given IP routine, can be constant for each of the lines analyzed by the considered IP routine. Under these conditions, the number of IP routines necessary to completely interleave the repeated data blocks is equal to m/SB. Furthermore, all the routines IP, after their execution, place together (m * SB * M _th ) bits in the interleaved sequence SE.

The parameters characterizing the routines IP _i = ( [SB _i,1 , SB _i,2 ,..., SB _i,Mth ], 1 ^st SR _i , 1 ^st SB _i , MRID, OR _i ) are according to the principles of the present invention known to the transmitter device, but also to the receiver device. More particularly, the receiver device must be capable of performing an interleaving inverse to that implemented by the transmitter device.

Furthermore, the deterministic information of any IP routine can be considered as a unique coding method which makes it possible to generate a semi-random data sequence from an initially periodic data stream (the repeated data blocks).

Finally, insofar as the interleaving algorithm takes into account the entire repeated sub-block S, the sub-frame Ss (formed by interlaced sequence SE) does not disclose any information on said sub-block S. Consequently, it is impossible for a receiving device to perform inverse interleaving without knowing the execution parameters.

In the rest of the statement, an example of a particular application of interleaving is given.

In this example, the sub-block S considered comprises m=7 bits, and is repeated Ms=4 times. There represents the matrix construction in which all the bits S _xy of the sub-block S are repeated line by line, for x ranging from 1 to 4 and y from 1 to 7. Still in this example, the number SB may be different for each lines and for each of the IP routines (noted in the order IP1, IP2, IP3, IP4, IP5, IP6, and IP7).

In particular, routine IP1 is characterized by the following SBi (for i ranging from 1 to 4):

- SB1=SB3=1;

- SB2=SB4=2.

Routine IP2 is characterized by the following SBi (for i ranging from 1 to 4):

- SB1=SB3=2;

- SB2=SB4=1.

Routine IP3 is characterized by the following SBi (for i ranging from 1 to 4):

- SB1=SB3=3;

- SB2=SB4=2.

Routine IP4 is characterized by the following SBi (for i ranging from 1 to 4):

- SB1=SB2=SB3=SB4=1.

Routine IP5 is characterized by the following SBi (for i ranging from 1 to 4):

- SB1=SB3=0;

- SB2=SB4=1.

Furthermore, the first line selected is, for each of the IP routines, the first line of the matrix of the .

Furthermore, the first bit selected for each of the IP routines is the first available bit of the first row (in other words, the very first bit selected for the first IP routine is bit S ₁₁ ). Still according to this example, the DMI index is equal to 2. Finally, the OR parameter imposes to analyze the rows in their order of classification in the matrix of the .

It thus results from the implementation of the interleaving algorithm a subframe Ss which takes the following form:

_S11 , _S23 , _S24 , _S36 , _S41 , S42, _S12 , _S13 , _S25 , _S37 , _S31 , _S43 , _S14 , _{S15 , S16 , S21} , _S22 , S ₃₄ , S ₃₅ , S ₃₂ , S ₄₄ , S ₄₅ , S ₁₇ , S ₂₆ , S ₃₃ , S ₄₆ , S ₂₇ , S ₄₇

The invention is not limited solely to the aspects previously exposed, and those skilled in the art may consider other algorithms making it possible to implement data interleaving.

It nevertheless remains understood that the interleaving as defined in the present invention makes it possible to construct a sub-frame Ss, from a sub-block S, in which all the bits are mixed by a known algorithm in order to eliminate any periodicity likely to appear during the repetition of the sub-blocks S. Thus, the interleaving makes it possible to construct from the repetition of Ms sub-blocks S of m bits, a sub-frame Ss of Ms*m bits interleaved so that the subframe Ss is formed by a succession of Ms groups of m bits and that at least one of these groups of m bits comprises a set of bits different from the other groups. Advantageously, each group of m bits comprises a set of bits different from the other groups.

In order to illustrate this aspect, the subframe Ss constructed in the preceding example is formed of 4 groups called respectively G1, G2, G3 and G4. Group G1 includes bits S ₁₁ , S ₂₃ , S ₂₄ , S ₃₆ , S ₄₁ , S ₄₂ , S ₁₂ . Group G2 includes bits S ₁₃ , S ₂₅ , S ₃₇ , S ₃₁ , S ₄₃ , S ₁₄ , S ₁₅ . Group G3 includes bits S ₁₆ , S ₂₁ , S ₂₂ , S ₃₄ , S ₃₅ , S ₃₂ , S ₄₄ . Group G4 includes bits S ₄₅ , S ₁₇ , S ₂₆ , S ₃₃ , S ₄₆ , S ₂₇ , S ₄₇ . Each group Gi (i ranging from 1 to 4) comprises a set of bits different from the other groups Gj (j ranging from 1 to 4 and different from i).

According to the proposed example, the sub-frame Ss comprises all the bits of the sub-block S repeated Ms times and mixed together. This algorithm thus makes it possible to generate a random sequence from periodic data. It functions in particular perfectly for generating non-periodic data, even when the sub-block S comprises a reduced number of bits.

The preparation method 100 also includes the generation 160 of a sub-frame Dd which comprises Md repetitions of the sub-block D. The data frame SD is then constructed 170 by concatenation, in order, of the sub-frame Ss and the Dd subframe.

In accordance with the above, the data frame thus prepared does not necessarily imply the addition of data.

Moreover, the size in bits Bs of the sub-block S is less than the size in bits Bd of the sub-block D.

For example, the size in bits Bs is between 2 bits and 64 bits, advantageously between 2 bits and 32 bits, even more advantageously between 10 bits and 20 bits.

Furthermore, the number Ms of repetitions of the sub-block S is greater than the number Md of repetitions of the sub-block D, for example Md is equal to 1.

The present invention can implement a preamble word. More particularly, the sub-block S can include a preamble word ("Sync Word" according to Anglo-Saxon terminology). This preamble word can advantageously be known to the receiver device 3.

Still advantageously, the sub-block S can be a header which corresponds to the address or to an identifier of the receiver device 3.

The advantages relating to these latter aspects will appear clearly in the remainder of the description.

The data frame SD, once formed, can be converted 180 into an analog signal, and more particularly, into a radiofrequency signal with a view to its transmission from the transmitter device 2 to the receiver device 3. As soon as it receives the radiofrequency signal defined by the data frame SD, the receiver device 3 proceeds to its processing 200.

There illustrates in this respect a processing method 200 in accordance with a first embodiment.

More particularly, the radiofrequency signal is initially received 205 by the receiver device 3.

As illustrated at , the receiver device 3 comprises an analog-digital converter CAN configured to convert the radiofrequency signal received 205 into digital data, and preferably binary. The analog-digital converter CAN generally operates with a delay, called the conversion delay denoted τ _e .

In this respect, the receiver device 3 also comprises an internal clock FH configured to impose a sampling of the received data. More particularly, the internal clock FH imposes a clock frequency, proportional, or even equal, to a sampling frequency at which the radiofrequency signal is likely to be converted into digital data by the analog-digital converter CAN.

In particular, the sampling frequency imposed by the internal clock FH corresponds to a period of time denoted T _E ( ). In the context of the present invention, the sampling frequency is an over-sampling frequency which thus translates the over-sampling applied by the analog-digital converter CAN to each data bit transmitted. More particularly, at the end of the conversion by the analog-digital converter, each data bit transmitted is represented by a certain number of samples recorded in a buffer memory MT, also called a register, of the receiver device 3. This number of samples is proportional to the oversampling frequency at which the ADC analog-to-digital converter operates. In other words, each transmitted bit translates in the register into a plurality of samples EC each taking the form of a bit.

Thus, and as illustrated in , the processing method 200 comprises the execution of a sampling step 210 of the radiofrequency signal received 205 at the oversampling frequency defined by the internal clock of the receiver device 3. The signal is then recorded 220 as it as the radio frequency signal is received 205 and sampled 210.

The samples EC resulting from this conversion are in particular recorded in the buffer memory MT of the receiver device 3. The recording step 220 can be carried out including by considering, where applicable, a write offset WS of the corresponding data in the buffer memory MT. This write offset may in particular depend on the conversion delay τe described above.

The conversion delay as well as the potential difference between the respective clocks of the transmitter device 2 and of the receiver device 3 are the source of a phase and/or frequency shift between said devices. It is then proposed in the present invention to carry out a phase and/or frequency adjustment in order to synchronize the receiver device 3 with the transmitter device 2.

To this end, the receiver device 3 can be configured to implement a computer program executing a sequence of steps making it possible to synchronize the signal received in phase and/or in frequency.

In particular, the computer program, when it is executed by the receiver device 3, takes into account the interleaving algorithm, and the parameters associated with it, implemented by the transmitter device 2. More particularly, the computer program implemented by the receiver device 3 is configured to perform inverse (or reciprocal) interleaving to that implemented by the transmitter device 2. In other words, the receiver device 3 is configured to implement an inverse interleaving which takes up the principles set out with regard to the interleaving carried out by the transmitter device 2.

Furthermore, the processing method 200 executed by the receiver device 3 also takes into account a certain number of parameters saved within said device, for example in a memory space of the receiver device 3, and among which are:

- the number of bits that a sub-block S comprises;

- the number of repetitions Ms of the sub-block S in the sub-frame Ss

- the approximate number of samples EC per data bit transmitted, this number depending on the oversampling frequency of the receiver device 3 and more particularly on a so-called nominal value oversampling frequency of the receiver device 3.

It is also understood that the processing method can also take into account other parameters, saved in the memory space of the receiver device 3, and among which are:

- the number of bits that a sub-block D comprises;

- the number of repetitions Md of the sub-block D in the sub-frame Dd.

The aforementioned parameters can be known and stored in the memory space of the receiver device 3 according to techniques known to those skilled in the art.

The consideration of the aforementioned parameters, and in particular stored in the memory space of the receiver device 3, makes it possible to implement the different stages of the processing method within the receiver device 3.

Thus, and still according to the embodiment, the processing method 200 comprises a sequence 230 of steps 230(i) to 230(vi). Step 230(i) comprises the selection of a sequence of samples SQ from a series of samples recorded in the buffer memory MT and having a size in bits at least equal to the size of the subframe Ss multiplied by a presumed number of samples per bit chosen from a set comprising a nominal value corresponding to the oversampling frequency, at least one value lower than the nominal value and at least one value higher than the nominal value.

Specifically, select step 230(i) is executed:

- for said assumed number of samples per bit; And

- from a given sample and at regular intervals of size equal to the assumed number of samples per bit.

The execution of the selection step 230(i) thus results in defining a first sequence of samples SQ having a size in bits of the subframe Ss. This sequence of samples SQ is likely to represent the subframe Ss.

In order to evaluate, or rather quantify, the level of representation that this sequence of SQ samples exhibits, the processing method 200 comprises the following steps which consist in processing said sequence of SQ samples.

In particular, step 230(ii) comprises the generation of a subframe S-1 by interleaving, said interleaving corresponding to the inverse interleaving having made it possible to form the subframe Ss from the Ms sub-blocks S ( And ).

The aspects relating to inverse interleaving use the same principles as the interleaving implemented within the framework of the preparation process.

The sub-frame S-1 is then split 230(iii) into a number Ms of test sub-blocks St ( And ).

The St test sub-blocks are then processed 230(iv). More particularly, the processing comprises the calculation of at least one average sub-block Sm and of a correlation measure MC on the basis of the at least one average sub-block Sm.

The at least one correlation measure calculated during step 230(iv) is saved during the execution of step 230(v). In particular, step 230(v) is executed so as to associate with the correlation measurement an index of the sample from which the selection was made and with the presumed number of samples per bit.

The calculation of an average sub-block Sm and the measurement of a correlation MC are carried out according to techniques known to those skilled in the art.

Steps 230(i) to 230(v) can be repeated 230(vi) from at least one other sample from which the previous selection was made.

It should be noted here that the order in which the starting samples of the various selections 230(i) to be performed are considered and the order in which the values of the presumed number of samples per bit are considered are of little importance. It may be easier, at least from a programming point of view, to go through them in a fixed order. For example, it seems easier to consider the first sample recorded in the register first, then the second, etc. For another example, the starting samples and the values of the presumed number of samples per bit to be considered could also be run through randomly, preferably excluding considering the same pair of these parameters twice, such consideration being useless. .

It is also to be considered that the writing of the samples in the buffer memory MT can be carried out indifferently in one direction or another. Also in this sense, the order in which the sending device 2 communicated the data frame may have to be considered. Indeed, independently of the order of the data blocks in the buffer memory MT of the receiver device 3, it is possible to implement the processing method 200 from a data subframe start sample Ss or of the sample at the expected end of the data subframe Ss, and this in particular in view of the prerequisites stated above.

The processing method also includes the determination 240, among the correlation measurements saved during the execution of one or more sequences 230, the correlation measurement corresponding to a greater correlation (that is to say the measurement presenting largest value among all saved measurements), and retrieve the index of the sample and the assumed number of samples per bit associated with this correlation measurement.

Finally, the processing method 200, according to this first embodiment, also comprises identification 250 of the sequence of samples selected from the index of the sample associated with the correlation measurement determined during the step 240, as corresponding to the subframe Ss and from which the data frame SD was constructed.

According to a first variant of this first embodiment illustrated in , processing step 230(iv) comprises in order:

- a distribution of the test sub-blocks St into two groups G1 and G2;

- for each group G1 and G2, the calculation of an average sub-block Sm;

- the calculation of a measure of correlation MC between the pair of average sub-blocks calculated previously.

The calculation of an average subgroup Sm and the correlation measurement implement techniques and algorithms known to those skilled in the art and are therefore, consequently, not described in the present invention.

According to a second variant of this first embodiment illustrated in , the sub-block S corresponds to a preamble word. To this end, said preamble word SyW is stored in the memory space of the receiver device 3. Thus, according to this second variant, the processing step 230(iv) comprises in order:

- the calculation of an average sub-block Sm from all the test sub-blocks St

- the calculation of a correlation measurement MC between the mean sub-block Sm calculated previously and the preamble word SyW stored in the memory space of the receiver device 3.

Whatever the variant considered, the processing method 200 according to this first embodiment makes it possible to execute phase synchronization on a reduced part of the data frame, and more particularly on the subframe Ss. reduce the complexity in terms of calculation, and consequently increase the data rate between the transmitting device and the receiving device.

More particularly, this phase synchronization makes it possible to determine the start of the data frame SD and thus to extract therefrom the subframe Ss and the subframe Dd.

Furthermore, the implementation of the processing method 200 can start before the entire SD data frame has been received by the receiver device 3.

The processing procedure 200, according to this first embodiment, can also comprise a frequency synchronization sequence. In particular, the processing method 200 may comprise the repetition of steps 230(i) to 230(v), before the execution of step 240, for at least one other value of the presumed number of samples per bit chosen from among the set comprising a nominal value corresponding to a nominal oversampling frequency of the receiver device 3, at least one value lower than said nominal value and at least one value higher than said nominal value. This sequence can in particular be executed in such a way as to save the calculated correlation measurements, by associating each correlation measurement with the index of the sample from which the selection was made and with the presumed number of samples per bit considered.

The addition of this sequence thus makes it possible to perform phase and frequency synchronization simultaneously.

Phase synchronization thus makes it possible to determine the beginning (and the end) of the SD data frame. It is thus possible to detect in said data frame SD the positioning of the sub-blocks D, and thus, in the event of repetition of the latter, to average them.

In other words, the processing method as described previously makes it possible, on the basis of a processing of a short sequence of the data frame (information relating to the sub-block S) to synchronize and extract the information relating to the whole of said frame. The required in terms of calculations are reduced, and also allow to consider a larger flow of data.

Furthermore, the processing method as described in the present invention limits data collisions. Indeed, the sub-block S can correspond to an identifier of the receiver device 3. In other words, the receiver device can be configured to recognize in the sub-block S a word corresponding to its identifier. More particularly, an SD data frame intended to be received by a particular receiver device, will carry a sub-block S corresponding to the identifier of the particular receiver device considered. In the event of a discrepancy between the sub-block S and the identifier of the particular receiving device, the latter may interrupt the processing process.

The processing method can be executed according to a second embodiment.

This second embodiment essentially takes up all the characteristics of the first embodiment.

There illustrates in this regard a processing method 300 in accordance with the second embodiment.

More particularly, the processing method 300 according to this second embodiment comprises the execution of steps 305, 310 and 320 which reproduce identically the terms of steps 205, 210 and 220 of the first embodiment of the processing method. 200.

Equivalent to processing method 200, processing method 300 also includes performing a sequence 330 that includes steps 330(i) through 330(vi). In this respect, steps 330(i) to 330(iv) which reproduce identically the terms of steps 230(i) to 230(iv) of sequence 230 of processing method 200.

Like step 230(iv), step 330(iv) can be executed according to either of the first and second variants illustrated, respectively, at and at the .

The at least one correlation measure calculated during step 330(iv) is saved during the execution of a step 330(v). In particular, this saving 330(v) is executed so as to associate with the correlation measurement an index of the sample from which the selection was made and with the presumed number of samples per bit.

The calculation of an average sub-block Sm and the measurement of a correlation MC are carried out according to techniques known to those skilled in the art.

Step 330(vi) includes comparing the correlation measure calculated in step 330(iv) with a predetermined threshold value.

The processing method also includes a sequence 340 based on the result of step 330(vi).

In particular, if the correlation measure is greater than the threshold value, the processing method 300 includes the execution of the following steps:

- associate the correlation measure with an index of the sample from which the selection was made and the assumed number of samples per bit;

- consider these two values as synchronization references for phase and frequency synchronization.

On the contrary, if the correlation measurement is lower than the threshold value, the processing method 300 comprises the execution of steps 330(i) to 330(vi) from at least one sample other than the sample from from which the previous selection was made.

It should be noted here that the order in which the starting samples of the various selections 330(i) to be performed are considered and the order in which the values of the presumed number of samples per bit are considered are of little importance. It may be easier, at least from a programming point of view, to go through them in a fixed order. For example, it seems easier to consider the first sample recorded in the register first, then the second, etc. For another example, the starting samples and the values of the presumed number of samples per bit to be considered could also be run through randomly, preferably excluding considering the same pair of these parameters twice, such consideration being useless. .

It is also to be considered that the writing of the samples in the buffer memory MT can be carried out indifferently in one direction or another. Also in this sense, the order in which the sending device 2 communicated the data frame may have to be considered. Indeed, independently of the order of the data blocks in the buffer memory MT of the receiver device 3, it is possible to implement the processing method 300 from a data subframe start sample Ss or of the sample at the expected end of the data subframe Ss, and this in particular in view of the prerequisites stated above.

The processing procedure 300, according to this second embodiment, can also comprise a frequency synchronization sequence. In particular, the processing method 300 may comprise the repetition of steps 330(i) to 330(vi), before the execution of step 340, for at least one other value of the presumed number of samples per bit chosen from among the set comprising a nominal value corresponding to a nominal oversampling frequency of the receiver device 3, at least one value lower than said nominal value and at least one value higher than said nominal value. This sequence can in particular be executed in such a way as to save the calculated correlation measurements, by associating each correlation measurement with the index of the sample from which the selection was made and with the presumed number of samples per bit considered.

The addition of this sequence thus makes it possible to perform phase and frequency synchronization simultaneously.

The present invention also relates to a computer program which when implemented on a computer executes the steps of the preparation method 100 according to the present invention.

The present invention also relates to a computer program which when implemented on a computer executes the steps of the processing method 200 or 300 according to the present invention.

The invention also relates to a communication system which comprises a transmitter device and a receiver device, the transmitter device being configured to implement the preparation method according to the present invention and the receiver device being configured to implement the processing method according to the present invention.

The implementation of the present invention, and in particular the processing method, makes it possible to synchronize in phase and/or in frequency the signal received by the receiver device. This synchronization also makes it possible to carry out a synchronized averaging of the sub-block S, but also of the sub-block D when Md is greater than 1.

Of course, the invention is not limited to the embodiments described and variant embodiments can be added without departing from the scope of the invention as defined by the claims.

Claims (19)

1. Method of preparing (100) an SD data frame, from digital data, to be transmitted in the form of a radio frequency signal from a transmitter device (2) to a receiver device (3), the method of preparing (100 ) including the following steps:
   a) grouping together (110) the digital data in the form of a data block, called the original block (10), having a determined size in bits;
   b) dividing (120) the original block (10) into two sub-blocks called, respectively, sub-block S and sub-block D;
   c) generating (130) a sub-frame Ss, said sub-frame Ss being generated from Ms repetitions (140) of the sub-block S, Ms being strictly greater than 1, the generation of the sub-frame Ss also comprising the execution of an interleaving (150) of all the bits of all the sub-blocks S,
   d) generating (160) a Dd subframe, said Dd subframe comprising Md repetitions of the D subframe;
   e) constructing (170) an SD data frame formed in the order of the Ss subframe and the Dd subframe, the data frame being intended to define the radio frequency signal to be transmitted.
2. Method of preparation (100) according to claim 1, in which the sub-block S forms a block called a preamble block capable of being stored in the memory of the receiver device (3) intended to receive the data frame in the form of a radio frequency signal.
3. A method of preparation (100) according to claim 1 or 2, wherein the size in bits Bs of the sub-block S is smaller than the size in bits Bd of the sub-block D.
4. Method of preparation (100) according to one of Claims 1 to 3, in which Ms is greater than Md, advantageously Md is equal to 1.
5. Preparation method (100) according to one of Claims 1 to 4, in which the interleaving of step c) is carried out in such a way as to construct from the repetition of Ms sub-blocks S of m bits, a sub -frame Ss of Ms*m interleaved bits and such that the subframe Ss is formed by a succession of Ms groups of m bits and that at least one of these groups of m bits comprises a set of bits different from the other groups , advantageously each group of m bits comprises a set of bits different from the set of the other groups.
6. A method of processing (200) a radio frequency signal received by a receiver device (3), the radio frequency signal being defined by a data frame SD which comprises in order a subframe Ss and a subframe Dd, the sub-frame Ss being formed from the interleaving of the data bits of Ms sub-blocks S, and the sub-frame Dd being formed from Md sub-blocks D of data, Ms and Md being integers, the interleaving of the bits having been obtained according to a determined algorithm and parameters, the concatenation, in order, of a sub-block S and of a sub-block D forming a data block called the original block (10) , the treatment method comprising the following steps:
   a) sampling (210) the radio frequency signal received according to an over-sampling frequency defined by the receiver device (3);
   b) progressively recording (220) the samples, resulting from the sampling carried out in step a), in a buffer memory of the receiver device (3);
   c) among a series of samples recorded in the buffer memory and having a size in bits at least equal to the size of the subframe Ss multiplied by an assumed number of samples per bit chosen from a set comprising a corresponding nominal value at an oversampling frequency, at least one value lower than the nominal value and at least one value higher than the nominal value:
   i. select (230i) a sequence of samples SQ from a given sample and at regular intervals of size equal to the presumed number of samples per bit;
   ii. generating (230ii) a subframe S-1 by interleaving the sequence of samples, said interleaving corresponding to the inverse interleaving having made it possible to form the subframe Ss from the Ms sub-blocks S;
   iii. splitting (230iii) the subframe S-1 into a number Ms of test sub-blocks St;
   iv. processing (230iv) the Ms test sub-blocks St, the processing of the Ms test sub-blocks St comprising calculating at least one average sub-block and a correlation measure based on the at least one sub-block -medium block;
   v. saving (230v) the at least one correlation measurement calculated in iv, by associating with said correlation measurement an index of the sample from which the selection was made and with the presumed number of samples per bit;
   vi. repeating (230vi) steps i to v from at least one other sample from which the previous selection was made;
   d) determining (240), among the saved correlation measurements, the correlation measurement corresponding to a greater correlation, and retrieving the index of the sample and the presumed number of samples per bit associated with this correlation measurement;
   e) identifying (250) the sequence of samples selected from the index of the sample associated with the correlation measure determined during step d), as corresponding to the subframe Ss and from which the SD data frame has been constructed.
7. A processing method according to claim 6, wherein said method further comprises a step d1) performed between steps c) and d), step d1) comprising, for at least another value of the assumed number of samples per bit chosen from among the set comprising a nominal value corresponding to a nominal oversampling frequency of the receiver, at least one value lower than said nominal value and at least one value higher than said nominal value, executing step c again), so in saving the calculated correlation measurements, by associating each correlation measurement with the index of the sample from which the selection was made and with the presumed number of samples per bit considered.
8. A method of processing (300) a radio frequency signal received by a receiver device (3), the radio frequency signal being defined by a data frame SD which comprises in order a subframe Ss and a subframe Dd, the subframe Ss being formed from the interleaving of the data bits of Ms sub-block S, and the sub-frame Dd being formed from Md sub-block D of data, Ms and Md being integers, the interleaving of the bits having been obtained according to a determined algorithm and parameters, the concatenation, in order, of a sub-block S and of a sub-block D forming a data block called the original block (10) , the treatment method comprising the following steps:
   a) sampling (310) the radio frequency signal received according to an over-sampling frequency defined by the receiver device (3);
   b) progressively recording (320) the samples, resulting from the sampling carried out in step a), in a buffer memory of the receiver device (3);
   c) among a series of samples recorded in the buffer memory and having a size in bits at least equal to the size of the subframe Ss multiplied by an assumed number of samples per bit chosen from a set comprising a corresponding nominal value at an oversampling frequency, at least one value lower than the nominal value and at least one value higher than the nominal value:
   i. select (320i) a sequence of samples SQ from a given sample and at regular intervals of size equal to the presumed number of samples per bit;
   ii. generating (320ii) a subframe S-1 by interleaving the sequence of samples, said interleaving corresponding to the inverse interleaving having made it possible to form the subframe Ss from the Ms sub-blocks S;
   iii. splitting (320iii) the subframe S-1 into a number Ms of test sub-blocks St;
   iv. processing (320iv) the Ms test sub-blocks St, the processing of the Ms test sub-blocks St comprising calculating at least one average sub-block and a correlation measure based on the at least one block AVERAGE ;
   v. saving (320v) the at least one correlation measurement calculated in iv, by associating with said correlation measurement an index of the sample from which the selection was made and with the presumed number of samples per bit;
   vi. comparing (320vi) the calculated correlation measure with a predetermined threshold value;
   if the correlation measurement is greater than the threshold value, perform the following steps:
   - associating the correlation measurement with an index of the sample from which the selection was made and with the presumed number of samples per bit;
   - consider these two values as the synchronization references for phase and frequency synchronization;
   if the correlation measure is less than the threshold value, then performing steps i again. see you from at least one other sample than the sample from which the previous selection was made.
9. Processing method (300) according to Claim 8, in which the said method comprises a step d1) comprising, for at least another value of the presumed number of samples per bit chosen from the set comprising a nominal value corresponding to a frequency of nominal over-sampling of the receiver device (3), at least one value lower than said nominal value and at least one value higher than said nominal value, the execution of step c again, so as to save the correlation measurements calculated, by associating each correlation measurement with the index of the sample from which the selection was made and with the presumed number of samples per bit considered.
10. Processing method (200, 300) according to one of Claims 6 to 9, in which the processing step iv) comprises in order:
    - a distribution of the test sub-blocks St into two groups;
    - for each group, the calculation of an average sub-block;
    - the calculation of a measure of correlation between the pair of average sub-blocks calculated previously.
11. Processing method (200, 300) according to one of Claims 6 to 9, in which the sub-block S is a block called a preamble block which is also stored in a memory of the receiver device (3), and in which the processing step iv) comprises in order:
    - the calculation of an average sub-block from the set of test sub-blocks St
    - the calculation of a measure of correlation between the mean sub-block previously calculated and the preamble block stored in the memory of the receiver device (3).
12. A processing method (200, 300) according to one of claims 6 to 11, wherein said given sample is initially the first sample stored in the buffer memory.
13. Processing method according to one of Claims 6 to 12, in which step c) is restarted from a sample following the sample from which steps i to vi were previously restarted.
14. Processing method according to one of Claims 6 to 13, in which step e) is followed by a step of determining the digital data by averaging.
15. Computer program which, when implemented on a computer, executes the steps of the preparation method (100) according to one of Claims 1 to 5.
16. Computer program which, when implemented on a computer, executes the steps of the processing method according to one of Claims 6 to 14.
17. Transmitter device (2) configured to implement the preparation method (100) according to one of Claims 1 to 5.
18. Receiver device (3) configured to implement the processing method according to one of Claims 6 to 14.
19. A communication system which comprises a transmitter device (2) according to claim 17 and a receiver device (3) according to claim 18.

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