Method and transmitter for transmitting data using a constellation

Abstract

A method is disclosed in a transmitter for a M=2 GHz signal divided into N subconstellations. m A method in a transmitter for transmitting data using a constellation having m-log2(N) symbols, where N and M are integers, and for any symbol in a reference sub-constellation, there exists a symbol with the same probability value in each of the other sub-constellations. The method comprises obtaining k groups of m-log2(N) shaped bits from a data source, each group of m-log2(N) shaped bits representing one symbol x in the reference sub-constellation. j , where j ∈ [1; k], and apply a systematic error correcting code to k groups of m-log2(N) shaped bits to obtain each symbol x j For each symbol x, we output one group of log2(N) parity bits. j using a group of at least log2(N) parity bits for k k symbols, and selecting symbols in the identified sub-constellation that are identified by m-log2(N) shaping bits; and transmitting each of the k selected symbols to a receiver via a communication channel.

Description

[Technical Field]

[0001] At least one of the embodiments generally relates to a method in a transmitter for transmitting data to a receiver over a communication channel, and at least one embodiment relates to a transmitter configured to implement the method. [Background technology]

[0002] In a communication system, a transmitter is coupled to a receiver by a communication channel (e.g., optical fiber). The transmitter typically includes an encoder configured to encode input data, e.g., a bit stream, into symbols belonging to a finite set called a constellation. One-dimensional ASK (Amplitude Shift Keying) and two-dimensional QAM (Quadrature Amplitude Modulation) are examples of such constellations. Here, a one-dimensional or two-dimensional constellation is one in which the symbols are R or R, respectively. 2 where R is a set of real numbers. These symbols are then transmitted over a communication channel to a receiver. The receiver includes a decoder configured to decode the received symbols into output data.

[0003] In communication systems in which uniformly distributed symbols are transmitted, shaping gains are typically not achieved. Therefore, it has been found that to approach the channel capacity, the transmitter should process the input data to change the probability distribution of the transmitted symbols. More precisely, the input data is processed so that the transmitted symbols have a non-uniform probability distribution that is adapted to the communication channel. This operation, called probability shaping, can result in energy savings, also known as shaping gains.

[0004] In addition to shaping, the signal must be protected against errors using so-called error correcting codes. Combining shaping and error correcting codes is complex.

[0005] Non-Patent Document 1 discloses a new coded modulation scheme that combines a distribution matcher for probabilistic shaping with a systematic error-correcting code at the transmitter. This method requires that the parity bits of the error-correcting code have an equal probability distribution, and therefore, the probability that a symbol is positive or negative is the same, so this method is suitable for shaping a symmetric distribution. However, this method is not suitable for shaping an asymmetric distribution. In addition, this method considers the sign bit as the shaping bit, and as a result, it is not compatible with a distribution matcher that changes the conditional distribution of the sign bit, which is not independent of the values ​​of other bits. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Boecherer et al., "Bandwidth Efficient and Rate-Matched Low-Density Parity-Check Coded Modulation", IEEE transactions on communications, vol. 63, no. 12, Dec. 2015 Summary of the Invention [Problem to be solved by the invention]

[0007] It is therefore desirable to find a way to transmit data that conforms to an asymmetric distribution and can be used by a distribution matcher that considers the sign bit as a shaped bit. [Means for solving the problem]

[0008] At least one embodiment of the present invention is directed to a multi-channel signal having M=2, which is divided into N sub-constellations in general. mA method in a transmitter for transmitting data using a constellation having N symbols, where N and M are integers, and for any symbol in a reference sub-constellation, there is a symbol in each of the other sub-constellations with the same probability value. The method comprises: Obtaining k groups of m-log2(N) shaped bits from a data source, each group of m-log2(N) shaped bits representing one symbol x in a reference sub-constellation; j Identify j∈[1;k], and obtain Apply a systematic error correcting code to k groups of m-log2(N) shaped bits to generate a j outputting one group of log2(N) parity bits per Each symbol x j identifying a sub-constellation using a group of at least log2(N) parity bits for m-log2(N) and selecting a symbol in the identified sub-constellation by m-log2(N) shaping bits; transmitting each of the k selected symbols to a receiver over a communication channel; Includes:

[0009] This method is compatible with distribution matchers that consider the sign bit as a shaping bit. In addition, this method is also compatible with asymmetric distributions.

[0010] In one embodiment, obtaining k groups of m-log2(N) shaped bits from a data source, each group of m-log2(N) shaped bits corresponding to one symbol x in a reference sub-constellation. j Identify j∈[1;k], and obtain Apply the distribution matcher to the data from the data source to obtain the k symbols x in the reference subconstellation. j and labeling each symbol with a group of m-log2(N) shaped bits using a labeling function; Includes:

[0011] In one embodiment, the labeling function is a natural labeling function.

[0012] In one embodiment, the labeling function is the Gray labeling function.

[0013] In one embodiment, N=2 and each symbol x j , identifying a sub-constellation using a group of at least log2(N) parity bits, and selecting a symbol identified by m-log2(N) shaping bits in the identified sub-constellation includes selecting a shift value in the set {0;2} according to the at least log2(N) parity bit group, and selecting a symbol based on the selected shift value. Sub Constellation symbol x j to obtain the symbol to transmit.

[0014] In one embodiment, selecting a shift value in the set {0;2} in response to at least log2(N) groups of parity bits includes selecting a shift value in response to doubling a modulo-2 sum of the groups of log2(N) parity bits and corresponding m-log2(N) shaping bits.

[0015] In one embodiment, the constellation is an M-ASK constellation.

[0016] In one embodiment, the data source is an equiprobable source.

[0017] At least one embodiment of the present invention is directed to a multi-channel signal having M=2, which is divided into N sub-constellations in general. m, wherein N and M are integers, and for any symbol in a reference sub-constellation, there is a symbol in each of the other sub-constellations with the same probability value. Obtaining k groups of m-log2(N) shaped bits from a data source, each group of m-log2(N) shaped bits representing one symbol x in a reference sub-constellation; j Identify j∈[1;k], and obtain Apply a systematic error correcting code to k groups of m-log2(N) shaped bits to generate a j outputting one group of log2(N) parity bits per Each symbol x j identifying a sub-constellation using a group of at least log2(N) parity bits for m-log2(N) and selecting a symbol in the identified sub-constellation by m-log2(N) shaping bits; transmitting each of the k selected symbols to a receiver over a communication channel; The device includes at least one processor configured to:

[0018] In one embodiment, obtaining k groups of m-log2(N) shaped bits from a data source, each group of m-log2(N) shaped bits corresponding to one symbol x in a reference sub-constellation. j Identify j∈[1;k], and obtain Apply the distribution matcher to the data from the data source to obtain the k symbols x in the reference subconstellation. j and labeling each symbol with a group of m-log2(N) shaped bits using a labeling function; Includes:

[0019] In one embodiment, the labeling function is a natural labeling function.

[0020] In one embodiment, the labeling function is the Gray labeling function.

[0021] In one embodiment, N=2 and each symbol x j , identifying a sub-constellation using a group of at least log2(N) parity bits, and selecting a symbol identified by m-log2(N) shaping bits in the identified sub-constellation includes selecting a shift value in the set {0;2} according to the at least log2(N) parity bit group, and selecting a symbol based on the selected shift value. Sub Constellation symbol x j to obtain the symbol to transmit.

[0022] In one embodiment, selecting a shift value in the set {0;2} in response to at least log2(N) groups of parity bits includes selecting a shift value in response to doubling a modulo-2 sum of the groups of log2(N) parity bits and corresponding m-log2(N) shaping bits.

[0023] Also disclosed is a computer program product comprising program code instructions that can be loaded into a programmable device, the program code instructions causing the programmable device to perform a method according to any one of the disclosed embodiments when the program code instructions are executed by the programmable device.

[0024] Also disclosed is a storage medium storing a computer program including program code instructions that, when read from the storage medium and executed by a programmable device, cause a method according to any one of the disclosed embodiments to be performed.

[0025] The characteristics of the invention will emerge more clearly from a reading of the following description of at least one example of embodiment, the said description being made with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a diagram illustrating a schematic diagram of a communication system in which the present embodiments can be implemented; [Figure 2] FIG. 1 illustrates symbols of an 8-ASK constellation. [Figure 3] FIG. 1 illustrates an example of a quantized target bit distribution for a 16-ASK constellation. [Figure 4] FIG. 1 shows a 16-ASK constellation of symbols and two sub-constellations of natural labeling according to one embodiment. [Figure 5] FIG. 1 illustrates an example of a quantized target bit distribution for an 8-ASK constellation. [Figure 6] 1 illustrates a method at a transmitter for transmitting binary data using a constellation with M=2 symbols according to a particular embodiment. [Figure 7] FIG. 1 illustrates an example of a target distribution of reference sub-constellations for a 16-ASK constellation according to one embodiment. [Figure 8A] FIG. 1 illustrates a method in a transmitter for transmitting binary data using a 16-ASK constellation defined as the union of two sub-constellations according to a particular embodiment. [Figure 8B] FIG. 1 illustrates a method in a transmitter for transmitting binary data using a 16-ASK constellation defined as the union of two sub-constellations according to a particular embodiment. [Figure 9A]FIG. 1 illustrates a method in a transmitter for transmitting binary data using a 16-ASK constellation defined as the union of two sub-constellations according to a particular embodiment. [Figure 9B] FIG. 1 illustrates a method in a transmitter for transmitting binary data using a 16-ASK constellation defined as the union of two sub-constellations according to a particular embodiment. [Figure 10A] FIG. 1 illustrates a reference sub-constellation and the last bit level probability of a 16-ASK constellation according to a particular embodiment. [Figure 10B] FIG. 1 illustrates a reference sub-constellation and the last bit level probability of a 16-ASK constellation according to a particular embodiment. [Figure 11] FIG. 2 is a diagram illustrating an example of a hardware architecture of a transmitter, according to certain embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0027] 1 shows a schematic diagram of a communication system 1 in which the present embodiment can be implemented. The communication system 1 comprises a transmitter 10 and a receiver 14 coupled to each other by a communication channel 12. The transmitter 10 is supplied with input data by at least one binary source S0 and outputs selected symbols in a given alphabet X of symbols. In one embodiment, the binary source S0 is equiprobable. The input data are, for example, bits of an audio / video bitstream. In one exemplary embodiment, the alphabet X is an M-ASK constellation, where M=2 m where M and m are integers. The symbols of the M-ASK constellation are defined as follows:

number

[0028] As a result, each symbol in this constellation can be represented by a sequence of m=log2M bits. Figure 2 shows the symbols of an 8-ASK constellation, where the first symbol is -7 and the last symbol is 7. In the following, various embodiments are described with respect to ASK constellations. However, it will be understood that the embodiments are not limited to ASK constellations. By way of example, the embodiments can also be used with one-dimensional constellations in which the symbols have values ​​different from those specified in the above equations, such as values ​​obtained using geometric shaping (in which case geometric and stochastic shaping are combined).

[0029] Referring to Figure 1, let X be a function of the probability distribution p(x i )=p(X i =x i ), x i Let p(y|x i ) for all x i For the Gaussian channel p(y|x i )~N(x i ,σ 2 ) as the channel distribution. Let Y be a random variable representing the communication channel output. For a Gaussian channel, Y is defined as Y = X + W, where W is Gaussian noise, e.g., W ∼ N(0, σ 2 )

[0030] For a Gaussian channel, the signal-to-noise ratio (SNR) is defined as:

number

number

number

[0031]

number

number

[0032] The goal of stochastic shaping is to process the inputs so that their probability distributions maximize or nearly maximize the mutual information I(X;Y). In other words, if the distribution of the inputs is such that

number

[0033] For M-ASK constellations, p(x) is often chosen as the MB distribution (Maxwell-Boltzmann distribution). In fact, in this case, the performance obtained is * (x) (i.e., for small ε,

number

[0034] According to the present principles, the target shaping distribution is quantized so that it can be expressed as the union of at least two subconstellations, where for any symbol with a given probability value pi in a first subconstellation, there is a symbol with the same probability value pi in the other subconstellation. Here, the first subconstellation is called the reference subconstellation and its distribution is called the reference distribution. In Figure 3, the distribution of the reference subconstellation is identified by the bold line.

[0035] In one embodiment, the target shaping distribution is quantized so that two adjacent symbols have the same probability value. This is the case for the distribution shown in Figure 3. For an M = 16-ASK constellation, log2(M) = 4 bits are required for symbol labeling. In one embodiment, the natural labeling of the symbols in this constellation is used and is provided by Table 1 below. [Table 1]

[0036] Bit level 4 is the sign bit and is used as a shaping bit. The first bit level b1, which is a parity bit, distinguishes the two sub-constellations as shown in Figure 4. Indeed, adjacent symbols with the same probability (according to Figure 3) have different values ​​of b1. Symbols with the same probability value have the same remaining labeling bits (bit levels 2 to 4), e.g., -15 and -13. Therefore, the overall 16-ASK constellation X is based on the standard Sub Constellation X r And this standard Sub The constellation can be expressed as a union of a shifted reference sub-constellation X r contains the symbols in the grey cells of Table 1, i.e. {-15;-11;-7,-3,1,5,9,13}. The second subconstellation contains the remaining symbols. In other words,

number

[0037] In another embodiment, a Gray labeling of the symbols in this constellation is used, as provided by Table 2 below. [Table 2]

[0038] As with natural labeling (Table 1), the overall 16-ASK constellation X is Sub Constellation X r And this standard Sub The constellation can be represented as a union with a shifted one. Bit level 1 is used as a parity bit and allows the distinction between the two sub-constellations. Indeed, adjacent symbols with the same probability (according to Figure 3) have different values ​​of b1. Consequently, as in the case of natural labeling, bits b2, b3 and b4 are represented as X r Used to label symbols in

[0039] Reference sub-constellation X r contains the symbols in the grey cells of Table 2 above. The second subconstellation contains the remaining symbols. However, unlike natural labeling, the rule for distinguishing the subconstellations depends on the values ​​of b2, b3 and b4, and more precisely on the value of the sum S. For each symbol, its bit-level sum S is calculated modulo 2. This sum S (last line of Table 2) is used in addition to the parity bit b1 to distinguish between the two subconstellations.

[0040] In another embodiment, the target shaping distribution is quantized so that two symbols that are not necessarily adjacent have the same probability value. In this case, the sub-constellations are not "shifted" from each other. This is the case for the distribution of the 8-ASK constellation shown in Figure 5, where symbols -3 and -5 have the same probability value but are not adjacent, while symbols -7 and -5 have the same probability value and are adjacent. In this figure, the distribution of the reference sub-constellation is identified by a bold line.

[0041] For an M=8-ASK constellation, log2(M)=3 bits are needed for labeling. The labeling of the symbols in this constellation is given by Table 3 below. [Table 3]

[0042] Bit level 3 is the sign bit and is used as a shaping bit. The first bit level distinguishes the two subconstellations. Symbols with the same probability value have the same remaining labeling bits (bit levels 2 and 3). Reference subconstellation X r contains the symbols in the grey cells of Table 3. The second subconstellation contains the remaining symbols.

[0043] This method can be extended to the case of more than two subconstellations, in which case for any symbol in the reference subconstellation, there exists a symbol with the same probability value in each of the other subconstellations. Given N subconstellations, where N is an integer, log2(N) bits are required to label and identify each of the N subconstellations. As a result, log2(N) parity bits are required for each symbol in the reference subconstellation to identify the subconstellation to which the symbol belongs.

[0044] FIG. 6 illustrates a specific embodiment of M=2 m 1 shows a method at a transmitter for transmitting data using a constellation having symbols.

[0045] In step S100, k groups of m-log2(N) shaped bits are obtained from a data source S. Each group of m-log2(N) shaped bits is assigned to a reference sub-constellation X r In a particular embodiment, the data sources S are equiprobable.

[0046] In one exemplary embodiment, the k groups of m-log2(N) bits are calculated by dividing the data from the data source S into k symbols {x1, x2,..., x} using a distribution matcher in step S100-1, as disclosed in FIG. k}, where each of the k symbols is a symbol of the reference sub-constellation X r The constant composition distribution matcher disclosed in Schulte et al.: "Constant composition distribution matching", IEEE Transactions on Information Theory 62(1), Nov. 2015, is an example of such a distribution matcher. Any other type of distribution matcher can also be used. The reference subconstellation X r The symbols in are approximately the reference subconstellation X r An example of such a target distribution is shown in Figure 7 when N=2 and the constellation is a 16-ASK constellation.

[0047] In step S100-2, for each symbol x, where j is an integer in [1;k], j ∈{x1,x2,...,x k} is a group b(x j) are labeled, where b(·) is a labeling function, such as the natural labeling function or the Gray labeling function. Thus, k symbols {x1, x2, ..., x k}, k groups of m-log2(N) shaped bits {b(x1),b(x2),...,b(x k )} is used as an input to the systematic error correcting code P. Thus, in step S104, each symbol x j For x, one group of log2(N) parity bits is output. j is the standard Sub Constellation X r An example of a systematic error correcting code is disclosed in Section VII of the above-mentioned non-patent document 1.

[0048] In step S106, each group of log2(N) parity bits identifies one subconstellation from among N subconstellations, and a symbol identified by the m-log2(N) shaping bits is selected in this identified subconstellation.

[0049] In step S108, the selected symbols are finally transmitted to the receiver over a communication channel.

[0050] FIG. 8A shows a method at the transmitter for transmitting data in the particular case where N=2 and natural labeling is used.

[0051] In step S100, k groups of m-1 shaped bits are obtained from a data source S. Each group of m-1 shaped bits is assigned to a reference sub-constellation X r Identify one symbol in

[0052] In one exemplary embodiment, the k groups of m-1 shaped bits are generated by using a distribution matcher in step S100-1 to match uniform data blocks of a data source S to k symbols {x1, x2,..., x k}, where x i is the reference sub-constellation X r Any type of distribution matcher can be used. The reference subconstellation X r The symbols in are approximately the reference subconstellation X r An example of the target distribution when N=2 and the constellation is a 16-ASK constellation is shown in Figure 7. In this case, the symbol x j ∈{x1,x2,...,x k Each} gives three formatting bits.

[0053] In step S100-2, for each symbol x, where j is an integer in [1;k], j ∈{x1,x2,...,x k} is a group b(x j ) are labeled using the natural labeling function. These symbols {x1,x2,...,x k}, the k groups of shaped bits {b(x1),b(x2),...,b(x k )} is used as an input to the systematic error correcting code P. Thus, in step S104, each symbol x j For each, one parity bit b1 j is output. Note that x j is the standard Sub Constellation X r It is a symbol in.

[0054] In step S106, each parity bit b1 j is the symbol x of the reference subconstellation in the set α={0,2}.j Shift value α j Therefore, the parity bit b1 j specifies in which subconstellation the symbol to be transmitted should be selected. As an example, the parity bit b1 j If = 0, then the symbol x j is from the first sub-constellation, while the parity bit b1 j If = 1, then the symbol x j is from the second sub-constellation. This is a convention, the opposite convention can also be used, in which case the parity bit b1 j If = 0, then the symbol x j is from the second sub-constellation, while the parity bit b1 j If = 1, then the symbol x j is from the first subconstellation. The determined shift value is the symbol x j is added to.

[0055] In step S108, the selected symbols are finally transmitted to the receiver via the communication channel. j If =0, the transmitted symbol is the symbol x in the reference subconstellation j and α j If =2, symbols in the shifted sub-constellation are transmitted.

[0056] FIG. 8B shows a method at the transmitter for transmitting data in the particular case where N=2 and Gray labeling is used.

[0057] In step S100, k groups of m-1 shaped bits are obtained from a data source S. Each group of m-1 shaped bits is assigned to a reference sub-constellation X r Identify one symbol in

[0058] In one exemplary embodiment, the k groups of m-1 shaped bits are generated by using a distribution matcher in step S100-1 to match uniform data blocks of a data source S to k symbols {x1, x2,..., x k}, where x i is the reference sub-constellation X r Any type of distribution matcher can be used. The reference subconstellation X r The symbols in are approximately the reference subconstellation X r An example of the target distribution when N=2 and the constellation is a 16-ASK constellation is shown in Figure 7. In this case, the symbol x j ∈{x1,x2,...,x k Each} gives three formatting bits.

[0059] In step S100-2, for each symbol x, where j is an integer in [1;k], j ∈{x1,x2,...,x k} is a group b(x j ) are labeled using the Gray labeling function. These symbols {x1,x2,...,x k}, the k groups of shaped bits {b(x1),b(x2),...,b(x k )} is used as an input to the systematic error correcting code P. Thus, in step S104, each symbol x j For each, one parity bit b1 j is output. Note that x j is the standard Sub Constellation X r It is a symbol in.

[0060] In step S106, each parity bit b1 j Regarding this parity bit b1 jand the associated shaping bits b(x j ) and the sum Sj is calculated modulo 2. That is,

number

[0061] In step S108, the selected symbols are finally transmitted to the receiver over a communication channel.

[0062] In the embodiments disclosed in Figures 6, 8A and 8B, the parity bits are used to identify one sub-constellation among the sub-constellations whose union forms a main constellation, e.g., a 16-ASK constellation. As a result, the code bits are available for the shaping operation. Code bit shaping can therefore be advantageously combined with systematic error correcting codes, as shown in Figures 9A and 9B.

[0063] 9A shows a method in a transmitter for transmitting binary data according to another embodiment, in the particular case where a 16-ASK constellation is considered and N=2. In this embodiment, natural labeling is used.

[0064] The target distribution shown in FIG. 7 can be realized as shown in FIG. 9A.

[0065] In step S100, three shaping bits b2 j b3 j b4 j k groups of , are acquired from the data source S0. Each group is assigned to a reference sub-constellation X r One symbol x in j In one particular embodiment, the second and third bit levels in Table 1, i.e., b2 j b3 j are equally likely and independent. Therefore, these two bits b2 j b3 j is obtained from a binary information source S0. The output of the information source S0 is used as the input of four binary DMs, namely DM1, DM2, DM3 and DM4. These binary DMs output four bit sequences identified as four binary unequal probability sources S1, S2, S3 and S4. The last bit level, i.e. the sign bit b4 j The probability of b2 j b3 j is chosen based on the value of p(b4 j |b2 j b3 j ) is chosen, and the probability is b1 j As a result, the switch is independent of the value of b2 j and b3 j Select a given unequal probability source (S1, S2, S3 or S4) based on the value of p(b4 j |b2 j b3 j ) are shown in Figure 10A.

[0066] In FIG. 10A, the parameter p i is b2 j and b3 j The last bit level b4 is conditioned on the value of j represents the probability of

[0067] In the particular case of a symmetric target distribution (for a Gaussian channel), i.e., p1'=p1 and p2'=p2, the number of unequal probability sources is divided by 2, and therefore the switch b2 j Select a given unequal probability source (S1 or S2) based on the value of b2. For example, j If =0, then S1 is selected, otherwise S2 is selected.

[0068] Taking this symmetry into account, the number of binary sources is divided by two and bit flipping is used, simplifying the shaping coder. This shaping method is disclosed in European Patent Application No. 21305730.0, filed June 1, 2021.

[0069] The symbols {x1,x2,...,x k}, k groups of shaped bits {b2 j b3 j b4 j} j∈[1;k] is used as an input to the systematic error correcting code P. Thus, in step S104, each symbol x j One parity bit b1 per j is output. Note that x j is the standard Sub Constellation X r It is a symbol in.

[0070] In step S106, each parity bit b1 j specifies one subconstellation from among the N subconstellations, and in this specified subconstellation, j b3 j b4 j} The symbol specified by the shaping bits is selected.

[0071] In step S108, the selected symbols are finally transmitted to the receiver over a communication channel.

[0072] 9B shows a method in a transmitter for transmitting binary data according to another embodiment, in the particular case where a 16-ASK constellation is considered and N=2. In this embodiment, Gray labeling is used.

[0073] The target distribution shown in FIG. 7 can be realized as shown in FIG. 9B.

[0074] In step S100, three shaping bits b2 j b3 j b4 j k groups of , are obtained from the data source S0. Each group is a reference sub-constellation X r One symbol x in j In one particular embodiment, the second and fourth bit levels in Table 2, i.e., b2 j b4 j are equally likely and independent. Therefore, these two bits b2 j b3 j is obtained from a binary information source S0. The output of the information source S0 is used as the input of four binary DMs, namely DM1, DM2, DM3 and DM4. These binary DMs output four bit sequences identified as four binary unequal probability sources S1, S2, S3 and S4. The third bit level, i.e. bit b3 j The probability of b2 j and b4 j is chosen based on the value of p(b3 j |b2 j b4 j ) is chosen, and the probability is b1 j As a result, the switch is independent of the value of b2 j and b4 j Select a given unequal probability source (S1, S2, S3 or S4) based on the value of p(b3 j |b2 j b4 j ) are shown in Figure 10B. In Figure 10B, the parameter p iis b2 j and b4 j The third bit level b3, conditional on the value of j In the specific case where p1'=p1 and p2'=p2, p(b3 j |b2 j b4 j )=p(b3 j |b2 j ) In this case, the number of unequal probability sources is divided by 2, so the switch is b2 j Select a given unequal probability source (S1 or S2) based on the value of b2. For example, j If =0, then S1 is selected, otherwise S2 is selected.

[0075] The symbols {x1,x2,...,x k}, k groups of shaped bits {b2 j b3 j b4 j} j∈[1;k] is used as input to a systematic error correcting code P, so that in step S104, each symbol x j One parity bit b1 per j is output. Note that x j is the standard Sub Constellation X r It is a symbol in.

[0076] In step S106, each parity bit b1 j Regarding this parity bit b1 j and the associated shaping bits b(x j ) and the sum Sj is calculated modulo 2. That is,

number

[0077] In step S108, the selected symbols are finally transmitted to the receiver over a communication channel.

[0078] FIG. 11 illustrates a schematic diagram of an example hardware architecture for transmitter 10, according to a particular embodiment.

[0079] The transmitter 10 comprises a processor or CPU (Central Processing Unit) 111, a random access memory RAM 112, a read-only memory ROM 113, a storage unit 114 such as a hard disk or a storage media reader, e.g., an SD (Secure Digital) card reader, and at least one set of communication interfaces COM 115 that enable the transmitter 10 to send and receive data, connected by a communication bus 110.

[0080] The processor 111 is capable of executing instructions loaded into the RAM 112 from the ROM 113, from an external memory (such as an SD card), from a storage medium (such as a HDD), or from a communication network. When the transmitter 10 is powered on, the processor 111 is capable of reading and executing instructions from the RAM 112. These instructions form a computer program that causes the processor 111 to perform the methods described in Figures 6 and 8A-9B.

[0081] The methods described with respect to Figures 6, 8 and 9 may be implemented in the form of software by execution of a set of instructions by a programmable machine, for example a DSP (Digital Signal Processor), microcontroller or GPU (Graphics Processing Unit), or in the form of hardware by a machine or dedicated component (chip or chipset), for example an FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit). Generally, the transmitter 10 includes electronic circuitry adapted and configured to perform the methods described in Figures 6, 8 and 9.

Claims

1. M=2 ｍ 1. A method in a transmitter for transmitting data using a constellation having symbols, the constellation having a quantized target shaping distribution expressed as a union of N sub-constellations, N and M being integers, wherein for any symbol in a reference sub-constellation belonging to the N sub-constellations, there exists a symbol with the same probability value in each of the other sub-constellations of the N sub-constellations, each of the other sub-constellations being a shifted version of the reference sub-constellation, the method comprising: m-log from data source ２ Obtaining k groups of (N) shaped bits, ２ Each group of (N) shaped bits corresponds to one symbol x in the reference sub-constellation. ｊ Identifying j∈[1;k], and obtaining The systematic error correcting code is m-log ２ applied to k groups of (N) shaped bits to each of the symbols x ｊ per log ２ outputting one group of (N) parity bits; Each of the symbols x ｊ For at least the log ２ (N) groups of parity bits are used to identify a sub-constellation, and the m-log ２ selecting a symbol identified by the (N) shaping bits; transmitting each of the k selected symbols to a receiver over a communication channel; A method comprising:

2. m-log from the data source ２ Obtaining k groups of (N) shaped bits, ２ Each group of (N) shaped bits corresponds to one symbol x in the reference sub-constellation. ｊ Identifying j∈[1;k], obtaining Applying a distribution matcher to the data of the data source to obtain k symbols x in the reference sub-constellation ｊ and Using a labeling function, m-log ２ labeling groups of (N) shaped bits; The method of claim 1 , comprising:

3. The method of claim 2 , wherein the labeling function is a natural labeling function.

4. The method of claim 2 , wherein the labeling function is a Gray labeling function.

5. N=2, and each of the symbols x ｊ For at least the log ２ (N) groups of parity bits are used to identify a sub-constellation, and the m-log ２ Selecting a symbol specified by the (N) shaping bits is performed by selecting at least the log ２ (N) parity bit groups, and select a shift value in the set {0; 2}, and assign the selected shift value to the symbol x of the reference sub-constellation. ｊ 5. The method of claim 1, further comprising adding to obtain the symbol to be transmitted.

6. The at least the log ２ Selecting a shift value in the set {0;2} according to the (N) parity bit groups is ２ A group of (N) parity bits and the corresponding m-log ２ 6. The method of claim 5, including selecting a shift value according to doubling a modulo-2 sum with the (N) shaping bits.

7. The method according to any one of claims 1 to 4, wherein the constellation is an M-ASK constellation.

8. The method of any one of claims 1 to 4, wherein the data source is an equiprobable source.

9. M=2 ｍ 1. A transmitter configured to transmit data using a constellation having symbols, the constellation having a quantized target shaping distribution expressed as a union of N sub-constellations, N and M being integers, wherein for any symbol in a reference sub-constellation belonging to the N sub-constellations, there exists a symbol with the same probability value in each of the other sub-constellations of the N sub-constellations, each of the other sub-constellations being a shifted version of the reference sub-constellation, the transmitter comprising: m-log from data source ２ Obtaining k groups of (N) shaped bits, ２ Each group of (N) shaped bits corresponds to one symbol x in the reference sub-constellation. ｊ Identifying j∈[1;k], and obtaining The systematic error correcting code is m-log ２ applied to k groups of (N) shaped bits to each of the symbols x ｊ per log ２ outputting one group of (N) parity bits; Each of the symbols x ｊ For at least the log ２ (N) groups of parity bits are used to identify a sub-constellation, and the m-log ２ selecting a symbol identified by the (N) shaping bits; transmitting each of the k selected symbols to a receiver over a communication channel; a transmitter comprising at least one processor configured to:

10. m-log from the data source ２ Obtaining k groups of (N) shaped bits, ２ Each group of (N) shaped bits corresponds to one symbol x in the reference sub-constellation. ｊ Identifying j∈[1;k], obtaining Applying a distribution matcher to the data of the data source to obtain k symbols x in the reference sub-constellation ｊ and Using a labeling function, m-log ２ labeling groups of (N) shaped bits; 10. The transmitter of claim 9, comprising:

11. The transmitter of claim 10 , wherein the labeling function is a natural labeling function.

12. The transmitter of claim 10 , wherein the labeling function is a Gray labeling function.

13. N=2, and each of the symbols x ｊ For at least the log ２ (N) groups of parity bits are used to identify a sub-constellation, and the m-log ２ Selecting a symbol specified by the (N) shaping bits is performed by selecting at least the log ２ (N) parity bit groups, and select a shift value in the set {0; 2}, and assign the selected shift value to the symbol x of the reference sub-constellation. ｊ to obtain the symbol to transmit.

14. The at least the log ２ Selecting a shift value in the set {0;2} according to the (N) parity bit groups is ２ A group of (N) parity bits and the corresponding m-log ２ 14. The transmitter of claim 13, including selecting a shift value in response to doubling a modulo-2 sum with the (N) shaping bits.

15. A computer program comprising program code instructions loadable into a programmable device, said program code instructions causing the programmable device to perform a method according to any one of claims 1 to 4 when said program code instructions are executed by said programmable device.

16. 10. A storage medium storing a computer program including program code instructions which, when read from the storage medium and executed by a programmable device, cause the method of any one of claims 1 to 4 to be performed.

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