Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
  • H04L1/0056—Systems characterized by the type of code used
  • H04L1/0067—Rate matching
  • H04L1/0068—Rate matching by puncturing
  • H04L1/0069—Puncturing patterns
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
  • H04L1/0009—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the channel coding
  • H04L1/0013—Rate matching, e.g. puncturing or repetition of code symbols
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
  • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
  • H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
  • H04L1/0041—Arrangements at the transmitter end
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
  • H04L1/0045—Arrangements at the receiver end
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
  • H04L1/0056—Systems characterized by the type of code used
  • H04L1/0067—Rate matching
  • H04L1/0068—Rate matching by puncturing

Definitions

• TITLE Process for transmitting data with variable puncturing within a constellation symbol
• the present invention relates to the field of telecommunications.
• the invention relates more particularly to the methods of transmitting data from a first telecommunications equipment to a second equipment with a puncturing of the data after coding and before transmission by the antenna. It applies in particular to portable telecommunications devices which establish a communication via a base station or an access point.
• a radio access network generally consists of several base stations or access points which allow a user equipment (UE: User Equipment according to the English terminology) also later called a terminal or UE, to have access to a telecommunications network and establish communication to exchange data.
• UE User Equipment according to the English terminology
• UE User Equipment
• the communications transmission medium is commonly referred to as the transmission or propagation channel, originally in reference to an air channel and by extension in reference to any channel.
• Wireless systems have a so-called RF transmission interface when it is a telecommunications system with aerial transmission of a signal belonging to a radio band (for example, of the 5G NR, 4G, GSM, UMTS type). , IEEE 802.1 lx, IEEE 802.16e, etc).
• the data transmitted may be subject to disturbances due to interference introduced by the transmission channel and/or due to noise sources.
• a widely known and used technique consists in adding redundancy to the data by means of an encoder sometimes called a channel encoder.
• the coding efficiency of the channel coder may have to meet certain constraints, for example be fixed in a telecommunications standard published by a group, for example 3GPP, IEEE. In some cases, punching must be implemented after coding to adapt the yield.
• the invention proposes a communication method having the objective of improving the protection of the data transmitted.
• the subject of the invention is a method for transmitting data implemented by a first piece of equipment intended for a second telecommunications piece of equipment.
• the invention further relates to telecommunications equipment intended to communicate with a second equipment.
• the input data are encoded by the same encoder to add redundancy and generate a stream of undifferentiated bits.
• Post-encoding puncturing is notable in that it distinguishes between encoded data according to which bits of a constellation symbol it is mapped to. According to a representation of the constellation according to two perpendicular axes which define four quadrants, the most significant bit of a set of bits mapped on a symbol is by convention the one which is located to the left of the set.
• a x 2 QAM modulation can be constructed by combining two x-order amplitude modulations in phase and quadrature, one carried by the I axis and the other by the Q axis in the baseband representation of digital modulation.
• the method advantageously makes it possible to maintain the same data transmission bit rate while guaranteeing better protection for the data transmitted.
• the data transmission method is such that each symbol of the constellation comprises at least one most significant bit and one least significant bit and such that the puncturing of the data is different between data mapped on the most significant bit and data mapped to the least significant bit of the same symbol.
• the data transmission method is such that the puncturing of the data is also a function of the position of the symbol in the constellation on which these data are mapped after puncturing.
• variable protection also takes into account the position of the symbol in the constellation.
• the transmitted symbols experience phase rotation.
• a phase error which exceeds a threshold dq induces a change of decision region for the symbols at the periphery of the constellation during the decoding of these symbols on reception.
• the method makes it possible in particular to increase the protection of the complex symbols at the periphery of the constellation and consequently to fight specifically against particular noise sources such as of the phase noise type which more particularly affect these symbols at the periphery.
• the method thus makes it possible to limit the interference due to these sources of noise.
• the data transmission method is such that the position of the symbol is determined by calculating a metric for evaluating the distance of the symbol from the center of the constellation.
• the calculation of the distance of the symbol from the center of the constellation gives the possible positions of the symbol on a circle of radius equal to the calculated distance.
• the symbols for which the calculated distance is the greatest correspond to periphery symbols. These symbols are the most sensitive to phase rotation.
• the data transmission method is such that: the puncturing of the data is according to at least two different levels of protection respectively for data mapped on bits of different weights of the same symbol, the puncturing comprises at least one punching step comprising a 1st punching matrix, the output of which feeds a demultiplexing having a 1st and a 2nd output, the 2 nd output feeding a 2 nd puncturing matrix to define at least two different levels of protection obtained respectively with the 1 st demultiplexing output and the output of the 2 nd puncturing matrix.
• the telecommunications equipment is such that the puncher comprises: an elementary structure comprising a 1st punching matrix whose output feeds a demultiplexing having a 1st and a 2nd output, the 2nd output feeding a 2 nd punching matrix to define the at least two different levels of protection obtained respectively with the 1 st output of the demultiplexing and the output of the 2 nd punching matrix.
• the puncturing of the data after coding is carried out by implementing at least two puncturing matrices separated by demultiplexing.
• Demultiplexing makes it possible to distribute the output data i.e. associated with different protection levels to obtain a determined bit rate on each of these outputs. This mode is much less complex than known techniques with several encoders in parallel to deliver high throughputs.
• the data transmission method is such that any puncturing step referred to as the previous step is followed by a new puncturing step whose 1 st matrix is common with the 2 nd matrix of the previous step, to define an additional different level of protection obtained with the output of the 2 nd punching die of the new punching step.
• each addition of a puncturing step makes it possible to obtain a new coding yield different from the previous ones and associated with the new level of protection. This mode thus makes it possible to increase the punching order with great simplicity.
• the data transmission method is such that, a puncturing ratio being associated with each puncturing matrix, these ratios are determined for an identical bit rate on each of the outputs of the 2 nd puncturing matrices of the steps puncturing, for a given modulation order and coding rate.
• the data transmission method is such that, a puncturing ratio being associated with each puncturing matrix, a change in data protection levels is obtained by modifying the ratio of at least one of the matrices punching.
• the data transmission method is such that the puncturing difference between data mapped on the same symbol occurs for all the symbols of the constellation. According to one embodiment, the data transmission method is such that the puncturing difference between data mapped on the same symbol only occurs for some of the symbols of the constellation.
• the communication method is such that it comprises: demodulation of the symbols with demapping of the data, de-puncturing of the data after demapping of the data, the puncturing of the data on transmission being different according to the weight of the bits in a symbol on which the data are mapped, data decoding after de-puncturing.
• the communication method is such that the de-puncturing of the data also takes into account a puncturing on transmission depending on the position of the symbol in the constellation on which these data are mapped.
• the equipment comprises: a demodulator for demodulating symbols with demapping of the data, a de-puncturing device for de-puncturing the data after demapping the data, the puncturing of the data on transmission being different depending on the weight of the bits in a symbol on which the data is mapped, a decoder for decoding the data after de-puncturing.
• the invention further relates to a computer program on an information medium, said program comprising program instructions adapted to the implementation of a method according to the invention when said program is loaded and executed in a telecommunications equipment.
• the invention further relates to an information carrier comprising program instructions suitable for implementing a method according to the invention, when said program is loaded and executed in telecommunication equipment.
• the invention further relates to a digital signal comprising data transmitted by a first equipment to a second equipment, the transmitted data being mapped on symbols of a constellation, each symbol of the constellation comprising at least two bits of weight different, the data having been punctured differently before mapping depending on the weight of the bits in a symbol on which this data is mapped.
• FIG 1 is a diagram of an embodiment of a transmission chain according to the invention.
• Figure 3 is a representation of a 16-QAM modulation in an (I,Q) frame that respects Gray coding with illustration of decision regions,
• FIG 4 is a diagram of an embodiment of a reception chain according to the invention.
• Figure 5 is a representation of a 64-QAM modulation in an (I,Q) frame that respects Gray coding with illustration of decision regions,
• Figure 6 is a representation of a 16-QAM modulation in an (I,Q) frame that respects Gray coding with identification of the positions farthest from the center and indication of an angle Q,
• Figure 7 is a representation of a 16-QAM modulation in an (I,Q) frame with illustration of decision regions and with indication of the impact of a rotation of an angle Q on the position of certain symbols,
• FIG 8 is a diagram of an embodiment of the elementary structure of the punch according to the invention connected at the output of the encoder to obtain two levels of protection,
• Figure 9 is a diagram of an embodiment of a cascade assembly of the elementary structure of the punch according to the invention to obtain three levels of protection
• FIG 10 is a diagram of an embodiment of the elementary structure of the punch according to the invention connected to the output of the encoder with a diagram of an equivalent representation of this structure with the encoder,
• Figure 11 is a representation of a 64 QAM modulation with the distinction of three zones Z1, Z2, Z3 of symbols according to their distance from the center of the constellation.
• the general principle of the invention is based on a puncturing of data to be transmitted which makes it possible to distinguish at least two different levels of protection associated respectively with the data mapped on bits of different weight of the symbols of a constellation associated with a digital modulation.
• the difference in level of protection between data mapped on the same symbol is implemented according to the invention for all the symbols or for only one symbol or certain symbols of the constellation.
• the puncturing of the data can also make it possible to distinguish at least two other different levels of protection associated respectively with the data mapped on symbols of a constellation located at different positions. In other words, depending on whether a piece of data is mapped on a symbol positioned at a certain point in the constellation or on a symbol positioned at another point in the constellation, then it does not benefit from the same puncturing ratio.
• the difference in level of protection between data mapped on different symbols of the constellation is implemented according to the invention for all the symbols or for only certain symbols of the same constellation.
• FIG. 1 is a diagram of an embodiment of a transmission chain for implementing a method according to the invention.
• This transmission chain is part of telecommunications equipment which can just as well be a base station SB as a terminal Tal such as a smartphone.
• the chain includes at least one channel COD encoder, one POIN puncher and one MAP modulator.
• the data transmission method 10 is implemented by the equipment SB/Tal.
• the method is such that, for at least one of the M symbols, the puncturing of the data is different depending on the weight of the bits in the symbol on which this data is mapped.
• the transmission 14 of the data after mapping is intended for another telecommunications equipment which can just as well be a terminal as a base station.
• the COD channel coder carries out the coding 11 of the input binary data coming from an information source which can just as well be a microphone of a mobile terminal as a local or remote application such as a short message application. (SMS), a multimedia content transmission application.
• SMS short message application.
• the encoder introduces binary redundancy to the input data with a coding rate Ri to output binary data with a certain rate.
• the POIN punch performs the punching 12 of the data after channel coding.
• the puncturing of the data after coding is carried out by implementing several puncturing matrices with a demultiplexer between two matrices. Punching makes it possible to increase the useful bit rate of information for a fixed bit rate.
• the MAP modulator 13 modulates the data after puncturing to generate at output complex modulated symbols associated with a modulation.
• the transmitter EM transmits the data after modulation via a transmission antenna ANT E in the form of a signal Se.
• the signal transmitted by the ANT E antenna generally comes from the modulation of a so-called RF (Radio Frequency) carrier by the modulating signal which carries the data.
• RF Radio Frequency
• the encoded data is arranged into a block of binary data and the modulation by the MAP modulator maps this binary data onto the symbols of a constellation to construct the signal which is involved in modulating the RF carrier.
• the data mapping can respect a so-called Gray coding.
• the modulating signal of the RF carrier described in baseband carries the information to be transmitted and is represented in the form of complex symbols distributed in the (I,Q) plane on which the data have been mapped.
• Each symbol of the constellation comprises at least one most significant bit and one least significant bit.
• the MAP modulator maps the data on a symbol among M symbols of a constellation of order M, M ⁇ 4 while respecting the constraint that data mapped on the most significant bit and data mapped on the least significant bit of the same symbol have been punched differently.
• the mapping thus covers a so-called binary-to-symbol coding operation which can be described as a transformation of a binary set ⁇ b k-1 , b k-2 ,..., bo ⁇ into a symbol S c of the constellation.
• the transformation generally respects a Gray coding and a specific combination of bits is assigned to each relative integer of the alphabet A.
• a Gray coding is deduced from a so-called pure binary coding.
• a pure binary coding is based on the operations of addition and multiplication in the Galois field formed of the integers ⁇ 0,1 ⁇ where the addition corresponds to the logical operation Exclusive OR and the multiplication to the logical ⁇ T' operation.
• the increment in the M-ary alphabet of a relative number (2p+1) to 2(p+1)+1 is achieved by adding (exclusive OR addition a bit of weight low equal to 1 on the current binary code word to generate the new binary code word associated with the symbol 2(p+11+1. p an integer.
• the most significant bit (MSB or Most Significant Bit b k-1 ) is the bit, in a given binary representation, having the largest weight or the largest position (the one on the left in the usual positional notation), that is the most robust bit to state transitions from one symbol to another.
• the least significant bit (LSB or Least Significant Bit) is the bit, in a given binary representation, having the smallest weight or the smallest position (the one on the right in the usual positional notation). It corresponds to the elementary unit of variation (of state) of a symbol.
• This concept of weight of bit in a symbol relates to the mode of construction of a coding pure binary where the robustness to state transitions increases with the weight of the bit in each codeword, i.e. with its position in the codeword.
• Gray coding is a specific coding derived from pure binary coding which only modifies two successive binary code words by one bit (a code word is the binary representation of the M-ary symbol). This Gray code minimizes the transition errors from one code word to another when the state index (index of the M-ary symbol) is incremented by 1.
• the transition from pure binary coding to Gray coding is done by performing an Exclusive OR (0) operation on the bits of a pure binary code word.
• Gn b n ⁇ b n +i
• G MSB b MSB (1) where b n and bn+i are two bits in the same code word of a pure binary coding at positions n and n+1 and respectively of weight n and n+1. The most significant bit is the leftmost bit in the representation of a pure binary coding.
• the weight of the bits in a symbol is prioritized according to its robustness to a binary-to-symbol decoding error.
• the combination of the two modulations generates the QAM modulation with M states to which corresponds a constellation with M symbols S m .
• the complex symbols of the signal modulating the RF carrier are each formed of 2xlog2(N) bits (b 2k-1 , b 2k-2 ,. b k, b k-1 ,. . bo ⁇ where ⁇ b 2k-1 , b 2k-2 ,. b k ⁇ describes the binary coding of in-phase amplitude modulation and ⁇ b k-1 , b k- 2,..
• bo ⁇ describes the binary coding of amplitude modulation in quadrature as given in [Table 3] in the Appendix
• the symbols are distributed in the I, Q plane in such a way that the adjacent symbols differ by only one bit in accordance with the Gray coding according to a determined position with respect to at the symbol of index 0 as illustrated by FIG. 3 for a 16-QAM modulation.
• the I and Q channels are modulated and demodulated independently.
• FIG. 4 is a diagram of an embodiment of a reception chain for the implementation of a communication method according to the invention.
• This reception chain is part of telecommunications equipment which can just as easily be a terminal Tal such as a smartphone or a base station SB.
• This chain performs at least the opposite functions to those on transmission illustrated in figure 1.
• This reception chain includes at least a DEMAP demodulator, a DEPOIN de-puncturing device and a DECOD decoder.
• the communication method 20 comprises at least the demodulation 22 of the symbols with demapping of the data, the de-puncturing 23 of the data after demapping of the data, the decoding 24 of the data after de-puncturing by the Tal/SB equipment.
• the DEMAP demodulator performs a demapping function 22 inverse to that implemented by the MAP modulator.
• the DEPOIN de-puncturing device performs a de-puncturing function 23 that is the reverse of that implemented by the POIN puncturing device in the sense that it makes it possible to restore the punctured bits.
• the decoder DECOD performs an inverse decoding function 24 of the coding function implemented by the coder COD.
• the demodulation 22 implemented by the DEMAP demodulator aims to determine from a received point the most probable transmitted symbol.
• the received points are tainted with thermal noise but also with noise of various origins such as phase noise, which generate a variation of the position of the complex symbols in the constellation by phase rotation.
• the method performs for example a maximum likelihood detection. According to this mode of implementation, the method determines the closest symbol of the observation (symbol received) according to a criterion of Euclidean distance between the symbols of the constellation and the symbol received.
• decision regions are schematized in figure 3 in the case of a distribution of the symbols in the constellation which respects the Gray coding (two adjacent symbols only differ by one bit).
• the decision region associated with a complex symbol as a whole is the intersection of the decision regions attached to each bit forming the symbol knowing that this symbol is positioned in the constellation according to its index specified during the binary coding operation.
• the rectangle AO represents the decision region associated with the most significant bits for the MA-4 amplitude modulation in quadrature i.e. along the Q axis. That is to say that in this region the most significant bit of each of the symbols of this modulation is at one while all the symbols outside this region have their most significant bit at zero.
• the rectangle B0 represents the decision region associated with the most significant bits for the MA-4 amplitude modulation in phase i.e. along the axis I.
• the intersection of the two rectangles AO and B0 i.e. the region (ABO) provides the decision region for the most significant bits of the 16-QAM modulation, each symbol of which has two most significant bits relating to each of the 4-AM modulations.
• This ABO decision region is where the two most significant bits of a 16-QAM symbol are at one according to this construction with two MA-4 modulations.
• the rectangle Al represents the decision region associated with the least significant bit for the MA-4 amplitude modulation along the Q axis.
• Rectangle B 1 represents the decision region associated with the least significant bit for the MA-4 amplitude modulation along the I axis.
• intersection of the two rectangles Al and Bl that is to say the region AB1 provides the decision region for the least significant bits of the 16-QAM modulation according to this construction with two MA-4 modulations.
• the estimated symbol meets the maximum likelihood criterion such that the decision regions considered for each symbol correspond to the intersection of the decision regions of the bits forming the symbol. These intersections correspond to those of the least significant bits.
• the demodulation 22 according to the invention which performs a binary to symbol decoding makes it possible to weight the estimation error of the transmitted bits associated with the variation of the decision regions according to the weight and possibly the position of the bit in the constellation.
• [Table 4] in the appendix and figure 5 relate to a 64-QAM.
• the 64-QAM modulation is generated by combining in phase and quadrature two MA-8 eight-state amplitude modulations carried by the I and Q channels respectively.
• Each MA-8 amplitude modulation is characterized by three bits of different weight (or levels) associated with their positions during binary coding. This results in three different types of zones for the delimitation of the decision regions of the bits emitted during the binary-to-symbol decoding operation.
• the first three bits describe in-phase MA-8 amplitude modulation and the last three bits describe quadrature MA-8 amplitude modulation.
• the decision regions ABo associated with the most significant bits MSB of position ⁇ 0 5 ,6 2 ⁇ result from the intersection of the regions of type Ao and Bo.
• the dotted square areas ABi represent the delimitation of the decision region for the bits of intermediate weight corresponding to the bits in position [G 4 ,G I ]. This is the intersection of the two decision regions Ai and B 1 associated with the bits of intermediate weight for the MA-8 modulations in phase and in quadrature.
• the intersection of the decision regions of type A 2 and B 2 that is to say the decision region AB 2 , provides the decision region for the least significant bits LSB of the 64-QAM modulation.
• These AB 2 type regions coincide with the decision regions associated with the complex symbol S m of the 64-QAM modulation.
• Figures 6 and 7 show a 16-QAM.
• the peripheral symbols are represented surrounded by a square in figure 6, they are those whose abscissas and ordinates are the largest in absolute value.
• the transmitted symbols experience phase rotation.
• a phase error which exceeds a certain threshold induces a change of decision region for the symbols at the periphery of the constellation during the decoding of these symbols on reception. This change therefore induces an error when making a decision on the transmitted symbol which occurs during digital demodulation.
• R2 3V2 " a (4) with 2 a the width of a decision region.
• a same phase rotation dq leads to an indeterminacy on the decision region for the symbols surrounded by a circle and located at intermediate distance RI from the center O of the constellation. Indeed, the rotation, with a precision of the order of 9%, positions one of these symbols received at the intersection of the straight lines delimiting four decision regions (points I and G in FIG. 7). This positioning can therefore generate indeterminacy on reception on the transmitted symbol.
• the radius RI is given by:
• the POIN puncher comprises an elementary structure.
• the elementary structure delimited by the broken line has an input Ei and two outputs Si and Si+1. It consists of a first punching module Pi with one input Ei and one output E'i, followed by a demultiplexer Mi [1:2] (one input E'i to two outputs Fi and Fi+1) whose output branch Fi+1 is connected to a second punching module Pi+1.
• the input of the second punching module Pi+1 is Fi+1 and its output is denoted F'i+1.
• the demultiplexer Mi is intended to distribute over its two outputs Fi and Fi+1 the data intended for the branches Si and Si+1 so that the output bit rates are controlled on each of the branches.
• Each punching module Pi, Pi+1 implements a punching matrix, denoted Pi, Pi+1 as the corresponding punching module, the size of which depends on the punching ratio of the module.
• the puncher POIN then comprises two outputs Si and Si+1 having protection levels which may be different from each other depending on the setting of the punching matrix Pi+1, ie at most two different levels of protection. If this punching matrix Pi+1 contains at least one zero then the two outputs Si and Si+1 have protection levels which are different from each other.
• the data on the output Si which corresponds to the output Fi of the demultiplexer Mi are mapped onto the least significant bits.
• the data on the output Si+1 which corresponds to the output F'i+1 of the second punching module Pi+1 are mapped on the most significant bits.
• the input data Ei are punctured differently depending on whether they are mapped on the least significant bits or on the most significant bits of a symbol of the constellation.
• the matrix Pi leads to a uniform punching on the two outputs Si and Si+1 when the matrix Pi+1 is inactive i.e. is only formed of "one".
• the previous puncher with two outputs can make it possible to obtain more than two levels of protection.
• a first parameterization of the punching matrix Pi+1 makes it possible to obtain two levels of protection on the two outputs Si and Si+1
• a second parameterization of the punching matrix Pi+1 makes it possible to obtain two other levels protection on the two outputs Si and Si+1.
• the telecommunications equipment SB/Tal intended to communicate with a second equipment Tal/SB comprises a POIN puncher with the elementary structure described above.
• the data transmission method 10 implemented by this embodiment of the SB/Tal equipment is such that the puncturing 3 of the data is according to at least two different levels of protection respectively for data mapped on bits of weight different from the same symbol.
• the method is such that the punching 3 comprises at least one punching step comprising a 1st punching matrix, the output of which feeds a demultiplexing having a 1st and a 2nd output, the 2nd output feeding a 2nd punching matrix to define the at least two different levels of protection obtained respectively with the 1 st output of the demultiplexing and the output of the 2 nd puncturing matrix.
• the POIN puncher comprises a first elementary structure followed by at least one second elementary structure cascaded in an interwoven manner called the front-back casc-av-arr cascade.
• the first punching module of the second structure i.e the matrix Pi+1
• the puncher POIN then comprises three outputs Si, Si+1, Si+2 having protection levels which may be different from each other, ie at most three different levels of protection. If the puncturing matrix Pi+2, i.e. the distinctive added matrix, contains at least one zero then the two outputs Si+1 and Si+2 have protection levels which are different from each other. If the punching matrix Pi+1 contains at least one zero then the output Si has a protection level which is different on the one hand from the protection level of the output Si+1 and on the other hand from the protection level of the Si+2 output.
• the front-to-back cascade architecture with resumption of the previous punching module makes it possible to increase the punching order (i.e. the number of punching levels) with great simplicity and flexibility.
• An additional level of punching is obtained by adding a single level of the elementary structure and setting the puncher according to the protection considered.
• the elementary front-to-rear cascading structure makes it easier to adapt the punching according to the order M of the modulation.
• the telecommunications SB/Tal equipment intended to communicate with another Tal/SB equipment comprises a POIN puncher with at least two structures elements according to a front-to-rear cascade assembly described above. Each elementary structure is associated with a punching step of the emission method.
• the data transmission method 10 implemented by this embodiment of the SB/Tal equipment is such that it comprises a first puncturing step comprising a 1st puncturing matrix whose output feeds a demultiplexing having a 1st and a 2nd output, the 2nd output supplying a 2nd punching matrix to define the at least two different protection levels obtained respectively with the 1st demultiplexing output and the output of the 2nd punching matrix.
• the process is such that any punching step called the previous step, therefore in particular the first punching step, is followed by a new punching step, the 1st die of which is common with the 2nd die of the previous step, to define an additional different level of protection obtained with the output of the 2 nd punching die of the new punching step.
• the transmission method implemented comprises two punching steps.
• Each additional elementary structure of the puncher adds a punching step to the method implemented.
• a puncturer has four outputs so with at least three elementary structures in front-to-rear cascade can make it possible to attribute a distinct protection to the data according to the position of the symbol on which these punctured data are mapped.
• This protection according to the position of the symbol is in addition to a separate protection between data mapped on the most significant bit and data mapped on the least significant bit of the same symbol.
• two levels of protection can be reserved for data mapped on a symbol of the periphery of the constellation, therefore depending on the position of the symbol with a distinction between these two levels depending on whether the data is mapped on a most significant bit or a bit low weight of this symbol.
• the invention makes it possible to jointly differentiate the protection within a symbol by taking into account the position of the bit in the code word and according to the position of the symbol in the constellation.
• the parameterization of the forward-backward cascading structure of the puncturer can take into account a metric for evaluating the distance of the complex symbol at the center of the constellation.
• the parameterization of the puncher determines the number of elementary structures in front-to-back cascade to distinguish levels of protection between the symbols according to their position in the constellation evaluated by the metric. Determination of punching dies
• the coder COD performs, for example, channel coding of the convolutional type or of the LDPC type with a rate R i , the code is called mother code with a rate R i .
• the punching ratio R pi greater than or equal to 1 designates the ratio between the number of bits at the input of the punching module Pi and the number of bits at the output of this module Pi.
• This report is deduced from the puncturing matrix Pi which specifies the number and position of the bits to be punctured and therefore not transmitted by the puncturing module Pi. are designated by the integer '0' in the matrix Pi and the transmitted bits are designated by the integer '1' in this matrix Pi.
• the puncturing ratio R pi is written: where N in,i designates the number of bits at the input of the punching module Pi and , designates the number of bits at the output of this Pi module. According to a simple implementation, represents the total number of punch die elements Pi and represents the number of '1' elements in the punch matrix Pi.
• the puncturing matrix Pi comprises a number of rows which is a multiple of the inverse of the efficiency R i of the mother code.
• the number of columns is a multiple of the numerator of the desired code yield R if after puncturing such that:
• R si is therefore the channel coding rate on branch i, output Si, after puncturing by the puncturing module Pi.
• the determination of the channel coding efficiency on the branch i thus makes it possible to determine at least one puncturing matrix which makes it possible to obtain the ratio R pi .
• the demultiplexing carried out by the demultiplexer Mi consists in adjusting the number of bits on each of the output branches Si and Si+1 taking into account the puncturing matrices Pi and Pi+1. This adjustment is determined step by step, according to the optimization constraints of the input and output flow rates of the puncher.
• the demultiplexer Mi distributes the bits over the branches Fi and Fi+1 taking into account the ratio /R pi+1 of the puncturing matrix Pi+1.
• the bit rates at different points of the elementary structure are then calculated as follows:
• the bit rate D Ei at the output of the channel encoder is expressed as a function of the bit rate at the output of the elementary structure as follows:
• the puncturing matrix Pi punctures the bits of the input flow in a uniform way, the only change of its parameterization makes it possible to modify the couple of outputs on the two outputs.
• the puncturing matrix Pi can be formed of only '1' so as not to perform puncturing on the coded bits at the output of the channel coder. These bits can for example correspond to the information bits coming from a systematic coder, information bits which are generally not punctured.
• the puncturing matrix Pi can be used for example to reduce the redundancy associated with certain symbols according to their position in the constellation.
• a second parameter setting for example R pi >1
• R pi a second parameter setting
• Figure 10 gives a diagram of two embodiments of the invention.
• the puncher POIN comprises an elementary structure as already described with regard to FIG. 8.
• the puncher punches the data after coding by an encoder COD.
• the output data of the puncher can be represented by two streams corresponding to the two outputs Si and Si+1 or can be represented in the form of a single stream combining the two outputs.
• the input data are first demultiplexed by a demultiplexer M'i to distinguish two outputs.
• the first output of the demultiplexer M'i is coded by a first channel coder COD.
• the output data of the first channel coder COD is punctured by a first matrix puncturing module Pi.
• the second output of the demultiplexer M'i is coded by a second channel coder COD identical to the first channel coder COD.
• the output data of the second COD channel encoder is punctured by a second die puncturing module Pi.
• the data punctured by this second die puncturing module Pi is again punctured by a third die puncturing module Pi+1.
• This second mode makes it possible to calculate the equivalent channel coding efficiency R eq,elem of the elementary puncturing structure with channel coding, between the entry point A and the exit point B after a series connection of the two outputs of the puncturing device.
• the equivalence of the structures of the two modes illustrated in Figure 10 illustrates the reduction in complexity provided by the elementary structure of multi-level punching when associated with each branch.
• Such a choice of coding parallelization can be implemented for very high bit rate systems, typically for systems operating in the millimeter band or in the THz band.
• the proposed multi-level puncturing structure allows a reduction in the complexity of a multi-level channel coding structure at transmission while ensuring downstream a binary coding with multiple protection signal.
• Puncher has two elementary structures For the puncher shown in Figure 9, ie with two elementary structures, and in the case where the three outputs Si, Si+1 and Si+2 have the same bit rate, the rates at different locations can be expressed as following :
• the equivalent punching ratio for the structure is expressed as: Puncher with J elementary structures
• a puncher which comprises J elementary structures in front-to-rear cascade provides J+1 outputs. If the bit rate is fixed identical to on each of the outputs also called branches then the throughput at the input of each non-uniform demultiplexer is calculated step by step taking into account the puncturing ratio of each puncturing module.
• the equivalent channel coding rates on each branch are therefore given by:
• the telecommunications equipment considered is compatible with an IEEE 802.1 lax standard.
• the target MCS Modulation and Coding Scheme
• 64-QAM 5/6 are specified by this standard.
• the puncher implemented according to the invention modifies the protection of the bits within each symbol as well as the protection of the symbols farthest from the center of the constellation while keeping the fixed code rate unchanged. by the MCS.
• the MCS of index 4 is a 16-QAM 3 ⁇ 4.
• information is not modified by the invention and is identical for all the points of the constellation. This therefore imposes the generation of several pairs (R p1 , R p2 ) as a function of the distance R to the center of the constellation.
• Two distinct levels are considered according to the distance on the one hand for the distances R0, RI and on the other hand for the distance R2.
• a puncher with an elementary structure two branches/two outputs ⁇ S1, S2 ⁇ ) and two separate settings may therefore be suitable since two levels of protection are obtained for each of the two settings.
• the two outputs of puncher makes it possible to distinguish between data mapped on the most significant bit and data mapped on the least significant bit of the same symbol.
• the two settings correspond to two pairs of values ( R p1 R p2 ) respectively for the points situated at the distances R0 and RI and for those situated at the distance R2 from the center of the constellation.
• the constraint of an unchanged RMCS efficiency whatever the point of the constellation imposes a set of two pairs of values (R p1 R p2 ).
• R p1 and R p2 can be selected according to the protection chosen as a function of the distance from the center of the constellation.
• the ratios R p1 and R p2 are greater than or equal to one by virtue of the punching operation.
• the channel coding rates R S1 and R S2 on each of the branches S1 and S2 are less than or equal to one.
• the SI branch is assigned to the least significant bits with an equivalent rate equal to 3/5 while the S2 branch is assigned to the most significant bits with a rate of 9/10.
• the overall yield is indeed equal to 3 ⁇ 4.
• the associated punch dies are made up of two rows and can have three columns. They can be in the form:
• a second pair ( R p1 R p2 ) is determined by considering a higher efficiency R S1 for the least significant bits than for the points at a distance R2 because the decision region of the symbols is identical to that of the least significant bits.
• the corresponding punching dies can have the form:
• the modulation is a 64-QAM 3 ⁇ 4 and the puncturing according to the invention is implemented for only certain symbols, those at the distance R2 i.e. furthest from the center.
• the MCS remains constant for all symbols.
• [Table 6] in the Appendix gives a summary of the values for this example.
• the method implements two pairs of puncturing and therefore of equivalent channel coding efficiency, one pair for the data mapped on the symbols at the distances RO and RI, one pair for the data mapped on the symbols at the distance R2.
• the table gives two values (2/3, 5/6) (3/5, 9/10) of the equivalent channel code rate pair for the data mapped on the symbols at the distance R2.
• the modulation is a 64-QAM 3 ⁇ 4.
• 64-QAM modulation is constructed with two 32-QAM modulations then three bits are associated with each symbol of an 8-QAM constellation.
• Three different levels of protection can therefore be used to protect the data differently depending on which of the three bits it is mapped to.
• the selected puncher comprises two elementary structures in cascade which makes it possible to obtain three outputs with three equivalent coding yields ( R S1 , R S2 , R S3 ) and three punching ratios ( R p1 , R p2 , R p3 )
• Three zones Z1, Z2, Z3 of symbols are distinguished as illustrated by FIG. 11 according to their distance from the center of the constellation. To protect these three areas, three different triplets of equivalent coding rates (R S1 , R S2 , R S3 ) and puncturing ratio (R p1 , R p2 , R p3 ) are determined.
• the code rate set by the MCS is kept unchanged for all the points of the constellation whatever their position.
• the equivalent channel coding rates on each of the branches are then given by:
• the S3 branch is assigned to the most significant bits, the S2 branch to the intermediate significant bits and the S1 branch to the least significant bits.
• the punching ratio set (1, 6/4, 14/12) is considered for symbols in the Z3 area.
• the punching ratio set (9/8, 4/3, 10/8) is considered for symbols in the Z2 area.
• the punching ratio set (4/3, 19/16, 1) is considered for symbols in the Z1 area.
• the puncher implemented according to the invention keeps unchanged on average over all the symbols of the constellation the code rate R MCS set by the MCS.
• the useful bit rate assigned to the various symbols of the constellation can be different according to their distance from the center of the constellation while keeping constant the average bit rate at the scale of the M symbols of the order modulation Mr.
• N 1 is the number of points in the constellation having the equivalent efficiency R eq,1 and N 2 is the number of points in the constellation having the equivalent efficiency R eq,2 .
• the return is equal to 5/6.
• the method can uniformly apply the puncturing of the standard on all the bits mapped on the symbols of zone 1. Or alternatively, the method can apply a variable puncturing within each symbol of zone 1 such as:

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• 2021
  • 2021-04-27 FR FR2104360A patent/FR3122303A1/fr not_active Withdrawn
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