Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
  • H04B7/022—Site diversity; Macro-diversity
  • H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
  • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
  • H04L27/3405—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
  • H04L27/3444—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power by applying a certain rotation to regular constellations
• • 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
  • H04L1/0047—Decoding adapted to other signal detection operation
  • H04L1/005—Iterative decoding, including iteration between signal detection and decoding operation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
  • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
  • H04L25/03006—Arrangements for removing intersymbol interference
  • H04L25/03178—Arrangements involving sequence estimation techniques
  • H04L25/03248—Arrangements for operating in conjunction with other apparatus
  • H04L25/03286—Arrangements for operating in conjunction with other apparatus with channel-decoding circuitry
• • 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
  • H04L2001/0092—Error control systems characterised by the topology of the transmission link
  • H04L2001/0097—Relays
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
  • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
  • H04L27/3488—Multiresolution systems

Definitions

• the field of the invention is that of digital communications, in transmission or in broadcasting.
• the invention relates to the transmission of coded data from at least one source entity to at least one destination entity.
• the invention relates to improving the quality of the transmission of such data, by means of so-called cooperative communications based on the use of one or more relays to improve the communications between the source entity or entities and the the recipient entities.
• the relay can either decode the bitstream and retransmit ("Decode & Forward” in English) or amplify and retransmit the received signal (“Amplify & Forward” in English) or compress and retransmit the received signal.
• turbo-codes Distributed (distributed turbo code).
• a single source transmits data to both the relay and the destination terminal.
• the relay decodes, interleaves and re-codes the message before relaying it to the recipient.
• the relay performs one of the turbo-coding steps, generally performed by the transmitter (which justifies the term "distributed turbo-code").
• the recipient thus receives two coded versions of the original message and decodes them together using an iterative decoding algorithm. This technique thus achieves an improvement in gain and diversity.
• the transmission is carried out in accordance with FIG. 1. More precisely, the transmission time is divided into two units: the first unit of time is devoted to transmitting the source to the relay, while the second unit time is allocated to the relay.
• Ysd, Ysr, Yrd the signal-to-noise ratio of the source-destination channel, relay-source, and relay-destination, respectively.
• the techniques of the prior art previously described have a yield that is half as low with regard to techniques based on simultaneous transmission of the source and relay to the recipient.
• the invention proposes a new solution that does not have all of these disadvantages of the prior art, in the form of a method of transmitting at least one source entity to a destination entity, via at least one entity relay,
• such a method comprises:
• modulated symbols representative of an estimate of said information sequence
• the at least one source entity and the at least one relay entity simultaneously transmit at least one of the "source” modulated symbols and at least one of said "relay” modulated symbols.
• the invention thus proposes a new cooperative emission technique implementing at least one relay entity, making it possible to improve the spectral efficiency of the techniques of the prior art by virtue of the fact that it implements a specific simultaneous transmission of a source entity and a relay entity.
• Multi-source and / or multi-relay systems can be clearly transposed from the method according to the invention described above. Subsequently, to simplify the description, it is most often considered a transmission system comprising a source entity and a relay entity. The case of a multi-relay system comprising two relay entities will be described later in more detail within the description of an embodiment of the invention.
• the source entity and the relay entity simultaneously transmit two types of symbols, the "source” modulated symbols and the "relay” modulated symbols.
• a source modulated symbol corresponds to a point of a first constellation of order n
• a modulated symbol "relay" corresponds to a point of a second constellation of order m.
• a symbol resulting from the simultaneous emission of a modulated symbol "source” and a modulated symbol “relay” corresponds to a point of a constellation of order n + m (including 2 n + m distinct points), the actual component of which is obtained by summation of the real components of the points associated with the source modulated symbol and the modulated symbol "relay” and whose imaginary component is obtained by summation of the imaginary components of the points associated with the source modulated symbol and with the modulated "relay" symbol.
• the simultaneous transmission of the source entity and the relay entity to the recipient thus makes it possible to increase the spectral efficiency because the destination entity receives information modulated in a distributed manner between the source entity and the relay entity .
• the "source” modulated symbol transmission step comprises a sub-step of encoding the information sequence, delivering at least one "source” codeword, and a modulation sub-step of at least one "source” code word, delivering the "source” modulated symbols.
• the step of transmitting modulated symbols "relay” includes a sub-step of decoding the "source” modulated symbols, delivering an estimate of the information sequence, a substep of coding the sequence of estimated information, delivering at least one "relay” code word, and a sub-step of modulation of the at least one "relay” code word, delivering said "relay” modulated symbols.
• each transmission step implemented by the relay entity and the source entity comprises an encoding step and a modulation step.
• the relay entity receives and decodes the information transmitted by the source entity before code it in turn and send it at the same time as the source entity in a second unit of time.
• the same information, possibly encoded and / or modulated differently by the relay entity and the source entity, is transmitted by both the relay entity and the source entity with a time offset of one unit, the relay entity transmitting a first information when the source entity simultaneously transmits a second information that it will then process.
• the relay entity and the source entity therefore transmit simultaneously but with a time offset for the same information.
• the coding sub-steps of the information and coding sequence of the estimate of the estimated information sequence implement different coding techniques.
• the method according to the invention is characterized by great flexibility of implementation. Indeed, the source entity and the relay entity can implement different or identical codings which allows many combinations of source entity and entity relay .
• the modulation sub-steps of the at least one "source” code word and the modulation of the at least one "relay” codeword implement different modulation techniques.
• This aspect is particularly advantageous because it allows a great flexibility of implementation of the invention.
• the resulting constellation of the signal resulting from the simultaneous transmission of the source entity and the relay entity, respectively of a "source” modulated symbol and of a "relay” modulated symbol corresponds to a constellation of order m + not.
• the real component of a point of this resulting constellation is obtained by summing a point of the real components of the points associated with the source modulated symbol and the modulated symbol "relay" while the imaginary component is obtained by summation of the imaginary components of the points associated with the modulated source symbol and the modulated symbol "relay".
• the modulation sub-steps of the at least one "source” codeword and modulation of the at least one "relay” codeword are respectively quadrature and phase modulations.
• the modulated symbols "source” and “relay” are therefore orthogonal.
• Each point of the first constellation n order used by the entity “source” being placed on a direction orthogonal to that of a point of the second constellation of order m used by the entity "relay”.
• This example based on the orthogonality of the constellations implemented by the source entity and the relay entity is not limiting. Indeed, according to the invention it is possible to use any non-zero rotation and different from 2 ⁇ (modulo 2) of a constellation implemented by the source entity with respect to that implemented by the relay entity.
• Another aspect of the invention also relates to a signal representative of an information sequence, transmitted by a source entity to a destination entity, via at least one relay entity, according to the transmission method described above.
• such a signal comprises at least one symbol resulting from the simultaneous transmission of a modulated "source” symbol by the source entity and of a “relay” modulated symbol by the relay entity,
• the modulated "source” symbol corresponding to a point of a first constellation of order n
• the modulated "relay” symbol corresponding to a point of a second constellation of order m
• the points of the first and second constellations being all distinct
• At least one symbol corresponding to a point of a higher order constellation associated with the first and second constellations of the invention is transmitted according to the invention. the source entity and the relay entity.
• This signal can be transmitted and / or stored on a data medium.
• This signal may of course include the various characteristics relating to the transmission method according to the invention.
• the invention relates to a source entity capable of transmitting an information sequence to a destination entity, via at least one relay entity.
• such a source entity comprises means for transmitting symbols modulated elements representative of the information sequence, said "source” modulated symbols, each "source” modulated symbol corresponding to a point of a first constellation;
• the transmission means being configured to transmit at least one of the "source” modulated symbols simultaneously to at least one "relay” modulated symbol representative of an estimate of the information sequence, each "relay” modulated symbol corresponding to a point of a second constellation, the points of the first and second constellations being all distinct.
• the invention in another embodiment, relates to a relay entity adapted to receive, from a source entity, at least one "source” modulated symbol representative of an information sequence, each "source” modulated symbol corresponding to one point of a first constellation, and to re-transmit the information sequence to a destination entity.
• such a relay entity comprises "relay" modulated symbol transmission means representative of an estimate of the information sequence, each "relay” modulated symbol corresponding to a point of a second constellation, the transmission means being configured to transmit at least one of the "relay” modulated symbols simultaneously to at least one of the "source” modulated symbols, the points of said first and second constellations being all distinct.
• Such a source entity and such a relay entity are particularly able to cooperate to implement the transmission method described above.
• the advantages and embodiments described above with regard to the method according to the invention are also applicable to each of these entities.
• the implementation of the invention consists in modifying the source entity so that the points of the constellations used respectively by the source entity and the relay entity are all distinct.
• the implementation of the invention consists in modifying the relay entity so that the points of the constellations used respectively by the source entity and the relay entity are all different.
• the invention in another embodiment, relates to a method for receiving a signal representative of an information sequence transmitted by an entity, via at least one relay entity.
• such a reception method comprises:
• a signal reception step comprising, at least one symbol resulting from the simultaneous transmission of a "source” modulated symbol by said source entity and a “relay” modulated symbol by the relay entity,
• a demodulation step of said signal delivering at least one "source” codeword representative of a "source” modulated symbol corresponding to a point of said first constellation and at least one "relay” codeword representative of a modulated symbol “Relay” corresponding to a point of said second constellation;
• the reception method according to the invention makes it possible to receive the signal previously described, to demodulate and decode together the modulated "source” and “relay” symbols transmitted respectively by the "source” entity and the "relay” entity. ".
• the destination entity receives a signal resulting from the superposition of the signals emitted respectively by the source entity and the relay entity.
• such a signal comprises at least one symbol resulting from the simultaneous emission of a modulated symbol "source” by said source and a symbol modulated "relay" by the relay entity.
• the demodulation step implements a demodulator having a demodulation order greater than or equal to the sum of the modulation commands of the modulators used by the source entity and the said at least one transmitting relay entity.
• the relay entity is of order greater than or equal to the sum of the modulation commands of the modulators used by the source entity and the relay entity.
• the order of the demodulator is exactly equal to the sum of the modulation orders of the modulators used by the source entity and the relay entity.
• the invention also relates to a destination entity able to receive a signal representative of an information sequence, transmitted by a source entity, via at least one relay entity,
• a destination entity able to receive a signal representative of an information sequence, transmitted by a source entity, via at least one relay entity,
• a destination entity comprises:
• signal demodulation means delivering at least one "source” code word representative of a "source” modulated symbol corresponding to a point of the first constellation and at least one "relay” code word representative of a symbol modulated "relay” corresponding to a point of said second constellation;
• Such a destination entity is particularly adapted to implement the reception method described above.
• the invention also relates to a system for transmitting an information sequence from a source entity to a destination entity, via at least one relay entity,
• Such a system includes:
• the source entity emitting modulated symbols representative of the information sequence, said "source” modulated symbols, each "source” modulated symbol corresponding to a point of a first constellation;
• the at least one relay entity emitting modulated symbols representative of an estimation of the information sequence, called “relay” modulated symbols, each "relay” modulated symbol corresponding to a point of a second constellation, the points of the first and second constellations being all distinct,
• the source entity and the at least one relay entity simultaneously transmit at least one of the "source” modulated symbols and at least one of the "relay” modulated symbols.
• This cooperative system may of course include the various characteristics relating to the transmission method according to the invention, which can be combined or taken isolation.
• the features and advantages of this system are the same as those of the emission process. Therefore, they are not detailed further.
• the invention also relates to a computer program comprising instructions for implementing a transmission or reception method described above when this program is executed by a processor.
• This program can use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code, such as in a partially compiled form, or in any other form desirable shape.
• FIG. 1 already described in relation with the prior art, illustrates the emission of conventional cooperative systems
• FIG. 2 shows the main steps of the transmission method according to the invention
• FIG. 3 illustrates the simultaneous transmission of the source entity and the relay entity according to the invention
• FIG. 4 is a schematic representation of the transmission system according to an example of the invention.
• FIG. 5 is a schematic representation of the transmission system according to the invention when two relay entities are for example taken into account
• FIGS. 6 to 9 illustrate different combinations of constellations implemented respectively by the source entity and the relay entity, as well as the resulting constellation resulting from the simultaneous transmission of the source entity and the relay entity,
• FIG. 10 presents the main steps of the reception method according to the invention
• FIG. 11 makes it possible to establish a comparison in terms of performances without and with cooperation of a relay entity according to the method of the invention.
• the general principle of the invention rests on the implementation of a decomposition of the coding and the modulation of a symbol to be transmitted. More specifically, the coding and modulation of an information symbol to be transmitted is performed in a distributed manner on at least one source entity and at least one relay entity that transmit simultaneously.
• the symbol resulting from the simultaneous emission of the relay entity and the source entity corresponds to a point of an n + m order constellation resulting from the superposition of the signals respectively emitted by the source entity and by the Relay entity.
• the signal emitted by the source entity comprises symbols called "source” modulated symbols, a “source” modulated symbol being represented by a point of a first constellation of order n.
• the signal emitted by the relay entity comprises symbols called "relay” modulated symbols, a “relay” modulated symbol being represented by a point of a second constellation of order m.
• the points of the first and second constellations are furthermore all distinct.
• the resulting signal is obtained due to the superposition of the signals emitted simultaneously by the source entity and the relay entity respectively to the destination entity.
• the relay entity Due to the correlation between the relay entity and the source entity, the relay entity transmits a signal constructed from an estimate of the signal emitted by the source entity, the higher order constellation implemented at the source entity.
• transmission according to the invention comes from two correlated transmitting entities which are further able to transmit simultaneously.
• the resulting constellation obtained during the superposition of the signals transmitted simultaneously by the source entity and the relay entity comes directly from the two complementary constellations implemented by the source entity and the relay entity.
• a point of the resulting constellation of order n + m is characterized by a real part (respectively imaginary) equal to the sum of the real part (respectively imaginary) of a point of the first constellation "source” d order n and the real part (respectively imaginary) of a point of the second constellation "relay" of order m.
• the invention relies on a complementarity of the source entity and the relay entity in order to increase the emission spectral efficiency while avoiding any risk of interference.
• a step of transmission (21), by the source entity, of modulated symbols representative of the information sequence, called "source” modulated symbols, each symbol is implemented.
• modulated “source” (Ss) corresponding to a point of a first constellation (Cl), of order n.
• FIGS. 6 to 9 representing various examples of n-order constellations (C1) used by the source entity, the "source” points are represented by "x”.
• the "source” modulated symbol transmission step (Ss) comprises a coding sub-step (211) of the information sequence, delivering at least one "source” code word, and a sub-step of coding (211) of the information sequence.
• the relay entity In parallel with the source entity (S), with the exception of the first transmission carried out by the source entity, the relay entity also implements a step of simultaneously transmitting (22) modulated symbols representative of a estimation (E) of said information sequence, called “relay” modulated symbols (Sr), each modulated "relay” symbol corresponding to a point of a second constellation (C2), of order m.
• FIGS. 6 to 9 representing various examples of n-order constellations (C1) used by the source entity, the source points are represented by "+".
• the step of transmitting modulated symbols "relay” (Sr) comprises a substep of decoding (221) modulated symbols "source” after reception (not shown) of the latter, delivering the estimate (E ) of the information sequence, a coding sub-step (222) of the estimate of said information sequence, delivering at least one "relay” codeword, and a modulation sub-step (223) of the at least one "relay” code word, delivering the modulated symbols "relay” (Sr).
• the invention is characterized in that the points of the first and second constellations (C1 and C2) are all distinct, and in that the source entity (S) and the relay entity (R) simultaneously transmit in the H channel (with the exception of the first transmission made by the source entity) at least one of the source modulated symbols (S s) and at least one of said modulated symbols "Relay" (Sr).
• the resultant symbols (Sd) corresponding to a point of a constellation (Ceq) are obtained in the H channel by superposition. of order n + m resulting from the superposition of the signals respectively emitted by the source entity (S) and by the relay entity (R).
• a point of the resulting constellation (Ceq) of order n + m is characterized by a real part (respectively imaginary) equal to the sum of the real part (respectively imaginary) of a point of the first constellation "source” d order n and the real part (respectively imaginary) of a point of the second constellation "relay" of order m.
• FIG. 3 illustrates, in particular, the simultaneous transmission of the source entity and the relay entity according to the invention.
• the source entity and the relay entity transmit simultaneously.
• the relay entity transmits a coded version of the information of the source entity received in the previous time unit. There is therefore a shift of one unit of time between the simultaneous transmissions of a relay entity and a source entity.
• FIG. 1 previously compared with regard to the prior art and of FIG. 3 illustrating the simultaneous emission according to the invention, it is possible to observe that according to the invention there is indeed for a unit of time considered (with the exception of the first considered as an initialization step of the method according to the invention) a simultaneous transmission of the source entity and the relay entity.
• the spectral efficiency is therefore highly optimized according to the method of the invention.
• a multi-source and / or multi-relay system implements as many simultaneous transmissions as there are source entities and relay entities in the system. transmission system considered.
• the spectral efficiency is therefore even more improved.
• FIG. 4 corresponds to a schematic representation of the transmission system according to an example of the invention embodying the steps of the method according to the invention previously described in relation with FIG. 2.
• an information sequence u s of length k s bits is coded (211) in code word c s within the source entity S by an encoder C s of yield R s .
• the code word c s is then modulated (212) in x s and transmitted on the H channel.
• n 1 of BPSK (binary phase shift keying) type whose constellation Cl is represented by the points in "x" on the FIG. figure 6.
• the relay entity receives a noisy version of the code word (c s y sj ⁇ ).
• This noisy code word is decoded (221) within the relay entity R by a decoder C s _1 of yield R s delivering an estimate û s .
• the estimate u s is then interleaved by an interleaver ⁇ to add redundancy and recoded (222) by an encoder C r R r r c yield code word.
• the encoder C r of the relay entity may be according to a first variant or a variant identical to the coder C s implemented within the source entity, which provides a great flexibility of implementation.
• the code word c r is then modulated (223) using a modulation according to a constellation C2 whose points are distinct from the constellation C1 used by the modulator of the source entity.
• a modulation of order m 1 of the binary phase shift keying (BPSK) type whose constellation C2 is represented by the "+" points on the FIG.
• the second constellation C2 used by the relay entity corresponds to the constellation C1 rotated by an angle ⁇ .
• the modulations implemented on the one hand by the source entity and on the other hand implemented by the two relay entities are respectively quadrature and phase modulations.
• ⁇ can be used.
• Various examples of value of ⁇ are in particular illustrated by FIGS. 7 to 9 described later.
• the modulation implemented by the source entity corresponds to the modulation on the axis of the reals
• the modulation implemented by the relay entity corresponds to the modulation on the axis of the imaginary.
• FIG. 5 schematically represents a transmission system according to the invention when two relay entities (R1 and R2) are for example taken into account.
• Such a multi-relay system is an obvious transposition of the general principle of the invention.
• the source entity S transmits towards the two relay entities RI and R2 and also directly towards the destination entity D.
• the direct transmission of the source entity to the recipient makes it possible, in particular, to ensure transmission from the source entity to the recipient, in particular in the event of a malfunction (failure, discharged battery, destruction) of the relay entity.
• the modulations on the one hand implemented by the source entity and on the other hand implemented by the two relay entities are respectively quadrature and phase modulations.
• the second C2 constellations used by each relay entity have points distinct from the first constellation C1 used by the source entity.
• the equivalent constellation (Ceq) observed by the destination entity (D) corresponds to a 16 MAQ type constellation corresponding to a quadrature amplitude modulation of order 4.
• relay entities R1 and R2 could also use constellations C2 and C2 'whose points would be distinct from a "relay” constellation C2 to the other "relay” constellation C2' and also distinct from the "source” constellation C 1.
• Figures 7 to 9 illustrate on the one hand other constellations used respectively by the relay entity and by the source entity and the resulting constellation of each of these combinations.
• the points of the "source” constellations are represented by “x”
• the points of the "relay” constellations are represented by “+”
• the points of the constellations resulting from the simultaneous emission of the source entity and of the relay entity are represented by "O”.
• FIG. 7 corresponds in particular to the modulation distribution described above in relation with FIG. 5, the resulting fourth-order 16-MAQ constellation comprises sixteen points.
• the modulations implemented on the one hand by the source entity and on the other hand by the relay entity are not quadrature and phase modulations as represented in the examples described above.
• the modulations implemented on the one hand by the source entity and on the other hand by the relay entity are quadrature and phase modulations.
• the modulation implemented by the source entity corresponds to the modulation on the axis of reals
• the modulation implemented by the relay entity corresponds to the modulation on the axis of the imaginary.
• the recipient entity simultaneously receives (101) the signals from the source entity and the relay entity, and iteratively decodes (103) the information of the source entity using the additional redundancy of the relay entity.
• the destination entity implements a demodulation (102) by means of a demodulator having a demodulation order greater than or equal to the sum of the modulation commands of the modulators used by the at least one source entity and the at least one transmitting relay entity of the transmission system previously described .
• the order of the demodulator is exactly equal to the sum of the modulation commands of the modulators used in order to avoid any additional complexity of processing.
• Such a demodulator jointly demodulates the signals received from the source entity and the relay entity to generate, for example, log likelihood ratios (LLRs) LLR (x s ) and LLR (x r ).
• LLRs log likelihood ratios
• the demodulator used is a demodulator.
• order n + m 2 of type QPSK.
• the demodulator Due to the specific construction of the equivalent constellation resulting from the superposition of signals transmitted simultaneously by the source entity and the relay entity as described above, the demodulator easily separates the "source” modulated symbols from the "relay” modulated symbols. .
• LLRs likelihood logarithm ratios
• x s LLR (x s ) and LLR (x r ) are delivered by the demodulator respectively at the input of the decoders C s _1 and C r _1 , the decoders C s and C r respectively corresponding to the coders C s and C r .
• the joint decoding (103) of the information of the source entity u s is an iterative decoding by extrinsic information exchange between the decoders C s _1 and C r _1 .
• the method according to the invention makes it possible to achieve good performance in terms of minimizing the bit error rate.
• the graph of FIG. 11 is a superposition of the impulse responses of the channel with (111) and without treatment (112), in other words without a relay entity, according to the cooperative emission method of the invention.
• bit error rate (BER)
• BER bit error rate
• the channels used according to the simulation shown in FIG. 11 are fast fading Rayleigh channels.
• the method according to the invention makes it possible to obtain a significant gain in terms of bit error rate with respect to a direct transmission (112) between the source entity and the destination entity.
• a gain of about 3 dB is obtained for a bit error rate of 10.

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