Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/26—Systems using multi-frequency codes
  • H04L27/2601—Multicarrier modulation systems
  • H04L27/2647—Arrangements specific to the receiver only
  • H04L27/2649—Demodulators
  • H04L27/26524—Fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators in combination with other circuits for demodulation
  • H04L27/26526—Fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators in combination with other circuits for demodulation with inverse FFT [IFFT] or inverse DFT [IDFT] demodulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] receiver or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/06—Receivers
  • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/06—Receivers
  • H04B1/16—Circuits
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B17/00—Monitoring; Testing
  • H04B17/30—Monitoring; Testing of propagation channels
  • H04B17/309—Measuring or estimating channel quality parameters
  • H04B17/336—Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
• • 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
• • 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
  • H04L1/0071—Use of interleaving
• • 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
  • H04L1/12—Arrangements for detecting or preventing errors in the information received by using return channel
  • H04L1/16—Arrangements for detecting or preventing errors in the information received by using return channel in which the return channel carries supervisory signals, e.g. repetition request signals
  • H04L1/18—Automatic repetition systems, e.g. Van Duuren systems
  • H04L1/1812—Hybrid protocols; Hybrid automatic repeat request [HARQ]
  • H04L1/1819—Hybrid protocols; Hybrid automatic repeat request [HARQ] with retransmission of additional or different redundancy
• • 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
  • H04L1/20—Arrangements for detecting or preventing errors in the information received using signal quality detector
  • H04L1/203—Details of error rate determination, e.g. BER, FER or WER
• • 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
  • H04L1/20—Arrangements for detecting or preventing errors in the information received using signal quality detector
  • H04L1/206—Arrangements for detecting or preventing errors in the information received using signal quality detector for modulated signals
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/0001—Arrangements for dividing the transmission path
  • H04L5/0003—Two-dimensional division
  • H04L5/0005—Time-frequency
  • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A) or DMT
  • H04L5/001—Time-frequency the frequencies being orthogonal, e.g. OFDM(A) or DMT the frequencies being arranged in component carriers

Definitions

• the invention relates to a reception method and a receiver for coded and modulated serial digital transmission over a non-stationary attenuation attenuated channel having a waveform selected from the group of cyclic waveforms comprising cyclically repeated, and said to single carrier, that is to say having fluctuations corresponding to those of a single carrier.
• SC-OFDM Single-carrier Orthogonal Frequency Division Multiplexing
• EW-SC-OFDM Single-carrier Orthogonal Frequency Division Multiplexing, and Expansion and Weighting
• SC-FDMA Single-carrier Frequency Division Multiple Access
• WCP-OFDM Single-Carrier Orthogonal Frequency Division Multiplexing with Weighted Cyclic Prefix
• Cyclic TDM Cyclic Time Division Multiplexing
• the known waveforms SC-OFDM or EW-SC-OFDM implementing an orthogonal frequency distribution in the form of multiple sub-carriers but having a single carrier transmission scheme can for example be used for the link the amount of wireless high-speed data transmissions from mobile terminals (eg, LTE, fourth-generation standard for high-speed wireless data transmissions between mobile phones and / or data terminals), or for the link descendant of DVD-NGH
• mobile terminals eg, LTE, fourth-generation standard for high-speed wireless data transmissions between mobile phones and / or data terminals
• PAPR reduced crest factor
• the estimation of the performance of the physical layer of such a transmission is important to allow the planning of the network dimensioning, for the optimization of the transmission parameters (interleaving, coding, guard intervals, number of subcarriers. .) on very high spatial correlation channels, requiring the terminal to travel long distances.
• a coded and modulated serial digital transmission over a non-stationary attenuation channel noise is established between:
• an emitter comprising:
• an encoding device adapted to generate, from a bit stream to be transmitted, said transmitted stream of bits, at least one stream of codewords, said flux emitted codeword resulting from coding according to at least one method predetermined coding, of said transmitted bit stream,
• a modulation device adapted to generate at least one modulated element stream, said flux emitted from modulated elements according to a predetermined modulation scheme, each flux emitted from modulated elements being representative of at least a portion of each stream issued coded words,
• ⁇ a transmitting device, on a noisy channel in nonstationary attenuation of a signal, said transmitted signal, incorporating a flow of transmitted symbols representative of each flux emitted from modulated elements,
• a receiving device adapted to receive a signal, said received signal, is received by a receiving device, said received signal incorporating a received symbol streams corresponding to a flux emitted component modulated on said channel, the received signal having a a waveform selected from the group of cyclic waveforms comprising cyclically repeated and single-carrier guard intervals having fluctuations corresponding to those of a single carrier, each modulated element being represented by a plurality of received symbols,
• ⁇ a demodulation device adapted to generate at least one coded word stream, said received stream of coded words, from each received stream of modulated elements,
• ⁇ at least one decoding device adapted to generate a bit stream, said received stream of bits, for decoding each received stream of codewords according to a decoding method corresponding to a coding method implemented by the transmitter.
• the transmission channel used generally of wireless type (radio frequencies and / or microwaves 7) has a non-stationary attenuation, that is to say which varies substantially in time during the transmission. of each code word. This phenomenon is reinforced by the presence of at least one interleaver.
• a problem that arises is the prediction of the performance of the transmission, that is to say the determination, without performing the decoding, of an error rate ER (error rate BER bit and / or PER word error rate) in the bit stream received as a function of attenuation variations of the channel during the reception of each coded word.
• ER error rate BER bit and / or PER word error rate
• Such a performance prediction must make it possible in particular to optimize the design of said constituent elements, and in particular to choose appropriate protocols to ensure good transmission quality: automatic retransmission request (ARQ technique) possibly hybrid (H-ARQ); incremental redundancy (IR); combination of Chase; adaptation of the characteristics of the transmitter and / or the transmission link: choice of the coding method, signal strength, modulation scheme, etc.
• ARQ technique automatic retransmission request
• H-ARQ possibly hybrid
• IR incremental redundancy
• combination of Chase adaptation of the characteristics of the transmitter and / or the transmission link: choice of the coding method, signal strength, modulation scheme, etc
• FR 2 952 254 describes a reception method and a receiver in which:
• Ck represents each attenuation value of the channel over time, where k is a time index, E s represents an average energy per emitted modulated element and No represents a spectral density of a Gaussian white noise on the channel,
• a mutual information value I k is elaborated for each value of said transmission quality Q k , according to a predetermined function of said transmission quality Q k ,
• an average ⁇ I n > of mutual information is elaborated for each coded word of the received stream of coded words, by averaging the different mutual information values I k elaborated in the first step for the different values taken by said Q k transmission quality on said coded word,
• a third step at least one value of the error rate ER of the received stream of bits is produced without performing the decoding for each coded word of the received stream of codewords, from each value of the average of mutual information.
• This method and this receiver are entirely satisfactory, and make it possible in particular to obtain a performance prediction without performing decoding, both by taking into account the true attenuation variations of the channel, and with a good accuracy of the results.
• high reliability and light and fast computer processing and therefore an optimization of the quality of the transmission.
• They are applicable in particular to waveform transmissions of OFDM or FDMA type.
• this performance prediction is in no way applicable to single-carrier cyclic waveforms for which interference exists between modulated elements by construction, a coded word not necessarily comprising an integer of modulated elements, preventing a priori any evaluation of the quality of transmission Q k .
• the aim of the invention is to propose a method and a receiver incorporating a prediction of the performance of the transmission without performing the decoding, as a function of attenuation variations of the channel during the reception of each coded word, applicable to the forms.
• single-carrier cyclic waveforms including SC-OFDM, EW-SC-OFDM, SC-FDMA, cyclic WCP-OFDM TDM, which provides good accuracy of results, high reliability and light computing fast, and therefore an optimization of the quality of the transmission.
• the invention aims at providing a reception method and a receiver incorporating a performance prediction applicable to these waveforms and which has the same qualities as the performance prediction described in FR 2 952 254.
• the invention also aims at providing such a method and such a receiver allowing a performance prediction using only the known parameters of the receiver waveform and respecting the structure of the real receiver which performs the equalization in the frequency domain before application of a fast inverse Fourier transform.
• the invention also aims at providing such a method and such a receiver that allow a fast performance prediction, and in particular without requiring the use of an additional Fourier transform operation dedicated solely to this prediction.
• the invention relates to a method for receiving digital data transmitted over a coded and modulated serial digital transmission over a non-stationary attenuation attenuated channel, in which:
• a signal said received signal, is received by a reception device, said received signal incorporating a stream of temporal symbols of information elements corresponding to a stream of temporal symbols of information elements transmitted on said channel and representative of information elements corresponding to the data to be transmitted, each information element being represented by a plurality of said time symbols, the received signal having a waveform chosen from the group of cyclic waveforms comprising cyclically repeated and single-carrier guard intervals with fluctuations corresponding to those of a single carrier,
• a predetermined equalization method is applied by said reception device to the time symbols of received information elements
• At least one stream of coded words said received stream of coded words, is generated by demodulation from the stream of temporal symbols of received information elements,
• bits received stream a stream of bits, called bits received stream, is generated by decoding each received stream of codewords, according to a decoding method corresponding to a coding method implemented on transmission on the channel of the transmitted symbol stream,
• digital data is stored associating a value of transmission quality with the information elements received
• a mutual information value Ik is produced for each value of said transmission quality according to a predetermined function of said transmission quality, characterized in that said transmission quality value comprises a signal-to-noise ratio plus equivalent interference calculated as a function of said equalization method from different values of signal-to-noise ratio of the channel measured for the different time symbols of information elements received from the received signal corresponding to the same information element and according to interference due to said waveform.
• a mean ⁇ I n > of mutual information is elaborated for each coded word of the received stream of code words, by averaging the different mutual information values 1 ⁇ elaborated in the first step for the different values taken by said transmission quality Qk on said code word,
• a third step at least one value of an error rate ER of the received stream of bits is elaborated without performing the decoding for each coded word of the received stream of code words, from each value of the average of mutual information ⁇ I n > developed in the second step, and using stored data representative of variations of an equivalent error rate according to at least one function, called standard function, of the signal / noise ratio, each standard function being predetermined for coding and decoding devices on an additive Gaussian white noise channel.
• the calculation of the signal-to-noise ratio plus equivalent interference is chosen according to the invention as a function of the waveform adopted and the equalization method implemented.
• the equalization method may be the subject of various variants (minimized mean square error equalization (MMSE) or Wiener filter, zero forcing equalization (ZF), .
• MMSE minimum mean square error equalization
• ZF Wiener filter, zero forcing equalization
• the invention applies more particularly (although not exclusively) to single-carrier cyclic waveforms comprising a fast Fourier transform applied to the time symbols of the received signal to produce blocks received at M frequency components. With these waveforms, the information elements are distributed over the different frequency components of the received blocks.
• the invention applies even more particularly to those waveforms for which the equalization method is applied to the blocks received at M frequency components (in the frequency domain). Indeed, in this case, the equalization process is greatly simplified.
• said waveform being chosen from the group of frequency-division single-carrier waveforms over a plurality of sub-carrier Ms, the received signal having time symbols of N elements of modulated information, N being an integer greater than M, said time symbols being separated from each other by guard intervals, the receiving device being adapted to:
• said transmission quality consists of the same value SINReq of a signal-to-noise ratio plus equivalent interference calculated as a function of said equalization method from said values of signal-to-noise ratios SNRi for all the frequency components s of a same block received.
• the received signal having a SC-OFDM waveform without weighting said value SINReq of the signal / noise ratio plus equivalent interference is calculated according to the following formula (I):
• H [h] is the gain of the channel calculated by discrete Fourier transform of a discrete impulse response
• W [k] W [k] H [k]
• - y is the average signal-to-noise ratio (in time / frequency).
• said equalization method being minimally squared (MMSE) or Wiener filter
• the received signal having an EW-SC-OFDM waveform comprising a frequency extension with weighting said SINReq value of the signal / noise ratio plus equivalent interference is calculated according to the formula (III) following:
• - I 0 is the central band of the unweighted frequencies (non-recombination of the sub-carriers), is formed of the bands; and 7; -2 end of the weighted frequencies (where the subcarriers are recombined), the low band IJ.J being referenced by an index 1, the high band 7; _2 by an index 2,
• H [k] is the gain of the channel calculated by discrete Fourier transform of a discrete impulse response
• W [k] W [k] H [k], - W 0 [k]: is the transfer function of the equalization and weighting process in the central frequency band I 0 corresponding to the neutral weighting (no recombination of the subcarriers),
• Wj [k] and W 2 [k] are the transfer functions of the equalization and weighting method respectively in the two frequency bands IJ.J and Ij_ 2 where the sub-carriers are recombined and weighted,
• said equalization method being minimally averaged (MMSE) or Wiener filter
• said value SINReq of the signal / noise ratio plus equivalent interference is calculated according to the following formula (IV) :
• each mutual information value 1 ⁇ is determined according to the function defined by the following formula (V):
• M being the cardinal of the alphabet ⁇ - ⁇ ⁇ ' ⁇ ⁇ '''' ⁇ -li modulated symbols.
• this analytical formula can be discretized for its evaluation by digital processing, for example according to the function defined by the following formula (VI):
• threshold + Max, ⁇ m ⁇ M _ x (real (SINR eq S m ), imag (SINR eq S m ))
• each mutual information value 1 ⁇ is determined according to the function I ⁇ b 1 k, yt) of the mutual information computed between the j th bit ( ⁇ ⁇ J ⁇ p _1 ) of the emitted symbol and the received symbol y ⁇ this function being defined by the following formula (VII):
• this analytical formula can be discretized for its evaluation by digital processing, for example according to
• the values of SNRi signal-to-noise ratios for each subcarrier are values measured over time, in particular by the receiver, as reception of the symbols received from the signal takes place. received.
• the mutual information values 1 and / or the mutual information mean ⁇ I N > and / or each error rate ER of the received bit stream is (are ) developed by the receiver.
• a method according to the invention is also characterized in that a deinterleaving is performed after demodulation of the symbols of the received stream of modulated symbols so as to form each coded word of the received stream of coded words, and in that each mutual information value 1 ⁇ and / or the mutual information mean ⁇ I n > and / or the error rate ER of the received stream of bits is elaborated for each coded word obtained at the end of such a deinterlacing.
• a control signal of the decoding device is elaborated as a function of each value of the error rate ER of the received stream of bits.
• a single value of the error rate ER of the received stream of bits is developed from a single standard function, and the control signal is adapted. to activate the decoding device if said value of the error rate ER of the bit stream received is less than a predetermined threshold value.
• a plurality of series of values of the error rate ER of the received stream of bits are elaborated from a plurality of standard functions, each standard function corresponding to a decoding method chosen from a plurality of predetermined decoding methods, and said control signal is designed to activate the decoding device according to the decoding method for which said value of the ER error rate of the received stream of bits is the closest to a predetermined threshold value while being lower than this threshold value.
• the decoding methods of the same plurality of decoding methods differ from each other only by a number of decoding iterations.
• the invention also extends to a receiver for encoded and modulated serial digital transmission over a non-stationary attenuation attenuated channel, comprising: a reception device adapted to receive a signal, said received signal, incorporating a stream of time symbols of information elements corresponding to a stream of temporal symbols of information elements transmitted on said channel and representative of elements of information corresponding to the data to be transmitted, each information element being represented by a plurality of said time symbols, the received signal having a waveform selected from the group of cyclic waveforms comprising repeated guard intervals cyclically, and say single-carrier, with fluctuations corresponding to those of a single carrier,
• an equalization device applying a predetermined equalization method to the time symbols of received information elements
• a demodulation device adapted to generate at least one stream of coded words, said received stream of coded words, from the stream of temporal symbols of received information elements,
• a decoding device adapted to generate a bitstream, said received bit stream, by decoding each received stream of coded words, according to a decoding method corresponding to a coding method implemented at the emission of the transmitted stream; symbols modulated on said channel,
• a channel performance prediction device adapted to produce at least one representative value of an error rate ER of the received bit stream, without performing the decoding, from stored digital data enabling a quality value to be associated; transmission to the received information elements, said channel performance prediction module being adapted to:
• said channel performance prediction device is adapted to use as a transmission quality value, a signal-to-noise ratio plus equivalent interference calculated according to said equalization method from different signal / signal ratio values. measured channel noise for different symbols received from the received signal corresponding to the same information symbol and according to interference due to said waveform.
• a receiver according to the invention is also advantageously characterized in that it is suitable for the implementation of a method according to the invention.
• said channel performance prediction device is adapted to elaborate each mutual information value 1 ⁇ according to the function defined by the formula (V).
• said performance prediction device is adapted to discretize this analytical formula for its evaluation by digital processing, that is to say to elaborate each mutual information value 1 ⁇ according to the formula (VI) .
• said device for predicting the performance of the channel is adapted to elaborate each value of mutual information 1 ⁇ according to the function defined by the formula (VII).
• said device for predicting the performances of the channel is adapted to discretize this analytical formula for its evaluation by digital processing, that is to say to elaborate each value of mutual information.
• a receiver according to the invention is also advantageously adapted to measure the SNRi signal-to-noise ratio values for each subcarrier over time as the received symbols of the received signal are received.
• said module for predicting performance of the channel is also suitable for: - in a second step, developed for each codeword of the received stream of codewords, an average ⁇ I n> mutual information, by averaging different mutual information values 1 ⁇ determined in the first step to the various values taken by said transmission quality on said coded word,
• a third step for each coded word of the received stream of coded words, elaborating at least one value of the error rate ER of the stream received from bits of each value of the mutual information average ⁇ I n > determined in the second step, and using stored data representative of variations of an equivalent error rate according to at least one function, called standard function, of the signal-to-noise ratio, each standard function being predetermined for the coding and decoding on an additive Gaussian white noise channel.
• standard function of the signal-to-noise ratio
• said performance prediction device is adapted to elaborate the mutual information values Tjt and / or the mutual information mean ⁇ I n > and / or each error rate ER of the stream received bits for each coded word from a de-interleaver module of the demodulation device.
• said performance prediction device is adapted to elaborate, for each coded word of the received stream of coded words, a control signal of the decoding device according to each value. the error rate ER of the received stream of bits.
• said channel performance prediction device is adapted to elaborate, for each coded word of the received stream of code words:
• said device for predicting the performance of the channel is adapted to elaborate, for each coded word of the received stream of coded words:
• each standard function corresponding to a decoding method chosen from among a plurality of predetermined decoding methods
• the invention extends to a coded and modulated serial digital transmission device on a nonstationary attenuation attenuated channel between:
• an emitter comprising:
• an encoding device adapted to generate, from a bit stream to be transmitted, said transmitted stream of bits, at least one stream of codewords, said flux emitted codeword resulting from coding according to at least one method predetermined coding, of said transmitted bit stream,
• a modulation device adapted to generate at least one modulated information element stream, said flux emitted pieces of information modulated in a predetermined modulation scheme, on at least one carrier signal, each flux emitted d modulated information elements being representative of at least a part of each transmitted stream of codewords,
• a transmitting device on a noisy channel in nonstationary attenuation, a transmitted signal incorporating a flow of time symbols of data elements corresponding to the data to be transmitted, each data element being represented by a plurality of temporal symbols, the emitted signal having a waveform selected from the group of cyclic waveforms comprising cyclically repeated and single-carrier guarding intervals having fluctuations corresponding to those of a single carrier,
• a receiving device adapted to receive a signal, said signal received, incorporating a stream of time symbols of information elements corresponding to a stream of time symbols of information elements transmitted on said channel
• ⁇ a demodulation device adapted to generate at least one stream of codewords, said received stream of code words, from the stream of time symbols of information received,
• ⁇ at least one decoding device adapted to generate a bit stream, said received stream of bits, for decoding each received stream of codewords according to a decoding method corresponding to a coding method implemented by the transmitter, characterized in that the receiver is in accordance with the invention and / or implements a method according to the invention.
• the inventors have found that the invention makes it possible in practice to obtain a fast and accurate performance prediction, and in particular considerably more accurate than in all the known prior methods, while remaining so fast. This result is surprising, in particular because the signal-to-noise ratio plus equivalent interference does not correspond to the transmission quality per modulated information element received.
• the invention makes it possible to envisage the production of a receiver for these waveforms whose performances are auto-adaptive and minimized as a function of the quality of transmission.
• a receiver has the particular advantage of having a minimum energy consumption which is a considerable advantage for receivers embedded on mobile systems, in particular on space systems. Indeed, the reduction of energy consumption makes it possible on the one hand to save money in use, and on the other hand to minimize the performance requirements of the energy sources, and therefore their costs, their weight and their size. , or improve their operating life when it comes to a storage battery.
• the invention extends to a non-stationary coded serial digital transmission method incorporating a reception method according to the invention, as well as to a non-stationary channel coded serial digital transmission device comprising a receiver according to the invention. .
• the invention extends to a computer program capable of being loaded into the RAM of a computing device, and comprising program code instructions for the execution of the steps of a method according to the invention by the said computer device.
• the invention also relates to a reception method, a receiver, a transmission method, a transmission device characterized in combination by all or some of the characteristics mentioned above or below.
• FIG. 1 is a block diagram showing a transmission device according to the invention incorporating a receiver according to the invention
• FIG. 2 is a block diagram showing a transmission device of a transmission device according to the invention
• FIG. 3 is a block diagram showing a reception device and a device for predicting the performance of a receiver according to the invention
• FIG. 4 is a schematic flow chart showing an embodiment of a reception method according to the invention.
• FIG. 5 is a diagram illustrating an example of the appearance of received time symbols and the duration of the coded words and time symbols received in a single carrier cyclic waveform
• FIG. 6 is a diagram illustrating an example of values of the equivalent signal-to-noise plus interference ratio calculated on the time symbols received from FIG. 5;
• FIG. 7 is a diagram illustrating the operations carried out in the frequency domain with an EW-SC-OFDM waveform
• FIG. 8 is a schematic diagram of examples of reference curves that can be used, according to different modulation schemes, for a predetermined function for determining a mutual information value on a Gaussian white noise additive-dependent channel. the signal-to-noise ratio of this channel,
• FIG. 9 is a schematic diagram showing the use of a reference curve similar to FIG. 8 for executing a step of a method according to the invention.
• FIG. 10 is a schematic diagram showing the use of a reference curve similar to FIG. 8 for carrying out a first part of a step of a method according to the invention
• FIG. 11 is a schematic diagram showing the use of a curve representative of a standard function for performing a second part of a step of a method according to the invention.
• FIG. 12 is a diagram illustrating the transmission and reception chain of a cyclic waveform with a single carrier in the time domain (TDM type)
• FIG. 13 is a diagram illustrating an example of PER obtainable by a method according to the invention compared to an estimated value in the case of a non-frequency selective channel,
• FIG. 14 is a diagram illustrating an example of PER obtainable by a method according to the invention compared to an estimated value in the case of a frequency selective channel.
• FIG. 1 generally represents a coded and modulated serial digital transmission device on a non-stationary attenuation attenuated channel with an EW-SC-OFDM waveform.
• This device comprises a transmitter 11, a receiver 12 and a physical link 13 wireless forming the transmission channel.
• the physical link 13 may for example be a radio frequency link, such as for example linking mobile terminals such as cellular telephones, personal digital assistants, laptops, wireless cards, land vehicles, ships, aircraft, satellites, space probes or other space systems ... at a base station, itself fixed (terrestrial) or mobile (vehicle, satellite, ...) accessing a data transmission network such as the Internet network or any other private network.
• the transmission can be bidirectional, that is to say that each mobile terminal is sometimes issuer, sometimes receiver.
• the transmitter 11 comprises a first module 14 delivering data in the form of a bit stream (baseband signal) to be transmitted, said transmitted bit stream.
• This transmitted bit stream is supplied to a coding module which executes a predetermined coding method to form, from the bits, a stream of coded words, the so-called coded word stream.
• a coding method makes it possible in particular to increase the reliability of the transmitted data by increasing the redundancies while ensuring the correction of errors, that is to say the restitution of the initial data despite the disturbances that can undergo the channel 13 of transmission.
• the invention applies to any coding method, and regardless of the exact nature of the coding method used.
• This may be in particular a coding method chosen from the so-called LDPC type hollow parity matrix), turbo-type methods and other iterative decoding coding methods.
• the coding module comprises a plurality of coders-notably two coders.
• the coding module 15 delivers coded words, which are then interleaved by an interleaver circuit 17, and then modulated, according to a predetermined modulation scheme, by a modulator circuit 18 which provides a stream of modulated and interleaved information elements. to a transmission device 19 capable of radiofrequency transmission on the physical link 13 of the signals in the form of time symbols of N information elements.
• the receiver 12 comprises a reception device 20 able to receive the signals transmitted via the physical link 13 by radiofrequency, and to deliver a stream of temporal symbols of received modulated and interleaved information elements, to a device able to apply a demodulation according to the modulation scheme and mapping used on transmission, then a de-interleaver circuit 22 which performs the inverse processing of the interleaver 17 of the transmitter 11, that is to say, allows the progressive reconstitution of a stream temporal symbols deinterleaved demodulated information elements, from the flow of time symbols of information elements from the demodulator circuit 21.
• the deinterleaver circuit 22 thus provides a stream of coded words, said stream received code words, from the stream of demodulated deinterleaved information elements.
• a decoding module 25 comprising one or more decoders (in particular two decoders), and making it possible to deliver a stream 27 of received bits included in the decoder. signal conveyed by the physical link 13 and corresponding to the stream of bits emitted by the generator circuit 14.
• the receiver 12 also comprises a performance prediction module 28 described hereinafter in more detail.
• FIG. 2 shows in more detail the transmission device 19 in the case of an EW-SC-OFDM waveform with M subcarriers (M being an integer greater than 1, and generally of the order of several hundred, for example equal at 426).
• M being an integer greater than 1, and generally of the order of several hundred, for example equal at 426.
• This waveform is known in itself and described for example by the publication "MMSE Frequency-domain Equalization Using Spectrum Combining for Nyquist Filtered Broadband Single-Carrier Transmission” [S. OKUYAMA], 2010.
• This transmitting device 19 firstly comprises a module 51 putting in parallel the modulated and interleaved information elements and applying a fast Fourier transform to them, to deliver blocks with M frequency components on the different sub-carriers.
• the transmission device 19 also comprises an expansion module 52 receiving the blocks delivered by the module 51 to apply to them an extension of K subcarriers, namely K / 2 subcarriers in the bands. and, respectively, 7; -2 (FIG. 7) at each end of the central frequency band 10 of the subcarriers, K being a non-zero integer less than M, for example of the order of 10% of M, for example equal to 42.
• the transmission device 19 also comprises a driver insertion module 53 in a deterministic manner, intermingled or not with the subcarriers carrying information, also adding subcarriers of zero value at both ends of the spectrum, so to deliver blocks with N frequency components, N being a non-zero integer greater than M + K, for example of the order of 512.
• the transmission device 19 also comprises a module 54 for weighting the subcarrier K by application of a Nyquist half-filter in the frequency domain whose transfer function is for example:
• a is the drop-off coefficient (roll-off factor) of the Nyquist filter
• M is the number of subcarriers carrying information.
• the blocks with N frequency components delivered by the weighting module 54 are subjected to a module 55 applying to them a transform Fast Fourier counter then a parallel / serial transformation to deliver time symbols of N information elements.
• These time series symbols are processed by a module 56 inserting guard intervals (cyclic prefixes corresponding to a part of the copied symbols) between the symbols, and the signal obtained is transmitted on the transmission line 13 by a transmission circuit 57 comprising a digital-to-analog converter and a radiofrequency transmitter connected to a transmitting antenna.
• the reception device 20 comprises a reception circuit 61 comprising an analog / digital converter and a radio frequency receiver connected to a reception antenna, making it possible to receive signals transmitted by a transmission device 19 and comprising temporal symbols h (n). N modulated and intertwined information elements.
• the received temporal symbols are processed by a module 62 removing the guard intervals between the symbols, and supplying temporal symbols at the input of a module 63 placing the modulated and interleaved information elements in parallel and applying them a fast Fourier transform to deliver blocks Y (K) received at N frequency components (step 29 figure 4).
• These received blocks Y (K) are supplied to the input of an equalization module 64 applying a predetermined equalization method W (K) in the frequency domain, and to the input of a module 65 for the desorption of K subcarriers extension.
• the equalized and unweighted blocks obtained are then supplied to the input of a module 66 suppressing the extension and thus delivering blocks with M frequency components at the input of a module 67 which removes the pilots from the symbol stream. information.
• the blocks Ye (K) received at M frequency components thus obtained are delivered to the input of a module 68 applying them an inverse fast Fourier transform then a parallel / series transformation to deliver modulated x (n) information elements. and interlaced at the input of the demodulator 21, which provides demodulated and interleaved information elements at the input of the deinterleaver 22, the latter providing demodulated information elements and interleaved.
• FIG. 4 illustrates the various steps performed by the receiver 12.
• the step 31 FIG. 4 represents the set of operations performed by the equalization module 64, the de-weighting module 65, the module 66 suppressing the extension, the module 67 for removing the pilots, and the module 68 applying a fast inverse Fourier transform to deliver information elements x (n) from the blocks Y (K) received at M frequency components.
• the received stream of code words is demodulated by the demodulator 21. It is then deinterlaced by the deinterleaver 22 in the subsequent step 32, then stored in the buffer 23 in step 41 .
• FIG. 4 thus represents a flow diagram of an exemplary reception method according to the invention implemented in a receiver 12 according to the invention.
• the performance prediction module 28 calculates in step 33, for each piece of information, according to the method of equalization, and according to the interference due to the waveform, a ratio SINReq signal / noise plus interference equivalent according to the equalization process.
• said value SINReq of the signal-to-noise ratio plus equivalent interference is calculated according to the formula (III).
• the transfer function of the equalization filter is given by: wm
• H (k) H [k] F [k]
• H [k] the gain of the global channel which takes into account the gain H [k] of the channel (discrete Fourier Fourier transform of the discrete impulse response) and the window weighting F [k] applied to the transmission.
• FIG. 5 represents an example of time symbols received of duration Ts corresponding to a coded word of duration Tmc with such a waveform.
• FIG. 6 represents an example of SINReq values of the signal-to-noise ratio plus equivalent interference that can be obtained with the formula above. As can be seen, these values are established while the duration Tmc of a coded word does not correspond to a multiple of the duration Tei of the information elements received for this coded word.
• SINReq of the signal-to-noise ratio plus equivalent interference is given by the formula (I).
• MMSE minimized mean square error
• Wiener filter equalization method the transfer function of the equalization filter is given by:
• the transmission and reception chain including the transmission channel, is represented in FIG.
• - CP corresponds to the addition of the cyclic prefix (cyclic copy of part of the N samples),
• h T (n) is a temporal Nyquist filter
• h c (n) is a filter representing the propagation channel
• the performance prediction module 28 makes it possible to determine an error rate, before the decoding (and therefore without requiring the latter to be performed), for each piece of information received, taking into account the attenuation variations of the channel on the channel. the pieces of information received, that is to say on the different parts of the corresponding received coded words.
• the method implemented for this purpose may be identical to that described in FR 2 952 254.
• step 33 the different values SINReq representing the transmission quality are calculated by the performance prediction module 28 from the received stream of codewords, for each piece of information of a corresponding received codeword. stored in the memory 23, the received stream of codewords.
• a mutual information value 1 ⁇ is developed by the performance prediction module 28, in the subsequent step 34, according to a predetermined function.
• a first variant embodiment of the invention consists of consider mutual information 7 ((b k 1 , b k 2 ,., b k p ), y ⁇ ) equal to mutual information
• This variant has the advantage of proposing a unique theoretical formula for calculating a reference curve of the mutual information which depends solely on the nature of the modulation considered. This approach does not take into account the actual implementation ("mapping") of the modulation nor the fact that the constituent p bits of the information element are not all protected in the same way against the noise of the channel.
• each mutual information value 1 ⁇ is determined according to the function defined by the aforementioned formula (I).
• the mutual information between the transmitted and received information elements depends only on the value of the SINReq signal / noise plus equivalent interference ratio. .
• a reference curve for each modulation scheme can therefore be obtained by numerical evaluation of the previous expression.
• the reference curves shown in FIG. 3 are obtained respectively for the following modulation schemes: QPSK, BPSK, 16QAM, 64QAM.
• a second variant consists of taking into account the actual implementation ("mapping") of the modulation and considering each bit.
• the mutual information ⁇ (b k 1 , yk), / ⁇ (b k 2 , yk is calculated ) .... / ⁇ (b k p , yk) between each bit and the received information element y ⁇
• the reference curve used to obtain the information mutual is then the sum of these p curves.
• each mutual information value I k is determined according to the function I k i ⁇ b yt) of the mutual information computed between the j th bit - J - P ⁇ ) of the element of transmitted information and the information element received y ⁇ , this function being defined by the aforementioned formula (VII).
• I k ( ⁇ k , yk) is between 0 and 1.
• the reference curve to be used on each piece of information is the sum of the curves for each of the p bits. Whatever the variant used, a reference curve is thus obtained representing a predetermined function providing a mutual information value 1 ⁇ as a function of a signal-to-noise ratio SNR.
• each reference curve referred to throughout the text is in practice materialized by a table of digital values stored in mass memory.
• the performance prediction module 28 uses such a table to determine the appropriate numerical values allowing the use of such a curve.
• step 34 of calculating mutual information 1 the performance prediction module 28 considers the reference curve mentioned above, that is to say the recorded digital values, and each value of the equivalent SINReq signal / noise plus interference ratio as a signal-to-noise ratio value to be plotted as abscissa to determine each value of 1 ⁇ .
• these different values are subjected to the deinterleaving process, and in the subsequent step, for each coded word of the received stream of coded words, a mean ⁇ I n > of mutual information is developed by averaging the different mutual information values determined for the different values taken by the ratio SINReq signal / noise plus equivalent interference on said coded word.
• the performance prediction module 28 reuses the same reference curve (i.e., the same table of numerical values) to determine an equivalent signal-to-noise ratio SNR eq on the coded word received from said mutual information mean ⁇ I n >.
• the performance prediction module 28 uses the inverse function
• the performance prediction module 28 calculates each value of the error rate ER from said value of equivalent signal-to-noise ratio SNR eq and stored data representative of variations of an equivalent error rate according to a predetermined standard function for the coding and decoding modules used on an additive Gaussian white noise channel.
• FIG. 6 represents an example of curves representative of such standard functions, the different curves being obtained for the same decoding coding modules and varying from one another as a function of the number of iterations used for the decoding.
• the performance prediction module 28 calculates, from these curves, that is to say tables of corresponding registered digital values, a set of ERi error rates. , i.e., an error rate value for each number of iterations that can be used at decoding. ERi error rate values are decreasing with the number of iterations. This set of values ERi therefore constitutes an error rate vector (ER), determined for each coded word received.
• ERi error rate vector ER
• a first curve CS1 corresponding, for example, to a single iteration
• a second curve CS2 corresponding, for example, to four iterations
• a third curve CS3 corresponding, for example, to eight iterations
• a fourth curve CS4 corresponding for example to sixteen iterations.
• the two steps 36, 37 can be combined in one and the same step 38, if the standard functions are combined with the inverse function I ⁇ 1 into a single function directly providing, for each number of iterations, curves of variation of the error rate ER as a function of the mean of mutual information ⁇ I n >.
• the received stream of de-interleaved codewords stored in the buffer memory 23 is decoded in step 42 by the decoding module 25 from, in particular, a control signal generated in step 39 from each value of FIG. error rate calculated by the performance prediction module 28.
• the control module of the performance prediction module 28 In a first variant in which the decoding method has a fixed number of iterations that can not be modified by control, the control module of the performance prediction module 28 generates a control signal chosen from among an authorization signal from the decoding and a signal prohibiting decoding. In this case, the performance prediction module 28 calculates a single error rate value ER (PER or BER).
• ER error rate value
• a decoding authorization signal will be developed when the value of the calculated error rate is lower than a predetermined and recorded set error rate
• a decoding prohibition signal will be developed when the value of the rate calculated error is greater than this setpoint error rate value.
• This variant is particularly interesting especially when the coded block is received on several disjointed time ranges that can spread over a very long period (several seconds in the case of the time dispersal of DVB-SH). It makes it possible to trigger a single decoding by codeword without attempting decoding upon receipt of each new piece of the coded word.
• the performance prediction module 28 also advantageously incorporates a control module making it possible, during step 39, to produce a control signal for the decoding module 25 so that the latter implementing, for each coded word received to be decoded, a number of iterations calculated as a function of the error rates ERi.
• the control module determines in the ER error rate set the ER opt value, of the error rate which is the largest and less than a predetermined and recorded set error rate, and controls the error rate. decoding module 25 as a function of the number of iterations corresponding to this value ER opt .
• the invention makes it possible to improve by a factor of the order of 500 the average duration necessary for the evaluation with respect to a complete simulator generating the coded packets.
• An empirical rule indicates that with such a complete simulator, to know the PER (error rate per packet), it is necessary to generate coded packets until 100 packets are false. Thus, for example, for a PER of 0.01, the number of packets to generate to obtain a single value of PER over time, it will generate 10,000 coded words.
• the tests show that the evaluation according to the invention is on average faster than the real time.
• the performances in PER on a channel of duration D will be obtained in a calculation time slightly lower than the duration D.
• the main configuration parameters of the simulator are: the type (row-columns, convolutional %) and the parameters of the de-interleaver to change the parameters as defined in the DVB-NGH standard (interleaving depth, interlace unit (number of symbols) ...); channel settings that allow the user to choose a channel template and modify the parameters associated with this model; the parameters of the physical link that allow the user to modify the parameters of the waveform (guard intervals, band, number of sub-carriers) as well as the coding rate.
• the invention can be the subject of many alternative embodiments and applications other than those mentioned above.

Landscapes

• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Quality & Reliability (AREA)
• Physics & Mathematics (AREA)
• Discrete Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Mathematical Physics (AREA)
• Electromagnetism (AREA)
• Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
• Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=50289753

Family Applications (1)

Country Status (4)

Families Citing this family (6)

Family Cites Families (2)

• 2013
  • 2013-10-18 FR FR1360177A patent/FR3012276A1/fr active Pending
• 2014
  • 2014-10-15 US US15/029,820 patent/US9654325B2/en not_active Expired - Fee Related
  • 2014-10-15 WO PCT/FR2014/052628 patent/WO2015055952A1/fr not_active Ceased
  • 2014-10-15 EP EP14796821.8A patent/EP3058675A1/de not_active Withdrawn

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events