| 摘要 |
One embodiment described herein relates to a method of predicting the performance of a communication system on a transmission channel. The system may comprise a transmitter suitable for applying bit interleaved coded modulation to information bits issued by a source to generate coded symbols, these coded symbols being transmitted by the transmitter over the transmission channel. The coded modulation may be based on a turbo-code comprising at least two constituent codes. The system may also comprise an iterative receiver, suitable for performing an iterative interference cancellation technique to process the coded symbols received from the transmission channel, the iterative receiver comprising an equalizer, a demodulator, and a turbo-decoder that are activated during each iteration performed by the iterative receiver. The turbo-decoder may comprise at least two decoders suitable for decoding the respective constituent codes of the turbo-code, the decoders being suitable for interchanging probabilistic quantities in an iterative manner. |
| 主权项 |
1. A method of predicting the performance of a communication system on a Multiple Input Multiple Output (MIMO) transmission channel, wherein the system comprises:
a transmitter suitable for applying bit interleaved coded modulation to information bits supplied by a source so as to generate coded symbols, these coded symbols being transmitted by the transmitter over the transmission channel, the coded modulation being based on a turbo-code comprising at least two constituent codes and adapted to encode the information bits in coded bits; and wherein the system further comprises an iterative receiver, suitable for performing an iterative interference cancellation technique in order to process the coded symbols received from the transmission channel, the iterative receiver comprising an equalizer, which estimates the coded symbols transmitted by the transmitter over the transmission channel said equalizer having an input and an output, a demodulator, which provides an estimation of the coded bits generated by the turbo-code, and a turbo-decoder which decodes the coded bits generated by the turbo-code said turbo-decoder having an input and an output wherein the equalizer, the demodulator and the turbo-decoder are activated during each iteration performed by the iterative receiver, the turbo-decoder comprising at least two decoders suitable for decoding the respective constituent codes of the turbo-code, the decoders being suitable for interchanging probabilistic quantities in an iterative manner wherein, during each iteration performed by the iterative receiver, the equalizer uses probabilistic quantities on the coded bits provided at a preceding iteration by the turbo decoder, the demodulator uses the estimation of the coded symbols provided by the equalizer and the turbo decoder uses the output of the demodulator and probabilistic quantities representative of a priori probabilities on the information bits to decode the coded bits and provides probabilistic quantities on the coded bits used at a subsequent iteration by the equalizer; the prediction method comprising, for each iteration i of the iterative receiver: a first determination process of determining a value γEq(i) representative of a signal to interference plus noise ratio at the output from the equalizer from an estimate of the transmission channel and from an estimate v of a variance of the coded symbols at the input to the equalizer at iteration i, this determination being performed by using a preestablished function characterizing the behavior of the equalizer; and a second determination process of determining:
a transmission error probability Pe(i) on the channel;a variance vi of the coded symbols wherein the variance vi is determined at the output from the turbo-decoder; andmean mutual information IE,DEC(i) between the information bits supplied by the source and probabilistic quantities representative of extrinsic probabilities on those information bits supplied at the output from the turbo-decoder; the second determination process being done from the value γEq(i) and from “a priori” mean mutual information IA,DEC(i) between the information bits supplied by the source and probabilistic quantities representative of a priori probabilities on these information bits available at the input of the turbo-decoder at iteration i, by using preestablished functions characterizing the behavior of the demodulator and of the turbo-decoder for a predetermined number (NDEC) of decoding iterations performed by the turbo-decoder; the variance vi being used during the first determination process of the following iteration i+1 of the iterative receiver to estimate the variance v of the coded symbols at the input of the equalizer, and the mean mutual information IE,DEC(i) being used during the second determination process of iteration i+1 as a priori mean mutual information IA,DEC(i+1); wherein the result of the second determination process after a given number of iterations of the iterative receiver is used to select a coded modulation scheme based on a turbo-code to be applied by the communication system to satisfy a given quality of service criterion. |
