The Research Of Concatenated Convolution Coding System Of FQPSK Modulation

With rapid development of mobile communication and satellite communication, people have realized that the spectrum resource is precious, then efficient modulation system get more and more in-depth research. FQPSK is a kind of frequency spectrum and power efficient modulation, its performance better than the current dominant modulation technology. Now, this system has become a standard modulation in the U.S. Telemetry Standards, so researching FQPSK modulation has important significance. Error-correcting has become a key technology to realize reliable communication of high speed broadband data. In order to adapt to the developing demands of future deep space communication which have the characteristics of low sending power, high power gain, higher data rate, and low complexity in hardware, this paper applies FQPSK modulation to concatenated convolution coding system, and analyzes its performance.This paper introduces principle of FQPSK modulation, generates the signal of FQPSK using the way of trellis coded and analyzes the advantages of this modulation firstly. In subsequent chapters, two common demodulation ways are presented, and studies FQPSK viterbi demodulation mainly. It can be proved viterbi demodulation is the best demodulation way through comparing BER performance of three demodulation ways. And then given simplified viterbi receiver and proved simplified viterbi receiver is still used the inherent memory of the modulation, the performance of BER only has slightly reduced. but have the significant reduction in receiver complexity. Meanwhile according to this conclusion we get simplified FQPSK trellis coded mode. Finally, because FQPSK modulation is essentially a convolution code, we can use trellis code of FQPSK as inner coding and apply it to concatenated convolution coding system, while simplified FQPSK modulation has a simple trellis mode, it has more benefit to apply. This paper are presented the two kinds of concatenated convolution coding system of FQPSK, and studied iterative decoding way of the two concatenation schemes, using the lower complexity soft input-soft output algorithm:Max-log-MAP algorithm, Through the simulation we can see the two kinds of concatenated convolution coding and iterative decoding system can obtain better BER performance than uncoded FQPSK system used viterbi receiver.