Study On Coded Continuous Phase Modulation Systems And Their Performances

Continuous phase modulation (CPM) is a kind of constant-envelope digital modulation schemes with continuous phase which provides good spectral- and power-efficiency. It can be used as an inner code combined with other codes in the serially concatenated coded-modulation system with interleaving and iterative decoding.In this thesis, a decomposition model of CPM system was introduced briefly. The decomposition model shows that a CPM system can be decomposed into a continuous-phase encoder (CPE) and a memoryless modulator (MM). We introduced the soft-output detection algorithm for continuous phase demodulator. At the same time the performances of CPM moduation were analyzed from CPM signals's Euclidean distance and spectral bandwidth. Then quantized performances of CPM systems were simulated.Tapped-delay-line representation of a frequency-selective and time-variant channel was introduced, and then we studied adaptive equalization as a technique of intersymbols interference (ISI) in multipath fading channel. LMS algorithm-based adaptive equalization was analyzed and its performances were simulated under difference multipaths.To achieve high bandwidth- and power-efficiency, we proposed a serially concatenated coded binary and non-binary continuous phase modulation system with interleaving and iterative decoding, and then simulation results in AWGN channel and frequency-selective channel with adaptive equalization are given. Besides, we concluded the performance: the joint iterative technique between demodulation and decoding in binary coded continuous phase modulation systerms can improve their performances distinctly. And in the first iteration, the phenomena are most remarkable.At the same time the performances of coded 8ary CPM systerms in AWGN channels are given.In the end of this thesis, the research status of CPM techniques using in spece-time systerms were introduced. And research issues of continuous phase modulation are proposed.