Cpm System Low Complexity Iterative Equalization Technology Research

With the rapid development of wireless communication technology in recent years,various upper layer applications of the wireless communication physical layertechnology have emerged. The valid spectrum resources are becoming more and morelimited over time, and the power consumption of the terminal is increasing. Thus theexisting wireless physical layer transmission technology still can not meet the growingdemand.As a constant envelope modulation technique, continuous phase modulation (CPM)has low peak to average power ratio (PAPR). Moreover, its spectrum is compact. Theseadvantages of high efficiency in spectrum and power make CPM an attractivemodulation technique in future wide-band wireless communication systems.Unfortunately, CPM signals will be corrupted by inter-symbol interference (ISI)when transmitted over multi-path fading channels. Turbo equalization is an effectiveapproach to overcome ISI by combining equalization and channel decoding. In thisthesis, we mainly study the low-complexity Turbo equalization technique for CPM inwireless communication systems.In Chapter One, the background and its significance of this topic are described.Then the previous study of Turbo equalization for linear modulation and CPM areanalyzed, and the contents of this thesis are introduced briefly.In Chapter Two, an iterative detection algorithm based on symbol-spacedfrequency domain equalization (FDE) for CPM is proposed. Firstly, the signal model,the trellis expression, and some decomposition methods for CPM are introdued.Secondly, the minimum mean square error (MMSE) FDE technique for CPM is studied.A data block structure for FDE of partial response CPM signal is designed, and alow-complexity iterative detection algorithm based on Laurent decomposition for CPMis also proposed. Lastly, the numerical results demonstrate the good performance of theproposed approach.In Chapter Three, a Turbo FDE algorithm based on differential precoding for CPMis proposed. Firstly, differential precoding technique for binary CPM is introduced. A low-complexity iterative equalization algorithm is proposed for precoded binary CPM,which is based on the principle of symbol-spaced soft interference cancellation. Wederive the proposed algorithm in detail and compare it with the traditional double FDEalgorithm for CPM, and the computational complexity is analysed. Lastly, the numericalresults show that this approach provides a good performance, and the impact of differentparameters on the system performace is also analyzed.In Chapter Four, a sample-spaced FDE algorithm for M-ary CPM is studied. Basedon the analysis of the circular prefix (CP) structure and the FDE algorithm, we analyzethe system performance by combining the optimal Viterbi demodulation algorithm forM-ary CPM. We also analyze the impact of different parameters on the systemperformaceIn Chapter Five, the contents of this thesis are summarized. Then the existingproblems and challenges of the technique of Turbo equalization for CPM are introducedin brief. Some suggestions for the further study are presented.