All-digital Qam Demodulation Receiver Non-collaborative Study

With the development of wireless communication, the demand for wireless communication and its application are increasing sharply; thus high bandwidth efficiency and robustness are required in these communication systems. In the traditional cooperative communication, training data is quite important for the demodulation of the receiver. In the non-cooperative communication environment, the receiver can not acquire any training data. For insurance, in the case of tracing and monitoring all kinds of illegal interferences by the wireless radio management committee according to the laws, the traditional demodulation methods are useless. Blind technique is independent of training data, and its universality and robustness meet the requirements of communication in the future. In this thesis, Software Radio design combines blind technique with QAM to implement the simulation of all digital QAM demodulation receivers in non-cooperative communication environment.Based on the research of many papers, our goal is to establish communication systems with Software Radio techniques. The improved algorithms in this thesis will implement all digital QAM demodulation system in non-cooperative communication environment. The innovations in this thesis are:(1) Carrier recovery algorithmWe have improved polar decision and reduced constellation algorithms. The simulation results of the improved algorithm show that it can be suitable for both square constellation and cross constellation high-order QAM signals. It has good performance over a large acquisition span of frequency with fast convergence.(2) Symbol recovery algorithmTiming recovery algorithm has been proposed based on the output power maximizing timing recovery algorithm which was proposed by C Richard Johnson. The results of simulation show that the improved algorithm can be applied in both BPSK and QAM signals, and be suitable for the demodulation in multi-path environment. The improved algorithm needs no training data with fast convergence and easy implementation. (3) Blind equalization algorithmBased on the CMA algorithm, the improved algorithm has been proposed. The simulation results show that the improved algorithm has increased the speed of convergence and has less steady-state residual deviation comparing with the CMA.In this thesis, we simulate the all digital QAM non-cooperative demodulation system. The results of simulation show that the system can achieve the standard of the requirements and the improved algorithms can meet the needs of the requirements. The simulation system is prepared for the implementation of hardware devices in future.