Research On Constant Modulus Algorithm Based On Particle Swarm Optimization In Shortwave Channel

In recent years, short-wave channel is widely used in the military, medical, emergency communications and so on, which is because of its strong abilities of anti-destroy and long distance signal transmission. It will be affected by multipath propagation and Doppler effects and fading and the complex noise when the signal transmits in short-wave channel. So it is inevitable to generate the severe inter-symbol interference(ISI), leading a higher rate of bit error, and having a strong impact on the communication quality of short-wave channel. Therefore, the research algorithms which can reduce inter-symbol interference on communication quality, is important theoretical and practical significance to reduce the rate of bit error and improve the quality of signal transmission channel.In view of the insufficiency of constant modulus algorithm(CMA), the thesis puts forward two kinds of variable step size constant modulus algorithm(VCMA) which is based on the analysis of the relevant basic theory knowledge and absorbs the advantage of decreasing BER algorithm. Combined with simulated annealing algorithm(SA) and the characteristics of particle swarm optimization(PSO), simulated annealing particle swarm optimization algorithm(SA-PSO) is applied to CMA and its variant, which is simulated in short-wave channel. The specific work is as follow:(1) Characteristics of short-wave channel, the classic Watterson short-wave channel model are studied and analyzed. And Watterson short-wave channel model is set up combining with its characteristics by using the Simulink of MATLAB.(2) Having described CMA in detail, the effect of step size factor on equalization performance of CMA is studied, the two VCMA is proposed with the purpose of overcoming the shortcomings of CMA(VCMA1 and VCMA2) which can improve performance of algorithm. VCMA1 and VCMA2 are described and analyzed in theory, which is verified in Watterson short-wave channel.(3) The relevant knowledge of the PSO algorithm is elaborately introduced, mainly including: the origin and concept, the basic idea and principle, process and main parameters; the basic ideas and characteristics of SA algorithm is analyzed and studied. The SA-PSO algorithm is analyzed combining the advantages of PSO and SA respectively.(4) The SA-PSO algorithm is applied to CMA and two VCMA algorithms and then SA-PSO-CMA, SA-PSO-VCMA1 and SA-PSO-VCMA2 are proposed. Firstly, SA-PSO-CMA, SA-PSO-VCMA1 and SA-PSO-VCMA2 are described and analyzed in theory. Secondly, SA-PSO-CMA, SA-PSO-VCMA1 and SA-PSO-VCMA2 are simulated in Watterson short-wave channel. Finally, CMA, VCMA, SA-PSO-VCMA are analyzed and compared detailedly by the simulation results.