CDMA Systems Multi-user Detection Method Based On Particle Filter

In recent years, particle filter is the focus in fields of nonlinear non-Gaussian signalprocessing research. It is a kind of Monte Carlo method based on the Bayesian theory. Byusing a large number of particles and its weights, the posterior probability density distributionis approximated and the optimal estimation accuracy can be achieved when the quantity ofparticles is large enough. At present particle filter is widely used in target tracking, parameterestimation, system identification, navigation, positioning and other fields.High spectrum efficiency, strong resistance to frequency selective fading and easy toimplement are advantages of CDMA systems. In this paper, Rayleigh fading channel issimulated using first order AR model, the Alpha stable distribution is adopted asnon-Gaussian noise model, so that the research of particle filter and its improved algorithmscan be achieved based on CDMA system and its application.Particle filter has the advantages of high estimation precision and wide range ofapplication. However, it has the problems of particle degeneracy, loss of diversity andcalculation complexity. In this paper and then novel improved particle filter algorithms areproposed according to proposal distribution.Swarm intelligence algorithms are novel methods which are inspired in principle ofbiological evolution and are used to solve complex optimization problems, having theadvantages of wide range of applications, high optimizing efficiency and do not need specificinformation, etc. Recently swarm intelligence algorithms are concerned widely by researchersin different research fields. As the member of swarm intelligence algorithm, genetic algorithm,particle swarm optimization algorithm is introduced in the paper. Combined with theadvantages of particle swarm optimization, the improved particle filter is proposed.Simulation results show that the improved intelligence algorithm has a faster convergence rateand is applied to optimize particle filter proposal distribution can improve estimation accuracy.However, more complicated computation is needed, that is the improved direction of swarmintelligence algorithms.