Research On Rake Receiving Technology In Spread Spectrum Communication Systems

The multipath interference of unmanned aerial vehicle(UAV)to ground communication is more serious,To solve this problem,the Rake receiver technology in spread spectrum communication system is deeply studied in this paper.Rake receiver is widely used in spread spectrum communication system for eliminating the impact of multipath fading on system performance.Traditional Rake receiver needs a separate search channel,which occupies channel resources,and because the algorithm of traditional is relatively simple,the error rate performance is not good.In this paper,a low-complexity adaptive Rake receiver is proposed,which is an adaptive Rake receiver based on fast approximated power iteration subspace tracking algorithm,and an adaptive Rake receiver well worked in low SNR environment is proposed,which is Bayesian Rake receiver.In this paper,key techniques in spread spectrum communication are analyzed in detail,and the simulation of these techniques is carried out such as spreading code sequence,carrier acquisition and synchronization.This paper has studied the multipath effect and the tap-delay-line model too.In the process of creating new Rake receiver,first this paper concludes the existing Rake receivers,and then finds the breakthrough point which can be innovated.Following this idea,this paper first proposes an adaptive Rake receiver based on the fast approximated power iteration subspace tracking algorithm with low complexity.The new Rake receiver adapts the subspace tracking algorithm to the Rake receiver,reduces the algorithm complexity of the adaptive Rake receiver in the channel estimation process,and guarantees the Rake receiver performance.Then the Bayesian Rake receiver is put forward by applying the Bayesian idea to the Rake receiver for improving the Rake receiver performance in the low SNR environment.Bayesian Rake receiver makes the prior knowledge applied,and after a detailed derivation,this paper gets the Bayesian Rake receiver algorithm steps.