Research On Detection Algorithms Of Massive MIMO System

As one of the key technologies of the fifth generation wireless communication system,massive MIMO has attracted widespread attention in recent years due to its high spectral efficiency and high link reliability.However,the existence of large-scale antenna array at the base station brings a great challenge to the signal detection algorithm.For traditional centralized algorithms,the raw baseband data received by the antenna modules needs to be transmitted to the central processing unit of the base station for processing,which results in high data rate.And the interconnection bandwidth will become a new technical bottleneck.The signal detection needs to be realized by using a distributed architecture.Firstly,this paper introduces several distributed base station structures and details three distributed detection algorithms under the daisy chain architecture: Recursive Least Square(RLS),Stochastic Gradient Descent(SGD)and Averaged Stochastic Gradient Descent(ASGD).Simulations are carreied out to campare the BER performance and their limitaions are analyzed.Then a simplified RLS algorithm is proposed by ulitlizing the channel hardening characteristics of the massive MIMO system,which can achieve the best tradeoff between complexity and BER performance.Then,the distributed Richardson(DRI)method under the daisy chain architecture is proposed,and the complexity of the algorithm is also analyzed.The simulation results verify the superiority of the BER performance under different cluster sizes.In order to maintain the good performance of the DRI algorithm when the number of antennas in the cluster is large,it is adjusted to the multiple iterations of distributed Richardson(MIDRI)algorithm by increasing the number of iterations on each cluster.At the same time,from the perspective of simplifying the detection process of the algorithm,using the diagonal dominance property of the filtering matrix in the massive MIMO system,a simplified distributed Richardson(SDRI)algorithm is further proposed.Simulations show that the SDRI algorithm can approach the performance of DRI algorithm with low complexity when the antenna ratio is large.Finally,this paper presents a binary tree base station structure and develops the DRI algorithm under this structure.Theoretical analysis and simulations show that the architecture can effectively reduce the transmission delay.