Research On Implementation Complexity Reduction Methods For Massive MIMO System

As an extension of traditional MIMO system,Massive MIMO can greatly improve the system’s frequency spectrum efficiency and has become an attractive research topic for the next generation wireless communication.Massive MIMO systems employ large number of antennas to serve limited number of users,which leads to very high implementation complexity.In order to provide feasible schemes that can reduce implementation complexity for the future applications of the Massive MIMO system, this thesis mainly studies the methods that can reduce the hardware complexity and cost of Massive MIMO system.The main contributions are as following:1. The Massive MIMO system model is established firstly and then the pilot contamination and its suppression algorithms have been analyzed.Simulation results show that the combination of the MMSE channel estimation algorithm and the precoding scheme based on the minimization of pilot contaminaton can restrain the influence of pilot contamination.2.After analyzing the effect of transmit antenna selection(TAS) on the performance of multi-user MIMO system,a low complexity suboptimal TAS algorithm is designed for the Massive MIMO system.And the minimum transmit antenna number problem is studied under the constraint of user rate.Simulation results show that the designed TAS algorithm can not only be computed simply but also achieve the approximate optimal performance.3.Base on the discussion of the effect of TAS algorithm on the system’s energy efficiency, two feasible algorithms are proposed based on the random TAS algorithm and the designed TAS algorithm respectively.The two algorithms maxim energy efficiency and figure out the corresponding transmit antenna number.Simulation results show that the TAS algorithm can increase the system’s energy efficiency.4.A new single RF chain receiver for the Massive MIMO system is studied. The SINR expressions of the received signals are analysed when there is delay error or not. And then a delay error calibration algorithm is proposed.The computer simulation results illustrate that the new type receiver can provide nearly the same performance as the conventional receiver in the typical wireless communication system.