Research On Massive-MIMO Uplink Enhancement For Time Division Duplexing

With the rapid development of the continuous emergence of various new services,the requirement of future wireless communication system for uplink performance is getting higher and higher.The research work in this paper is mainly based on the uplink enhancement technology of Massive-MIMO.The massive multiple-input multiple-ouput(MIMO)Technology is recognized as a promising technique for the 5th generation mobile commu-nication systems.Therefore,there are still some challenge faced by the massive MIMO technology,for example,practical deployment difficulty,high hardware cost and high complexity of multi-technology integration.In addition to this integration,firstly,this paper studies the key technologies of 5th generation mobile communication systems and Massive MIMO,and then builds a Massive-MIMO simulation platform,which lays the founda-tion for the follow-up researches.The antenna array topologies have a straightforward impact on the performance of Massive-MIMO systems.Large-scale modular antenna ar-rays can be assembled by a series of small modular arrays with unified structure and low cost and the combination of modules is also more flexble.The paper researchs the structure of modular array,and then evaluate the performance differences of different splicing modes between modules.Considering the complexity and cost of the actual deployment,this paper further studies and evaluates whether the performance differences between modules are calibrated or not.Based on the research of modular array,the paper proposes two asymmetric transceiver schemes to enhance the uplink receiving freedom and evaluates their performances.The number of antennas deployed by large-scale antenna arrays will reach tens or even hundreds,and the spacing between antennas is small.Therefore,we must pay attention to the influence of antenna mutual cou-pling on large-scale MIMO systems.The paper researchs the basic theory of antenna and the the paper summarizes two methods of calculating cou-pling matrix:the method based on S-parameter and the method based on open circuit voltage,and carries out the theoretical analysis and simulation verification.Meanwhile,the paper proposes a decoupling scheme based on TDD.Finally,the influence of antenna spacing on the system performance considering coupling effect is studied.The research results of this paper has certain guiding significance for the actual deployment of large-scale antenna arrays.