摘要大规模MIMO无线通信技术是新一代移动通信最具潜力的研究方向之一，它能够提升频谱资源的整体利用率，提高用户与基站间通信的功率效率，增强系统的鲁棒性。而在大规模MIMO系统中，有限的导频资源会使系统产生导频污染，使基站无法获得准确的信道估计，进而导致上、下行链路在数据传输处理时产生严重干扰。本文主要研究了大规模MIMO系统导频污染问题及其解决方法，主要研究工作如下：75463

（1） 通过分析大规模MIMO系统的信道模型、上行信道估计，获得导频污染产生的原因： 由于所有小区共用同一套正交导频序列导致基站无法获得准确的信道估计；又通过分析基站对上行数据进行最大比合并、对下行数据进行最大比传输过程，获得如下结论：导频污染使得与目标小区用户使用相同导频的其他小区用户对该目标小区用户产生干扰，这也是影响大规模MIMO系统性能的主要因素。

（2）为降低导频污染对大规模MIMO系统整体性能的影响，提出一种基于服务质量(Quality of Service, QoS)的导频优化分配方法，在目标小区内上行接收信干噪比满足QoS指标的用户尽可能多的前提下，最大化目标小区所有用户的和速率。仿真结果表明，所提方法与传统的导频分配方法及智能导频分配方法相比，目标小区内满足QoS指标的用户数目显著提高，目标小区所有用户的和速率最大。

毕业论文关键词  大规模MIMO系统，导频污染，优化分配，服务质量

毕业设计说明书外文摘要

Title           Pilot  Allocation  and  Optimization in  Massive  MIMO  System                         

Abstract Massive MIMO wireless communication technology is one of the most potential research field on the next generation of mobile communications。 It can improve the overall efficiency of spectrum resources, the efficiency of power between the user and the base station communication, and the robustness of the system。 However，the massive MIMO system with limited pilot resources produces pilot contamination, so that the accurate channel estimation is unavailable at base station (BS), which leads to a serious interference in the data transmission process。 This paper studies the problem of pilot contamination in massive MIMO system and its solutions, the main research work is as follows:

(1) Through the analysis of channel model, the uplink channel estimation in massive MIMO system, we obtain that pilot contamination is due to the fact that all cells share the same set of orthogonal pilot sequence, and the BS can not get the accurate channel estimation。 By analyzing data transmitting process, we obtain that pilot contamination has a serious impact on system performance because of users from other cells using the same pilot with users in the target cell。 

(2) To reduce the impact of pilot contamination in massive MIMO system, we propose an optimization pilot allocation method based on quality of service (QoS)。 Simulation results show that the proposed method can significantly improve the number of users in target cell provided that the QoS indicators are satisfied, and maximize the sum-rate of all users in target cell, compared to the conventional and smart pilot allocation methods。

Keywords  Massive MIMO system, Pilot contamination, Optimal allocation, Quality of service

目   次

1  绪论 1

1。1  大规模MIMO系统研究背景 1

1。2  大规模MIMO系统的发展现状 2

1。3  导频污染及其减轻方法