大规模MIMO多小区多用户TDD系统导频污染抑制方法
Pilot Contamination Suppression in Massive MIMO Multi-cell Multi-user TDD Systems
作者：吴玉成(重庆大学 通信工程学院, 重庆 400044)；刘统(重庆大学 通信工程学院, 重庆 400044)；曹猛(重庆大学 通信工程学院, 重庆 400044)；杨婷婷(重庆大学 通信工程学院, 重庆 400044)
Author：WU Yucheng(College of Communication Eng.,Chongqing Univ.,Chongqing 400044,China)；LIU Tong(College of Communication Eng.,Chongqing Univ.,Chongqing 400044,China)；CAO Meng(College of Communication Eng.,Chongqing Univ.,Chongqing 400044,China)；YANG Tingting(College of Communication Eng.,Chongqing Univ.,Chongqing 400044,China)
收稿日期：2016-09-27 年卷（期）页码：2018,50(2):105-111
期刊名称：工程科学与技术
Journal Name：Advanced Engineering Sciences
关键字：大规模MIMO;导频污染;导频调度;用户分组
Key words：Massive MIMO;pilot contamination;pilot scheduling;user grouping
基金项目：国家自然科学基金资助项目（91438104）；重庆市自然科学基金重点项目资助（CSTC2013jjB40004）
中文摘要
针对大规模MIMO系统中导频污染问题，提出一种基于路径损耗执行用户分组的导频调度策略（pilot scheduling based on path loss to perform user grouping，PLUG），该策略以用户受导频干扰程度为依据将用户划分为中心用户组和边缘用户组，受导频污染较轻的中心用户分配相同导频，受导频污染严重的边缘用户分配正交导频，从而抑制导频污染的影响。PLUG策略假定每个小区的边缘用户数相同，为提高PLUG策略灵活性，进一步提出一种改进的基于路径损耗执行用户分组的导频调度策略（improved pilot scheduling based on path loss to perform user grouping，IPLUG），该策略利用判决参数实现每个小区边缘用户数的动态选取，成功地避免一些信道条件好的用户被误划为边缘用户造成导频开销浪费，或信道条件差的用户被误划为中心用户导致通信质量下降，提高了用户分组的准确性和合理性。理论分析和仿真结果表明，所提策略均能在不明显降低中心用户性能的前提下显著提高小区边缘用户的信道估计归一化MSE、上行链路SINR和上行可达速率。由此可知，所提策略可有效抑制大规模MIMO系统的导频污染并降低通信中断概率。
英文摘要
In order to suppress the pilot contamination in Massive MIMO system,a pilot scheduling scheme based on path loss to perform user grouping (PLUG) was proposed.The proposed PLUG scheme divided the users into the center user group and the edge user group according to different levels of pilot contamination.The proposed PLUG scheme assigned the same pilot sequences to the center users who suffering from slight pilot contamination and assigns orthogonal pilot sequences to the edge users who suffering from severe pilot contamination,thus inhibiting the impact of pilot contamination.The PLUG scheme assumed that the number of edge users in each cell is the same.To improve flexibility of PLUG,an improved pilot scheduling scheme based on path loss to perform user grouping (IPLUG) was proposed.By introducing the decision parameters,the strategy dynamically grouped and selected the number of edge users per cell.It avoided users in good channel conditions being wrongly divided into edge user group which would increase the pilot overhead,or users in bad channel conditions being wrongly divided into center user group whichwould decrease the quality of communication.In this way,the accuracy and rationality of user grouping were improved. Theory analysis and simulation results showed that the proposed scheduling can improve the channel estimation normalizedMSE,uplinkSINRand achievable rate of edge users with little performance loss of center users.In conclusion,the proposed schemes can effectively suppress the pilot pollution of Massive MIMO system and reduce the probability of communication interruption.
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