一种基于用户优先级的大规模MIMO导频分配方案

Pilot assignment scheme in massive MIMO systems based on user location priority

针对大规模多输入多输出时分双工系统中的导频污染问题,提出一种按照用户区域优先级智能分配导频序列的算法。该算法利用最小均方估计对信道进行估计,得到上行链路信干噪比的表达式,然后以距离为约束条件、信干噪比为目标函数,得到目标函数最优值。进而将小区区域进行分类,信道质量较好的区域随机分配导频序列,信道质量较差区域按照优先级智能分配导频序列,最后将所提算法和传统的随机分配算法进行比较。理论和仿真结果表明:所提算法在提高系统信干噪比、系统容量方面均有较好的效果,能够有效地降低导频污染对通信性能的影响。

The performance of massive multiple input multiple output （MIMO） time division duplex （TDD） systems is affected by pilot contamination. According to the priority of user location, this paper proposes a smart pilot sequences assignment scheme. The channel estimation is carried out based on the minimum mean square error （MMSE） algorithm. And the expression of signal to interference plus noise power ratio （SINR） in uplink training is presented. Based on the SINR expression, a convex problem using the distance as constraint conditions and the SINR as the objective function to analyze the effect of pilot contamination is proposed. According to the optimization problem, the cellular are classified, which the poor user with the most severe pilot contamination has the best channel quality, and the users with moderate inter-cell interference adopt the random pilot assignment scheme. Finally the proposed smart pilot assignment scheme and the traditional random pilot assigmnent algorithm are compared, and the excellent perforraance of this proposed scheme has been confirmed in MATLAB simulations.