去蜂窝大规模MIMO系统中基于迭代剔除的导频分配

Pilot Allocation in Cell-Free Massive MIMO Systems based on iteration removal

针对去蜂窝大规模多输入多输出系统中导频污染问题,提出了一种基于迭代剔除的导频分配算法。首先利用各用户相对位置信息,为系统中用户建立适当半径的导频许可圈,为导频许圈的用户分配相互正交的导频,然后已经分配过导频的用户会从用户集剔除,不再参与后继导频许可圈中用户挑选和导频分配过程,最后利用贪婪导频分配算法为速率最低的用户更新导频。实验结果表明,基于迭代剔除的导频分配算法在合适的半径下可有效降低导频污染,实现去蜂窝大规模MIMO系统的网络吞吐量提升。

A pilot allocation algorithm based on iteration removal is proposed to solve the problem of pilot contamination in cellfree massive multi-input multi-output systems. First, use the relative position information of each user to establish a pilot-permitcircle with an appropriate radius for users in the system, and assign mutually orthogonal pilot sequences to users in the pilot-permit-circle. Then users who have been assigned pilot sequences will be removed from the user sets, no longer participate in the user selection and pilot allocation process in the subsequent pilot-permit-circle, and finally use the greedy pilot allocation algorithm to update the pilot for the user with the lowest rate. The simulation results show that the pilot allocation algorithm based on iteration removal can effectively reduce the pilot contamination under a suitable radius, and realize the network throughput improvement of the cell-free massive MIMO systems.