In this paper, the problem of pilot contamination in a multi-cell massive multiple input multiple output (MIMO) system is addressed. We propose a pilot assignment scheme, in which compared to the conventional methods, the corresponding optimization problem is solved in a low-complexity manner. To this end, by utilization of multi-path model comprising angle of arrival (AoA) distributions of users for propagation channels, the pilot assignment pattern would be defined by an optimization problem with discrete variables, and a criterion is presented to realize the obtained problem via an alternative involving continuous optimization variables. In addition, the resultant problem is dealt with in an iterative manner, where the sequential convex programming (SCP) is exploited. The numerical analysis reveals that the proposed method converges by only limited iterations. Furthermore, the proposed scheme out-performs compared to the conventional methods from complexity point of view, for a negligible degradation in the uplink sum rate.

在本文中，解决了多单元大规模多输入多输出（MIMO）系统中的导频污染问题。我们提出了一种导频分配方案，与常规方法相比，该方案以低复杂度的方式解决了相应的优化问题。为此，通过利用包括用户传播信道到达角（AoA）分布的多径模型，将通过具有离散变量的优化问题来定义导频分配模式，并提出实现所获得问题的准则通过涉及连续优化变量的替代方案。另外，以迭代方式处理所产生的问题，其中利用了顺序凸编程（SCP）。数值分析表明，该方法仅通过有限的迭代即可收敛。此外，从复杂度的角度来看，与上行链路总速率的可忽略的下降相比，所提出的方案优于传统方法。