This letter shows that optimizing the transmit powers along with judiciously designed nonorthogonal pilots can significantly reduce pilot contamination and improve the overall throughput of the uplink multi-cell massive multiple-input multiple-output (MIMO) system as compared to the conventional schemes that use orthogonal pilots. Given the optimized nonorthogonal pilots, power control as a function of the large-scale path-loss can be thought of as a stochastic optimization problem due to the presence of fast fading. This letter advocates a deterministic approach to solving this problem, then further proposes a stochastic optimization method that utilizes successive convex approximation as a benchmark to quantify the performance of the proposed approach. Simulation results reveal significant advantage of using optimized nonorthogonal pilots together with power control to combat pilot contamination.

中文翻译：

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具有非正交导频的大规模 MIMO 系统的功率控制

这封信表明，与使用正交的传统方案相比，优化发射功率以及明智设计的非正交导频可以显着减少导频污染并提高上行链路多小区大规模多输入多输出 (MIMO) 系统的整体吞吐量飞行员。给定优化的非正交导频，由于存在快速衰落，作为大规模路径损耗函数的功率控制可以被认为是一个随机优化问题。这封信提倡一种确定性的方法来解决这个问题，然后进一步提出了一种随机优化方法，该方法利用逐次凸逼近作为基准来量化所提出方法的性能。