Uplink Spectral and Energy Efficiency of Cell-Free Massive MIMO With Optimal Uniform Quantization
Uplink Spectral and Energy Efficiency of Cell-Free Massive MIMO With Optimal Uniform Quantization
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DOI：
10.1109/tcomm.2020.3028305
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发表时间：
2021-01
影响因子：
8.3
通讯作者：
M. Bashar;H. Ngo;K. Cumanan;A. Burr;P. Xiao;Emil Björnson;E. Larsson
中科院分区：
文献类型：
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作者：
M. Bashar;H. Ngo;K. Cumanan;A. Burr;P. Xiao;Emil Björnson;E. Larsson
研究了在考虑门限量化和非理想信道捕获的情况下，有限门限门限无信元大规模多输入多输出(MIMO)系统的性能。根据执行和利用信道估计的位置，研究了三种情况，我们称之为估计和量化、量化和估计以及分散。考虑了最大比合并(MRC)、迫零(ZF)和最小均方误差(MMSE)接收机。利用MAX算法和Bussgang分解对最优均匀量化进行建模。利用量化器的最佳步长，给出了频谱效率和能量效率的解析表达式。最后，提出了一种接入点(AP)分配算法来提高去中心化方案的性能。数值结果分析了有限门限和完全门限两种情况下的性能差距，表明利用相对较少的量化比特，有限门限无小区海量MIMO的性能接近完美门限的性能。
This paper investigates the performance of limited-fronthaul cell-free massive multiple-input multiple-output (MIMO) taking account the fronthaul quantization and imperfect channel acquisition. Three cases are studied, which we refer to as Estimate&Quantize, Quantize&Estimate, and Decentralized, according to where channel estimation is performed and exploited. Maximum-ratio combining (MRC), zero-forcing (ZF), and minimum mean-square error (MMSE) receivers are considered. The Max algorithm and the Bussgang decomposition are exploited to model optimum uniform quantization. Exploiting the optimal step size of the quantizer, analytical expressions for spectral and energy efficiencies are presented. Finally, an access point (AP) assignment algorithm is proposed to improve the performance of the decentralized scheme. Numerical results investigate the performance gap between limited fronthaul and perfect fronthaul cases, and demonstrate that exploiting relatively few quantization bits, the performance of limited-fronthaul cell-free massive MIMO closely approaches the perfect-fronthaul performance.