Energy Efficiency of Uplink Cell-Free Massive MIMO With Transmit Power Control in Measured Propagation Channel
Energy Efficiency of Uplink Cell-Free Massive MIMO With Transmit Power Control in Measured Propagation Channel
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DOI：
10.1109/ojcas.2021.3125894
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发表时间：
2021-11
影响因子：
2.6
通讯作者：
Thomas Choi;Masaaki Ito;I. Kanno;Jorge Gómez-Ponce;Colton Bullard;T. Ohseki;K. Yamazaki;A. Molisch
中科院分区：
文献类型：
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作者：
Thomas Choi;Masaaki Ito;I. Kanno;Jorge Gómez-Ponce;Colton Bullard;T. Ohseki;K. Yamazaki;A. Molisch
无小区大规模MIMO(CF-mMIMO)使用分布在广域内的高频谱效率(SE)的接入点(AP)为大量用户设备(UE)提供无线连接。上行链路的能量效率(EE)由(I)发射功率控制(TPC)算法，(Ii)AP和UE的数量、配置和位置，以及(Iii)AP和UE之间的传播信道确定。本文基于3.5 GHz下广泛的(约30,000个可能的AP位置和128个可能的UE位置)信道测量数据，对这三个方面进行了研究。我们比较了三种不同的TPC算法，即最大化发射功率(max-power)、最大化最小SE(max-min SE)和最大化最小EE(max-min EE)，同时保证目标SE。我们还比较了各种天线布置，包括全分布式和半分布式系统，其中AP可以放置在规则网格上或随机放置，UE可以簇状放置或相距较远。总体而言，我们表明，最大-最小EE TPC在改善上行链路EE方面是非常有效的，特别是当一组服务的UE中没有UE处于糟糕的信道条件以及BS天线完全分布的情况下。
Cell-free massive MIMO (CF-mMIMO) provides wireless connectivity for a large number of user equipments (UEs) using access points (APs) distributed across a wide area with high spectral efficiency (SE). The energy efficiency (EE) of the uplink is determined by (i) the transmit power control (TPC) algorithms, (ii) the numbers, configurations, and locations of the APs and the UEs, and (iii) the propagation channels between the APs and the UEs. This paper investigates all three aspects, based on extensive (~30,000 possible AP locations and 128 possible UE locations) channel measurement data at 3.5 GHz. We compare three different TPC algorithms, namely maximization of transmit power (max-power), maximization of minimum SE (max-min SE), and maximization of minimum EE (max-min EE) while guaranteeing a target SE. We also compare various antenna arrangements including fully-distributed and semi-distributed systems, where APs can be located on a regular grid or randomly, and the UEs can be placed in clusters or far apart. Overall, we show that the max-min EE TPC is highly effective in improving the uplink EE, especially when no UE within a set of served UEs is in a bad channel condition and when the BS antennas are fully-distributed.