Energy Efficiency of the Cell-Free Massive MIMO Uplink With Optimal Uniform Quantization
Energy Efficiency of the Cell-Free Massive MIMO Uplink With Optimal Uniform Quantization
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DOI：
10.1109/tgcn.2019.2932071
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发表时间：
2019-07
影响因子：
4.8
通讯作者：
M. Bashar;K. Cumanan;A. Burr;H. Ngo;E. Larsson;P. Xiao
中科院分区：
文献类型：
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作者：
M. Bashar;K. Cumanan;A. Burr;H. Ngo;E. Larsson;P. Xiao
一个无小区的大规模多输入多输出（MIMO）上行链路被认为是，接入点（AP）连接到一个中央处理单元（CPU）通过有限容量的无线微波链路。通过利用Bussgang分解对量化的效果进行建模，在CPU处可获得加权信号的量化版本。考虑到信道估计误差和量化失真的影响，推导出频谱效率的封闭表达式。能量效率最大化问题被认为是与每用户功率，回程容量和吞吐量要求的约束。为了解决这个非凸问题，我们将原问题解耦为两个子问题，即接收机滤波器系数设计和功率分配。接收机滤波器系数的设计被配制成一个广义特征值问题，而利用逐次凸逼近（SCA）和启发式次优方案转换成一个标准的几何规划（GP）问题的功率分配问题。提出了一种迭代算法交替求解每个子问题。所提出的方案的复杂性分析和收敛性进行了研究。数值结果表明，所提出的算法优于等功率分配的情况下。
A cell-free Massive multiple-input multiple-output (MIMO) uplink is considered, where the access points (APs) are connected to a central processing unit (CPU) through limited-capacity wireless microwave links. The quantized version of the weighted signals are available at the CPU, by exploiting the Bussgang decomposition to model the effect of quantization. A closed-form expression for spectral efficiency is derived taking into account the effects of channel estimation error and quantization distortion. The energy efficiency maximization problem is considered with per-user power, backhaul capacity and throughput requirement constraints. To solve this non-convex problem, we decouple the original problem into two sub-problems, namely, receiver filter coefficient design, and power allocation. The receiver filter coefficient design is formulated as a generalized eigenvalue problem whereas a successive convex approximation (SCA) and a heuristic sub-optimal scheme are exploited to convert the power allocation problem into a standard geometric programming (GP) problem. An iterative algorithm is proposed to alternately solve each sub-problem. Complexity analysis and convergence of the proposed schemes are investigated. Numerical results indicate the superiority of the proposed algorithms over the case of equal power allocation.