Low-Complexity Widely-Linear Precoding for Downlink Large-Scale MU-MISO Systems
Low-Complexity Widely-Linear Precoding for Downlink Large-Scale MU-MISO Systems
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DOI：
10.1109/lcomm.2015.2392751
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发表时间：
2015-01
期刊：
影响因子：
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通讯作者：
S. Zarei;W. Gerstacker;R. Schober
中科院分区：
文献类型：
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作者：
S. Zarei;W. Gerstacker;R. Schober
本文针对大规模多用户多输入单输出(MISO)系统下行链路，提出了一种采用实值传输符号的广线性最小均方误差(WL-MMSE)预编码方案。与现有的用于单用户多输入多输出(SU-MIMO)系统的WL-MMSE收发机同时使用WL预编码器和WL检测器相比，所提出的方案仅在用户终端(UT)使用WL预编码和简单的常规检测。此外，为了避免与大矩阵求逆相关的计算复杂性，我们使用多项式展开(PE)对WL-MMSE预编码器进行了改进。仿真结果表明，在UT个数大于基站天线个数的过载系统中，只需在矩阵多项式中加入少量项的PE WL-MMSE预编码器比采用传统MMSE预编码的系统具有更高的和码率。因此，可以在小区中服务更多共享相同时间/频率资源的UT。我们用由随机矩阵理论得到的渐近和速率的解析表达式来验证我们的模拟结果。
In this letter, we present a widely-linear minimum mean square error (WL-MMSE) precoding scheme employing real-valued transmit symbols for downlink large-scale multi-user multiple-input single-output (MU-MISO) systems. In contrast to the existing WL-MMSE transceivers for single-user multiple-input multiple-output (SU-MIMO) systems, which use both WL precoders and WL detectors, the proposed scheme uses WL precoding only and simple conventional detection at the user terminals (UTs). Moreover, to avoid the computational complexity associated with inversion of large matrices, we modify the WL-MMSE precoder using polynomial expansion (PE). Our simulation results show that in overloaded systems, where the number of UTs is larger than the number of base station antennas, the proposed PE WL-MMSE precoder with only a few terms in the matrix polynomial achieves a substantially higher sum rate than systems employing conventional MMSE precoding. Hence, more UTs sharing the same time/frequency resources can be served in a cell. We validate our simulation results with an analytical expression for the asymptotic sum rate which is obtained by using results from random matrix theory.