Deploying antenna arrays with an asymptotically large aperture will be central to achieving the theoretical gains of massive MIMO in beyond-5G systems. Such extra-large MIMO (XL-MIMO) systems experience propagation conditions which are not typically observed in conventional massive MIMO systems, such as spatial non-stationarities and near-field propagation. Moreover, standard precoding schemes, such as zero-forcing (ZF), may not apply to XL-MIMO transmissions due to the prohibitive complexity associated with such a large-scale scenario. We propose two novel precoding schemes that aim at reducing the complexity without losing much performance. The proposed schemes leverage a plane-wave approximation and user grouping to obtain a low-complexity approximation of the ZF precoder. Our simulation results show that the proposed schemes offer a possibility for a performance and complexity trade-off compared to the benchmark schemes.
翻译:部署无孔径的天线阵列对于在5G系统之外实现大规模MIMO的理论收益至关重要。这种超大型MIMO(XL-MIMO)系统经历的传播条件通常在传统的大型MOIMO系统中没有观察到,例如空间非静止和近地传播。此外,标准预编码计划,例如零推进(ZF),可能不适用于XL-MIMO的传输,因为这种大规模设想方案过于复杂。我们提出了两个新的预编码计划,目的是减少复杂性,而不会失去很多性能。拟议的计划利用平波近比和用户组合,以获得ZF前编码器的低复杂性近距离。我们的模拟结果表明,拟议的计划有可能与基准计划相比产生性能和复杂性交易。