高铁是移动通信应用场景中的一个短板。现有高铁无线通信的传输速率已无法支撑人们日益增长的高吞吐量移动数据业务的需求。采用去蜂窝化无小区大规模MIMO网络架构，并结合大规模分布式MIMO车载中继，形成双边大规模分布式MIMO，可充分挖掘多天线提供的空间复用增益，大幅提高高铁无线通信的吞吐量和可靠性。针对双边大规模分布式MIMO面临的信息理论和无线传输问题，本项目拟研究其信道容量和频谱效率性能，揭示信道容量与信道参数、系统频谱效率与系统配置之间的显式关系；突破时变MIMO及双边大规模分布式MIMO信道多普勒分集的性能分析；提出波束域非相干空时编码，并利用广义近似消息传递方法，解决波束域空间复用盲接收问题；针对相干传输，在确定性等同理论分析的基础上，提出低复杂度的预编码补偿方法，拓展低复杂度的波束域传输，并研究采用混合预编码结构的双边大规模分布式MIMO，解决其实现问题。

High-speed train (HST) is a short board in the application of the mobile communications. Data rate of wireless communications on the existing HST cannot meet the growing demand of high throughput mobile data services. In this project, a double-sided large-scale distributed-MIMO (D-MIMO) is proposed for HST wireless communications, where the cell-free massive MIMO network architecture is adopted and a mobile relay with large-scale D-MIMO is mounted on an HST. With double-sided large-scale D-MIMO, spatial-domain resources can be exploited, and then throughput and reliability of wireless communications on HST can be greatly improved. In this project, we will study the wireless transmission theory and technologies of double-sided large-scale D-MIMO. The explicit relationship between channel capacity and channel parameters, spectrum efficiency and system configurations will be revealed. The Doppler diversity performance of MIMO as well as double-sided large-scale D-MIMO will be derived. Non-coherent space-time coding in beam domain is proposed, and an improved generalized approximate message passing using sparse characteristics in beam-domain will also be studied. For coherent transmission, based on deterministic equivalent theory, a low-complexity precoding method is proposed, and a low-complexity beam domain transmission technique is extended. For practical implementation, hybrid digital and analogy beamforming will also be studied for double-sided large-scale D-MIMO.