高铁毫米波最优自适应波束成形与联合传输

Optimal adaptive beamforming and joint transmission for millimeter wave under high-speed railway

摘要:

高铁车地移动通信系统的吞吐量不仅受到频谱的限制，而且受到高移动性的限制，已成为制约智能高铁发展的重要瓶颈。一种提高系统吞吐量的有效方法是使用拥有较宽连续频谱的毫米波频段以及使用大规模多输入多输出(MIMO)和多波束成形技术。然而，使用固定波束宽度的多波束流在列车高速行驶过程中会产生严重的波束间干扰，因此，论文提出了基于最优波束宽度的自适应波束成形和联合传输方案。当列车距离基站较近时，激活全部波束，实现波束的空间复用，提高系统容量和传输可靠性。当列车距离基站较远时，为了避免波束间的严重干扰，用更多的天线阵元形成较少的波束，获得更大的波束增益，并与相邻基站进行波束联合传输，提升系统的吞吐量。仿真结果表明，与现有波束成形及传统自适应选择方案相比，所提方案吞吐量在小区边缘附近可以提升超过150%。

Abstract:

The throughput of high-speed railway train-ground mobile communication system is not only limited by spectrum, but also limited by high mobility, which has become an important bottleneck restricting the development of intelligent high-speed railway. An effective way to improve the system throughput is to use millimeter wave band with wide continuous spectrum and large-scale Multiple-Input Multiple-Output(MIMO) and multi-beamforming technology. However, the multi-beam streams with fixed beam width will result in serious inter-beam interference when the train is running at high speed. An adaptive beamforming and joint transmission scheme based on optimal beam width is proposed in this paper. When the train is close to the Base Station(BS), all beams are activated to realize spatial multiplexing thereafter to improve system capacity and transmission reliability. When the train is far away from the BS, in order to avoid serious interference between beams, more antenna array elements are utilized to form fewer beams to obtain greater beam gain, and beams of the adjacent BS are cooperated to transmit to improve the throughput of the system. Simulation results show that the performance of the proposed scheme is significantly better than that of the existing beamforming and traditional adaptive selection schemes.