Abstract: In the high-speed railway communication, the position information of train is predictable. However, the number of relaying antennas on the roof is limited, the feedback delay is large, Doppler effect is often serious, handover is frequent, and so on. Therefore, the traditional beamforming is not suitable for high speed railway communications. By taking the advantage of the predictability of the location information of the train, this paper proposes a kind of location information auxiliary multi-beam opportunistic beamforming, which can improve the accuracy of the weighted vector of the beam for the opportunistic beamforming algorithm. The scheme also supports multiple beam parallel transmission, so as to realize better multiuser diversity gain with multi-beam selection. Because opportunistic beamforming needs only some parameters such as SNR in the receiver, the feedback overhead is also reduced. Thus, the scheme proposed in the paper is suitable for high speed railway communications.

Key words: high speed railway, multi-beam, opportunistic beamforming

摘要： 鉴于高速铁路通信中，列车位置信息可预测、列车车顶中继转发天线数有限，以及反馈信息时延大、多普勒衰落较大、频繁切换等特性，传统的波束赋形并不适用于高速铁路场景。位置信息辅助的多波束机会波束赋形能够利用列车位置信息可预测的优势，在机会波束赋形算法中有效地提高发送波束随机相位与来波相位匹配的概率，同时支持多个波束并行传输，以多波束选择实现更好的多用户分集增益，且机会波束赋形无需反馈完全信道状态信息。因此位置信息辅助的多波束机会波束赋形技术适用于高速铁路通信。

关键词: 高速铁路, 多波束, 机会波束赋形