GSM-R网络中基于位置和中继功率控制的切换优化方案

Position Information and Relay Power Control Based Optimized Handover Scheme for GSM-R Network

GSM-R(GSM for Railway)的可靠性和高效性引起人们的关注。列车速度的提升导致多普勒效应更严重、切换触发位置更靠后、越区切换更频繁。多普勒效应恶化接收信号质量使中断率增加;切换触发位置靠后变相缩小重叠区覆盖范围使越区切换失败率增加;频繁的越区切换进一步降低系统可靠性。因此列车速度的提升对GSM-R网络的安全性和可靠性产生重要影响。同时,我国铁路网络的不断扩展对GSM-R系统的容量提出更高的要求。本文首先对GSM-R网络传统切换策略进行建模和性能分析。随后,提出一种利用列车位置信息和中继功率控制技术的切换优化方案。在该方案中,列车到达切换位置前,利用中继站获得分集增益,提升信道容量和链路可靠性;处于切换位置时,通过中继的功率控制,保证本小区的信号满足最低通信要求,变相扩大重叠区覆盖范围的同时有利于触发切换提升切换成功率。仿真结果表明:本文提出的方案有效地提升切换成功概率和信道容量,明显改善了GSM-R系统的性能。

The reliability and efficiency of the GSM-R （GSM for Railway） networks dedicated to railway trans- portation begin to attract attention of the public. Speed-raising of trains causes the severe Doppler Effect, post- ponement of handover triggering and frequent handover. These lead to handover failures and reduction of relia- bility. Meanwhile, the expansion of railway networks demands larger capacity of the GSM-R system. In this paper, the traditional handover strategy for GSM-R has been modeled and analyzed. Then a scheme based on the train position information and relay power control is proposed to optimize the system handover perform- ance. This proposal employs relays to get diversity gains before the train arrives at the handover point in order to improve the channel capacity and link reliability. The simulation results show that the proposed scheme in- creases the handover success probability and the channel capacity effectively, so that it obviously improves the performance of the GSM-R networks.