一种支持车-地宽带互联的WiFi移动应用优化方案

WiFi-based Optimized Scheme for Broadband Train-ground Internetworking

本文研究如何改进WiFi协议及其算法以优化其移动应用性能,从而支持不间断的旅客列车车-地宽带互联。为此,本文首先探讨并建立802.11a移动应用的系统模型,然后基于802.11a移动应用仿真系统深入分析802.11a移动应用在不同多径传输、不同移动速度和不同信噪比条件下的性能,并通过不同的系统配置,研究不同数据帧长、不同发送速率对802.11a移动应用性能的影响。研究发现,802.11a在受限的多径传输环境下可以支持移动应用,但信道估计周期不能超过信道的相干时间,并且6 Mbit/s1、2 Mbit/s和24 Mbit/s这3种发送速率更适合于移动应用。最后针对旅客列车车-地宽带互联,提出WiFi移动应用方案TGI@11a,不仅将802.11a移动应用的误码率由高于5‰下降到低于0.4‰,同时将有效发送速率由最高6 Mbit/s提高到20 Mbit/s。

An optimized scheme is studied for WiFi application in broadband train-ground internetworking.WiFi used not to be aimed at mobile applications in design.The 802.11a system model for mobile access is built up,and its performance in different multi-path propagation,and at different moving speeds and different signal-to-noise rates is analyzed.The influence of different frame durations and different transmitting bit rates on 802.11a system performance is studied with different system configurations.Simulation results show as follows： 802.11a can be utilized in a limited mobile scenario,but the channel estimation period should be less than its coherent time;the transmitting bit rates of 6,12 and 24 Mbit/s are more suitable for mobile access;the TGI@11a scheme proposed for WiFi based broadband train-ground internetworking decreases the bit error rate from higher than 5‰ to lower than 0.4‰ and increases the effective maximum transmitting bit rate from 6 Mbit/s to 20 Mbit/s.