随着无线网络技术的发展,基于无线多跳网的视频通信在智能交通、灾难应急和军事指挥等多个领域得到越来越广泛的应用.但是,如何保证无线视频的传输质量,是亟待解决的一个关键问题.已有多路径视频传输研究忽略了信道变化和路径间干扰.针对该问题,提出一种基于率失真预测的多路径选择优化算法.该算法不仅分析了网络拥塞对传输质量的影响,而且考虑了路径传输干扰等影响因素.首先,通过对无线信道建模,计算干扰条件下MAC层数据包碰撞概率和处理时间;其次,将无线节点建模为M/M/1/K排队系统,利用排队论预测网络拥塞导致的延迟和丢包;最后,通过建立视频传输与MAC 层性能以及网络拥塞之间的率失真函数关系,预测传输路径的视频失真.并以预测失真为尺度,选择失真近似最小的多路径作为路由.通过NS-2 网络模拟环境中的大量实验,验证了模型的有效性.仿真分析结果表明,该算法能够显著提高无线多跳网络中的视频传输质量.

With the increase in bandwidth and computing power of wireless devices, video applications over wireless ad-hoc networks are expected to become widespread in intelligent vehicles, emergency communication, and battlefield command. However, a crucial problem is how to select the best paths for video streaming of qualify-on-service (QoS) in multi-hop wireless networks. Most of the existing research done on this topic tend to ignore the impacts of time- varying channel and wireless interference on the quality of multi-path video streaming. This paper proposes an optimized multi-path selection algorithm which takes not only network congestion into account, but also interference. Packet collision and delay in a MAC layer is predicted using the interference model. Each node is modeled as an M/M/1/K queuing system. Packet delay and loss, due to congestion, are predicted using the queuing theory. The distortion of path is defined as a function of packet losses and delays along the path. The paths with the minimum estimated distortion are selected as the optimal routings. Extensive experiments in NS-2 simulation environment have been carried out. The experimental results show that this algorithm achieves a certain level of satisfaction in the QoS of video streaming.

基金项目: 国家自然科学基金(60902004); 国家重点基础研究发展计划(973)(2009CB320907); 国家发改委高技术计划([2010]3044)