基于ETX度量的无线多跳网络路由研究与优化

发布时间：2018-04-23 02:24

本文选题：无线多跳网络 + ETX　；参考：《大连理工大学》2015年硕士论文

【摘要】：路由协议的度量对于无线多跳网络研究有着至关重要的意义,其中期望传输次数ETX路由度量可以综合考虑到无线网络传输中遇到的非对称链路、无线链路丢包、链路干扰等问题。但是由于ETX的探测封包发出的周期与路由度量更新周期默认是固定的而且比较长,因此当无线多跳网络链路质量变化较大时,ETX就不能及时的对链路的优劣进行判断并切换。进而导致基于ETX度量路由的性能下降。本文分析了现有基于ETX度量的路由算法存在的一些不足,并基于原始ETX度量进行了改进,提出了两种优化的针对于无线多跳网络的路由机制。本主要贡献如下：首先通过NS-2的仿真验证了ETX在特定无线多条跳网络环境中产生的问题,并找到影响其性能表现的因素；然后基于优化链路状态路由OLSR,提出一种具有机会主义的,在ETX长期路由度量下加入短期路由度量进行路由切换的机制-—LSETX,使其可以快速响应无线链路质量的变化并切换到吞吐量较高的路由；接下来进一步考虑到无线多跳网络中实际应用的情况：当用户较多而每个用户的数据流量较小时,ETX固定周期的发送探测包可能造成链路的利用率下降。进而提出了一种ETX探测、更新周期可变的机制vpETX。其ETX探测、更新周期可以通过获取应用层数据速率而动态改变,进而达到优化路由性能的目的。最后通过仿真实验对基于LSETX路由度量的机会主义路由与vpETX路由机制进行有效性验证,实验结果表明：对应无线多跳网络中不同场景,基于LSETX度量的机会主义路由和vpETX路由机制相对于基于原始ETX度量的路由机制均可以提高网络吞吐量,两种优化机制的吞吐量提升分别达到20%和17.96%。同时端到端数据传输延时和丢包率得到有效的降低。
[Abstract]:The measurement of routing protocols is of great significance to the research of wireless multi-hop networks, in which the ETX routing metrics can take into account the asymmetric links encountered in wireless network transmission, wireless link packet loss. Link interference, etc. However, because the cycle of detection packet and the update cycle of routing metric are fixed and long by default, ETX can not judge and switch the link in time when the quality of wireless multi-hop network is changed greatly. In turn, the performance of metric routing based on ETX is degraded. This paper analyzes some shortcomings of existing routing algorithms based on ETX metric and improves them based on the original ETX metric and proposes two optimized routing mechanisms for wireless multi-hop networks. The main contributions are as follows: firstly, the problems of ETX in a specific wireless multi-hop network environment are verified by the simulation of NS-2, and the factors that affect its performance are found. Then based on the optimized link state routing OLSRs, an opportunistic approach is proposed. LSETX is added to the ETX long term routing metric for routing handoff, which enables it to quickly respond to changes in wireless link quality and switch to high throughput routing. Then consider the practical application in wireless multi-hop network: when the number of users is more and the data flow per user is small the transmission packet of ETX fixed period may cause the link utilization to decrease. Furthermore, a new mechanism, vpETX, which can detect and update ETX with variable cycle, is proposed. The ETX detection and update cycle can be dynamically changed by acquiring the data rate of the application layer, and then the routing performance can be optimized. Finally, the effectiveness of opportunistic routing and vpETX routing mechanism based on LSETX routing metric is verified by simulation experiments. The experimental results show that: corresponding to different scenarios in wireless multi-hop networks, The opportunistic routing mechanism based on LSETX metric and the vpETX routing mechanism can improve the network throughput compared with the routing mechanism based on the original ETX metric. The throughput of the two optimization mechanisms can reach 20% and 17.96% respectively. At the same time, the end-to-end data transmission delay and packet loss rate are effectively reduced.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN92

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