Abstract: Radio-Metric Ad hoc On-Demand Distance Vector（RM-AODV） path selection protocol is the basis of HWMP path selection protocol defined in IEEE 802.11s standard.Different from traditional AODV routing protocol working on layer 3 with IP address and using hop count as the routing metric，RM-AODV works on layer 2 with MAC address and uses airtime metric for path selection.In view of tree-based netflow of wireless mesh network，RM-AODV messages are also reused to support tree-based proactive extension in IEEE 802.11s standard.Simulations are performed in a typical wireless mesh work topology to research the path discovery time of RM-AODV，and the impact of relative position with root portal on path discovery time is analysed.

Key words: Wireless Mesh Network（WMN）, path selection, Hybrid Wireless Mesh Protocol（HWMP）, Radio-Metric Ad hoc On-Demand Distance Vector（RM-AODV）

摘要： RM-AODV路径选择协议是IEEE 802.11s标准中HWMP路由选择协议的基础。不同于传统AODV协议在第3层使用IP地址路由和跳数作为路由metric，RM-AODV工作在第2层使用MAC地址和空时metric进行路径选择。为了适应无线mesh网络流量呈树状汇聚的特点，IEEE 802.11s标准还对RM-AODV进行树状先验式扩展。在典型无线mesh网络拓扑中通过仿真对RM-AODV的路径发现时间进行研究，进一步分析相对根节点的不同位置对路径发现时间的影响。

关键词: 无线mesh网络, 路径选择, 混合无线mesh网络协议（HWMP）, 按需距离矢量路由协议（RM-AODV）