An Experimental Study of Routing Metrics in 802.11n Wireless Mesh Networks

In the recent past, link quality-based routing metrics, such as ETX and ETT, have been shown to significantly outperform the traditional hopcount metric in legacy 802.11a/b/g wireless mesh networks (WMNs). The new 802.11n standard introduces a number of enhancements at the MAC/PHY layers (MIMO technology, channel bonding, frame aggregation, and more aggressive modulation and coding schemes) marking the beginning of a new generation of 802.11 radios. In this paper, we conduct one of the first experimental studies of the performance of link quality-based routing metrics in a 21-node indoor 802.11n WMN. Our study reveals that the gains of link quality-based metrics over the hopcount metric in legacy 802.11 WMNs do not carry over in 802.11n MIMO WMNs. We analyze the causes of this behavior and make recommendations for the design of new routing metrics in 802.11n WMNs.