Energy-Efficient Multi-Rate Opportunistic Routing in Wireless Mesh Networks

Opportunistic or anypath routing protocols are focused on improving the performance of traditional routing in wireless mesh networks. They do so by leveraging the broadcast nature of the wireless medium and the spatial diversity of the network. Using a set of neighboring nodes, instead of a single specific node, as the next hop forwarder is a crucial aspect of opportunistic routing protocols, and the selection of the forwarder set plays a vital role in their performance. However, most opportunistic routing protocols consider a single transmission rate and power for the nodes, which limits their potential. To address this limitation, this paper proposes a multi-rate and multi-power opportunistic routing protocol called Energy-efficient Multi-rate Opportunistic Routing (EMOR). EMOR considers multiple transmission rates and power for each node, and in addition to selecting the forwarder set, it should select the transmission rate and power to reach this set in each node. Using different transmission rates and power levels can enhance EMOR's ability to effectively utilize the spatial diversity of the network. To prioritize the forwarder set, EMOR uses a transmission energy-based routing metric called Expected Opportunistic Transmission Energy (EOTE). EMOR also employs a distributed polynomial algorithm, Multi-rate Multi-power Opportunistic Bellman-Ford (MMOBF), to select the forwarder set, transmission rate, and transmission power in each node, minimizing the cost from the node to the destinations. The simulation results show that EMOR significantly outperforms the multi-rate opportunistic routing and multi-power opportunistic routing in terms of performance metrics such as packet delivery ratio, delay, and energy consumption.