Exploiting Overhearing: Flow-Aware Routing for Improved Lifetime in Ad Hoc Networks

For nodes of mobile ad hoc networks, energy is a scarce resource that can be quickly depleted by communications. Moreover, due to the nature of wireless communication medium, nodes can waste a substantial amount of energy by overhearing packets in their neighborhood, most of which may not be meant for them. The overall impact of overhearing is not well-studied: many of the schemes claiming to be energy-efficient neglect this cost by only focusing on energy costs due to local traffic. In this paper, we propose that nodes exploit overheard packets to gather awareness of current neighboring flows and adapt their local routing dynamically. By combining this awareness with battery-aware routing metrics, which includes the battery levels of the neighbors, we introduce various routing schemes that increase the network lifetime.

1. Introduction

Often as a requirement of portability, wireless nodes in MANET have limited energy resources like batteries that can be quickly depleted by expensive wireless communications (including the energy cost of handling traffic for other nodes). In recent years, a large body of work considered the energy consumed, but only at the nodes participating in the existing flows. For MANET, a single communication packet can affect not only the sender and the receiver, but also all the nodes within the communication region of the sender. The important fact to notice is that, in addition to interference, this substantially increases the energy consumption at nodes overhearing this packet not meant for them [4], [7], to the extent that a node's battery can be completely depleted without being involved in any flow.