Energy-aware delay-constrained routing in wireless sensor networks

Recent years has witnessed a growing interest in the applications of unattended wireless sensor networks. Due to the limitation of the energy supply that sensors have, almost all of the proposed routing protocols have aimed at energy efficiency as the ultimate objective and considered relaying data to a stationary gateway (sink). However, many new issues have been posed by the increasing interest in applications that demand certain quality of service (QoS) guarantees. Such issues even get more challenging when the gateway is mobile. In this paper, we propose an energy-aware approach for routing del ay-con strained data. The approach pursues multi-hop packet relaying to minimize transmission energy and employs weighted fair queuing (WFQ) packet scheduling methodology along with leaky bucket constrained data sources in order to provide soft real-time guarantees for data delivery. Such employment of WFQ at each node provides a service differentiation between two different classes of traffic, namely real-time and non-real-time traffic. In the case of a mobile gateway, uninterrupted data flow for both types of traffic is achieved by dynamic adjustment of the route set-up to react to the gateway's departure out of transmission range of relaying nodes. Simulation results demonstrate the effectiveness of the proposed approach. Copyright (C) 2004 John Wiley Sons, Ltd.