Energy-efficient capacity-constrained routing in wireless sensor networks

A critical issue in the design of routing protocols for wireless sensor networks is the efficient utilization of resources such as scarce bandwidth and limited energy supply. Many routing schemes proposed in the literature try to minimize the energy consumed in routing or maximize the lifetime of the sensor network without taking into consideration limited capacity of wireless links. This can lead to congestion, increased delay, packet losses and ultimately to retransmission of packets, which will waste considerable amount of energy. This paper present a Minimum-cost Capacity-constrained Routing (MCCR) protocol which minimize the total energy consumed in routing while guaranteeing that the total load on each sensor node and on each wireless link does not exceed its capacity. The protocol is derived from polynomial-time minimum-cost flow algorithms. Therefore protocol is simple and scalable. The paper improves the routing protocol in [1] to incorporate integrality, node capacity and link capacity constraints. This improved protocol is called Maximum Lifetime Capacity-constrained Routing (MLCR). The objective of MLCR protocol is to maximize the time until the first battery drains its energy subject to the node capacity and link capacity constraints. A strongly polynomial time algorithm is proposed for a special case of MLCR problem when the energy consumed in transmission by a sensor node is constant. Simulation results show that the lifetimes of sensor nodes are longest under MLCR protocol. Periodically rearranging the routes using MCCR protocol to account for the dynamically changing system parameters also achieves performance close to MLCR protocol. A preliminary version of this paper appears in the proceedings of ICWN 2004, Las Vegas, USA. Partly supported by a grant from ONR