An energy conserving medium access control protocol for multihop packet radio networks

Mobile hosts typically have scarce energy due to short battery lifetimes. We propose a scheduling algorithm which is suitable for battery-constrained multihop packet radio networks. The proposed algorithm, called ECTS (energy conserving transmission scheduling), focuses on conserving battery power while preserving topology transparency, guaranteed minimum throughput, bounded maximum delay, and fair transmission policy. The ECTS algorithm conserves the power using strategies that allow the network interface to use the low power sleep mode instead of the idle mode, and eliminates data collisions using RTS (request-to-send) and CTS (clear-to-send) control slots. As observed in previous experiments, the cost of mode transition is quite expensive. To relieve this unnecessary power consumption, the ECTS algorithm significantly reduces the number of mode transitions. For low-power hosts, the ECTS protocol reduces the number of mode transitions further. We have simulated and compared the energy efficiency of our protocol with the IEEE 802.11 and GRAND (Galois radio network design) algorithms. Simulation results show our protocol is very efficient in terms of power conservation.