Design Considerations for Medium Access Control in Wireless Sensor Networks

In this paper, we address the design problem of throughput and energy-efficient Medium Access Control (MAC) in wireless sensor networks. First, we assume a static network model with a fixed assignment of disjoint transmitter and receiver node groups. To obtain reliable channel feedback in multi-destination sensor networks, we propose the Group TDMA algorithm to separate in time distinct transmitter groups interfering at nonintended receivers. We formulate the throughput and energy-efficient time allocations for Group TDMA as linear programs based on traffic load distributions of transmitter groups as well and energy properties of the underlying (single-destination) MAC protocols. Next, we extend the analysis to dynamic transmitter-receiver assignments by developing a topology-based receiver activation heuristic that partitions nodes (without capabilities of simultaneous transmission and reception) into disjoint transmitter and receiver groups in any sensor network topology. We activate receiver groups over disjoint time intervals relying on the achievable throughput rates or residual energies as measures of time allocation. For any separately activated group of receivers, we impose the Group TDMA algorithm to create time orthogonality among distinct transmitter groups. The joint method of receiver activation and Group TDMA offers efficient polynomial-time solutions to the MAC problem in wireless sensor networks.