An Efficient Distributed TDMA MAC Protocol for Large-Scale and High-Data-Rate Wireless Sensor Networks

A time division multiple access (TDMA) channel control approach is an efficient method for large-scale wireless sensor networks, especially when the network is congested. However, it is generally difficult to allocate the time slots to the sensors in a distributed way. A distributed approach, called Tree MAC Tree MAC, was proposed wherein the sensors in the network are constructed in a tree hierarchy with the sink as the root, and a time cycle is divided into frames and each frame into time slots. Tree MAC guarantees that in each time cycle a sensor has one time slot to transfer its data to the sink. However, the key disadvantage of Tree MAC is its inefficiency and low channel utilization. In this paper, we propose a new approach, called Pack MAC, based on Tree MAC that tries to utilize the unused time slots in order to improve the channel utilization. It has been shown that Pack MAC can be realized with a negligible overhead, but better channel utilization than Tree MAC. Furthermore, it has also been shown using simulation that in Pack MAC both the transmission delay and the network throughput can be improved significantly in comparison with Tree MAC.