MAC transmission protocols for delay-tolerant sensor networks

Wireless data transmissions often experience long delays in sensor networks due to harsh environments and limited resources. Many sensor applications allow transmission latency and require improved performance in energy conservation, throughput, reliability and mobility. The MAC layer is suitable for detecting unstable wireless channels and improve transmission performance in Delay-Tolerant Sensor Networks (DTSN). This paper builds on various strategies on MAC designs in DTSN, and presents a comprehensive study on MAC protocols in DTSNs. We study MAC protocols, which trade long, unpredictable delays in data transmissions for energy conservation, mobility, throughput and/or reliability. We also present MAC protocols in DTSN which adapt their access control and transmission processes to the predictable delays. From the aspect of delay tolerance, the paper examines these MAC protocols through the trade-off between delay and other performance metrics, and shows the effectiveness and limitations of these MAC designs. Next, we review and analyze current MAC protocols that are suitable for DTSNs, and then discuss future research trends towards the design of new MAC protocols for DTSNs.