Dynamic channel access with asynchronous sleep-wake scheduling to improve energy efficiency in CRSNs

Wireless sensor network (WSN) suffer uncontrolled interference while using license free spectrum due to the increasing crowd in the band. The cognitive radio (CR) is a promising solution for this problem. CR technology can be applied in WSN to form cognitive radio sensor network (CRSN). With the consideration of energy consumption of channel sensing and switching, when the sensor nodes should sense and switch to a licensed channel due to increased packet loss rate in licensed free channel can be determined. Two dynamic channel accessing schemes are proposed for intra-cluster data transmission and inter-cluster data transmission. The opportunistic channel sensing improves the energy efficiency in CRSNs. And also an asynchronous sleep-wake scheduling mechanism is used for reducing energy consumption. This scheduling mechanism allows the sensor nodes to sleep when the nodes are not participating in data transmission, by that network lifetime can be increased. Simulation results demonstrate that the channel accessing schemes and asynchronous sleep-wake scheduling scheme can significantly reduce the energy consumption and effectively achieves network lifetime extension in CRSNs.