A Model for Evaluating Connectivity Availability in Random Sleep Scheduled Delay-Tolerant Wireless Networks

In Wireless Sensor Network (WSN), one of the primary issues is energy conservation for extending network lifetime. Communication protocols for WSN help reduce the energy consumption via adopting sleep scheduling in the network. Random sleep scheduling is a desirable mechanism for its simplicity and steady duty cycle. However, the low duty cycle sleeping of nodes may destroy the connectivity of network, which is the assumption taken by most traditional routing protocols. If certain delay is acceptable, partially connected routing can achieve successful packet forwarding in networks with the deficiency of connectivity. This paper presents a connectivity availability model to evaluate the end to end packet delivery ratio of multi-hop networks subjected to the impact of both partial connectivity and sleep latency. Deployment guidelines are given for WSN with random sleep scheduling policy satisfying reliability, timeliness and duty cycle requirements. The simulated and computed results validate the proposed approach.