Delay performance of intermittently connected wireless sensor networks with cooperative relays

We consider wireless sensor networks (WSN) powered by energy harvested from the environment, which is assumed to be sporadic and random in nature. Wireless nodes in such networks experience random active and sleep periods depending on their energy availability, leading to intermittent connectivity in the network. This paper addresses the problem of minimizing the multi-hop transmission delay in such networks by applying cooperative relaying. We develop a theoretical model to analyze the transmission delay over such intermittently connected links with selective cooperative relaying. A novel two-hop cooperative relaying scheme is proposed that balances the trade-off between the benefit from cooperative relaying and the additional energy consumption caused by it. Performance of the proposed two-hop cooperative relay scheme is presented using simulations.