Maximum lifetime routing problem in asynchronous duty-cycled wireless sensor networks

In this paper the problem of maximum lifetime routing is investigated in asynchronous duty-cycled wireless sensor networks. To model this problem, a new energy balance based asynchronous MAC protocol is proposed called K-Persistent FRTS–RCTS, which stands for K-Persistent flooding of RTS and random sending of CTS. In this protocol, each transmitter in order to send a data packet, first transmits at most K packets of RTS to its neighbors by flooding, but if the transmitter does not receive any CTS packets, it transmits the RTS packet directly to the sink. The CTS packet is sent to the transmitter either by one of the waking neighbors via a uniform random mechanism or by the sink node in response to the received RTS packet. It is shown that by using K-Persistent FRTS–RCTS MAC, the problem is formulated as a mixed integer nonlinear programming problem. In this problem, the optimization variables consist of the maximum number of RTS flooding requests (K) as the integer values and the flow rate of information on any route and the duty cycle of nodes both as the real values. To assess the performance of the proposed method, it is compared to the same maximum lifetime routing problem under the 1-Persistent FRTS–RCTS and the well-known X-MAC protocols. Evaluation results indicate that K-Persistent FRTS–RCTS MAC outperforms two mentioned MAC protocols in terms of both network lifetime and topology changes.