Formulation of Maximum Lifetime Routing Problem in Duty Cycled Wireless Sensor Networks

In this paper the problem of maximum lifetime routing is investigated in asynchronous Duty-Cycled Wireless Sensor Networks (DCWSNs). To model this problem, first a novel energy balance based asynchronous MAC protocol utilizing K-Persistent Flooding of RTS and Random sending of CTS named K-Persistent FRTS-RCTS is proposed. In this protocol, each transmitter in order to send a data packet, first transmits at most K packet of RTS to its neighbors in flooding way and if it does not receive any CTS packet, transmits the RTS packet to the sink directly. The CTS packet is sent to the transmitter either by one of the waking neighbors with a special random mechanism or by the sink node in response to the received RTS packet. It is shown that the problem is formulated as a mixed integer nonlinear programming (MINLP) problem under the proposed MAC protocol. In this problem optimizing parameters are consisted of the maximum number of RTS flooding requests (K) as integer values, flow rate of information on any route and duty cycle of nodes both as real values. The solution of the problem is evaluated under various scenarios. The achieved solution can be used as a benchmark for evaluating and comparing distributed methods that aim to enhance the network lifetime