Abstract

The sensor nodes in the wireless sensor networks have limited battery power, which motivates to work on energy conserved MAC schemes for better lifetime and latency efficient. Previous work carried out in energy conserved MAC schemes are limit the idle listening time, reduces overhearing (sensor node hear a packet destined for other nodes) and minimizing the used control packet size. The current existing work presented ELE-MAC (i.e. Energy Latency Efficient MAC) which adopts less control packets to preserve energy in sparsely distributed sensor nodes of the wireless sensor networks. It performs statistically the same or better latency characteristic compared to adaptive SMAC. ELE-MAC follows the adaptive listening technique, which reduce the sleep delay introduced by the periodic sleep of each node in case of a multi-hops network. The proposal in this work, extends the ELE-MAC to work efficiently with wireless sensor network comprises of high node density by combining the RTS and SYNC control packets. The extended version uses two separate frequencies for data and control packets to avoid the use of handshake mechanisms (e.g. RTS/CTS) in order to reduce energy consumption and packet delay. It enables a receiver to send a busy tone signal on th control channel and notify the neighbors about the ongoing reception of data in progress. This process avoids packet collisions and in turn improves the node lifetime and throughput. The nodes in a sensor network have their own different traffic loads according to the tasks assigned and their locations. The extension of ELE MAC adopts the different traffic loads of each node as performance metric for reducing the latency. Each sensor node calculates its utilization after the last synchronization time, and adjusts its duty cycle according to the calculated utilization, and then send new schedule to its neighbors via broadcasting.