Enhanced lightweight medium access (eL-MAC) protocol for wireless sensor network

Wireless sensor network (WSN) is increasingly being used in a variety of applications which include habitat monitoring, smart health care system, building automation, to name a few. Many approaches were developed for all protocol layers, but an energy-efficient Medium Access Control (MAC) layer remains a key design challenge. MAC with scheduled based architecture provides greater advantage over other designs, such as contentionbased and frequency division multiple access (FDMA), in terms of minimizing packet collision, overhearing, idle listening, and over emitting. Reliable and energy efficient data transmission are required to prolong the network lifetime. This paper presents the testbed development of an enhanced lightweight medium access (eL-MAC) protocol which introduces distributed time slot assignment and slotting communication mechanism. Therefore, with eL-MAC, idle listening, overhearing and hidden terminal will be eliminated where nodes transmit in its own time slot and sleep in other time slot if there is no activity. This will reduce energy consumption as nodes are active when transmitting and receiving and idle only in the beacon session. The testbed developed consists of 9 TelosB sensor nodes programmed with TinyOS. NesC programming language was used to implement the protocols in the WSN module. Experimental results were compared to the results obtained from simulation. As expected, there is a slight degradation in throughput and packet received ratio in the experiment but is consistent for all values. This concludes that the developed testbed reflects the eLMAC protocol and has been successfully implemented. Keywords-component; Medium Access Layer (MAC), Time Division Multiple Access (TDMA), Contention-based MAC, Wireless Sensor Network (WSN), Distributed time slot assignment.