Enhanced lightweight medium access control protocol for wireless sensor networks

摘要

A new emerging wireless technology called Wireless Sensor Network (WSN) is a system which composed of a number of sensor nodes that interact with each other intentionally to gather information from the enquired area. These sensor nodes are designed to support unattended operation for long duration, mostly in remote areas, in smart building or even in hostile environment. The limitation features in sensor node architecture which include limited processing capabilities, low memory capacities and low data rate motivates the current research study to focus on designing an energy efficient mechanism that can lengthen the sensor nodes operational duration and relatively prolongs the network lifetime while providing reliable data transmission. This thesis proposes a novel approach, called an Enhanced Lightweight Medium Access Control (eL-MAC) protocol that provides a reliable data transmission and energy efficient MAC. The protocol overcomes problems due to data collision caused by hidden nodes. In addition, the protocol efficiently reduces idle energy consumption by implementing scheduled-based active-sleep algorithm where the node turns to sleep mode in an arranged manner when there is no participation in data communication. Furthermore, it is a structureless network architecture in which the timeslot is allocated in a distributed manner via an application aware mechanism called Adaptive Multi-timeslot Allocation (AMTA). This allocation mechanism allows the node to occupy more than a slot in a frame based on the traffic condition of the application. The simulation results show that eL-MAC protocol improves power consumption and can prolong the network lifetime compared to Lightweight Medium Access Control (LMAC). Moreover, time slot management introduced in AMTA increases channel utilization by overcoming the effect of prolonging the timeslot length. The feasibility of eL-MAC protocol for low rate data transmission WSN applications is further confirmed by experimental test bed results which show a deviation of less than 10% of throughput performance compared to simulation and an impressive packet received ratio of greater than 90%.