Priority based slot allocation for media access in Wireless Sensor Networks

In most computer and communication networks, nodes share common medium for transmitting data. The Medium Access Control (MAC) protocol is responsible for regulating access to common medium. The use of Wireless Sensor Networks (WSNs) has been widely accepted in almost all the walks of life. As the nodes in WSN have limited power source, energy efficiency plays an important role. To increase the lifetime of WSNs, energy conservation must be essential for different layers of protocol suite especially the MAC layer. MAC protocols improve energy efficiency of WSNs by reducing collisions, control overhead, idle listening and overhearing. MAC protocol design varies according to application requirements and network architecture. In this paper, we discuss Priority based Slot Allocation scheme for media access in WSN (PSAWSN) where nodes are assigned a Priority Index (PI) based on the number of requests by nodes in a particular period modelled by Poisson distribution. Slot is allocated to node having higher priority stored in PI. PSAWSN also provides reliability by handling node failures and analyses parameters such as Average Service Utilization of Manager (ASU) and Average Waiting Time (AWT) of contending nodes. Analysis of results shows that both ASU and AWT increase as the number of contending nodes is increased for increasing values of mean arrival rate.