Special Issue Article
Enhanced Packet Scheduling Scheme for Wireless Sensor Networks
In Wireless Sensor Networks (WSNs), a set of sensor nodes which have sensing, processing, and radio communication capabilities are scattered throughout a certain geographical region and collaboratively monitor the region of interest and track certain events and other phenomena. To the changing requirement of WSN applications since their scheduling policies are predetermined, most existing packet scheduling algorithms of WSN are neither dynamic nor suitable for large scale application and sometimes static which cannot be changed in the application requirement. In WSNs especially for real time applications efforts to reduce energy consumptions, end to end transmission delay must be considered. Though various ways like data aggregation are existing, packet scheduling is more important as it assures the delivery of various types of packets depending upon the priority. Mostly First Come First Served (FCFS) is one of the often used scheduling mechanisms in WSNs. The proposed scheme is Dynamic Multilevel Priority (DMP) packet scheduling. In this scheme, each node maintains three levels of priority queues. Real time data packets will be placed at highest priority(priority 1)queue. Non real time packets that arrive from remote nodes is meant for second highest priority(priority 2)queue. Non real time packets which are sensed at the local node is given the least priority(priority 3).Through simulation it is inferred that proposed scheme outperforms the existing scheduling mechanism. A real-time task holds the resources for a longer period of time, other tasks need to wait for an undefined period time, causing the occurrence of a deadlock. Deadlock avoidance algorithm is proposed to get rid of this drawback.