Mutli Level Priority based Packet Scheduling Scheme for Wirless Sensor Netowrks

Many wireless sensor network (WSN) applications heavily rely on information being transmitted in a timely manner. In such sensor networks, packet scheduling plays a vital role in reducing end-to-end data transmission delays. It also helps in reducing sensors energy consumptions, thus increasing the lifetime of the wireless sensor network. Most of the existing packet-scheduling mechanisms of Wireless Sensor Networks use FIRST COME FIRST SERVE (FCFS). It is the most simplest and traditional packet scheduling scheme which process packets as they arrive. As a result many packets may have to wait for a long time and this might lead to their expiration. These results in long end-toend transmission delay, high energy consumption, deprivation of high priority real time data packets also it results in improper allocation of data packets to queues. These are not dynamic to the changing requirements of Wireless Sensor networks applications since their scheduling policies are predetermined.

A Dyanmic Multilevel Packet scheduling scheme has been proposed that brings in dynamism by virtually organizing sensor nodes into hierarchical structure based on distance to base station (BS). Each node has three levels of priority queues. Real time packets are placed into the highest priority queue and can preempt data packets in other queues. Non-real-time packets are placed into two other queues based on their processing time (e.g., real-time health data sensed by body sensors and non-real-time temperature data). Leaf nodes have two queues for real-time and non-real-time data packets since they do not receive data from other nodes and thus, reduce end-to-end delay. Our proposed packet scheduling scheme outperforms conventional schemes in terms of average data waiting time and end-to-end transmission delay and it also reduces sensor energy consumption.