VSRS: Variable Service Rate Scheduler for Low Rate Wireless Sensor Networks

Abstract

This paper proposes a variable service rate scheduler VSRS for heterogeneous wireless sensor and actuator networks (WSANs). Due to recent advancement, various applications are being upgraded using sensor networks. Generally, traffic consists of delay sensitive and delay tolerant applications. Handling such traffic simultaneously is a critical challenge in IEEE 802.15.4 sensor network. However, the standard CSMA/CA does not focus on traffic-based data delivery. Therefore, this paper presents a solution for prioritybased traffic over no-priority i.e. regular traffic using CSMA/CA IEEE 802.15.4 MAC sublayer. The VSRS scheduler uses a queuing model for scheduling incoming traffic at an actor node using a dual queue. The scheduler updates priority of each incoming packet dynamically using network priority weight metric. The VSRS scheduler scans queues and picks the highest network priority packet. A packet weight is updated after selection from the respective queue. This core operation of an actor node offers good packet delivery ratio, throughput, and less delay experience of long distance traveled packets against no priority traffic. The work is validated using theoretical analysis and computer generated network simulators; proves that the priority based approach using weight factor works better over the First-Come-First-Serve (FCFS) mechanism.