Real-Time Query Scheduling for Wireless Sensor Networks

Recent years have seen the emergence of wireless sensor network systems that must support high data rate and real- time queries of physical environments. This paper proposes Real-Time Query Scheduling (RTQS), a novel approach to conflict-free transmission scheduling for real-time queries in wireless sensor networks. First, we show that there is an inherent trade-off between prioritization and throughput in conflict-free query scheduling. We then present three new real-time scheduling algorithms. The non-preemptive query scheduling algorithm achieves high throughput while intro- ducing priority inversions. The preemptive query schedul- ing algorithm eliminates priority inversion at the cost of reduced throughput. The slack stealing query scheduling algorithm combines the benefits of preemptive and non- preemptive scheduling by improving the throughput while meeting query deadlines. Furthermore, we provide schedu- lability analysis for each scheduling algorithm. The anal- ysis and advantages of our scheduling algorithms are vali- dated through NS2 simulations.