Conflict-Free Transmission Scheduling For Real-Time Queries In Wireless Sensor Networks
In the past we have seen the emergence of wireless cyber-physical systems that must support real-time queries of
physical environments through wireless sensor networks. 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, it is shown that
there is an inherent tradeoff between latency and real-time capacity in query scheduling. Then three new real-time schedulers
are developed namely non-preemptive query scheduler, preemptive query scheduler and the slack stealing query scheduler.
The non-preemptive query scheduler supports high real-time capacity but cannot provide low response times to high-priority
queries due to priority inversions. The preemptive query scheduler eliminates priority inversions at the cost of reduced
capacity. The slack stealing query scheduler combines the benefits of the preemptive and non-preemptive schedulers to
improve the capacity while alongside meeting the end-to-end deadlines of queries. The schedulability analysis for each
scheduler will be provided. The analysis and advantages of this approach are validated through NS2 simulations.