RACE: A Real-Time Scheduling Policy and Communication Architecture for Large-Scale Wireless Sensor Networks

In wireless sensor networks (WSN), individual sensor nodes are inherently unreliable and have very limited capabilities to ensure real-time properties. In fact, one of the most predominant limitations in wireless sensor networks is energy consumption, which hinders the capacity of the network to provide real-time guarantees (e.g. low duty-cycles, low transmission range). Many approaches have been proposed to deal with energy/latency trade-offs, but they are likely to be insufficient for the applications where reduced delay guarantee is the main concern. We present and evaluate a packet scheduling policy and routing algorithm called RACE that inherently accounts for time constraints. We show that this algorithm is particularly suitable for communication in sensor networks in which a large number of wireless devices are seamlessly integrated into a physical space to perform real-time monitoring and control. Detailed simulations of representative sensor network environments demonstrate that RACE significantly reduces the end-to-end deadline and miss ratio in the sensor network. Also RACE will balance load and energy consumption of network and life time of network will be increased.