A predictive QoS control strategy for wireless sensor networks

The number of active sensors in a wireless sensor network has been proposed as a measure, albeit limited, for quality of service (QoS) for it dictates the spatial resolution of the sensed parameters. In very large sensor network applications, the number of sensor nodes deployed may exceed the number required to provide the desired resolution. Herein we propose a method, dubbed predictive QoS control (PQC), to manage the number of active sensors in such an over-deployed network. The strategy is shown to obtain near lifetime and variance performance in comparison to a Bernoulli benchmark, with the added benefit of not requiring the network to know the total number of sensors available. This benefit is especially relevant in networks where sensors are prone to failure due to not only energy exhaustion but also environmental factors and/or those networks where nodes are replenished over time. The method also has advantages in that only transmitting sensors need to listen for QoS control information and thus enabling inactive sensors to operate at extremely low power levels