Bandwidth management in wireless sensor networks.

Wireless sensor networks are often used in monitoring and control applications, where software running on generalpurpose computers “pull” information from remote sensors and “push” actuations into the network. The sensors themselves form a multihop wireless network communicatingwith one or more sensor access points (SAPs) that interface between application software and the sensor network. This paper addresses the problem of managing wireless network bandwidth and improving network capacity in a sensor network deployed as a shared infrastructure, concurrently used by different applications. Our bandwidth management architecture incorporates three ideas: first, we develop a simple rule system that allows applications and the network administrator to specify how traffic generated by sensors should be treated by the sensor network. Each rule is a function that maps a sensor data type and generated value to a transmission rate and a traffic class. Second, we show how using multiple SAPs and SAP selection method that considers packet loss probabilities, path load, and path lengths improves the capacity of the network and the performance of individual sensor streams. Third, we show that hopby-hop flow control, rather than end-to-end congestion control, is a better way to cope with the nature of sensor network traffic and avoids unnecessary packet losses that waste valuable wireless network bandwidth. Our experimental results from a 40-node indoor wireless sensor testbed show that these three techniques are simple to implement and allow scarce network bandwidth to be used efficiently.