Density Adaptive Sleep Scheduling in Wireless Sensor Networks

Abstract

Broadcasting by flooding is one of the most fundamental services for both wired and wireless networks. This also includes several sensor network applications that use broadcasting to spread information from one sensor node to the other sensor nodes in the entire sensor network. These wireless sensor networks have certain characteristics such as limited power and battery driven. However the simple flooding mechanism causes lots of duplicated packets and consumes a lot of resources. In view of these constraints, the broadcasting service should reduce redundant transmissions such that energy conservation is obtained since the devices within a wireless sensor network have limited battery power. Since it is not necessary for each sensor node to be active all the time a more sophisticated method might be introduced to flood an entire network and the other side is more efficient. In this work, an asynchronous sleep scheduling is proposed by an adapted duty cycle for each sensor where the duty cycle is based on the RSS based density estimation for each sensor node. By using the proposed duty cycle the reachability is compared with that of the fixed duty cycle and the adapted duty cycle by using neighborhood discovery density estimation model. The results show that the reachability of the network with an adapted duty cycle in combination with RSS based density estimation is two times more than that of the neighborhood density estimation in a 100m x 100m WSN of 200 sensor nodes. Further the results show the reachability is as good as in the case of the 90% fixed duty cycle but is more energy efficient.