Optimal Backoff Exponent estimation for environmental monitoring IEEE 802.15.4 star-topology sensor networks

In the IEEE 802.15.4 standard, the Backoff Exponent (BE) index defines the duration of a node´s backoff period during a transmission attempt. In the context of an environmental monitoring research project, we examine the effect of the BE index value in overall network performance. We show that the minimum and maximum assigned values have a significant performance impact and propose a method for calculating the appropriate index value as a function of packet size, data rate and the number of active sensor nodes. In the same context, we also develop a network calculus approach for throughput estimation of IEEE 802.15.4 star topology networks and evaluate it over an extensive range of network configurations.