On the Number of Cluster Heads Minimizing the Error Rate for a Wireless Sensor Network using a Hierarchical Topology Over IEEE802.15.4

This paper investigates a three-level tree-based network topology using IEEE 802.15.4 for wireless sensor networks, where some nodes randomly elect themselves cluster heads (CHs): the CHs (level one) communicate with the other sensor nodes gathered in clusters (level two) on one side and with the sink (level zero), on the other. In particular, the percentage of samples taken from nodes that are correctly received at the sink is maximised, by optimising the number of CHs. Simulation results show that this optimum value exists, as a trade off between the load within clusters, which depends on their size and is controlled by increasing the number of CHs, and the probability of collisions among CH packets, that can be minimised by decreasing the number of CHs. To clarify the role of the different network parameters, such as the network size, the IEEE 802.15.4 superframe order, etc. in the determination of this optimum value, a simple and approximate statistical analysis of the PER is also included