Area Throughput of an IEEE 802.15.4 Based Wireless Sensor Network

In this paper we present a mathematical model to evaluate the performance of all IEEE 802.15.4 based multi-sink Wireless Sensor Network (WSN). Both sensors and sinks axe assumed to be Poisson distributed in a given finite domain. Sinks send periodic and synchronous queries, and each sensor transmits its sample to a sink, selected among those that. are audible. The IEEE 802.15.4 Multiple Access Control (MAC) protocol is used by sensors to access the channel: both Beacon-Enabled and Non Beacon-Enabled modes are considered. Our aim is to describe how the Area Throughput, defined as the amount of samples per unit of time successfully transmitted to the sinks from the given area, depends on the density of sensors and the query interval. We jointly account for MAC issues (i.e. packet collisions) and connectivity aspects (i.e. network topology, power losses and radio channel behaviour). Performance is evaluated by varying the traffic offered to the network (i.e. the number of sensors deployed), the packet size, the number of Guaranteed Time Slots allocated, and the Superframe Order. A comparison between results obtained in the Beacon-Enabled and the Non Beacon-Enabled cases is also provided, showing how the Area Troughput can be optimised.