Modeling Query-Based Wireless CSMA Networks Through Stochastic Geometry

A mathematical model for characterizing the performance of wireless access networks based on a carrier-sense multiple-access (CSMA) mechanism is derived. The model is developed through a statistical description of the interference power coming from stochastic geometry and by taking into account the hidden node problem. As an example of a specific application of the model, the IEEE 802.15.4 standard is considered. Nodes are assumed to be uniformly distributed according to a Poisson point process (PPP) in a 2-D infinite plane. They have to communicate with the network coordinator through direct links (star topology), following a query-based application. The total interference power is modeled considering the actual density of nodes that are simultaneously transmitting. This takes into account the operation of the CSMA with collision avoidance (CSMA/CA) algorithm used by nodes to access the channel, according to the IEEE 802.15.4 standard. Results show the impact of node density, packet length, and sensing range on the system performance, which is evaluated in terms of success probability in transmitting packets from nodes to the coordinator.