Analysis of Unslotted IEEE 802.15.4 Networks with Heterogeneous Traffic Classes

We propose a modeling framework composed of a Markov chain and the related coupling equations to evaluate the performance of unslotted IEEE 802.15.4 wireless sensor networks based on CSMA/CA Medium Access Control. Different from the related literature, the proposed model is able to capture heterogeneous classes of nodes with class-specific traffic generation rate and includes a more refined calculation of the probability of finding the channel busy during the carrier sensing process. The proposed model is used to derive class-specific performance figures including the probability of a successful transmission and the average delay for a successful/unsuccessful transmission.