Modelling and Performance Analysis of IEEE 802.11 DCF Using Coloured Petri Nets

IEEE 802.11, as the standard protocol for wireless local area networks, has achieved substantial developments during recent years and has been widely used in industry and in our daily life. The fundamental access method of the protocol is the distributed coordinated function (DCF), in which the carrier sense multiple access with collision avoidance is used to enable the automatic medium sharing among wireless stations. In this article, a coloured Petri net model for IEEE 802.11 DCF is developed aiming at analysing its performance by simulation. The model is carefully built to capture almost all aspects of the protocol precisely, including the physical and virtual carrier sense functions, traffic generation, backoff procedure, transmission, reception, retransmission, request-to-send/clear-to-send, etc. The topology and ratio ranges are specified so as to address the hidden node problem. The model is organized in a hierarchical and modularized manner, and the symmetries existed in the protocol are exploited to build a compact and scalable model. The model is simulated to compute some performance metrics for each node and for all nodes, including throughput, delivery ratio and delay. The results are compared with NS-2 to validate the model.