A Timed Petri Net Model For The IEEE 802.15.4 CSMA-CA Process

The IEEE 802.15.4 specification has generated a lot of interest in recent times, especially within the Wireless Sensor Network (WSN) research community, primarily because energy efficiency is one of the specifications' design cornerstone. As this specification is relatively new, it is incumbent that its operational mechanisms are well understood, to allow for efficient cross layer interactions between the different processes that make up the specification and existing or new higher layer protocols. In this paper, we present a deterministic Petri-Net model of the IEEE 802.15.4 CSMA-CA process, that is timer driven and operates within the bounds of the contention access period (CAP). Using this model, we are able to analyze the performance characteristics of the CSMA-CA process, especially in terms of channel throughput and energy consumption. We also verify the extracted system indices by comparing them to those gotten from a full model of the specification, implemented using the OPNET network simulation platform.