Accurate and Efficient Modeling of 802.15.4 Unslotted CSMA/CA through Event Chains Computation


Many analytical models have been proposed for evaluating the performance of event-driven 802.15.4 Wireless Sensor Networks (WSNs), in Non-Beacon Enabled (NBE) mode. However, existing models do not provide accurate analysis of large-scale WSNs, due to tractability issues and/or simplifying assumptions. In this paper, we propose a new approach called Event Chains Computation (ECC) to model the unslotted CSMA/CA algorithm used for channel access in NBE mode. ECC relies on the idea that outcomes of the CSMA/CA algorithm can be represented as chains of events that subsequently occur in the network. Although ECC can generate all the possible outcomes, it only considers chains with a probability to occur greater than a pre-defined threshold to reduce complexity. Furthermore, ECC parallelizes the computation by managing different chains through different threads. Our results show that, by an appropriate threshold selection, the time to derive performance metrics can be drastically reduced, with negligible impact on accuracy. We also show that the computation time decreases almost linearly with the number of employed threads. We validate our model through simulations and testbed experiments, and use it to investigate the impact of different parameters on the WSN performance, in terms of delivery ratio, latency, and energy consumption.


Computer Science

Research Center/Lab(s)

Intelligent Systems Center


The authors thank the AE and the reviewers for their insightful comments. This material is based upon work supported by the National Science Foundation under Grant No. CNS-1355505, CNS-1545037, and CNS-1545050. This work has been also partially supported by the University of Pisa, in the framework of the PRA 2015 program.

Keywords and Phrases

Carrier sense multiple access; Chains; Complex networks; Energy utilization; Standards; Beacon-Enabled modes; CSMA/CA; IEEE 802.15.4; Performance analysis; Performance metrics; Simplifying assumptions; Threshold selection; Wireless sensor networks (WSNs); Non-beacon enabled mode; Unslotted CSMA/CA

International Standard Serial Number (ISSN)

1536-1233; 1558-0660

Document Type

Article - Journal

Document Version


File Type





© 2016 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Dec 2016