ABSTRACT The IEEE 802.15.4 standard utilizes the CSMA-CA mechanism to control nodes’ access to the shared wireless communication medium. CSMA-CA implements the Binary Exponential Backoff (BEB) algorithm by which a node refrains from sending any packet before the expiry of its backoff period. After that, the node is required to sense the medium for two successive time slots to assert that the medium is clear from any ongoing transmissions (this is referred to as Clear Channel Assessment (CCA)). Upon finding the medium busy, the node doubles its backoff period and repeats that process. While effective in reducing the likelihood of collisions, this approach takes no measures to preserve the priorities among the nodes contending to access the medium. In this paper we propose the Priority-Based BEB (PB-BEB) algorithm in which we enhance BEB such that nodes’ priority is preserved. We provide a simulation study to examine the performance of PB-BEB. Our simulations show that the latter not only outperforms BEB in terms of fairness, but also show promising results in terms other parameters like channel utilization, reliability, and power conservation.
Cite this paper
M. Khanafer, M. Guennoun and H. Mouftah, "Priority-Based CCA Periods for Efficient and Reliable Communications in Wireless Sensor Networks," Wireless Sensor Network, Vol. 4 No. 2, 2012, pp. 45-51. doi: 10.4236/wsn.2012.42007.
 LAN/MAN Standards Committee of the IEEE Computer Society, Part 15.4: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low- Rate Wireless Personal Area Networks (LR-WPANs), October 2003, pp. 1-679.
Y.-K. Huang, A.-C. Pang and H.-N. Hung, “An Adaptive GTS Allocation Scheme for IEEE 802.15.4,” IEEE Transactions on Parallel and Distributed Systems, Vol. 19, No. 5, 2008, pp. 641-651. doi:10.1109/TPDS.2007.70769
M. Takaffoli, E. Elmallah and W. Moussa, “Scheduled Access Using the IEEE 802.15.4 Guaranteed Time Slots,” Proceedings of IEEE International Conference on Communications (ICC’10), Cape Town, South Africa, 23-27 May, 2010, pp. 1-5.
E. D. N. Ndih, N. Khaled and G. D. Micheli, “An Analytical Model for the Contention Access Period of the Slotted IEEE 802.15.4 with Service Differentiation,” Proceedings of IEEE International Conference on Communications (ICC’09), Dresden, Germany, 14-18 June 2009, pp. 1-6.
R. Severino, M. Batsa, M. Alves and A. Koubaa, “A Traffic Differentiation Add-On to the IEEE 802.15.4 Protocol: Implementation and Experimental Validation over a Real-Time Operating System,” Proceedings of 13th Euromicro Conference on Digital System Design: Architectures, Methods, and Tools (DSD’10), Lille, France, 1-3 September 2010, pp. 501-508.
S. Jardosh, P. Ranjan and D. Rawal, “Prioritized IEEE 802.15.4 for Wireless Sensor Networks,” Proceedings of the 6th Conference on Wireless Advanced (WiAD’10), London, UK, 27-29 June 2010, pp. 1-7.
S. Pollin, M. Ergen, S. C. Ergen, B. Bougard, L. Van derPerre, I. Moerman, A. Bahai, P. Varaiya and F. Catthoor, “Performance Analysis of Slotted Carrier Sense IEEE 802.15.4 Medium Access Layer,” IEEE Transactions on Wireless Communications, Vol. 7, No. 9, 2008, pp. 3359-3371.
R. Jain, D. Chiu and W. Hawe, “A Quantitative Measure of Fairness and Discrimination for Resource Allocation in Shared Computer Systems,” DEC-TR-301, September 1984.