Optimization and modeling of modified unslotted CSMA/CA for wireless sensor networks

IEEE 802.15.4 protocol is intended to accomplish the characteristics of low power and low rate Wireless Sensor Network. It employs carrier sense multiple access with collision avoidance (CSMA/CA) protocol to access the network using either unslotted or slotted mode. This paper concentrates on the un...

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Bibliographic Details
Published in:Alexandria engineering journal 2020-04, Vol.59 (2), p.681-691
Main Authors: Gamal, Mahmoud, Sadek, Nayera, Rizk, Mohamed R.M., Ahmed, Magdy Abd ElAzim
Format: Article
Language:English
Subjects:
Backoff
CSMA/CA
IEEE 802.15.4
Markov model
OPNET
Optimization
WSN
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Summary:IEEE 802.15.4 protocol is intended to accomplish the characteristics of low power and low rate Wireless Sensor Network. It employs carrier sense multiple access with collision avoidance (CSMA/CA) protocol to access the network using either unslotted or slotted mode. This paper concentrates on the unslotted CSMA/CA where the node tends to wait for a very limited backoff exponent value, and cannot perform clear channel assessment until backoff procedure is completed. Therefore, the collision probability and the average delay are high. To enhance the unslotted CSMA/CA performance, this paper proposes a modified unslotted CSMA/CA that divides the backoff delay into Main Backoff and Secondary Backoff. The Markov model for the modified CSMA/CA is presented to assess a single hop IEEE 802.15.4 behavior, and derive expressions for average delay, energy consumption and reliability. An optimization problem is also presented to minimize the delay while guaranteeing energy consumption and reliability constraints for the modified CSMA/CA. OPNET simulation tool is applied to compare the modified to the standard unslotted CSMA, and to validate the Markov model proposed. The results demonstrate that the modified CSMA improves the reliability, while reducing the average delay significantly.
ISSN:1110-0168
DOI:10.1016/j.aej.2020.01.035