Message Priority CSMA/CA Algorithm for Critical-Time Wireless Sensor Networks

IEEE 802.15.4 Wireless Sensor Network (WSN) is among of the most deployed networks for several applications. On the one hand IEEE 802.15.4 features provide a good solution for low-cost and low-power wireless communications. But, on the other hand, this standard does not process the quality of service in real time applications, where we should reduce the latency in parallel of the energy consumption. IEEE 802.15.4 standard is based on the CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) algorithm, which does not take into account any indications of nodes priority. However, in some applications, such event-monitoring networks, we need to ensure low latency, especially for real time messages. In this paper we present a new priority based scheme for managing node priority to get access to the channel. In our contribution, Message Priority CSMA/CA (MP-CSMA/CA) algorithm, the probability to gain channel access is based on the message priority. The main of our algorithm is to differentiate services; it gives more chance to nodes that have real-time messages, to access the medium firstly. The results show an efficient quality of service provided by our proposed algorithm.