Study on adaptive priority-based service-differentiation scheme for IEEE 802.15.4 Wireless Sensor Networks

The IEEE 802.15.4 standard uses carrier sense multiple access with collision avoidance (CSMA/CA) algorithm as the medium access mechanism, which employs a binary exponential backoff (BEB) mechanism to control the access of nodes to the wireless medium. However, CSMA/CA algorithm does not support network self-adaptivity and differentiated services. We address these problems by proposing an adaptive priority-based service-differentiation CSMA/CA algorithm (APB-CSMA/CA) for differentiated services for IEEE 802.15.4. The proposed algorithm includes two mechanisms, 1) adaptive backoff mechanism. The nodes can dynamically adjust the backoff period according to the actual status of current network. 2) priority-based service-differentiation mechanism. In this mechanism, different parameters are given to different classes of services to provide multi-levels differentiated services. In addition, a theoretical analysis based on Markov chain is proposed to derive a mathematical model for our proposal. Both analytical and simulation results show that the proposed algorithm performs better than IEEE 802.15.4, which significantly improves reliability and channel utilization.