Traffic Adaptive Priority Assignment Scheme for Congestion in IEEE 802.15.4 Networks

In this paper, we tackle the issue of exploiting the priority based packet assignments and transmissions in congested wireless sensor networks. Since the heavy traffic makes it difficult to provide QoS solutions, we propose a traffic adaptive priority assignment scheme (TAPA), which monitors the buffer length of each node to identify the congestion symptom and dynamically adjusts its backoff value and frame retransmission parameter according to predefined access categories (ACs). In addition, when TAPA detects congestion symptoms, it deliberately restrains from participating in the route discovery procedure by dropping RREQs and RREPs. We also conducted a performance evaluation via simulations and showed that TAPA provides a more efficient QoS solution than conventional IEEE 802.15.4 in terms of packet delivery ratio and end-to-end delay.