An Enhanced Collision-Avoidance MAC Protocol for IEEE 802.15.4

When an IEEE 802.15.4 network has many nodes and is almost saturated, the probability of collision is large, and the throughput is small. The main reasons are the adoption of slotted CSMA/CA and the mechanism that if a data transmission cannot be completed before the end of contention access period (CAP), it has to wait until the start of the CAP in the next superframe. This paper proposes an enhanced collision-avoidance MAC protocol for IEEE 802.15.4, and establishes a simulation model to analyze and compare the enhanced collision-avoidance MAC and the IEEE 802.15.4 MAC. The proposed protocol, compatible with the IEEE 802.15.4 protocol, has less probability of collision (almost 0), higher probability of successful transmission (close to 1), and larger network throughput (more than two times of that of IEEE 802.15.4).