A collision-aware backoff mechanism for IEEE 802.15.4 wireless sensor networks

The IEEE 802.15.4 standard uses carrier sense multiple access with collision avoidance (CSMA/CA) as the medium access mechanism. This mechanism employs a binary exponential backoff (BEB) algorithm to control the access of nodes to the wireless medium. The main drawbacks of this algorithm are that the range of the backoff exponent is very small and it updates the length of the backoff period in a deterministic manner without taking into consideration the actual state of the communication channel. These inefficiencies degrade the system performance when the network has many nodes and the collision probability is large. We address these problems by proposing a novel collision-aware backoff algorithm (CABEB) which can dynamically select a suitable backoff period according to the collision probability of the nodes. The simulation results verify the efficiency of the proposed algorithm.