Dynamic Slot Allocation Using Non Overlapping Backoff Algorithm in IEEE 802.15.6 WBAN

A dynamic slot allocation scheme using non-overlapping contention windows is presented in this paper to improve the utilization of the IEEE 802.15.6 Wireless Body Area Network (WBAN) superframe. Firstly, a Non Overlapping Backoff Algorithm (NOBA) that avoids inter-priority collisions due to backoff is presented. The results of this scheme are compared with the standard Binary Exponential Backoff (BEB) and the Prioritized Fibonacci Backoff (PFB) schemes. The NOBA provides improvement in the sum throughput, individual throughputs and access delay. Secondly, to avoid the wastage due to fixed slot size, a Dynamic Slot Allocation (DSA) scheme is introduced. It assigns the dynamic slots and phases in a superframe depending on the traffic requirements. Thirdly, a DSA-NOBA scheme that combines both the DSA and the NOBA is presented. The performance of DSA-NOBA is compared against the standard IEEE 802.15.6 superframe (with BEB) and Dynamic Phase Allocation (DPA) schemes using the individual throughput, sum throughput, latency, energy, superframe time and superframe efficiency as performance metrics. Over a range of payload sizes, the DSA-NOBA makes the superframe 50% more efficient than the standard IEEE 802.15.6 superframe with BEB, consequently also providing improvement in all the performance metrics. The most notable among them is energy, whose consumption is reduced by half when compared with the standard.