Benefits of the IEEE 802.15.4's MAC layer acknowledgements in Ad-Hoc networks: An experimental analysis

This paper highlights the benefits of IEEE 802.15.4's unslotted carrier sense multiple access collision avoidance (CSMA-CA) MAC layer acknowledgements (ACKs) in ad-hoc wireless networks. We performed different experimental studies to analyse the impact of enabling and disabling the ACKs on event detection ratio (EDR), available bandwidth estimator, and flow admission control algorithms. Comparison of the best performance of both, i.e., enabling and disabling the ACKs w.r.t. EDR demonstrates the following benefits of enabling the ACKs. 97% EDR by only transmitting a single message corresponding to each event, 52% higher EDR, 59% fewer total transmissions, and 78% lower event propagation delay to a sink node. The ACKs improves the effectiveness of the state-of-the-art flow admission control algorithms by up to 166%. Enabling the ACKs, and using no admission control algorithm is up to 40% more effective compared to using the admission control algorithms with the ACKs disabled. Similarly, estimating the residual data relaying capacity of the IEEE 802.15.4 communication link using an available bandwidth estimator is only useful when the ACKs are enabled.