Hidden terminal aware grouping scheme for IEEE 802.11ah based dense IoT networks

IEEE 802.11ah, a prevalent standard for the Internet of Things, introduces major enhancements to PHY and MAC layer of the legacy standard. One of the significant improvements in IEEE 802.11ah is the restricted access window (RAW) mechanism. The RAW mechanism is a group-based contention technique that limits the contention among the devices by partitioning them into several groups, dividing the channel time into various time slots and assigning each group with a RAW slot. Although the grouping schemes reduce contention among the devices, it eventually leads to hidden terminals in the dense networks. In this article, we propose a hidden terminal aware grouping (HTAG) mechanism to alleviate the hidden terminal problem. The proposed scheme groups the devices based on the SINR and implements a hidden terminal avoidance algorithm to ensure each group with a minimum number of hidden terminals. We present a simple yet accurate analytical model to evaluate the performance of the RAW mechanism with the proposed HTAG scheme in terms of throughput, delay and energy consumption. Results show significant improvement in the performance of the RAW mechanism using the HTAG scheme compared to the state-of-the-art schemes. Finally, all the analytical findings are validated using extensive simulations in ns-3.