K-Means Based Grouping of Stations with Dynamic AID Assignment in IEEE 802.11ah Networks

The IEEE 802.11ah amendment extends the success of traditional IEEE 802.11 networks to sub-GHz frequency bands by allowing higher signal coverage and introducing new capabilities to handle a massive number of stations in applications for the Internet of Things. The restricted access window (RAW) mechanism is the key technique to limit contention by dividing stations into RAW groups and RAW time slots according to AID numbers that can be changed dynamically via AID Switch Response frames. To date, however, such feature has not been investigated, especially in cooperation with some grouping scheme. This paper presents the first investigation on the use of AID Switch Response frames to implement dynamic grouping. The goal is to improve throughput fairness among stations that are geographically distributed over some area. The grouping scheme is based on the K-Means algorithm, which takes as input the length and signal strength of data frames received by the AP, and the modulation and coding schemes (MCS) adopted by stations. Simulation results show significant gains in throughput fairness obtained with the proposed grouping scheme compared to random grouping over different network scenarios.