FASUS: A fast association mechanism for 802.11ah networks

Fast association aims to quickly associate a large number of stations with an access point in 802.11ah networks. Existing fast association mechanisms suffer from efficiency, fairness and robustness problems. In this paper, we propose the mechanism of Fast Association based on Speculating the nUmber of Stations (FASUS). FASUS adopts new methods for retransmission, thresholding and adaptive round selection, which greatly improve the association performance. Experiments show that FASUS is able to reduce the association time by 67.1% when compared with the Linear Increase Linear Decrease (LILD) method, which is one of the best-known mechanisms for 802.11ah networks. We formulate a mathematical model to analyze the association process and to determine the optimal number of stations per round. Furthermore, we propose two methods to address the inter- and intra-network interference in congested networks. To improve the robustness and fairness of the network, we propose new solutions to address two possible attacks: 1) the Denial-of-Service (DoS) attack, which can disable the whole network, and 2) the selfish node attack, which may unfairly allow the attackers to associate in a much faster way than normal stations.