A Hierarchical Deep Learning Approach for Optimizing CCA Threshold and Transmit Power in Wi-Fi Networks

The nodes, e.g., access points and clients, in current WiFi networks rely on carrier sense multiple access (CSMA) for channel access. This means they rely on a clear channel assessment (CCA) threshold to determine when it is safe to transmit a packet. In practice, this threshold is fixed, and nodes do not adapt their CCA threshold given varying channel conditions. To this end, this paper proposes and studies the use of deep reinforcement learning (DRL) to optimize the CCA threshold and transmit power of an AP. It allows an AP to learn the optimal policy for setting its CCA threshold and transmit power given its queue length and interference level. We outline a semi-Markov decision process (Semi-MDP) for the problem at hand and solve it using a decentralized deep hierarchical reinforcement learning (HRL) approach. We then evaluate its performance using traffic generated via a Poisson distribution and also from a trace file. The results show that when compared to two competing solutions, an AP with HRL reduces its average queue length by 24.4% and 52.4%, respectively.