A Channel Allocation Algorithm for Reducing the Channel Sensing/Reserving Asymmetry in 802.11ac Networks

Abstract

The major goal of IEEE 802.11ac is to provide very high throughput (VHT) performance while at the same time guaranteeing backward compatibility. To achieve this goal, 802.11ac adopts the channel bonding technique that makes use of multiple 20 MHz channels in 5 GHz band. Due to the heterogeneity of bandwidth that each device exploits, and the fixed total transmission power in the standards, a problem called `Hidden Channel' arises. In this paper, we first analyze the problem and show how the contention parameters and transmission time affect collision probability and fairness in some deployment scenarios. Then, we propose a heuristic channel allocation algorithm that aims to avoid such problematic situations effectively. Through simulations, we demonstrate that our proposed channel allocation algorithm lowers the packet error rate (PER) compared to uncoordinated and received signal strength indicator(RSSI) based allocation schemes and increases the network-wide throughput as well as the throughput of a station that experiences poor performance. This implies improved fairness performance among transmission pairs with various channel bandwidths.