IEEE 802.11ac: Effect of channel bonding on spectrum utilization in dense environments

IEEE 802.11ac is a recent amendment that enhances the throughput of WLANs. It uses spatial diversity, new modulation and coding schemes (MCS), and channel bonding to increase the data rate. The channel bonding allows 802.11ac stations, also called Very High Throughput (VHT) stations, to operate on channels wider than the legacy 20 MHz channel in the 5 GHz band. Particularly, a VHT station may support up to 160 MHz transmissions. Increasing the channel width enhances the data rate but reduces the number of non-overlapping channels. For example, the 5 GHz spectrum in Europe offers either 19 nonoverlapping 20 MHz channels or only two 160 MHz channels. In dense WLAN deployment environments, the use of channel bonding increases the number of networks and stations sharing the same medium, and may increase the collisions rate. In this paper we show that the spectrum utilization increases when it is divided into multiple narrow channels instead of fewer wide channels. This increase is very significant when the frame aggregation is disabled. We show that 8 × 20 MHz channels may offer 252 Mbps compared to only 51 Mbps in a 160 MHz channel.