Impact of Device Population on Beam Alignment Performance of 802.11ad

Millimeter Wave (MmWave) based communication standards including IEEE 802.11ad WiFi show great promise in supporting next generation service demands such as real-time streaming of ultra-high-definition video. However, MmWave signals suffers from high path loss and often required to have unobstructed line-of-sight. Narrow beamwidth antenna arrays along with adaptive beamforming is currently deployed to mitigate those issues. Nevertheless, the impact of device population on beam alignment has not yet been well studied in the literature. In this paper, we quantify the loss of antenna gain when there are multiple devices in the communication range completing for channel access to perform beamforming. We further study the link outage probability for devices with angular displacement similar to change in orientation of hand-held or head-worn devices in home wireless networks. The simulation results reveal that loss of antenna gain can be as high as 7dB and link outage probability increases up to 90% for 16 antenna sectors and 10 competing devices.