BeamSwitch: System Solution for Energy-Efficient Directional Communication on Mobile Devices

Directional communication has the potential to improve the energy efficiency of wireless communication without sacrificing its quality. We present a system solution, BeamSwitch, for directional communication on mobile devices. BeamSwitch employs a special multi-antenna system that consists of multiple identical directional antennas, or beams, a single regular omni-directional antenna, and a single RF chain. It uses one of the directional beams for transmitting data frames and receiving their acknowledgements and the regular antenna for all other transceiving. BeamSwitch tracks the signal strength of incoming frames and selects the right beam for data transmission. We report an extensive evaluation of BeamSwitch including both measurements with a prototype with three beams and Qualnet-based simulation. Our evaluation shows that BeamSwitch with three 6 dBi directional antennas can improve the energy efficiency of a commercial 802.11 network interface card (NIC) by up to 20% and simultaneously provide better or close communication quality. BeamSwitch achieves this under diverse radio propagation environments and extreme mobility (up to 360° per second direction change).