Out-of-Band Multiple Path Discovery Protocol for Robust In-Band Millimeter Wave Links

Millimeter-wave technology has proved to be one of the enabling technologies of the fifth generation of wireless networks. Despite the merits of the millimeter-wave spectrum, its directionality imposes more overhead on communication systems than the non-millimeter wave spectrum. In this paper, we propose using signaling in another frequency band to discover the paths surrounding a receiver working in the millimeter-wave spectrum. In this way, the receiver does not have to do an expensive beam scan in the millimeter wave band and repair the interrupted ongoing millimeter communication much faster by choosing the beam covering the best path discovered by another frequency band. Our experiments in various environments by millimeterwave hardware platforms show that a non-millimeter wave frequency band's paths can be used to align the beams in millimeterwave frequency. Existing out-of-band path discovery methods typically need a specially designed hardware for scanning and can only find the single line-of-sight path. Our proposed method uses commercial off-the-shelf products to perform out-of-band scanning and discover both line-of-sight path and non-line-of-sight paths for millimeter wave communication.