  Mobility scenarios involving short contact times pose a challenge for high
bandwidth data transfer between autonomous vehicles and roadside base stations
(BS). Millimeter wave bands are a viable solution as they offer enormous
bandwidth in the 60GHz band with several Gbps data transfer rates. However,
beamforming is used as a default mode in this band, which requires accurate and
continuous alignment under relative motion. We propose a method in which an
off-the-shelf IEEE 802.11ad WiFi router is configured to serve as the BS as
well as a radar exploiting special structure of 802.11ad preamble. We embed the
radar functionality within standards-compliant operations that do not modify
the core structure of the frames beyond what is defined by the 802.11ad
protocol. This not only reduces the beam training time, but also ensures
scalability with increasing vehicular traffic because radar allows accurate
ranging of up to 0.1m at distances up to 200m. We further analyze the ensuing
cost-benefit trade-off between the time allotted to the proposed in-band radar
and communication modes. Our results reveal 83% reduction on the overhead
incurred during the beam training achieved for a specific simulated vehicular
scenario over the classical 802.11ad operation.
