  Communication systems operating at high frequency bands must use narrow beams
to compensate the high path loss. However, it is incredibly time-consuming to
achieve beam alignment between the transmitter and receiver due to the large
volume of beam space with narrow beams. The high latency of initial beam
establishment will challenge the implementation of future 6G networks at high
frequency bands. To tackle this problem, this paper proposes an initial beam
establishment method using the material sensing results from joint
communications and sensing (JCAS) systems. The reflection loss (RL) induced by
each reflector can be predicted by exploiting the pre-identified material
information of reflectors in the environment. The base station (BS) first scans
the beam directions with low RL and establishes the connection immediately
without sweeping the rest of the beam directions. In this way, the latency of
initial beam establishment is significantly reduced.
