Abstract: A method for establishing a direct communication using an unmanned aerial vehicle (UAV) with a reconfiguration intelligent surface (RIS) includes configuring RIS parameters based on compensating for undesired oscillations of a position and an orientation associated with the UAV. A signal reflection associated with a beam signal is steered to a target area based on the RIS parameters and by the RIS of the UAV. The signal beam is from a transmitter.

Abstract: A method of generating channel estimates of a communication channel in an OFDM system includes receiving references symbols from at least one time frequency observation block of a predetermined block size in frequency and time; generating subspace-transformed reference symbols from the received reference symbols; and subspace filtering the subspace-transformed reference symbols to generate a channel estimate for a communication channel target time; wherein a latency between a communication channel time instant of a currently received reference symbol and the communication channel target time is smaller than the observation block size in time.

Abstract: A method of generating channel estimates of a communication channel in an OFDM system includes receiving reference symbols from at least one time-frequency observation block of a predetermined block size infrequency and time. Subspace-transformed reference symbols are generated from the received reference symbols. The subspace-transformed reference symbols are subspace filtered to generate a channel estimate for a communication channel target time. A latency between a communication channel time instant of a currently received reference symbol and the communication channel target time is smaller than the observation block size in time.