A ground-or roof-top-based
repeater in an OFDM
system uses multiple transmission antennas to retransmit
satellite signals. By using multiple transmission antennas, multiple identical OFDM signals are transmitted. Dithering is performed by, using a phase of Rayleigh process generator, introducing a slight variable-frequency
phase offset to all but one of the multiple identical transmitted OFDM signals, and thus the effective overall channel is more dynamic and provides spatial diversity to minimize long periods of
fading in
fading subchannels of the OFDM signals when the
receiver is in a slow moving or stationary situation. To overcome the additional cancellation problem that can occur when two or more of the transmitting antennas are in a line-of-site position with the
receiver and approximately the same distance from the
receiver, a
delay is deliberately introduced to make the delayed
signal(s) appear to be reflected signals. This
delay will not negatively
impact the OFDM receiver performance as long as the
delay is within the
guard interval used in the OFDM process.