Patent ID: 6141337
Filing Date: 2000-10-31
Classification: H04B,H04J,H04W

Abstract:
A spread spectrum communication system, in which spread spectrum communication is conducted between a master station and a subordinate station, wherein:the subordinate station establishes a frame synchronization according to a downward reference signal transmitted from the master station and sends an upward control signal according to the frame synchronization,the master station derives a propagation delay time on a radio channel from a relationship between a downward control signal and the upward control signal,the subordinate station transmits an upward data signal in synchronism with a frame synchronizing signal, andthe master station receives the upward data signal at timing in accordance with the propagation delay time;said spread spectrum communication system comprising:a downward pilot channel for transmitting a reference signal in a downward direction from the master station to the subordinate station;an upward control channel which is spread by a spreading code having a repetition period substantially equal to one-symbol time for transmitting data in an upward direction from the subordinate station to the master station; andan upward traffic channel which is spread by a spreading code having a repetition period longer than the one-symbol time;wherein the master station comprises:a first matched filter for receiving the upward control channel,a second matched filter for receiving the upward traffic channel having a configuration for changing a coefficient thereof for each symbol,a mechanism which measures a propagation delay by comparing timing of a signal demodulated by the first matched filter with reference timing used in the master station, anda mechanism which controls timing of changing a coefficient of the second matched filter according to a result of measurement of the propagation delay; andthe subordinate station comprises:a mechanism which extracts the reference timing of the master station by receiving the reference signal via the downward pilot channel, anda mechanism which transmits an upward data signal to the upward traffic channel in synchronism with the reference timing extracted from the downward control signal.