Patent ID: 6552998
Filing Date: 2003-04-22
Classification: H04H,H04J,H04L

Abstract:
A two-way communication system comprising:a center station; subscriber stations each for mutually exchanging signals with said center station; a relay station for relaying signals between said center station and said subscriber stations; a relay transmission line connected between said center station and said relay station and duplex systematized by a working system and a stand-by system; and a subscriber transmission line connected between said relay station and said subscriber stations, wherein said center station measures a round-trip propagation delay when a subscriber station starts its operation and then sets a transmission delay of said subscriber station so as to equalize the round-trip propagation delay measured to said subscriber station to a fixed system delay; and wherein said center station measures a round-trip propagation delay of a subscriber station after a link switching operation when a link switching operation from a working system to a stand-by system occurs due to a failure in said relay transmission line, and resets transmission delays of all subscriber stations connected to said relay station based on a difference between the measured delay and a round-trip propagation delay of a signal to said subscriber station before said link switching operation.