Patent ID: 6388997
Filing Date: 2002-05-14
Classification: H04B,H04J,H04W

Abstract:
A system for communicating with a plurality of user stations, comprising:a base station; a transmission format; said transmission format comprising a plurality of time frames of equal duration, each of said time frames comprising a base transmission portion, a collective guard portion, and a user transmission portion, said collective guard portion located between said base transmission portion and said user transmission portion, each base transmission portion comprised of a plurality of base time slots and each user transmission portion comprised of a plurality of user time slots; said base station comprising a base station transmitter for transmitting a polling message from the base station to two or more of the plurality of said user stations in a base time slot of a first of said time frames, said base station comprising a base station receiver for receiving a reply message from at least one of said two or more user stations during the collective guard band portion of said first time frame; a propagation delay calculator, said propagation delay calculator comprising the capability to determine a propagation delay between said base station and said at least one user station; and said base station transmitter further for transmitting a timing command during the base transmission portion of a time frame subsequent to the first time frame to the at least one user station for instructing the at least one user station to adjust the transmission time of the at least one user station, the timing command based at least in part on said propagation delay.