초록 ▼

A system and method for time division duplex communication over a single frequency band wherein guard time overhead is reduced by active adjustment of reverse link transmission timing as a function of round trip propagation time. A time frame is divided into a plurality of time slots, during each of

A system and method for time division duplex communication over a single frequency band wherein guard time overhead is reduced by active adjustment of reverse link transmission timing as a function of round trip propagation time. A time frame is divided into a plurality of time slots, during each of which the base station transmits to a user station and the user station transmits to the base station. Communication is initiated by a round trip timing transaction. In response to a general polling message from the base station, a user station seeking to establish communication transmits a short reply message. The base station calculates the distance of the user station by measuring the propagation delay with respect to receipt of the reply message. The base station sends a timing adjustment command to the user station instructing the user station to advance or retard its timing according to the calculated distance, so as to minimize guard times between time slots. Thereafter, the base station monitors the user station transmissions and periodically commands the user station to advance or retard its timing in a like manner. The user station may transmit a control preamble at the start of each time slot to allow the base station to perform round trip timing calculations, and/or to allow adjustment of user station power or antenna selection. The system is capable of independently selecting frequency bands and time slots for a duplex communication link, providing a pure Time Division Duplex (TDD) mode, Frequency Division Duplex (FDD mode or Hybrid Time Division Duplex/Frequency Division Duplex (TDD/FDD) mode.

대표청구항 ▼

[ What is claimed is:] [1.] A base station for time aligning received signals, comprising:a receiver for receiving signals transmitted by a plurality of user stations,a propagation delay calculator coupled to the receiver that determines a propagation delay for each signal received by the receiver,a

[ What is claimed is:] [1.] A base station for time aligning received signals, comprising:a receiver for receiving signals transmitted by a plurality of user stations,a propagation delay calculator coupled to the receiver that determines a propagation delay for each signal received by the receiver,a timing adjustment command unit coupled to the propagation delay calculator, the timing adjustment command unit responsive to the propagation delay and outputting a timing adjustment command directing a one user station of a plurality of user stations in communication with the base station to advance or retard a time for transmitting, andadjustable means to select a first frequency band and a first time slot for a forward link and a second frequency band and a second time slot for a reverse link such that a pure TDD mode, a pure FDD mode or a hybrid TDD/FDD mode is selected, said first frequency band may be the same as said second frequency band, and said first time slot may be the same as said second time slot.