06094421 is referenced by 167 patents and cites 109 patents.

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.

Title
Timing adjustment control for efficient time division duplex, frequency division duplex or hybrid time division duplex/frequency division duplex communication
Application Number
464285
Publication Number
6094421
Application Date
January 21, 1997
Publication Date
July 25, 2000
Inventor
Logan Scott
Breckenridge
CO, US
Agent
Lyon & Lyon
Assignee
Omnipoint Corporation
CO, US
IPC
H04L 25/02
View Original Source