Cwill Telecommunications, Inc.

Ping Liu

Guanghan Xu

Hui Liu

Liu Hui

In a synchronous code division multiple access (SCDMA) time division duplex (TDD) communication system, a remote terminal uses both open loop and closed loop techniques for synchronization with a base station. The timing of reception of information by tile remote terminal is performed with an open loop technique, while the timing of transmissions from the terminal is performed with a closed loop technique. Furthermore, a clock locked loop in the terminal compensates for differences between clocks of the terminal and the base station. The clock locked loop responds to signals from both the aforesaid open loop and closed loop techniques.

Method for timing recovery and compensation in time-division-duplex wireless communications

An improved system and method for determining and tracking the carrier offset in a communications system. In an exemplary implementation, sampled spread spectrum digital signals are compensated with an expected carrier offset and stripped of pseudo-noise codes to produce demodulated signals. The demodulated signals are applied to a carrier offset estimator. The carrier offset estimator divides pairs of demodulated signals with a predetermined interval to produce results containing phase change information. The results are then averaged, and the average is normalized with respect to the predetermined interval to yield a new estimate of the carrier offset. The expected carrier frequency is adjusted based on the new offset estimate for frequency compensation in subsequent reception and transmission operations.

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Austin, TX, United States of America

Ping Liu