Orthogonal code synchronization system and method for spread spectrum CDMA communications

• US 20050220051A1
• Filed: 05/17/2005
• Published: 10/06/2005
• Est. Priority Date: 02/28/1997
• Status: Abandoned Application

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Lavean, Gil
• Application Number:
  US11/130,885
• Publication Number:
  US 20050220051A1
• Time in Patent Office: Days
• US Class Current: 370/330
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04B 2201/709709 Methods of preventing interference
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging

Abstract

A mobile terminal first transmits to a base station a signal in a reverse-link direction wherein a timing used for said signal is set according to a transmission received in a forward-link direction from the base station. At the base station, a synchronization sequence in the transmitted signal is detected and the timing of the transmitted signal is evaluating. The base station then sends timing adjustment information in the form of synchronization commands to the mobile terminal based on said evaluation. These synchronization commands indicate timing adjustments in one-eighth of a chip increments.

Claims

1. A method for reverse-link synchronization comprising:

transmitting from a mobile terminal to a base station a signal in a reverse-link direction wherein a timing used for said signal is set according to a transmission received in a forward-link direction from the base station;

at the base station;

detecting a synchronization sequence in the transmitted signal;

evaluating the timing of said transmitted signal; and

sending timing adjustment information as synchronization commands, the synchronization commands indicating timing adjustments in one-eighth of a chip increments, to the mobile terminal based on said evaluation.

2. The method of claim 1, wherein after reverse-link synchronization is established, further comprises:

continuously monitoring the timing of the mobile terminal; and

sending synchronization commands based on said monitored timing.

3. A method for reverse-link synchronization comprising:

transmitting from a mobile terminal to a base station a signal in a reverse-link direction wherein a timing used for said signal is set according to a transmission received in a forward-link direction from the base station;

at the base station;

detecting a synchronization sequence in the transmitted signal;

evaluating the timing of said transmitted signal by comparing the detected synchronization sequence to a reference sequence;

sending timing adjustment information as synchronization commands, the synchronization commands indicating timing adjustments in one-eighth of a chip increments, to the mobile terminal based on said evaluation; and

at the mobile terminal, adjusting the reverse-link transmission timing according to said adjustment information.

4. The method of claim 3, wherein after reverse-link synchronization is established, further comprises:

at the base station;

continuing to evaluate the timing of subsequent mobile terminal transmissions; and

sending synchronization commands to the mobile terminal based on said evaluations; and

at the mobile terminal, incrementally adjusting the reverse-link transmission timing according to said synchronization commands.