Orthogonal code synchronization system and method for spread spectrum CDMA communications

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.

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.