Method for searching pilot signals to synchronize a cdma receiver with an associated transmitter

Abstract

A wireless transmit-receive unit includes an antenna, detection circuitry configured to detect a pseudorandom (PN) offset of a pilot signal received by the antenna while the antenna is adapted to an omnidirectional receive pattern, and monitoring circuitry configured to monitor a received signal strength of the pilot signal as a directional receive pattern of the antenna is steered in order to determine an azimuth angle of the directional pattern that maximizes the pilot signal at the detected PN offset.

What is claimed is: 
     
         1 . A wireless transmit/receive unit (WTRU) comprising:
 an adaptive antenna configured to have a receiving pattern adaptable to be directional or omnidirectional;   steering circuitry configured to:
 adapt the receiving pattern into the directional or the omnidirectional receiving pattern; and 
 steer a direction of the directional pattern over a range of azimuth angles; 
   detection circuitry configured to detect a pseudorandom (PN) offset of a pilot signal received by the antenna while the antenna is adapted to the omnidirectional receive pattern; and   monitoring circuitry configured to monitor a received signal strength of the pilot signal as the directional receive pattern is steered in order to determine a maximizing azimuth angle of the directional pattern for receiving the pilot signal at the detected PN offset.   
     
     
         2 . The WTRU of  claim 1 , wherein the steering circuitry is further configured to adapt the antenna to a directional receive pattern at an azimuth angle that maximizes the received signal strength of the pilot signal. 
     
     
         3 . The WTRU of  claim 1 , wherein the detection circuitry is further configured to detect the PN offset of the pilot signal by using a method comprising:
 searching a set of PN offsets at an initial frequency;   if no pilot signal is detected,
 stepping through one or more frequency bins; and 
 scanning the set of PN offsets at each of the one or more frequency bins until a pilot signal is detected. 
   
     
     
         4 . A wireless transmit/receive unit (WTRU) comprising:
 a receiver;   an adaptive antenna connected to the receiver and configured to have a receiving pattern adaptable to be directional or omnidirectional;   steering circuitry configured to:
 adapt the receiving patter into a directional or an omnidirectional receiving pattern; and 
 steer a direction of the directional pattern over a range of azimuth angles; 
   detection circuitry configured to detect a plurality of PN offsets of a multipath pilot signal received by the antenna while the antenna is adapted to the omnidirectional receive pattern;   monitoring circuitry configured to monitor, for each PN offset of the plurality of PN offsets, a received signal strength of the pilot signal as the directional receive pattern is steered in order to determine a maximizing azimuth angle of the directional pattern for maximizing a received signal strength of the pilot signal at that detected PN offset; and   synchronization circuitry configured to synchronize the receiver to a selected one of the plurality of PN offsets and further adapting the antenna to a directional receive pattern at an azimuth angle that produces a maximal signal strength of the pilot signal.   
     
     
         5 . A wireless transmit/receive unit (WTRU) comprising:
 an antenna;   detection circuitry configured to detect a pseudorandom (PN) offset of a pilot signal received by the antenna while the antenna is adapted to an omnidirectional receive pattern; and   monitoring circuitry configured to monitor a received signal strength of the pilot signal as a directional receive pattern of the antenna is steered in order to determine an azimuth angle of the directional pattern that maximizes the pilot signal at the detected PN offset.