Method and apparatus for utilizing a directional beam antenna in a wireless transmit/receive unit

Abstract

A method and apparatus for utilizing a switched beam directional antenna in a wireless transmit/receive unit (WTRU) is disclosed. A wireless communication system includes a serving cell, a neighbor cell and a WTRU. The WTRU is configured to generate and steer a directional beam in a plurality of directions. Once the WTRU registers with the wireless communication system, the WTRU receives messages transmitted by the serving cell. The WTRU measures signal quality of messages received in each of a plurality of predetermined directions while steering the directional beam antenna. The WTRU selects a particular one of the directions having the best signal quality. As the WTRU constantly moves, the WTRU monitors signal quality in the selected direction, and switches to another direction when the signal quality in a current direction drops below a predetermined threshold.

1 . A method for steering a subscriber based smart antenna (SBSA), the method comprising:
 measuring a signal level on each element of a serving carrier/beams (SCB) list in a dormant time slot of an FS frame, the SCB list including all serving cell broadcast control channel (BCCH) carrier and SBSA beam combinations; and   if a current frame is a synchronization frame on a BCCH of the serving cell, and there is a new strongest element in the SCB list, decoding a BSIC on the new strongest element in the SCB list and setting an active beam to the new strongest element in the SCB list.   
     
     
         2 . The method of  claim 1  further comprising:
 measuring a signal level on each element of a neighbor carrier/beams (NCB) list in a dormant time slot of an FN frame, the NCB list including all neighbor cell BCCH carriers and SBSA beam combinations.   
     
     
         3 . The method of  claim 2  further comprising:
 if the current frame is an FB frame and there is a new element among a predetermined number of strongest elements of the NCB list, decoding a base station identity code (BSIC) of the new element.   
     
     
         4 . The method of  claim 1  further comprising:
 measuring a signal level on each element of a neighbor carrier (NC) list in a dormant time slot of an FN frame, the NC list including all neighbor cell BCCH carriers.   
     
     
         5 . The method of  claim 4  further comprising:
 if the current frame belongs to the FB frame and there is a new element among a predetermined number of strongest elements of the NC list, decoding a base station identity code (BSIC) of the new element.   
     
     
         6 . The method of  claim 1  wherein the signal level is measured using a midamble in a time slot. 
     
     
         7 . The method of  claim 6  wherein a first half of the midamble is used for measuring a signal level in one SBSA beam and a second half of the midamble is used for measuring a signal level in the other SBSA beam. 
     
     
         8 . A method for steering a subscriber based smart antenna (SBSA), the method comprising:
 measuring a signal level on each element of a serving carrier/beams (SCB) list in a dormant time slot of an FS frame, the SCB list including all serving cell broadcast control channel (BCCH) carrier and SBSA beam combinations; and   if there is a new strongest element in the SCB list, changing an active beam to the new strongest element in the SCB list.   
     
     
         9 . The method of  claim 8  further comprising:
 measuring a signal level on each element of a neighbor carrier/beams (NCB) list in a dormant time slot of an FN frame, the NCB list including all neighbor cell BCCH carriers and SBSA beam combinations.   
     
     
         10 . The method of  claim 9  further comprising:
 if a current frame belongs to an FB frame and there is a new element among a predetermined number of strongest elements in the NCB list, decoding a base station identity code (BSIC) of the new element.   
     
     
         11 . The method of  claim 8  further comprising:
 measuring a signal level on each element of a neighbor carrier (NC) list in a dormant time slot of an FN frame, the NC list including all neighbor cell BCCH carriers.   
     
     
         12 . The method of  claim 11  further comprising:
 if a current frame belongs to an FB frame and there is a new element among a predetermined number of strongest elements of the NC list, decoding a base station identity code (BSIC) of the new element.   
     
     
         13 . The method of  claim 8  wherein the signal level is measured using a midamble in a time slot. 
     
     
         14 . The method of  claim 13  wherein a first half of the midamble is used for measuring a signal level in one SBSA beam and a second half of the midamble is used for measuring a signal level in the other SBSA beam. 
     
     
         15 . A wireless transmit/receive unit (WTRU) for steering a subscriber based smart antenna (SBSA), the WTRU comprising:
 an SBSA for generating a plurality of beams;   a transceiver for transmitting and receiving a signal via the SBSA;   a beam steering unit for steering a beam to one of the plurality of beams; and   a controller configured to measure a signal level on each element of a serving carrier/beams (SCB) list in a dormant time slot of an FS frame, the SCB list including all serving cell broadcast control channel (BCCH) carrier and SBSA beam combinations, and if a current frame is a synchronization frame on a BCCH of the serving cell, and there is a new strongest element in the SCB list, decode a BSIC on the new strongest element in the SCB list and setting an active beam to the new strongest element in the SCB list.   
     
     
         16 . The WTRU of  claim 15  wherein the controller is configured to measure a signal level on each element of a neighbor carrier/beams (NCB) list in a dormant time slot of an FN frame, the NCB list including all neighbor cell BCCH carriers and SBSA beam combinations. 
     
     
         17 . The WTRU of  claim 16  wherein the controller is configured to, if the current frame is an FB frame and there is a new element among a predetermined number of strongest elements of the NCB list, decode a base station identity code (BSIC) of the new element. 
     
     
         18 . The WTRU of  claim 15  wherein the controller is configured to measure a signal level on each element of a neighbor carrier (NC) list in a dormant time slot of an FN frame, the NC list including all neighbor cell BCCH carriers. 
     
     
         19 . The WTRU of  claim 18  wherein the controller is configured to, if the current frame belongs to the FB frame and there is a new element among a predetermined number of strongest elements of the NC list, decode a base station identity code (BSIC) of the new element. 
     
     
         20 . The WTRU of  claim 15  wherein the signal level is measured using a midamble in a time slot. 
     
     
         21 . The WTRU of  claim 20  wherein a first half of the midamble is used for measuring a signal level in one SBSA beam and a second half of the midamble is used for measuring a signal level in the other SBSA beam. 
     
     
         22 . A wireless transmit/receive unit (WTRU) for steering a subscriber based smart antenna (SBSA), the WTRU comprising:
 an SBSA for generating a plurality of beams;   a transceiver for transmitting and receiving a signal via the SBSA;   a beam steering unit for steering a beam to one of the plurality of beams; and   a controller configured to measure a signal level on each element of a serving carrier/beams (SCB) list in a dormant time slot of an FS frame, the SCB list including all serving cell broadcast control channel (BCCH) carrier and SBSA beam combinations and, if there is a new strongest element in the SCB list, change an active beam to the new strongest element in the SCB list.   
     
     
         23 . The WTRU of  claim 22  wherein the controller is configured to measure a signal level on each element of a neighbor carrier/beams (NCB) list in a dormant time slot of an FN frame, the NCB list including all neighbor cell BCCH carriers and SBSA beam combinations. 
     
     
         24 . The WTRU of  claim 23  wherein the controller is configured to, if a current frame belongs to an FB frame and there is a new element among a predetermined number of strongest elements in the NCB list, decode a base station identity code (BSIC) of the new element. 
     
     
         25 . The WTRU of  claim 22  wherein the controller is configured to measure a signal level on each element of a neighbor carrier (NC) list in a dormant time slot of an FN frame, the NC list including all neighbor cell BCCH carriers. 
     
     
         26 . The WTRU of  claim 25  wherein the controller is configured to, if a current frame belongs to an FB frame and there is a new element among a predetermined number of strongest elements of the NC list, decode a base station identity code (BSIC) of the new element. 
     
     
         27 . The WTRU of  claim 22  wherein the signal level is measured using a midamble in a time slot. 
     
     
         28 . The WTRU of  claim 27  wherein a first half of the midamble is used for measuring a signal level in one SBSA beam and a second half of the midamble is used for measuring a signal level in the other SBSA beam.