Method and apparatus for transmitting pilot on multiple antennas

Abstract

A method and an apparatus for transmitting pilots on multiple antennas are disclosed. A wireless transmit/receive unit (WTRU) may transmit a primary dedicated physical control channel (DPCCH) and at least one secondary DPCCH via multiple antennas using different channelization codes. When a required transmit power exceeds a maximum allowed transmit power of the WTRU, power scaling may be applied equally to the primary DPCCH and the secondary DPCCH, such that a power ratio between the primary DPCCH and the secondary DPCCH remains the same before scaling as after scaling. The secondary DPCCH may include a same number of pilot bits as the primary DPCCH both in a normal mode and in a compressed mode, respectively. The same total pilot energy ratio may be maintained between the primary DPCCH and the secondary DPCCH both in a normal mode and in a compressed mode, respectively.

1 . A method for use in a wireless transmit/receive unit (WTRU) comprising:
 determining whether a required transmit power for transmitting a primary dedicated physical control channel (DPCCH) and at least one secondary DPCCH exceeds a maximum allowed transmit power;   performing power scaling of the primary DPCCH and the at least one secondary DPCCH, wherein a power ratio between the primary DPCCH and the secondary DPCCH remains the same; and   transmitting the primary DPCCH and the at least one secondary DPCCH via multiple antennas using different channelization codes.   
     
     
         2 . The method of  claim 1  wherein a same number of pilot symbols are transmitted on the primary DPCCH and the secondary DPCCH both in a normal mode and in a compressed mode. 
     
     
         3 . The method of  claim 1  wherein a same total pilot energy ratio is maintained between the primary DPCCH and the secondary DPCCH both in a normal mode and in a compressed mode. 
     
     
         4 . The method of  claim 1  further comprising:
 transmitting an enhanced dedicated channel (E-DCH) dedicated physical data channel (E-DPDCH), wherein a normalized remaining power margin (NRPM) for an E-DCH transport format combination (E-TFC) selection is performed by taking a secondary DPCCH transmit power into account. 
 
     
     
         5 . The method of  claim 4  wherein the secondary DPCCH transmit power is determined based on a primary DPCCH power target and a gain factor signaled from a higher layer. 
     
     
         6 . The method of  claim 4  wherein a gain factor for the secondary DPCCH is boosted on a condition that E-DCH data is transmitted on a secondary stream. 
     
     
         7 . The method of  claim 6  wherein an amount of boosting of the gain factor for the secondary DPCCH is determined based on a combination of an E-DPDCH gain factor, a scaling factor signaled by a higher layer and a traffic to pilot power ratio signaled by a higher layer. 
     
     
         8 . The method of  claim 1  wherein the secondary DPCCH is continuously transmitted at a different power setting when a second stream is transmitted. 
     
     
         9 . The method of  claim 1  wherein the secondary DPCCH carries ten pilot symbols including two non-frame synchronization word (FSW) symbols. 
     
     
         10 . The method of  claim 1  wherein, when discontinuous transmission (DTX) is active, the WTRU does not transmit the secondary DPCCH in a slot where the WTRU does not transmit the primary DPCCH. 
     
     
         11 . A wireless transmit/receive unit (WTRU) comprising:
 a plurality of antennas; and   a processor configured to determine whether a required transmit power for transmitting a primary dedicated physical control channel (DPCCH) and at least one secondary DPCCH exceeds a maximum allowed transmit power and perform power scaling of the primary DPCCH and the at least one secondary DPCCH, wherein a power ratio between the primary DPCCH and the secondary DPCCH remains the same; and   a transceiver operatively coupled to the antennas and the processor, the transceiver configured to transmit the primary DPCCH and the at least one secondary DPCCH via the plurality of antennas using different channelization codes.   
     
     
         12 . The WTRU of  claim 11  wherein a same number of pilot symbols are transmitted on the primary DPCCH and the secondary DPCCH both in a normal mode and in a compressed mode. 
     
     
         13 . The WTRU of  claim 11  wherein a same total pilot energy ratio is maintained between the primary DPCCH and the secondary DPCCH both in a normal mode and in a compressed mode. 
     
     
         14 . The WTRU of  claim 11  wherein the transceiver is configured to transmit an enhanced dedicated channel (E-DCH) dedicated physical data channel (E-DPDCH), wherein a normalized remaining power margin (NRPM) for an E-DCH transport format combination (E-TFC) selection is performed by taking a secondary DPCCH transmit power into account. 
     
     
         15 . The WTRU of  claim 14  wherein the secondary DPCCH transmit power is determined based on a primary DPCCH power target and a gain factor signaled from a higher layer. 
     
     
         16 . The WTRU of  claim 14  wherein a gain factor for the secondary DPCCH is boosted on a condition that E-DCH data is transmitted on a secondary stream. 
     
     
         17 . The WTRU of  claim 16  wherein an amount of boosting of the gain factor for the secondary DPCCH is determined based on a combination of an E-DPDCH gain factor, a scaling factor signaled by a higher layer and a traffic to pilot power ratio signaled by a higher layer. 
     
     
         18 . The WTRU of  claim 11  wherein the secondary DPCCH is continuously transmitted at a different power setting when a second stream is transmitted. 
     
     
         19 . The WTRU of  claim 11  wherein the secondary DPCCH carries ten pilot symbols including two non-frame synchronization word (FSW) symbols. 
     
     
         20 . The WTRU of  claim 11  wherein, when discontinuous transmission (DTX) is active, the WTRU does not transmit the secondary DPCCH in a slot where the WTRU does not transmit the primary DPCCH.