Method and apparatus for preamble transmission

Abstract

A method performed by a WTRU may comprise measuring a power of a downlink pathloss reference and comparing the measured power of the downlink pathloss reference to a threshold. The WTRU may determine whether to transmit a preamble, on a secondary carrier, based on whether the measured power of the downlink pathloss reference is less than the threshold. The method may further comprise not transmitting the preamble on the secondary carrier in one or more instance.

What is claimed: 
     
         1 . A wireless transmit/receive unit (WTRU) comprising:
 a transmitter configured to transmit a first preamble at a first power level;   a receiver configured to receive downlink control information (DCI), on a first carrier, wherein the DCI indicates a second carrier;   the transmitter configured to, on a condition that a maximum power level would be exceeded by a second preamble transmission and another uplink transmission, transmit the second preamble at a second power level on the second carrier, wherein the second power level is lower than the first power level; and   a receiver configured to receive a random access response (RAR) to the second preamble on a primary cell.   
     
     
         2 . The WTRU of  claim 1 , wherein the first carrier and second carrier are different carriers. 
     
     
         3 . The WTRU of  claim 1 , wherein the first carrier and second carrier are the same carrier. 
     
     
         4 . The WTRU of  claim 1 , wherein the transmitter is configured to transmit the first preamble at the first power level based on a priority of another uplink transmission. 
     
     
         5 . The WTRU of  claim 1 , wherein the transmitter is configured to transmit the second preamble at the second power level based on a priority of another uplink transmission. 
     
     
         6 . The WTRU of  claim 1 , further comprising:
 circuitry configured to determine whether to transmit a second preamble on the second carrier based on whether the second preamble would coincide with another uplink transmission.   
     
     
         7 . A wireless transmit/receive unit (WTRU) comprising:
 a transmitter configured to transmit a first preamble at a first power level;   a receiver configured to receive downlink control information (DCI), on a first carrier, wherein the DCI indicates a second carrier;   the transmitter configured to transmit a second preamble at a second power level on the second carrier, wherein the second power level is lower than the first power level; and   a receiver configured to receive a random access response (RAR) to the second preamble on a primary cell.   
     
     
         8 . The WTRU of  claim 7 , wherein the first preamble is transmitted on a different carrier than the second preamble. 
     
     
         9 . The WTRU of  claim 7 , wherein the first preamble is transmitted on a same carrier than the second preamble. 
     
     
         10 . The WTRU of  claim 7 , wherein the transmitter is configured to transmit the first preamble at a first power level based on a priority of another uplink transmission. 
     
     
         11 . The WTRU of  claim 7 , wherein the transmitter is configured to transmit the second preamble at the second power level based on a priority of another uplink transmission. 
     
     
         12 . The WTRU of  claim 7 , further comprising:
 circuitry configured to determine whether to transmit a second preamble on the second carrier based on whether the second preamble would coincide with another uplink transmission.   
     
     
         13 . The WTRU of  claim 7 , wherein the second power level is determined based at least in part on a maximum power level and another uplink transmission. 
     
     
         14 . A wireless transmit/receive unit (WTRU) comprising:
 a transmitter configured to transmit a first preamble at a first power level;   a receiver configured to receive downlink control information (DCI), on a first carrier, wherein the DCI indicates a second carrier;   the transmitter configured to transmit a second preamble at a second power level on the second carrier, wherein the second power level is lower than the first power level; and   a receiver configured to receive a random access response (RAR) to the second preamble on a primary cell.   
     
     
         15 . The WTRU of  claim 14 , wherein the first preamble is transmitted on a different carrier than the second preamble. 
     
     
         16 . The WTRU of  claim 14 , wherein the first preamble is transmitted on a same carrier than the second preamble. 
     
     
         17 . The WTRU of  claim 14 , wherein the transmitter is configured to transmit the first preamble at a first power level based on a priority of another uplink transmission. 
     
     
         18 . The WTRU of  claim 14 , wherein the transmitter is configured to transmit the second preamble at the second power level based on a priority of another uplink transmission. 
     
     
         19 . The WTRU of  claim 14 , further comprising:
 circuitry configured to determine whether to transmit a second preamble on the second carrier based on whether the second preamble would coincide with another uplink transmission.   
     
     
         20 . The WTRU of  claim 14 , wherein the second power level is determined based at least in part on a maximum power level and another uplink transmission.