Method and apparatus for obtaining uplink timing alignment on a secondary cell

Abstract

A method for uplink timing alignment in a wireless transmit/receive unit. The method includes receiving control signaling from an evolved Node B, receiving a message for Random Access Channel on a secondary cell, and completing the RACH upon receipt of the message, wherein the message includes a medium access control (MAC) control element with at least an 11-bit time advance command.

1 . A method for uplink timing alignment in a wireless transmit/receive unit (WTRU), the method comprising:
 receiving control signaling from an evolved Node B (eNB);   receiving a message for Random Access Channel (RACH) on a secondary cell (SCell);   completing the RACH upon receipt of the message; and   wherein the message includes a medium access control (MAC) control element (CE) with at least an 11-bit time advance command (TAC).   
     
     
         2 . The method of  claim 1 , wherein the MAC CE is scheduled by a Cell Radio Network Temporary Identifier (C-RNTI). 
     
     
         3 . The method of  claim 1 , wherein the MAC CE is scheduled on any physical downlink control channel (PDCCH) in a WTRU specific search space (SS). 
     
     
         4 . The method of  claim 1 , wherein the MAC CE is received using a HARQ process. 
     
     
         5 . The method of  claim 1 , wherein the MAC CE is received in a MAC packet data unit (PDU) multiplexed with other data. 
     
     
         6 . The method of  claim 1 , further comprising:
 receiving a PDCCH order.   
     
     
         7 . The method of  claim 6 , further comprising:
 maintaining a count of a number of preamble retransmissions for power ramping.   
     
     
         8 . The method of  claim 7 , further comprising:
 resetting the count when the message is received.   
     
     
         9 . The method of  claim 7 , further comprising:
 resetting the count when a preamble transmission is triggered on a different SCell.   
     
     
         10 . The method of  claim 7 , further comprising:
 resetting the count when an activation state or a configuration state of the SCell or of a Timing Advance Group (TAG) of the SCell changes.   
     
     
         11 . The method of  claim 7 , further comprising:
 resetting the count when an indication that a request is for an initial preamble transmission for the SCell is received in the control signaling for the PDCCH order.   
     
     
         12 . The method of  claim 6 , further comprising:
 applying an amount of power ramping using a value received in control signaling in the PDCCH order.   
     
     
         13 . The method of  claim 6 , further comprising:
 maintaining a count when an indication is that the request is for a preamble retransmission for the SCell is received in control signaling for the PDCCH order.   
     
     
         14 . A wireless transmit/receive unit (WTRU) for uplink timing alignment, comprising:
 a receiver configured to receive control signaling from an evolved Node B (eNB);   the receiver further configured to receive a message for RACH on a secondary cell (SCell);   a processor configured to complete the RACH upon receipt of the message; and   wherein the message includes a medium access control (MAC) control element (CE) with at least an 11-bit time advance command (TAC).   
     
     
         15 . The WTRU of  claim 14 , wherein the MAC CE is scheduled by a Cell Radio Network Temporary Identifier (C-RNTI). 
     
     
         16 . The WTRU of  claim 14 , wherein the MAC CE is scheduled on any physical downlink control channel (PDCCH) in a WTRU specific search space (SS). 
     
     
         17 . The WTRU of  claim 14 , wherein the MAC CE is received using a HARQ process. 
     
     
         18 . The WTRU of  claim 14 , wherein the MAC CE is received in a MAC packet data unit (PDU) multiplexed with other data. 
     
     
         19 . The WTRU of  claim 14 , wherein the receiver is further configured to receive a PDCCH order. 
     
     
         20 . The WTRU of  claim 19 , wherein the processor is further configured to maintain a count of a number of preamble retransmissions for power ramping.