Method of handling time alignment command during a random access procedure
Disclosed is the radio (wireless) communication system providing a radio communication service and the terminal, and more particularly, a method of handling time alignment command during a random access procedure in an Evolved Universal Mobile Telecommunications System (E-UMTS) evolved from the Universal Mobile Telecommunications System (UMTS) or a Long Term Evolution (LTE) system is provided.
1. A terminal for performing a random access procedure in wireless communication system, the terminal comprising:
a transceiver adapted to receive a time advance command (TAC) for operating a time alignment timer (TAT) that is used to control how long the terminal is considered uplink time aligned,
wherein the TAC is received in a random access response message;
a processor adapted to determine whether a random access preamble to be used by the terminal in the random access procedure was not selected by the terminal;
wherein if it is determined that the random access preamble was not selected by the terminal, the TAC is applied, and the TAT is started or restarted,
wherein if it is determined that the random access preamble was selected by the terminal and if the TAT is not running, the TAC is applied, the TAT is started, and the TAT is stopped when a contention resolution is considered not successful; and
wherein if it is determined that the random access preamble was selected by the terminal and if the TAT is running, the received TAC is ignored.
2. The terminal of claim 1 , wherein the random access procedure is a non-contention based random access procedure if the random access preamble was not selected by the terminal.
3. The terminal of claim 2 , wherein a one-to-one mapping is existed between the terminal and the random access preamble during the non-contention based random access procedure.
4. The terminal of claim 2 , wherein a dedicated random access preamble is used in the non-contention based random access procedure.
5. The terminal of claim 1 , wherein the random access procedure is a contention based random access procedure if the random access preamble was selected by the terminal.
6. The terminal of claim 5 , wherein a one-to-N mapping is existed between the terminal and the random access preamble during the contention based random access procedure.
7. The terminal of claim 1 , wherein the random access procedure is a non-contention based random access procedure if the random access preamble was explicitly signaled and an index of the random access preamble was not 00000.
8. The terminal of claim 7 , wherein the index of the random access preamble is a ‘ra-PreambleIndex’, which is related with at least a ‘PRACH resource index’ that is an index of a PRACH within a system frame or a ‘ra-PRACH-MaskIndex’ defining in which PRACHs within a system frame the terminal can transmit the random access preamble.
9. The terminal of claim 1 , wherein the random access procedure is a contention based random access procedure if the random access preamble was not explicitly signaled.
10. The terminal of claim 1 , wherein a total number of random access preamble used in the random access procedure is 64, and some of the random access preambles are allocated for a non-contention based random access procedure and rest of the random access preambles are allocated for a contention based random access procedure.
11. The terminal of claim 1 , wherein the TAC is ignored if the terminal switches to perform a non-contention based random access procedure from a contention based random access procedure.