Method for transmitting uplink and wireless device using same
A method is provided for uplink transmission in a wireless communication system. A user equipment (UE) configures multiple timing advance groups (TAGs), determines a power for transmitting a sounding reference signal (SRS) toward a first serving cell in a first TAG, determines a power for transmitting an uplink channel toward a second serving cell in a second TAG, determines whether a portion of a last symbol of an i th subframe for transmitting the SRS toward the first serving cell in the first TAG is overlapped with an (i+1) th subframe for transmitting the uplink channel toward the second serving cell in the second TAG, and drops the SRS transmission on the last symbol in the i th subframe if a total power of the SRS and the uplink channel exceeds a maximum value on the overlapped portion of the last symbol.
1. A method for uplink transmission in a wireless communication system, the method comprising:
configuring, by a user equipment (UE), multiple timing advance groups (TAGs);
determining, by the UE, a power for transmitting a sounding reference signal (SRS) toward a first serving cell in a first TAG;
determining, by the UE, a power for transmitting an uplink channel toward a second serving cell in a second TAG;
determining, by the UE, whether a portion of a last symbol of an i th subframe for transmitting the SRS toward the first serving cell in the first TAG is overlapped with an (i+1) th subframe for transmitting the uplink channel toward the second serving cell in the second TAG; and
dropping, by the UE, the SRS transmission on the last symbol in the i th subframe if a total power of the SRS and the uplink channel exceeds a maximum value on the overlapped portion of the last symbol.
2. The method of claim 1 , further comprising:
transmitting a random access preamble; and
after receiving a random access response including a timing advance command (TAC), adjusting an uplink transmission timing based on the TAC.
3. The method of claim 2 , wherein the random access response further includes a transmit power control (TPC) command.
4. The method of claim 1 , further comprising:
starting a first time alignment timer for the first TAG; and
starting a second time alignment timer for the second TAG.
5. The method of claim 1 , wherein the uplink channel includes at least one of a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH) and a random access channel.
6. The method of claim 1 , further comprising:
receiving a periodic configuration indicating a SRS periodicity and a SRS subframe offset,
wherein the i th subframe is determined based on the periodic configuration.
7. The method of claim 1 , further comprising:
receiving a request for the SRS transmission.
8. A user equipment (UE) for uplink transmission in a wireless communication system, the UE comprising:
a radio frequency (RF) unit configured to transmit and receive radio signals; and
a processor operatively coupled with the RF unit and configured to:
configure multiple timing advance groups (TAGs),
determine a power for transmitting a sounding reference signal (SRS) toward a first serving cell in a first TAG,
determine a power for transmitting an uplink channel toward a second serving cell in a second TAG,
determine whether a portion of a last symbol of an ith subframe for transmitting the SRS toward the first serving cell in the first TAG is overlapped with an (i+1)th subframe for transmitting the uplink channel toward the second serving cell in the second TAG, and
drop the SRS transmission on the last symbol in the ith subframe if a total power of the SRS and the uplink channel exceeds a maximum value on the overlapped portion of the last symbol.
9. The UE of claim 8 , wherein the processor is further configured to:
transmit a random access preamble, and
after receiving a random access response including a timing advance command (TAC), adjust an uplink transmission timing based on the TAC.
10. The UE of claim 9 , wherein the random access response further includes a transmit power control (TPC) command.
11. The UE of claim 8 , wherein the processor is further configured to:
start a first time alignment timer for the first TAG, and
start a second time alignment timer for the second TAG.
12. The UE of claim 8 , wherein the uplink channel includes at least one of a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH) and a random access channel.
13. The UE of claim 8 , wherein the processor is further configured to receive a periodic configuration indicating a SRS periodicity and a SRS subframe offset,
wherein the i th subframe for the SRS symbol is determined based on the periodic configuration.
14. The UE of claim 8 , wherein the processor is further configured to receive a request for the SRS transmission.