Starting a time alignment timer before receiving an initial timing advance command
A wireless device receives a radio resource control (RRC) message comprising an indication that the wireless device starts a time alignment timer of a cell group in response to the RRC message. When the RRC message comprises the indication, the time alignment timer of the cell group is started before receiving an initial medium access control (MAC) timing advance command (TAC) for the cell group and after receiving the RRC message.
1. A wireless device comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the wireless device to:
receive a radio resource control (RRC) message comprising an indication that the wireless device starts a time alignment timer of a cell group in response to the RRC message; and
when the RRC message comprises the indication, start the time alignment timer of the cell group before receiving an initial medium access control (MAC) timing advance command (TAC) for the cell group and after receiving the RRC message.
2. The wireless device of claim 1 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to transmit uplink data signals via a cell of the cell group:
before receiving the initial MAC TAC; and
before performing an initial random access process for the cell.
3. The wireless device of claim 2 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to receive the initial MAC TAC comprising a timing advance value after the transmission of the uplink data signals.
4. The wireless device of claim 3 , wherein the RRC message comprises a time alignment timer information element (IE) indicating a value of the time alignment timer of the cell group.
5. The wireless device of claim 4 , wherein the start of the time alignment timer is before:
reception of the initial MAC TAC comprising the timing advance value; and
performance of the initial random access process for the cell.
6. The wireless device of claim 5 , wherein the uplink data signals are transmitted based on a stored timing advance value.
7. The wireless device of claim 6 , wherein uplink transmission timing of one or more cells in the cell group is based on a timing of a reference cell in the cell group.
8. The wireless device of claim 5 , wherein the RRC message indicates a timing advance of zero for the transmission of the uplink data signals.
9. The wireless device of claim 8 , wherein uplink transmission timing of one or more cells in the cell group is based on a timing of a reference cell in the cell group.
10. The wireless device of claim 1 , wherein the cell group is a timing advance group.
11. The wireless device of claim 1 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to transmit uplink data signals via a cell of the cell group, wherein the cell is a secondary cell.
12. The wireless device of claim 11 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to receive an activation command activating the cell.
13. The wireless device of claim 12 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to receive the initial MAC TAC comprising a timing advance value after transmitting the uplink data signals.
14. The wireless device of claim 13 , wherein the RRC message comprises a time alignment timer information element (IE) indicating a value of the time alignment timer of the cell group.
15. The wireless device of claim 14 , wherein the start of the time alignment timer is before performing an initial random access process for the cell.
16. The wireless device of claim 15 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to transmit the uplink data signals via the cell of the cell group:
before receiving the initial MAC TAC; and
before performing the initial random access process.
17. The wireless device of claim 14 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to transmit the uplink data signals via the cell of the cell group:
before receiving the initial MAC TAC; and
before performing an initial random access process for the cell.
18. The wireless device of claim 17 , wherein the cell group is a timing advance group.
19. A base station comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the base station to:
transmit, to a wireless device, a radio resource control (RRC) message comprising an indication that the base station starts a time alignment timer of a cell group in response to transmitting the RRC message; and
when the RRC message comprises the indication, start the time alignment timer of the cell group before transmitting an initial medium access control (MAC) timing advance command (TAC) for the cell group and after transmitting the RRC message.
20. The base station of claim 19 , wherein the instructions, when executed by the one or more processors, further cause the base station to receive uplink data signals from the wireless device via a cell of the cell group:
before transmitting the initial MAC TAC; and
before performing an initial random access process, with the wireless device, for the cell.