Uplink timing advance configuration in a wireless network

1. A wireless device comprising:

one or more processors; and

memory storing instructions that, when executed, cause the wireless device to:

receive at least one message comprising configuration parameters of a plurality of cells grouped into a plurality of timing advance groups (TAGs),

wherein the plurality of cells consisting of:

a plurality of downlink-uplink cells, each of the plurality of downlink-uplink cells having a configured uplink and a configured downlink; and

at least one downlink-only cell, each of the at least one downlink-only cell having a configured downlink with no configured uplink; and

wherein a TAG is configurable to consist of one or more downlink-only cells if the wireless device has a first capability, otherwise each TAG comprises one or more downlink-uplink cells in the plurality of downlink-uplink cells;

receive at least one timing advance command (TAC) for a first TAG; and

apply the TAC to uplink transmission timing of at least one downlink-uplink cell in the first TAG.

2. A wireless device of claim 1 , wherein the instructions, when executed, further cause the wireless device to transmit a second message to a base station, the second message comprising one or more parameters indicating the first capability.

3. The wireless device of claim 1 , wherein the first TAG comprises a first subset of the plurality of cells, uplink transmission timing in the first TAG being derived employing a first cell in the first TAG.

4. The wireless device of claim 1 , wherein time alignment timer of a second TAG is disabled when the second TAG consists of one or more downlink-only cells.

5. The wireless device of claim 1 , wherein time alignment timer is not configured for a second TAG when the second TAG consists of one or more downlink-only cells.

6. The wireless device of claim 1 , wherein the at least one message comprises a TAG index for a TAG.

7. The wireless device of claim 1 , wherein the TAC comprises a TAG index and a timing advance value.

8. A wireless device comprising:

one or more processors; and

memory storing instructions that, when executed, cause the wireless device to:

receive at least one message comprising configuration parameters of a plurality of cells grouped into a plurality of timing advance groups (TAGs),

wherein the plurality of cells consisting of:

a plurality of downlink-uplink cells, each of the plurality of downlink-uplink cells having a configured uplink and a configured downlink; and

at least one downlink-only cell, each of the at least one downlink-only cell having a configured downlink with no configured uplink; and

wherein a TAG is configurable to consist of one or more downlink-only cells if the one or more downlink-only cells are unlicensed cells, otherwise the TAG comprises one or more downlink-uplink cells in the plurality of downlink-uplink cells;

receive at least one timing advance command (TAC) for a first TAG; and

apply the TAC to uplink transmission timing of at least one downlink-uplink cell in the first TAG.

9. The wireless device of claim 8 , wherein the first TAG comprises a first subset of the plurality of cells, uplink transmission timing in the first TAG being derived employing a first cell in the first TAG.

10. The wireless device of claim 8 , wherein time alignment timer of a second TAG is disabled when the second TAG consists of one or more downlink-only cells.

11. The wireless device of claim 8 , wherein time alignment timer is not configured for a second TAG when the second TAG consists of one or more downlink-only cells.

12. The wireless device of claim 8 , wherein the at least one message comprises a TAG index for a TAG.

13. The wireless device of claim 8 , wherein the TAC comprises a TAG index and a timing advance value.

14. A base station comprising:

one or more processors; and

memory storing instructions that, when executed, cause the base station to:

transmit at least one message comprising configuration parameters of a plurality of cells grouped into a plurality of timing advance groups (TAGs),

wherein the plurality of cells consisting of:

a plurality of downlink-uplink cells, each of the plurality of downlink-uplink cells having a configured uplink and a configured downlink; and

at least one downlink-only cell, each of the at least one downlink-only cell having a configured downlink with no configured uplink; and

wherein a TAG is configurable to consist of one or more downlink-only cells only if the wireless device has a first capability, otherwise each TAG comprises one or more downlink-uplink cells in the plurality of downlink-uplink cells;

transmit at least one timing advance command (TAC) for a first TAG; and

receive uplink signals on a cell in the first TAG, wherein a timing of uplink signals depends, at least, on the at least one TAC.

15. A wireless device of claim 14 , wherein the instructions, when executed, further cause the base station to receive a second message from a wireless device, the second message comprising one or more parameters indicating the first capability.

16. The base station of claim 14 , wherein the first TAG comprises a first subset of the plurality of cells, uplink transmission timing in the first TAG being derived employing a first cell in the first TAG.

17. The base station of claim 14 , wherein time alignment timer of a second TAG is disabled when the second TAG consists of one or more downlink-only cells.

18. The base station of claim 14 , wherein time alignment timer is not configured for a second TAG when the second TAG consists of one or more downlink-only cells.

19. The base station of claim 14 , wherein the at least one message comprises a TAG index for a TAG.

20. The base station of claim 14 , wherein the TAC comprises a TAG index and a timing advance value.