Random access in a wireless device and wireless network

1. A method comprising:

receiving, by a wireless device from a first base station, at least one first message comprising:

configuration parameters for a plurality of cells comprising a plurality of cell groups comprising:

a first cell group for communication with the first base station; and

a second cell group for communication with a second base station, the second cell group comprising a licensed assisted access (LAA) cell; and

one or more random access channel (RACH) configuration parameters for a RACH of the LAA cell;

performing a listen before talk (LBT) procedure to transmit a preamble via the RACH of the LAA cell of the second base station in response to initiating a random access process with the second base station;

incrementing a counter in response to the LBT procedure indicating that the channel is occupied;

determining a failure of the random access process in response to the counter reaching a first value; and

transmitting, by the wireless device to the first base station, at least one second message in response to the failure of the random access process with the second base station, wherein the at least one second message comprises:

an indication of the failure of the random access process with the second base station; and

one or more parameters indicating that at least one LBT failure occurred during the failed random access process.

2. The method of claim 1 , wherein the failure of the random access process is due to a first number of LBT failures during the random access process.

3. The method of claim 2 , wherein the configuration parameters comprise the first number.

4. The method of claim 1 , further comprising incrementing the counter in response to not receiving a random access response (RAR) within a RAR window in response to transmitting the preamble, wherein the preamble is transmitted in response to the LBT procedure indicating a clear channel.

5. The method of claim 4 , wherein the RAR window starts at a subframe that contains an end of the preamble transmission plus a first predetermined number of subframes.

6. The method of claim 4 , wherein the one or more RACH configuration parameters comprise the RAR window.

7. The method of claim 4 , further comprising monitoring a control channel associated with a random access radio network temporary identifier in response to transmitting the preamble.

8. The method of claim 1 , wherein the one or more RACH configuration parameters indicate a plurality of RACH resources for the LAA cell.

9. The method of claim 1 , wherein the LBT procedure comprises sensing the LAA cell before transmitting the preamble.

10. The method of claim 1 , wherein the configuration parameters comprise one or more LBT parameters for the LBT procedure.

11. 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 from a first base station, at least one first message comprising:

configuration parameters for a plurality of cells comprising a plurality of cell groups comprising:

a first cell group for communication with the first base station; and

a second cell group for communication with a second base station, the second cell group comprising a licensed assisted access (LAA) cell; and

one or more random access channel (RACH) configuration parameters for a RACH of the LAA cell;

perform a listen before talk (LBT) procedure to transmit a preamble via the RACH of the LAA cell of the second base station in response to initiating a random access process with the second base station;

increment a counter in response to the LBT procedure indicating that the channel is occupied; and

determine a failure of the random access process in response to the counter reaching a first value;

transmit, to the first base station, at least one second message in response to the failure of the random access process with the second base station, wherein the at least one second message comprises:

an indication of the failure of the random access process with the second base station; and

one or more parameters indicating that at least one LBT failure occurred during the failed random access process.

12. The wireless device of claim 11 , wherein the failure of the random access process is due to a first number of LBT failures during the random access process.

13. The wireless device of claim 12 , wherein the configuration parameters comprise the first number.

14. The wireless device of claim 11 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to increment the counter in response to not receiving a random access response (RAR) within a RAR window in response to transmitting the preamble, wherein the preamble is transmitted in response to the LBT procedure indicating a clear channel.

15. The wireless device of claim 14 , wherein the RAR window starts at a subframe that contains an end of the preamble transmission plus a first predetermined number of subframes.

16. The wireless device of claim 14 , wherein the one or more RACH configuration parameters comprise the RAR window.

17. The wireless device of claim 14 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to monitor a control channel associated with a random access radio network temporary identifier in response to transmitting the preamble.

18. The wireless device of claim 11 , wherein the one or more RACH configuration parameters indicate a plurality of RACH resources for the LAA cell.

19. The wireless device of claim 11 , wherein the LBT procedure comprises sensing the LAA cell before transmitting the preamble.

20. The wireless device of claim 11 , wherein the configuration parameters comprise one or more LBT parameters for the LBT procedure.