Dual connectivity based on listen before talk information

1. A method comprising:

receiving, by a first base station from a second base station, an application protocol message comprising radio resource status information of one or more licensed assisted access (LAA) cells of the second base station, wherein the radio resource status information comprises at least one listen before talk (LBT) parameter based on one or more results of one or more LBT processes performed by the second base station on the one or more LAA cells;

deciding, by the first base station, to request the second base station to allocate radio resources for a bearer of a wireless device based on the at least one LBT parameter;

transmitting, by the first base station to the second base station, a request message to add the second base station for dual connectivity of the wireless device; and

transmitting, by the first base station to the wireless device, configuration parameters of a cell group comprising the one or more LAA cells for communication with the second base station.

2. The method of claim 1 , wherein the at least one LBT parameter comprises one or more of LBT failure information, LBT success information, tried physical resource block (PRB) or subframe, failed PRB or subframe, PRB or subframe usage, contention level, average contention window (CW) size, current CW size, or an indication of absence of other technology.

3. The method of claim 2 , wherein the LBT failure information is based on a first number of PRBs or subframes with failed LBT during a measurement period.

4. The method of claim 2 , wherein the LBT failure information corresponds to downlink transmissions, or uplink transmissions, or downlink and uplink transmissions.

5. The method of claim 2 , wherein the PRB or subframe usage is based on a second number of PRBs or subframes used for packet transmission during a measurement period.

6. The method of claim 2 , wherein the PRB or subframe usage corresponds to downlink transmissions, or uplink transmission, or downlink and uplink transmissions.

7. The method of claim 2 , wherein the average CW size is based on one or more contention window sizes used for transmissions during a measurement period.

8. The method of claim 2 , wherein the indication of absence of other technology indicates other technologies do not share spectrum of the one or more LAA cells.

9. The method of claim 1 , wherein the application protocol message is received from the second base station via one or more mobility management entities (MMEs).

10. The method of claim 1 , wherein the at least one LBT parameter indicates that the one or more LAA cells are not highly occupied.

11. A base station apparatus comprising:

one or more processors;

memory storing instructions that, when executed by the one or more processors, cause the base station to:

receive from a second base station, an application protocol message comprising radio resource status information of one or more licensed assisted access (LAA) cells of the second base station, wherein the radio resource status information comprises at least one listen before talk (LBT) parameter based on one or more results of one or more LBT processes performed by the second base station on the one or more LAA cells;

decide to request the second base station to allocate radio resources for a bearer of a wireless device based on the at least one LBT parameter;

transmit to the second base station, a request message to add the second base station for dual connectivity of the wireless device; and

transmit to the wireless device, configuration parameters of a cell group comprising the one or more LAA cells for communication with the second base station.

12. The base station apparatus of claim 11 , wherein the at least one LBT parameter comprises one or more of LBT failure information, LBT success information, tried physical resource block (PRB) or subframe, failed PRB or subframe, PRB or subframe usage, contention level, average contention window (CW) size, current CW size, or an indication of absence of other technology.

13. The base station apparatus of claim 12 , wherein the LBT failure information is based on a first number of PRBs or subframes with failed LBT during a measurement period.

14. The base station apparatus of claim 12 , wherein the LBT failure information corresponds to downlink transmissions, or uplink transmissions, or downlink and uplink transmissions.

15. The base station apparatus of claim 12 , wherein the PRB or subframe usage is based on a second number of PRBs or subframes used for packet transmission during a measurement period.

16. The base station apparatus of claim 12 , wherein the PRB or subframe usage corresponds to downlink transmissions, or uplink transmission, or downlink and uplink transmissions.

17. The base station apparatus of claim 12 , wherein the average CW size is based on one or more contention window sizes used for transmissions during a measurement period.

18. The base station apparatus of claim 12 , wherein the indication of absence of other technology indicates other technologies do not share spectrum of the one or more LAA cells.

19. The base station apparatus of claim 11 , wherein the application protocol message is received from the second base station via one or more mobility management entities (MMEs).

20. The base station apparatus of claim 11 , wherein the at least one LBT parameter indicates that the one or more LAA cells are not highly occupied.