Listen before talk procedure and bandwidth part switching

1. A method comprising:

receiving, by a wireless device, configuration parameters of a first bandwidth part (BWP) and a second BWP of an unlicensed cell;

determining, with the first BWP being an active BWP, a first number of consecutive listen before talk (LBT) procedures, for a first channel of the active BWP, performed based on a contention window being a maximum contention window of a plurality of contention windows corresponding to the first channel; and

based on switching from the first BWP to the second BWP as the active BWP, determining a second number of consecutive LBT procedures, for a second channel of the active BWP, performed based on the contention window being the maximum contention window of a plurality of contention windows corresponding to the second channel.

2. The method of claim 1 , wherein the first number of consecutive LBT procedures is for the first BWP, and wherein the second number of consecutive LBT procedures is for the second BWP.

3. The method of claim 1 , wherein the first channel and the second channel are of a same channel access priority class.

4. The method of claim 1 , wherein the first channel and the second channel are in different unlicensed bands.

5. The method of claim 1 , wherein the first BWP and the second BWP are in different unlicensed bands.

6. The method of claim 1 , further comprising resetting the second number to a predefined value in response to the switching from the first BWP to the second BWP.

7. The method of claim 6 , wherein the predefined value is one.

8. The method of claim 1 , wherein the configuration parameters comprise parameters for performing LBT procedures on the second BWP, and wherein the method further comprises determining, based on the parameters, whether to reset the second number to a predefined value in response to the switching from the first BWP to the second BWP.

9. The method of claim 1 , further comprising:

receiving a downlink control information (DCI) indicating the switching to the second BWP; and

in response to the switching, determining whether to reset the second number to a predefined value based on the DCI indicating whether to reset the second number.

10. The method of claim 1 , further comprising transmitting an uplink transmission in the second channel based on the maximum contention window.

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 configuration parameters of a first bandwidth part (BWP) and a second BWP of an unlicensed cell;

determine, with the first BWP being an active BWP, a first number of consecutive listen before talk (LBT) procedures, for a first channel of the active BWP, performed based on a contention window being a maximum contention window of a plurality of contention windows corresponding to the first channel; and

based on switching from the first BWP to the second BWP as the active BWP, determine a second number of consecutive LBT procedures, for a second channel of the active BWP, performed based on the contention window being the maximum contention window of a plurality of contention windows corresponding to the second channel.

12. The wireless device of claim 11 , wherein the first number of consecutive LBT procedures is for the first BWP, and wherein the second number of consecutive LBT procedures is for the second BWP.

13. The wireless device of claim 11 , wherein the first channel and the second channel are of a same channel access priority class.

14. The wireless device of claim 11 , wherein the first channel and the second channel are in different unlicensed bands.

15. The wireless device of claim 11 , wherein the first BWP and the second BWP are in different unlicensed bands.

16. The wireless device of claim 11 , wherein the instructions further cause the wireless device to reset the second number to a predefined value in response to the switching from the first BWP to the second BWP.

17. The wireless device of claim 16 , wherein the predefined value is one.

18. The wireless device of claim 11 , wherein the configuration parameters comprise parameters for performing LBT procedures on the second BWP, and wherein the instructions further cause the wireless device to determine, based on the parameters, whether to reset the second number to a predefined value in response to the switching from the first BWP to the second BWP.

19. The wireless device of claim 11 , wherein the instructions further cause the wireless device to:

receive a downlink control information (DCI) indicating the switching to the second BWP; and

in response to the switching, determine whether to reset the second number to a predefined value based on the DCI indicating whether to reset the second number.

20. A system comprising:

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

transmit configuration parameters of a first bandwidth part (BWP) and a second BWP of an unlicensed cell; and

a wireless device comprising one or more second processors and second memory storing second instructions that, when executed by the one or more second processors, cause the wireless device to:

receive the configuration parameters of the first BWP and the second BWP of the unlicensed cell;

determine, with the first BWP being an active BWP, a first number of consecutive listen before talk (LBT) procedures, for a first channel of the active BWP, performed based on a contention window being a maximum contention window of a plurality of contention windows corresponding to the first channel; and

based on switching from the first BWP to the second BWP as the active BWP, determine a second number of consecutive LBT procedures, for a second channel of the active BWP, performed based on the contention window being the maximum contention window of a plurality of contention windows corresponding to the second channel.