Techniques for radio access technology (RAT) fallback in wireless communications

1. A method for wireless communication, comprising:

performing reselection from a first radio access technology (RAT) to a second RAT to perform an emergency call; and

deprioritizing, based on and after performing the reselection, access to the first RAT to continue to use the second RAT for at least a period of time corresponding to a timer that is initialized after termination of the emergency call, wherein deprioritizing access to the first RAT comprises modifying, for at least the period of time, cell reselection parameters including:

a first threshold signal power or quality defined in the first RAT to use in measuring, on a second RAT frequency, cells of the second RAT for reselection from the first RAT to the second RAT, and

a second threshold signal power or quality defined in the second RAT to use in measuring, on a first RAT frequency, cells of the first RAT for reselection from the second RAT to the first RAT.

2. The method of claim 1 , wherein modifying the cell reselection parameters includes decreasing the first threshold signal power or quality.

3. The method of claim 2 , wherein modifying the cell reselection parameters includes increasing the second threshold signal power or quality.

4. The method of claim 1 , wherein deprioritizing access to the first RAT comprises blocking, for at least the period of time, one or more networks corresponding to the first RAT.

5. The method of claim 4 , wherein blocking the one or more networks comprises at least one of commanding a non-access stratum (NAS) layer to refrain from selecting the one or more networks or commanding a radio resource control (RRC) layer to refrain from measuring signals from the one or more networks.

6. The method of claim 1 , further comprising:

reprioritizing, based on detecting expiration of the timer, access to the first RAT.

7. The method of claim 1 , wherein deprioritizing access to the first RAT is further based at least in part on at least one of determining that voice calls are not supported on the first RAT, determining that only emergency services fallback is supported on the first RAT, determining a non-limited service mode (LSM) for the first RAT, or determining non-roaming mode for the first RAT.

8. The method of claim 1 , wherein performing the reselection is based on determining that emergency calls are not supported on the first RAT.

9. An apparatus for wireless communication, comprising:

a transceiver;

a memory configured to store instructions; and

one or more processors coupled with the transceiver and the memory, wherein the one or more processors are configured to:

perform reselection from a first radio access technology (RAT) to a second RAT to perform an emergency call; and

deprioritize, based on and after performing the reselection, access to the first RAT to continue to use the second RAT for at least a period of time corresponding to a timer that is initialized after termination of the emergency call, wherein the one or more processors are configured to deprioritize access to the first RAT at least in part by modifying, for at least the period of time, cell reselection parameters including:

a first threshold signal power or quality defined in the first RAT to use in measuring, on a second RAT frequency, cells of the second RAT for reselection from the first RAT to the second RAT, and

a second threshold signal power or quality defined in the second RAT to use in measuring, on a first RAT frequency, cells of the first RAT for reselection from the second RAT to the first RAT.

10. The apparatus of claim 9 , wherein the one or more processors are configured to modify the cell reselection parameters by decreasing the first threshold signal power or quality.

11. The apparatus of claim 10 , wherein the one or more processors are configured to modify the cell reselection parameters by increasing the second threshold signal power or quality.

12. The apparatus of claim 9 , wherein the one or more processors are configured to deprioritize access to the first RAT at least in part by blocking, for at least the period of time, one or more networks corresponding to the first RAT.

13. The apparatus of claim 12 , wherein the one or more processors are configured to block the one or more networks by at least one of commanding a non-access stratum (NAS) layer to refrain from selecting the one or more networks or commanding a radio resource control (RRC) layer to refrain from measuring signals from the one or more networks.

14. The apparatus of claim 9 , wherein the one or more processors are further configured to:

reprioritize, based on detecting expiration of the timer, access to the first RAT.

15. The apparatus of claim 9 , wherein the one or more processors are configured to deprioritize access to the first RAT further based at least in part on at least one of determining that voice calls are not supported on the first RAT, determining that only emergency services fallback is supported on the first RAT, determining a non-limited service mode (LSM) for the first RAT, or determining non-roaming mode for the first RAT.

16. The apparatus of claim 9 , wherein the one or more processors are configured to perform the reselection based on determining that emergency calls are not supported on the first RAT.

17. An apparatus for wireless communication, comprising:

means for performing reselection from a first radio access technology (RAT) to a second RAT to perform an emergency call; and

means for deprioritizing, based on and after performing the reselection, access to the first RAT to continue to use the second RAT for at least a period of time corresponding to a timer that is initialized after termination of the emergency call, wherein the means for deprioritizing access to the first RAT include means for modifying, for at least the period of time, cell reselection parameters including:

a first threshold signal power or quality defined in the first RAT to use in measuring, on a second RAT frequency, cells of the second RAT for reselection from the first RAT to the second RAT, and

a second threshold signal power or quality defined in the second RAT to use in measuring, on a first RAT frequency, cells of the first RAT for reselection from the second RAT to the first RAT.

18. The apparatus of claim 17 , wherein the means for deprioritizing modifies the cell reselection parameters by decreasing the first threshold signal power or quality.

19. The apparatus of claim 18 , wherein the means for deprioritizing modifies the cell reselection parameters by increasing the second threshold signal power or quality.

20. The apparatus of claim 17 , wherein the means for deprioritizing deprioritizes access to the first RAT by blocking, for at least the period of time, one or more networks corresponding to the first RAT.

21. The apparatus of claim 20 , wherein the means for deprioritizing blocks the one or more networks by at least one of commanding a non-access stratum (NAS) layer to refrain from selecting the one or more networks or commanding a radio resource control (RRC) layer to refrain from measuring signals from the one or more networks.

22. The apparatus of claim 17 , further comprising:

means for reprioritizing, based on detecting expiration of the timer, access to the first RAT.

23. The apparatus of claim 17 , wherein the means for deprioritizing deprioritizes access to the first RAT further based at least in part on at least one of determining that voice calls are not supported on the first RAT, determining that only emergency services fallback is supported on the first RAT, determining a non-limited service mode (LSM) for the first RAT, or determining non-roaming mode for the first RAT.

24. A non-transitory computer-readable medium, comprising code executable by one or more processors for wireless communication, the code comprises code for:

performing reselection from a first radio access technology (RAT) to a second RAT to perform an emergency call; and

deprioritizing, based on and after performing the reselection, access to the first RAT to continue to use the second RAT for at least a period of time corresponding to a timer that is initialized after termination of the emergency call, wherein the code for deprioritizing access to the first RAT includes code for modifying, for at least the period of time, cell reselection parameters including:

a first threshold signal power or quality defined in the first RAT to use in measuring, on a second RAT frequency, cells of the second RAT for reselection from the first RAT to the second RAT, and

a second threshold signal power or quality defined in the second RAT to use in measuring, on a first RAT frequency, cells of the first RAT for reselection from the second RAT to the first RAT.

25. The non-transitory computer-readable medium of claim 24 , wherein the code for deprioritizing modifies the cell reselection parameters by decreasing the first threshold signal power or quality.

26. The non-transitory computer-readable medium of claim 25 , wherein the code for deprioritizing modifies the cell reselection parameters by increasing the second threshold signal power or quality.

27. The non-transitory computer-readable medium of claim 24 , wherein the code for deprioritizing deprioritizes access to the first RAT by blocking, for at least the period of time, one or more networks corresponding to the first RAT.

28. The non-transitory computer-readable medium of claim 27 , wherein the code for deprioritizing blocks the one or more networks by at least one of commanding a non-access stratum (NAS) layer to refrain from selecting the one or more networks or commanding a radio resource control (RRC) layer to refrain from measuring signals from the one or more networks.

29. The non-transitory computer-readable medium of claim 24 , further comprising:

code for reprioritizing, based on detecting expiration of the timer, access to the first RAT.

30. The non-transitory computer-readable medium of claim 24 , wherein the code for deprioritizing deprioritizes access to the first RAT further based at least in part on at least one of determining that voice calls are not supported on the first RAT, determining that only emergency services fallback is supported on the first RAT, determining a non-limited service mode (LSM) for the first RAT, or determining non-roaming mode for the first RAT.