Managing tune-away in a multi-subscriber identity module communication device

1. A method for managing tune-away in a multi-subscription communication device having a plurality of radio frequency (RF) chains, the method comprising:

determining, by the multi-subscription communication device, a first signal strength of a first cell signal and a second signal strength of a second cell signal;

identifying one of the first cell signal or the second cell signal as a weaker cell signal to use for performing a tune-away procedure based on a comparison of the first signal strength of the first cell signal and the second signal strength of the second cell signal; and

performing, by the multi-subscription communication device, the tune-away procedure to the identified weaker cell signal, wherein one or more of the plurality of RF chains are tuned to the first cell signal to perform the tune-away procedure in response to identifying the first cell signal as the identified weaker cell signal and wherein one or more of the plurality of RF chains are tuned to the second cell signal to perform the tune-away procedure in response to identifying the second cell signal as the identified weaker cell signal.

2. The method of claim 1 , wherein determining a first signal strength of a first cell signal and a second signal strength of a second cell signal comprises:

determining the first signal strength and the second signal strength just prior to the tune-away procedure.

3. The method of claim 1 , wherein determining a first signal strength of a first cell signal and a second signal strength of a second cell signal comprises:

determining a signal strength of each component carrier of the first cell signal and a signal strength of each component carrier of the second cell signal.

4. The method of claim 3 , further comprising:

identifying from among the component carriers of the first and second cell signals a component carrier with a weakest signal strength; and

performing the tune-away procedure to a cell signal of the first and second cell signals having the component carrier with the weakest signal strength.

5. The method of claim 4 , further comprising:

determining a carrier aggregation scheduling mechanism used in the first and second cell signals; and

identifying from among secondary component carriers of each of the first and second cell signals a component carrier with a weakest signal strength in response to determining that the carrier aggregation scheduling mechanism is cross-carrier scheduling.

6. The method of claim 5 , further comprising:

determining whether a transceiver corresponding to the secondary component carrier with the weakest signal strength can be configured to perform the tune-away procedure; and

identifying a component carrier with a weakest signal strength associated with a different transceiver that can be configured to perform the tune-away procedure in response to determining that the transceiver corresponding to the component carrier with the weakest signal strength cannot be configured to perform the tune-away procedure.

7. The method of claim 4 , further comprising:

determining a carrier aggregation scheduling mechanism used in the first and second cell signals; and

identifying from among a primary component carrier and secondary component carriers of the first and second cell signals, respectively, a component carrier with a weakest signal strength in response to determining that the carrier aggregation scheduling mechanism is same-carrier scheduling.

8. The method of claim 7 , further comprising:

determining whether a transceiver corresponding to the component carrier with the weakest signal strength can be configured to perform the tune-away procedure; and

identifying a component carrier with a weakest signal strength associated with a different transceiver that can be configured to perform the tune-away procedure in response to determining that the transceiver corresponding to the component carrier with the weakest signal strength cannot be configured to perform the tune-away procedure.

9. The method of claim 7 , wherein performing the tune-away procedure to the weaker of the first cell signal and the second cell signal comprises tuning a receiver of the multi-subscription communication device to the component carrier with the weakest signal strength and not tuning a transmitter of the multi-subscription communication device associated with the receiver to the component carrier with the weakest signal strength in response to determining that the carrier aggregation scheduling mechanism is same-carrier scheduling.

10. The method of claim 7 , further comprising:

determining whether the primary component carrier includes the weakest signal strength; and

performing the tune-away procedure using receiver-only tune-away (ROTA) in a transceiver corresponding to the component carrier with the weakest signal strength in response to determining that the primary component carrier includes the weakest signal strength.

11. The method of claim 7 , further comprising:

determining whether the primary component carrier includes the weakest signal strength; and

performing the tune-away procedure using a transceiver corresponding to the component carrier with the weakest signal strength in response to determining that the primary component carrier does not include the weakest signal strength.

12. The method of claim 7 , further comprising determining just before a next tune-away period begins whether an assignment of the primary component carrier has been changed,

wherein determining the carrier aggregation scheduling mechanism used in the first and second cell signals is performed in response to determining that the assignment of the primary component carrier has been changed.

13. The method of claim 12 , further comprising:

identifying from among secondary component carriers of each of the first and second cell signals a component carrier with a weakest signal strength in response to determining that the carrier aggregation scheduling mechanism is cross-carrier scheduling.

14. The method of claim 1 , further comprising:

determining a type of carrier aggregation used in the first and second cell signals;

adjusting a signal strength difference threshold based on the determined type of carrier aggregation;

comparing a difference between the first signal strength and the second signal strength to the signal strength difference threshold; and

selecting one of the first cell signal and the second cell signal for the tune-away procedure when the difference between the first signal strength and the second signal strength exceeds the signal strength difference threshold.

15. A multi-subscription communication device, comprising:

a plurality of radio frequency (RF) chains; and

a processor coupled to the plurality of RF chains and configured to:

determine a first signal strength of a first cell signal and a second signal strength of a second cell signal;

identify one of the first cell signal or the second cell signal as a weaker cell signal to use for performing a tune-away procedure based on a comparison of the first signal strength of the first cell signal and the second signal strength of the second cell signal; and

perform the tune-away procedure to the identified weaker cell signal, wherein one or more of the plurality of RF chains are tuned to the first cell signal to perform the tune-away procedure in response to identifying the first cell signal as the identified weaker cell signal and wherein one or more of the plurality of RF chains are tuned to the second cell signal to perform the tune-away procedure in response to identifying the second cell signal as the identified weaker cell signal.

16. The multi-subscription communication device of claim 15 , wherein the processor is further configured to determine the first signal strength and the second signal strength just prior to the tune-away procedure.

17. The multi-subscription communication device of claim 15 , wherein the processor is further configured to determine a signal strength of each component carrier of the first cell signal and a signal strength of each component carrier of the second cell signal.

18. The multi-subscription communication device of claim 17 , wherein the processor is further configured to:

identify from among the component carriers of the first and second cell signals a component carrier with a weakest signal strength; and

perform the tune-away procedure to a cell signal of the first and second cell signals having the component carrier with the weakest signal strength.

19. The multi-subscription communication device of claim 18 , wherein the processor is further configured to:

determine a carrier aggregation scheduling mechanism used in the first and second cell signals; and

identify from among a secondary component carrier of each of the first and second cell signals a component carrier with a weakest signal strength in response to determining that the carrier aggregation scheduling mechanism is cross-carrier scheduling.

20. The multi-subscription communication device of claim 19 , wherein the processor is further configured to:

determine whether a transceiver corresponding to the secondary component carrier with the weakest signal strength can be configured to perform the tune-away procedure; and

identify a component carrier with a weakest signal strength associated with a different transceiver that can be configured to perform the tune-away procedure in response to determining that the transceiver corresponding to the component carrier with the weakest signal strength cannot be configured to perform the tune-away procedure.

21. The multi-subscription communication device of claim 18 , wherein the processor is further configured to:

determine a carrier aggregation scheduling mechanism used in the first and second cell signals; and

identify from among a primary component carrier and a secondary component carrier of the first and second cell signals, respectively, a component carrier with a weakest signal strength in response to determining that the carrier aggregation scheduling mechanism is same-carrier scheduling.

22. The multi-subscription communication device of claim 21 , wherein the processor is further configured to:

determine whether a transceiver corresponding to the component carrier with the weakest signal strength can be configured to perform the tune-away procedure; and

identify a component carrier with a weakest signal strength associated with a different transceiver that can be configured to perform the tune-away procedure in response to determining that the transceiver corresponding to the component carrier with the weakest signal strength cannot be configured to perform the tune-away procedure.

23. The multi-subscription communication device of claim 21 , wherein the processor is further configured to tune a receiver of the multi-subscription communication device to the component carrier with the weakest signal strength and not tune a transmitter of the multi-subscription communication device associated with the receiver to the component carrier with the weakest signal strength in response to determining that the carrier aggregation scheduling mechanism is same-carrier scheduling.

24. The multi-subscription communication device of claim 21 , wherein the processor is further configured to:

determine whether the primary component carrier includes the weakest signal strength; and

perform the tune-away procedure using receiver-only tune-away (ROTA) in a transceiver corresponding to the component carrier with the weakest signal strength in response to determining that the primary component carrier includes the weakest signal strength.

25. The multi-subscription communication device of claim 21 , wherein the processor is further configured to:

determine whether the primary component carrier includes the weakest signal strength; and

perform the tune-away procedure using a transceiver corresponding to the component carrier with the weakest signal strength in response to determining that the primary component carrier does not include the weakest signal strength.

26. The multi-subscription communication device of claim 21 , wherein the processor is further configured to:

determine just before a next tune-away period begins whether an assignment of the primary component carrier has been changed; and

determine the carrier aggregation scheduling mechanism used in the first and second cell signals in response to determining that the assignment of the primary component carrier has been changed.

27. The multi-subscription communication device of claim 26 , wherein the processor is further configured to:

identify from among secondary component carriers of each of the first and second cell signals a component carrier with a weakest signal strength in response to determining that the carrier aggregation scheduling mechanism is cross-carrier scheduling.

28. The multi-subscription communication device of claim 15 , wherein the processor is further configured to:

determine a type of carrier aggregation used in the first and second cell signals;

adjust a signal strength difference threshold based on the determined type of carrier aggregation;

compare a difference between the first signal strength and the second signal strength to the signal strength difference threshold; and

select one of the first cell signal and the second cell signal for the tune-away procedure when the difference between the first signal strength and the second signal strength exceeds the signal strength difference threshold.

29. A non-transitory processor-readable storage medium having stored thereon processor-executable software instructions configured to cause a processor of a multi-subscription communication device having a plurality of radio frequency (RF) chains to perform operations comprising:

determining a first signal strength of a first cell signal and a second signal strength of a second cell signal; and

identifying one of the first cell signal or the second cell signal as a weaker cell signal to use for performing a tune-away procedure based on a comparison of the first signal strength of the first cell signal and the second signal strength of the second cell signal; and

performing, by the multi-subscription communication device, the tune-away procedure to the identified weaker cell signal, wherein one or more of the plurality of RF chains are tuned to the first cell signal to perform the tune-away procedure in response to identifying the first cell signal as the identified weaker cell signal and wherein one or more of the plurality of RF chains are tuned to the second cell signal to perform the tune-away procedure in response to identifying the second cell signal as the identified weaker cell signal.

30. A multi-subscription communication device, comprising:

means for determining a first signal strength of a first cell signal and a second signal strength of a second cell signal;

means for identifying one of the first cell signal or the second cell signal as a weaker cell signal to use for performing a tune-away procedure based on a comparison of the first signal strength of the first cell signal and the second signal strength of the second cell signal; and

means for performing the tune-away procedure to the identified weaker cell signal, wherein one or more of the plurality of RF chains are tuned to the first cell signal to perform the tune-away procedure in response to identifying the first cell signal as the identified weaker cell signal and wherein one or more of the plurality of RF chains are tuned to the second cell signal to perform the tune-away procedure in response to identifying the second cell signal as the identified weaker cell signal.