Reducing battery power consumption during discontinuous reception and transmission

1. A wireless communication device comprising:

radio frequency circuitry configured to be powered on and off to discontinuously receive radio frequency signals broadcast by one or more base stations in a wireless network; and

baseband circuitry connected to the radio frequency circuitry configured to process the received radio frequency signals to identify a first subset of the one or more base stations for which to perform system frame number (SFN) decoding, wherein the first subset is identified based on a signal quality associated with the received radio frequency signals;

wherein the baseband circuitry is further configured to decode a SFN of each base station in the first subset of base station to identify a second subset of base stations.

2. The wireless communication device of claim 1 , wherein:

the baseband circuitry is further configured to perform the decoding during a decoding period, during at least part of which the radio frequency circuitry is turned off.

3. The wireless communication device of claim 1 , wherein:

a base station of the one or more base stations is identified for inclusion in the first subset when an associated signal quality compares in a predetermined manner to a signal quality threshold.

4. The wireless communication device of claim 1 , wherein the radio frequency circuitry is configured to:

turn on when the baseband circuitry is determining the first subset of the one or more base stations; and

turn off for at least part of the period for which the baseband circuitry is decoding the SFN of the each base station included in the first subset.

5. The wireless communication device of claim 1 , wherein:

the baseband circuitry is configured to determine the signal quality of the received radio frequency signals by determining a value of a common pilot channel signal to noise ratio (CPICH SNR) corresponding to the received radio frequency signals and comparing the determined CPICH SNR value with a threshold CPICH SNR value.

6. A wireless communication device comprising:

radio frequency circuitry configured to be powered on and off to discontinuously receive radio frequency signals broadcast by one or more base stations in a wireless network; and

baseband circuitry connected to the radio frequency circuitry configured to process the received radio frequency signals to identify a subset of the one or more base stations for which to perform system frame number (SFN) decoding, wherein the subset is identified based on a signal quality associated with the received radio frequency signals;

wherein the baseband circuitry is further configured to:

perform a first identification of the one or more base stations to include in the subset based on a signal quality of the received radio frequency signals determined during a first period of time when the radio frequency circuitry is turned on; and

perform a second identification of the one or more base stations to include in the subset based on a signal quality of the received radio frequency signals determined during a second period of time when the radio frequency circuitry is turned on.

7. A method for wireless communication, comprising:

operating a mobile wireless communication device to power on and off radio frequency circuitry within the mobile wireless communication device to discontinuously receive radio frequency signals broadcast by one or more base stations in a wireless network;

operating baseband circuitry within the mobile wireless communication device to identify one or more of the base stations to include in a first selection of base stations based on a signal quality of the received radio frequency signals; and

operating the baseband circuitry to identify one or more base stations in the first selection of base stations to include in a second selection of base stations by decoding a system frame number (SFN) of the first selection of base stations.

8. The method of claim 7 , wherein:

identifying the one or more base stations to include in the first selection of base stations is performed when the radio frequency circuitry is powered on; and

decoding the SFN of the first selection of base stations is performed when the radio frequency circuitry is powered off.

9. The method of claim 7 , wherein determining the signal quality of the received radio frequency signals comprises:

determining a value of common pilot channel received signal code power (CPICH RSCP) corresponding to the received radio frequency signals; and

comparing the determined CPICH RSCP value with a threshold CPICH RSCP value.

10. The method of claim 7 , wherein the signal quality of the received radio frequency signals is determined by:

determining a value of common pilot channel signal to noise ratio (CPICH SNR) corresponding to the received radio frequency signals; and

comparing the determined CPICH SNR value with a threshold CPICH SNR value.

11. The method of claim 7 , wherein the signal quality of the received radio frequency signals is determined by:

determining a value of common pilot channel ratio of received energy to total received power spectral density (CPICH Ec/Io) corresponding to the received radio frequency signals; and

comparing the determined CPICH Ec/Io value with a threshold CPICH Ec/Io value.

12. The method of claim 7 , wherein decoding the SFN of the first selection of base stations comprises:

determining whether the decoded SFN increments across two consecutive frames.

13. The method of claim 7 , wherein identifying the one or more base stations in the first selection of base stations to include in the second selection of base stations is performed independent of a result of cyclic redundancy check (CRC).

14. The method of claim 7 , further comprising:

performing a first identification of the one or more of the base stations to include in the first selection of base stations based on a signal quality of the received radio frequency signals determined during a first period of time when the radio frequency circuitry is powered on; and

performing a second identification of the one or more of the base stations to include in the first selection of base stations based on a signal quality of the received radio frequency signals determined during a second period of time when the radio frequency circuitry is powered on.

15. A non-transitory computer readable medium embodied with a computer program product configured to cause a mobile wireless communication device to perform operations comprising:

powering on and off radio frequency circuitry within the mobile wireless communication device to discontinuously receive radio frequency signals from base stations in a wireless network;

operating baseband circuitry within the mobile wireless communication device to process the discontinuously received radio frequency signals to select one or more of the base stations to include in an active set of base stations for use as a potential hand-off target base station, wherein the one or more of the base stations is selected for the active set of base stations based on a signal quality of the received radio frequency signals;

operating the baseband circuitry to verify the active set of base stations and

operating the baseband circuitry to decode a system frame number (SFN) of each base stations in the verified active set of base stations to identify a second set of base stations for use as the potential hand-off target base station.

16. The non-transitory computer readable medium of claim 15 , wherein the computer program product is configured to cause the communication device to perform operations comprising:

identifying the one or more base stations to include in the active set of base stations when the radio frequency circuitry is powered on; and

decoding the SFN of the verified active set of base stations when the radio frequency circuitry is powered off.

17. The non-transitory computer readable medium of claim 15 , wherein the computer program product is configured to cause the communication device to determine the signal quality of the received radio frequency signals comprising:

determining a value of common pilot channel signal to noise ratio (CPICH SNR) corresponding to the received radio frequency signals; and

comparing the determined CPICH SNR value with a threshold CPICH SNR value.

18. The non-transitory computer readable medium of claim 15 , wherein the computer program product is configured to cause the communication device to determine the signal quality of the received radio frequency signals comprising:

determining a value of common pilot channel ratio of received energy to total received power spectral density (CPICH Ec/Io) corresponding to the received radio frequency signals; and

comparing the determined CPICH Ec/Io value with a threshold CPICH Ec/Io value.

19. The non-transitory computer readable medium of claim 15 , wherein the computer program product is configured to cause the communication device to decode the SFN of the active set of base stations comprising:

determining whether the decoded SFN increments across two consecutive frames.

20. The non-transitory computer readable medium of claim 15 , wherein the computer program product is configured to cause the communication device to identify the one or more base stations in the active set of base stations to include in the second selection of base stations independent of a result of cyclic redundancy check (CRC).