Optimization of PLMN selection for power saving

1 . A method, implemented by a terminal device in a wireless communication network, the method comprising:

connecting to a Visited Public Land Mobile Network (VPLMN); and

while connected to the VPLMN, searching for a Home Public Land Mobile Network (HPLMN) each time any of a plurality of timers expires, the searching comprising:

searching across a plurality of frequency bands supported by the terminal device in response to a first timer of the plurality of timers expiring;

searching across a subset of the plurality of frequency bands supported by the terminal device in response to a second timer of the plurality of timers expiring, wherein the subset of the plurality of frequency bands comprises at least two frequency bands; and

searching across one of the at least two frequency bands supported by the terminal device in response to a third timer of the plurality of timers expiring, wherein each of the first, second, and third timers are respectively associated with a gradually decreasing frequency band range.

2 . The method of claim 1 , wherein searching across the one of the at least two frequency bands supported by the terminal device in response to the third timer expiring comprises searching a last known frequency band supported by the HPLMN.

3 . The method of claim 1 , further comprising adjusting one or more of the first, second, and third timers based on an extent to which the terminal device is mobile.

4 . The method of claim 3 , wherein adjusting the one or more of the first, second, and third timers based on the extent to which the terminal device is mobile comprises shortening or lengthening at least one of the first, second, and third timers based respectively on whether a mobility of the terminal device has increased or decreased.

5 . The method of claim 1 , further comprising reporting to the wireless communication network that the searching for the HPLMN using the plurality of timers is supported by the terminal device, and in response, receiving signaling from the wireless communication network configuring the terminal device to enable the searching for the HPLMN using the plurality of timers.

6 . The method of claim 1 , further comprising adjusting one or more of the first, second, and third timers based on distance from the terminal device to a geographic location.

7 . The method of claim 6 , wherein adjusting the one or more of the first, second, and third timers based on the distance to the geographic location comprises shortening or lengthening at least one of the first, second, and third timers based respectively on whether the distance from the terminal device to the geographic location has decreased or increased, the geographic location being a location associated with having HPLMN coverage.

8 . A terminal device comprising:

processing circuitry and a memory, the memory comprising instructions executable by the processing circuitry whereby the terminal device is configured to:

connect to a Visited Public Land Mobile Network (VPLMN); and

while connected to the VPLMN, search for a Home Public Land Mobile Network (HPLMN) each time any of a plurality of timers expires, wherein to search for the HPLMN, the terminal device is configured to:

search across a plurality of frequency bands supported by the terminal device in response to a first timer of the plurality of timers expiring; and

search across a subset of the plurality of frequency bands supported by the terminal device in response to a second timer of the plurality of timers expiring, wherein the subset of the plurality of frequency bands comprises at least two frequency bands; and

search across one of the at least two frequency bands supported by the terminal device in response to a third timer of the plurality of timers expiring, wherein each of the first, second, and third timers are respectively associated with a gradually decreasing frequency band range.

9 . The terminal device of claim 8 , wherein to search across the one of the at least two frequency bands supported by the terminal device in response to the third timer of the plurality of timers expiring, the terminal device is configured to search a last known frequency band supported by the HPLMN.

10 . The terminal device of claim 8 , further configured to adjust one or more of the first, second, and third timers based on an extent to which the terminal device is mobile.

11 . The terminal device of claim 8 , further configured to report to a wireless communication network that the searching for the HPLMN using the plurality of timers is supported by the terminal device, and in response, receive signaling from the wireless communication network configuring the terminal device to enable the searching for the HPLMN using the plurality of timers.

12 . The terminal device of claim 8 , further configured to adjust one or more of the first, second, and third timers based on distance from the terminal device to a geographic location.

13 . A method, implemented by a base station in a wireless communication network, the method comprising:

configuring a terminal device to search for a Home Public Land Mobile Network (HPLMN) each time any of a plurality of timers expires, the configuring comprising:

configuring the terminal device to search across a plurality of frequency bands supported by the terminal device in response to a first timer of the plurality of timers expiring;

configuring the terminal device to search across a subset of the plurality of frequency bands supported by the terminal device in response to a second timer of the plurality of timers expiring, wherein the subset of the plurality of frequency bands comprises at least two frequency bands; and

configuring the terminal device to search across one of the at least two frequency bands supported by the terminal device in response to a third timer of the plurality of timers expiring, wherein each of the first, second, and third timers are respectively associated with a gradually decreasing frequency band range.

14 . The method of claim 13 , wherein configuring the terminal device to search for the HPLMN each time any of the plurality of timers expires further comprises configuring the terminal device to search for the HPLMN while the terminal device is connected to a Visited Public Land Mobile Network (VPLMN).

15 . A base station comprising:

processing circuitry; and

a memory comprising instructions executable by the processing circuitry whereby the base station is configured to configure a terminal device to search for a Home Public Land Mobile Network (HPLMN) each time any of a plurality of timers expires, wherein to configure the terminal device the base station is configured to:

configure the terminal device to search across a plurality of frequency bands supported by the terminal device in response to a first timer of the plurality of timers expiring;

configure the terminal device to search across a subset of the plurality of frequency bands supported by the terminal device in response to a second timer of the plurality of timers expiring, wherein the subset of the plurality of frequency bands comprises at least two frequency bands; and

configure the terminal device to search across one of the at least two frequency bands supported by the terminal device in response to a third timer of the plurality of timers expiring, wherein each of the first, second, and third timers are respectively associated with a gradually decreasing frequency band range.

16 . The base station of claim 15 , wherein to configure the terminal device to search for the HPLMN each time any of the plurality of timers expires, the base station is configured to configure the terminal device to search for the HPLMN while the terminal device is connected to a Visited Public Land Mobile Network (VPLMN).