Cellular system selection frequency scan scope

1. A wireless user equipment (UE) device, comprising:

at least one antenna for performing wireless communications;

a radio coupled to the at least one antenna; and

a processing element coupled to the radio;

wherein the UE is configured to:

determine that the UE does not have cellular service;

determine first information based on a last cell the UE camped on;

determine whether the first information was acquired within a first time period;

in response to determining that the first information was acquired within the first time period, perform one or more frequency scans limited to a first set of frequencies; and

in response to determining that the first information was not acquired within the first time period, perform one or more frequency scans limited to a second set of frequencies, wherein the first set of frequencies is a subset of the second set of frequencies.

2. The UE of claim 1 ,

wherein in the UE is further configured to:

receive a system information block from the last cell, wherein the system information block contains neighbor cell frequencies; and

store the neighbor cell frequencies in a local enhanced acquisition database (ACQ-DB);

wherein at least the first set of frequencies comprise frequencies stored in the local enhanced ACQ-DB.

3. The UE of claim 1 ,

wherein the UE is further configured to receive, from a companion UE, a local assisted acquisition database (ACQ-DB), wherein at least the first set of frequencies comprise frequencies stored on the UE in the local assisted ACQ-DB.

4. The UE of claim 1 ,

wherein at least the first set of frequencies comprise frequencies stored in location assisted databases stored on the UE.

5. The UE of claim 1 ,

wherein to perform the one or more frequency scans, the UE is further configured to scan frequencies stored in a first database associated with a first time stamp prior to scanning frequencies stored in a second database associated with a second time stamp, wherein the first time stamp is more recent than the second time stamp.

6. The UE of claim 1 ,

wherein the UE is further configured to:

increase a time period between the one or more frequency scans based in part on a mobility state of the UE.

7. The UE of claim 1 ,

wherein the UE is further configured to:

determine that the first information was not acquired within a second time period, wherein the second time period is greater than the first time period; and

in response to determining that the first information was not acquired within the second time period, perform one or more frequency scans limited to a third set of frequencies, wherein the second set of frequencies is a subset of the third set of frequencies.

8. The UE of claim 1 ,

wherein to determine that the UE does not have cellular service, the processing element is further configured to determine that the UE is camped on a visiting public land mobile network (VPLMN).

9. A non-transitory computer accessible memory medium comprising program instructions which, when executed at a wireless user equipment (UE) device, cause the UE to:

store neighbor cell frequencies in a local enhanced acquisition database (ACQ-DB), wherein the neighbor cell frequencies are received in a system information block from a last cell the UE was camped on;

determine that the UE does not have cellular service;

determine first information based on a last cell the UE was camped on;

determine a time period during which the first information was acquired; and

perform one or more frequency scans limited to a set of frequencies based in part on the time period, wherein when the time period is less than a first value, the set of frequencies comprise frequencies stored on the UE in the local enhanced ACQ-DB.

10. The non-transitory computer accessible memory medium of claim 9 ,

wherein when the time period is less than the first value, the set of frequencies comprises a first set of frequencies stored in the local enhanced ACQ-DB;

wherein when the time period is greater than the first value but less than a second value, the set of frequencies comprises the first set of frequencies and a second set of frequencies stored in the local enhanced ACQ-DB; and

wherein when the time period is greater than the second value, the set of frequencies comprises the first and second sets of frequencies and a third set of frequencies stored in the local enhanced ACQ-DB.

11. The non-transitory computer accessible memory medium of claim 9 ,

wherein the program instructions are further executable by the UE to receive, from a companion UE, a local assisted acquisition database (ACQ-DB), wherein the set of frequencies further comprise frequencies stored on the UE in the local assisted ACQ-DB.

12. The non-transitory computer accessible memory medium of claim 9 ,

wherein the set of frequencies further comprise frequencies stored in location assisted databases stored on the UE.

13. The non-transitory computer accessible memory medium of claim 9 ,

wherein the program instructions are further executable by the UE to:

increase a time period between the one or more frequency scans based in part on a mobility state of the UE.

14. An apparatus, comprising:

a memory; and

a processing element in communication with the memory, wherein the processing element is configured to:

determine that a user equipment device (UE) does not have cellular service;

determine whether first information associated with a last cell the UE camped on was acquired within a first time period;

in response to determining that the first information was acquired within the first time period, perform one or more frequency scans limited to a first set of frequencies; and

in response to determining that the first information was not acquired within the first time period, perform one or more frequency scans limited to a second set of frequencies, wherein the first set of frequencies is a subset of the second set of frequencies.

15. The apparatus of claim 14 ,

wherein the processing element is further configured to:

determine that the first information was not acquired within a second time period, wherein the second time period is greater than the first time period; and

in response to determining that the first information was not acquired within the second time period, perform one or more frequency scans limited to a third set of frequencies, wherein the second set of frequencies is a subset of the third set of frequencies.

16. The apparatus of claim 14 ,

wherein to determine that the UE does not have cellular service, the processing element is further configured to determine that the UE is in a connected mode out of service (COOS) state.

17. The apparatus of claim 16 ,

wherein the first set of frequencies comprise frequencies stored in one or more of:

a local acquisition database (ACQ-DB);

a local enhanced ACQ-DB; or

a location assisted database; and

wherein the processing element is further configured to further limit the first set of frequencies to frequencies corresponding to the last cell; and

wherein the frequencies corresponding to the last cell comprises frequencies of a last registered public land mobile network (RPLMN) database.

18. The apparatus of claim 14 ,

wherein to determine that the UE does not have cellular service, the processing element is further configured to determine that the UE is camped on a visiting public land mobile network (VPLMN).

19. The apparatus of claim 18 ,

wherein the first set of frequencies comprise frequencies stored in one or more of:

a local acquisition database (ACQ-DB);

a local enhanced ACQ-DB; or

a location assisted database; and

wherein the processing element is further configured to further limit the first set of frequencies to frequencies corresponding to a home PLMN, equivalents of the home PLMN, and a provider preferred PLMN.

20. The apparatus of claim 19 ,

wherein the VPLMN provides limited service.