Reselection of a radio access technology (RAT) for a multimode user equipment (UE)

A method performed by a user equipment (UE), comprising:

• determining that the UE camps on a first Radio Access Technology (RAT) for service by a first public land mobile network (PLMN);
• storing information about the first RAT for the first PLMN;
• determining, in response to service in the first RAT being interrupted, that the UE camps on a second RAT for service by a second PLMN;
• determining whether there is a trigger event to enable the UE to switch back from the second RAT to the first RAT, wherein the first RAT is more advanced than the second RAT;
• in response to a determination that there is the trigger event, based on the stored information about the first PLMN, while being camped on the second RAT for service by the second PLMN, performing a search of an available cell of the first PLMN different from the second PLMN without searching for an available PLMN to determine whether a cell in the first RAT for the first PLMN is available for the UE to camp on;
• and
• in response to a determination that a cell in the first RAT for the first PLMN is available, selecting the available cell in the first RAT to register the UE with the first PLMN.

A non-transitory computer-readable medium storing instructions that, when executed by a processor of a user equipment (UE), cause the UE to perform operations, the operations comprising:

• determining that the UE camps on a first Radio Access Technology (RAT) for service by a first public land mobile network (PLMN);
• storing information about the first RAT for the first PLMN;
• determining, in response to service in the first RAT being interrupted, that the UE camps on a second RAT for service by a second PLMN;
• determining whether there is a trigger event to enable the UE to switch back from the second RAT to the first RAT, wherein the first RAT is more advanced than the second RAT;
• in response to a determination that there is the trigger event, based on the stored information about the first PLMN, while being camped on the second RAT for service by the second PLMN, performing a search of an available cell of the first PLMN different from the second PLMN without searching for an available PLMN to determine whether a cell in the first RAT for the first PLMN is available for the UE to camp on;
• and
• in response to a determination that a cell in the first RAT for the first PLMN is available, selecting the available cell in the first RAT to register the UE with the first PLMN.