Avoidance of service interruptions in visited public land mobile network (VPLMNs)
First Claim
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1. A method in a user equipment of selecting among available public land mobile networks (PLMNs), each PLMN including at least one cell, comprising the steps of:
- scanning for available PLMNs when the user equipment is connected to a visited public land mobile network (VPLMN);
picking an available PLMN for evaluation;
reading system information of at least one cell in the picked available PLMN, wherein the system information includes a minimum required quality level in the cell, a minimum required receive level in the cell, and a maximum transmit power level to access the cell on a random access channel;
evaluating a cell selection criterion based on the read system information;
repeating the picking, reading, and evaluating steps for remaining available PLMNs; and
selecting an available PLMN having a highest priority and having a cell fulfilling the cell selection criterion;
wherein the scanning step includes a step of determining a list of available PLMNs, and the evaluating step includes a step of removing a picked available PLMN from the list if the cell selection criterion is not fulfilled by the at least one cell in the picked available PLMN.
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Abstract
By evaluating a cell selection criterion S during scans for available public land mobile networks (PLMNs), a user equipment (UE) can avoid network service interruptions by not selecting PLMNs for which there exist no suitable cells. The cell selection criterion can be evaluated based on cell parameters either read during the PLMN selection procedure or locally stored before the PLMN selection procedure. It is possible to reduce the time required for PLMN scans and UE power consumption.
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Citations
15 Claims
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1. A method in a user equipment of selecting among available public land mobile networks (PLMNs), each PLMN including at least one cell, comprising the steps of:
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scanning for available PLMNs when the user equipment is connected to a visited public land mobile network (VPLMN); picking an available PLMN for evaluation; reading system information of at least one cell in the picked available PLMN, wherein the system information includes a minimum required quality level in the cell, a minimum required receive level in the cell, and a maximum transmit power level to access the cell on a random access channel; evaluating a cell selection criterion based on the read system information; repeating the picking, reading, and evaluating steps for remaining available PLMNs; and selecting an available PLMN having a highest priority and having a cell fulfilling the cell selection criterion; wherein the scanning step includes a step of determining a list of available PLMNs, and the evaluating step includes a step of removing a picked available PLMN from the list if the cell selection criterion is not fulfilled by the at least one cell in the picked available PLMN. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus in user equipment for selecting among available public land mobile networks (PLMNs), each PLMN including at least one cell, comprising:
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a processor configured to scan for available PLMNs when the user equipment is connected to a visited public land mobile network (VPLMN);
to pick an available PLMN for evaluation;
to read system information of at least one cell in the picked available PLMN, wherein the system information includes a minimum required quality level in the cell, a minimum required receive level in the cell, and a maximum transmit power level to access the cell on a random access channel;
to evaluate a cell selection criterion based on the read system information;
to repeat the picking, reading, and evaluating for remaining available PLMNs; and
to select an available PLMN having a highest priority and having a cell fulfilling the cell selection criterion; andwherein the processor is configured, in scanning for available PLMNs, to determine a list of available PLMNs; and
in evaluating the cell selection criterion, to remove a picked available PLMN from the list if the cell selection criterion is not fulfilled by the at least one cell in the picked available PLMN. - View Dependent Claims (7, 8, 9, 10)
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11. Non-transitory computer-readable medium containing a computer program for causing a receiver to select among available public land mobile networks (PLMNs), each PLMN including at least one cell, the computer program implementing the steps of:
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scanning for available PLMNs when the user equipment is connected to a visited public land mobile network (VPLMN); picking an available PLMN for evaluation; reading system information of at least one cell in the picked available PLMN, wherein the system information includes a minimum required quality level in the cell, a minimum required receive level in the cell, and a maximum transmit power level to access the cell on a random access channel; evaluating a cell selection criterion based on the read system information;
repeating the picking, reading, and evaluating steps for remaining available PLMNs; andselecting an available PLMN having a highest priority and having a cell fulfilling the cell selection criterion; and wherein the scanning step includes a step of determining a list of available PLMNs, and the evaluating step includes a step of removing a picked available PLMN from the list if the cell selection criterion is not fulfilled by the at least one cell in the picked available PLMN. - View Dependent Claims (12, 13, 14, 15)
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Specification