IOPS Dual PLMN Mobile Originated Call Selection
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Solution Overview
Problem
There is a need for a method to enable mobile originated (MO) calls using user equipment registered on both a normal public land mobile network (PLMN) and an isolated public safety (IOPS) PLMN, particularly in scenarios where the backhaul to the macro E-UTRAN is lost or not available, to ensure continuous public safety communication services.
Innovation Solution
The user equipment registers on both a normal PLMN connected to the macro EPC and an IOPS PLMN isolated from the macro EPC, allowing the user to set one as the primary and the other as a secondary PLMN based on user preference, dialing history, or random selection, and attempts to make MO calls sequentially through these networks to ensure connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the user equipment registers on both normal PLMN and IOPS PLMN simultaneously, then the reliability of communication service is improved during network outages, but the device complexity increases due to dual registration management
Solution Approach 1:
The patent implements dynamic PLMN selection where the user equipment can switch between normal PLMN and IOPS PLMN based on real-time network conditions. The system dynamically determines which PLMN to use for MO calls by checking network availability and service status, rather than maintaining static dual registration. This dynamic approach maintains reliability by ensuring service continuity while reducing complexity through context-aware PLMN selection.
Solution Approach 2:
The patent changes the operational parameter of PLMN selection mode from simultaneous dual registration to sequential selection with preference ordering. The system maintains a preference list of PLMNs and changes the active PLMN parameter based on network conditions, service type, and user preferences. This parameter change approach simplifies the registration management while ensuring reliable communication by selecting the most appropriate PLMN for each calling scenario.
2Reliability
If the system attempts MO calls through multiple PLMNs sequentially, then the connectivity reliability is improved, but the loss of time increases due to sequential attempt delays
Solution Approach 1:
The patent implements preliminary action by pre-establishing a preference list of PLMNs and pre-configuring selection criteria before actual calling occurs. The system prepares multiple PLMN options in advance with associated selection priorities, so when an MO call is needed, the selection process can quickly proceed through the pre-evaluated list without extensive real-time decision-making. This preliminary preparation reduces call establishment time while maintaining connectivity reliability through pre-planned fallback options.
Solution Approach 2:
The patent applies skipping by allowing the system to rapidly traverse through the PLMN preference list and skip PLMNs that are known to be unavailable or unsuitable. Rather than methodically testing each PLMN in sequence with equal delay, the system can quickly skip over PLMNs that fail initial availability checks or have known service restrictions, rushing through the selection process to reach a working PLMN faster. This skipping mechanism reduces unnecessary delays while ensuring eventual connectivity.
3Ease of operation
If the user equipment prioritizes normal PLMN for MO calls, then the ease of operation is improved with automatic selection, but the reliability deteriorates when normal PLMN is unavailable
Solution Approach 1:
The patent implements beforehand cushioning by pre-configuring fallback PLMN options in the preference list before normal PLMN availability is lost. The system anticipates potential failures of the preferred normal PLMN and has alternative PLMNs ready in advance. When the normal PLMN becomes unavailable, the cushioning effect kicks in by automatically transitioning to pre-planned alternative options without requiring user intervention or causing service interruption. This prior cushioning maintains both ease of operation through automation and reliability through prepared contingencies.
Solution Approach 2:
The patent employs feedback mechanisms where the system continuously monitors the availability and service status of the normal PLMN and automatically adjusts PLMN selection based on this feedback. When the normal PLMN is available and functioning properly, the system uses it for automatic selection, providing ease of operation. When feedback indicates the normal PLMN is unavailable or degraded, the system automatically switches to alternative PLMNs from the preference list, maintaining reliability. This closed-loop feedback system balances ease of operation with reliability dynamically.
Data Source
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AI summary
In a wireless communication system, an IOPS-capable user equipment is registered on both a normal PLMN and an IOPS PLMN. The user equipment is configured to set one of the first PLMN and the second PLMN as a primary PLMN and the other one of the first PLMN and the second PLMN as a secondary PLMN randomly, according to an MO PLMN preference provided by a user of the user equipment, or according to a dialing history of the user equipment. Therefore, PLMN precedence can be provided for the user equipment in the IOPS dual PLMN mode of operation to make MO calls.