PLMN Selection for CSFB in Shared Networks
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Solution Overview
Problem
In shared network environments, particularly in LTE networks, the Circuit Switched Fallback (CSFB) process is inefficient due to the inability of User Equipment (UE) to seamlessly transition between different PLMN identities, leading to prolonged call setup times and service disruptions, especially when UE moves to cells with different LAI, causing unnecessary location updates and increased CSFB time.
Innovation Solution
A method and network element that determine the capability of User Equipment (UE) to support network sharing, allowing for the selection of the most appropriate PLMN identity based on the UE's capabilities, thereby minimizing delays and optimizing resource allocation during CSFB procedures by distinguishing between supporting and non-supporting UEs and allocating them to either a common or multiple PLMNs accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE is allocated to a common PLMN in a shared network environment, then network compatibility and coverage are improved, but CSFB time increases due to unnecessary location updates when moving between cells with different LAI
Solution Approach 1:
The invention segments the PLMN allocation strategy by UE capability: supporting UEs receive multiple PLMN identities while non-supporting UEs receive a common PLMN. This segmentation resolves the contradiction by allowing supporting UEs to avoid location updates (reducing CSFB time) while maintaining broad compatibility for non-supporting UEs through the common PLMN.
Solution Approach 2:
The network performs preliminary determination of UE capability regarding network sharing support before PLMN allocation. This preliminary action enables the network to pre-allocate appropriate PLMN identities (common or multiple) based on UE capability, preventing subsequent location update issues during CSFB and reducing overall CSFB time.
2Productivity
If the network determines UE capability and allocates appropriate PLMN identities, then CSFB efficiency is improved, but device complexity increases due to capability determination and differentiated allocation procedures
Solution Approach 1:
The UE self-identifies its capability regarding network sharing support through its behavior and responses during initial attachment or location update procedures. The network determines capability based on UE-provided information (such as lack of network sharing support indication), reducing the need for complex network-side capability determination mechanisms while improving CSFB efficiency through differentiated PLMN allocation.
Data Source
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AI summary
The invention relates to a method for performing a selection of a public land mobile network identity in a shared network environment, in which environment at least two public land mobile network identities are available for providing circuit switched based service to user equipment. The method comprises at least a step of determining a capability of the user equipment (201) and a step of selecting the public land mobile network identity (202) at least partly on the basis of the capability of the user equipment among the at least two public land mobile network identities. According to the invention information on the capability of the user equipment is either received from the user equipment or from a database comprising capability information on the user equipment. Furthermore, the invention relates to a network element and a system for implementing at least party the method according to the invention.