HSS Location Accuracy for Inter-RAT Mobility
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Solution Overview
Problem
In Evolved Packet Core networks, double registrations of user terminals with both MME and SGSN lead to inaccurate location and status information, causing issues in providing Location Services, charging, and voice services, especially when users switch between LTE and 2G/3G access, as the HSS cannot determine the most recent registration status.
Innovation Solution
A method is introduced where the HSS sends requests for location and status information to both MME and SGSN, with selection logic applied to determine the most recent information, ensuring accurate data is sent to application servers, and includes procedures like waiting for UE activation or paging to obtain current information when the UE is in idle mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the HSS maintains double registration of user terminals with both MME and SGSN to support inter-RAT mobility, then adaptability and versatility are improved, but location and status information accuracy deteriorates
Solution Approach 1:
The HSS proactively sends requests for location and status information to both MME and SGSN before application servers need this information. This preliminary action ensures that the HSS has the necessary data ready and reduces the burden on application servers while maintaining accurate location information despite double registration
Solution Approach 2:
The HSS receives feedback from both MME and SGSN regarding user terminal location and status information, then uses this feedback to determine which information is most recent and accurate. This feedback mechanism allows the HSS to maintain accuracy despite having multiple registration sources
2Measurement precision
If the HSS requests location information from both MME and SGSN for user terminals with double registration, then location information accuracy is improved, but device complexity and signaling overhead increase
Solution Approach 1:
The HSS combines the location information requests to both MME and SGSN into a single coordinated process, where it sends requests to both nodes simultaneously and then merges the responses to determine the most accurate location information. This merging approach maintains accuracy while managing complexity through unified processing
3Measurement precision
If the network pages user terminals in idle mode to obtain current location information, then location information accuracy is improved, but loss of time and signaling overhead increase
Solution Approach 1:
The HSS performs preliminary actions by sending location information requests to MME and SGSN before application servers need the information. This allows the network to proactively obtain location data without requiring subsequent paging operations, thereby reducing time loss and signaling overhead while maintaining accuracy
Data Source
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AI summary
According to a first aspect of the present invention there is provided a method of operating a mobility management node to provide location and/or status information for a user terminal connected to an Evolved Packet Core network. The method comprises receiving a request for location and/or status information for the user terminal from a subscriber register, determining the location and/or status information for the user terminal, and sending a response to the subscriber register including the determined location and/or status information.