Synchronizing CSG Access Checks Across CS and PS Domains
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Solution Overview
Problem
Inconsistent CSG access checks between mobile stations and network nodes in 3GPP-compliant mobile networks lead to unnecessary handover-related communications, wasted bandwidth, and power consumption due to different knowledge of PLMN information after handovers, causing potential service interruptions and inefficiencies.
Innovation Solution
Implementing specific approaches within mobile stations, base station subsystems, and serving general packet radio service support nodes to synchronize CSG access checks using CS and PS domain PLMN information, ensuring consistent access checks by omitting or disabling inconsistent access check portions during handovers, and requiring both access checks to succeed for handover initiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mobile station performs CSG access check using PLMN information from PS domain registration, then access check accuracy is improved, but inconsistency with CS domain access check results occurs
Solution Approach 1:
The patent applies preliminary action by having the mobile station perform both CS domain and PS domain registration procedures before the access check, ensuring that both domains have current PLMN information. This allows the access check to use synchronized PLMN data from both domains, preventing inconsistency between CS and PS domain access check results while maintaining accuracy.
2Speed
If handover proceeds without verifying consistent access check results, then handover speed is improved, but unnecessary handover attempts and resource waste occur
Solution Approach 1:
The patent applies partial action by performing a selective verification - only checking access check consistency when PLMN information changes are detected or when transitioning between CS and PS domains. This avoids excessive verification in all handover scenarios, maintaining fast handover speed while preventing unnecessary handover attempts and resource waste in critical cases.
3Reliability
If multiple access checks are performed to ensure consistency, then access permission accuracy is improved, but signaling overhead and processing time increase
Solution Approach 1:
The patent applies local quality by performing access checks at specific network nodes (MSC, SGSN, and mobile station) only when locally relevant PLMN information changes are detected. Each node performs the access check with the PLMN information most relevant to its domain, avoiding redundant checks across all nodes and reducing overall signaling overhead while maintaining access permission accuracy.
Data Source
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AI summary
Example disclosed mobile station methods comprise performing a first access check based on a first equivalent public land mobile network (EPLMN) list and a first registered public land mobile network (RPLMN) identifier to determine whether a mobile station is allowed to access a closed subscriber group (CSG) cell, performing a second access check based on a second EPLMN list and a second RPLMN identifier, and conditioning reporting of the CSG cell based on the first and second checks. Example disclosed network methods comprise receiving a message from a packet switched domain network node indicating whether a mobile station is allowed to access a CSG cell, and if the message indicates that the mobile station is not allowed to access the CSG cell, informing a circuit switched domain network node that a DTM handover failure has occurred.