HNB-GW Gateway System for Accurate UE Camping Detection
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Solution Overview
Problem
The accuracy of detecting user equipment (UE) camping on a femto cell and decamping from a femto cell is low, particularly for CSG-compatible UEs, and the existing decamping detection process is time-consuming, leading to potential delivery of incorrect presence information.
Innovation Solution
A gateway system with enhanced management tables in the HNB-GW and AAA server to identify CSG-compatible UEs and implement a shorter decamping detection timer, allowing for real-time detection of UE movement without affecting the UE or HNB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the existing decamping detection procedure using periodic location registration timer is used, then the detection process is simple, but the detection time is too long (minimum 6 minutes) and accuracy is low
Solution Approach 1:
The HNB-GW performs preliminary actions by storing the UE's IMSI and HNB-ID in association when the UE camps on the femto cell. This pre-prepared information allows the gateway to quickly detect decamping by checking whether the UE is still registered with the same HNB, eliminating the need to wait for periodic location registration and enabling rapid decamping detection without affecting UE or HNB operations
Solution Approach 2:
The system implements feedback mechanisms where the HNB continuously reports UE registration status to the HNB-GW. When a UE decamps from the femto cell, the HNB stops sending location registration requests, and the HNB-GW detects this absence of feedback to determine decamping has occurred, enabling accurate and timely detection
2Measurement precision
If CSG-compatible UEs are supported without additional management mechanisms, then device compatibility is maintained, but camping detection accuracy deteriorates because IMSI cannot be notified
Solution Approach 1:
The HNB-GW acts as an intermediary that bridges the gap between HNBs and CSG-compatible UEs. When a CSG-compatible UE camps on an HNB, the HNB-GW stores the UE's IMSI and HNB-ID in association as preliminary information. This intermediary mechanism enables accurate camping detection for CSG-compatible UEs without requiring changes to the UEs themselves, maintaining their compatibility while improving detection accuracy
Solution Approach 2:
The HNB-GW performs preliminary information storage by recording the UE's IMSI and HNB-ID when camping occurs. This pre-established information base allows the system to accurately track and detect both camping and decamping events for CSG-compatible UEs, solving the identification problem without affecting UE compatibility
Data Source
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AI summary
In order to improve the accuracy of at least one of detecting that a UE camps on a femto cell and detecting that the UE decamps from the range femto cell, a gateway (110_1) forms a gateway system and relays traffic between a core network (20) and a base station (30_2). When TMSI or P-TMSI temporarily assigned to a UE (40_1) requesting to camp on the base station (30_2) is received from the base station (30_2) through a public network, the gateway (110_1) requests a server (120), which communicates with the core network (20) and the gateway (110_1), to notify IMSI permanently assigned to the UE (40_1) and associated with the TMSI or P-TMSI. In response to the request, the sever (120) acquires the IMSI from the core network (20) and notifies it to the gateway (110_1). The gateway (110_1) identifies the UE (40_1) by using the IMSI.