Relay Apparatus Handover Control in Multi-Stage Networks
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Solution Overview
Problem
In radio communication systems, existing handover control methods fail to identify a target cell during handover in network topologies with multiple-stage HNBGW-HNB structures, leading to incomplete handover processes due to PSC ambiguity and lack of unique cell identification.
Innovation Solution
A method for handover control in radio communication systems where a first relay apparatus acquires cell information of a second base station under the control of a lower-level relay apparatus, using this information to identify the target cell during handover, enabling accurate handover operations even in complex network topologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If PSC is reused for multiple femtocells in large-scale deployments, then the number of available femtocells increases, but PSC ambiguity occurs making unique cell identification impossible
Solution Approach 1:
The patent segments the cell identification function into two parts: PSC for radio access and Cell Identity for unique network identification. This segmentation allows PSC to be reused across multiple femtocells while the Cell Identity maintains uniqueness, resolving the contradiction between scaling femtocell数量 and maintaining identification uniqueness.
Solution Approach 2:
The patent introduces Cell Identity as an intermediary parameter that bridges the gap between PSC and unique cell identification. The RNC uses Cell Identity (obtained through SI acquisition) as the ultimate identifier for handover target cells, while PSC serves only as an initial access indicator, eliminating PSC ambiguity issues.
2Ease of operation
If legacy UE without SI Acquisition function reports PSC for handover, then handover process can be initiated, but target cell cannot be uniquely determined due to PSC ambiguity
Solution Approach 1:
The patent performs preliminary SI acquisition to obtain Cell Identity before handover execution. The RNC proactively acquires system information from the target femtocell to get its unique Cell Identity, ensuring accurate target cell identification before the handover command is issued, even when UE cannot provide it.
Solution Approach 2:
The patent implements a feedback mechanism where the RNC verifies target cell identification by acquiring system information from the target femtocell. This feedback loop ensures that the reported PSC actually corresponds to the intended target cell, correcting any ambiguity before handover execution.
3Measurement precision
If RNC stores database information for PSC disambiguation, then target cell identification improves, but system complexity and memory requirements increase
Solution Approach 1:
The patent enables the RNC to self-acquire target cell identification information by directly obtaining system information from the target femtocell. Instead of maintaining complex databases, the RNC performs lightweight SI acquisition on-demand, reducing system complexity while maintaining identification accuracy.
4Area of stationary object
If multiple HNBGW are deployed in multi-stage topology, then network coverage and capacity increase, but handover target cell identification fails due to PSC ambiguity propagation
Solution Approach 1:
The patent segments the identification hierarchy into HNBGW-level Cell Identity and individual femtocell Cell Identity. In multi-stage topologies, each HNBGW has its own Cell Identity, and each femtocell under it has a unique Cell Identity, creating a segmented identification structure that prevents ambiguity propagation across multiple HNBGW levels.
Solution Approach 2:
The patent adds a hierarchical dimension to cell identification by introducing Cell Identity at both HNBGW and femtocell levels. This dimensional expansion allows unique identification in multi-stage topologies where flat PSC-based identification fails, enabling handover control across complex network architectures.
Data Source
AI summary
A method of handover control, a relay apparatus, and a method for selecting a target cell are provided that make it possible to identify a target cell in a hand-in phase even in a network topology in which relay apparatuses are connected in multiple stages. In a radio communication system in which a base station controller (14) and a first relay apparatus (1) are connected to a communication network, wherein the base station controller has under its control at least one first base station (12) connected thereto, and the first relay apparatus has under its control at least a second relay apparatus (2) connected thereto, wherein the second relay apparatus has under its control at least one second base station (4-6) connected thereto, the first relay apparatus acquires cell information of a cell controlled by the second base station under the control of the second relay apparatus, and in a hand-in phase for handover from the first base station (12), to which a radio station (16) is wirelessly connected, to the second base station (6), the first relay apparatus identifies a target cell of the handover by using the cell information.