Inter-cell Soft Handover Method for UMTS Heterogeneous Networks
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Solution Overview
Problem
In UMTS heterogeneous networks, the difference between uplink (UL) and downlink (DL) coverage boundaries leads to UL resource waste and interference, reducing macro cell performance and causing DL interference in the soft handover area, which existing solutions like Cell Individual Offset (CIO) regulation fail to adequately address.
Innovation Solution
A method for inter-cell soft handover that includes sending control messages with specific intra-frequency measurement events and parameters to User Equipment (UE), redefining the soft handover process based on three measured event reports (Event1a, Event1d, and Event1b) to optimize handover operations, avoiding resource waste and interference by adjusting reporting ranges and delay parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If CIO is regulated to enable the handover area to cover the unbalance area, then UL interference to low-power cells is reduced, but DL interference of the macro cell to UE in the soft handover area is caused
Solution Approach 1:
The patent changes the measurement event parameters (Event1a, Event1d, Event1b) including reporting ranges and delay parameters to optimize handover timing and thresholds. This adjusts the handover area boundaries to better align with UL/DL coverage boundaries, reducing both UL interference to low-power cells and DL interference from macro cell without requiring CIO regulation.
2Area of stationary object
If soft handover area is expanded to cover UL/DL unbalance area, then coverage is improved, but UL processing resources of macro cell are wasted
Solution Approach 1:
The patent implements dynamic handover parameter adjustment based on measured event reports. By using multiple events (Event1a for cell addition, Event1d for cell deletion, Event1b for active set update) with different reporting ranges and delay parameters, the system dynamically optimizes the soft handover area to match actual UL/DL coverage conditions, preventing resource waste while maintaining coverage.
3Ease of operation
If conventional soft handover process is used, then handover simplicity is maintained, but resource waste and interference problems occur in heterogeneous networks
Solution Approach 1:
The patent segments the handover process into distinct measurement events (Event1a, Event1d, Event1b) with specific triggering conditions and actions. This segmentation allows precise control over handover timing and conditions, enabling the system to maintain simplicity while avoiding resource waste and interference by only initiating handover when appropriate measurement criteria are met.
Data Source
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AI summary
Provided is a method and implementation device for inter-cell soft handover. The method for inter-cell soft handover includes that: a control message at least including multiple events of intra-frequency measurement control and their corresponding parameters is sent to User Equipment (UE); measured event reports, reported by the UE, of the multiple events are received; and a soft handover process is executed according to the multiple measured event reports. The soft handover process is redefined on the basis of three soft handover event measurement reports, so that waste of a processing resource of a macro cell in a Universal Mobile Telecommunications System (UMTS) heterogeneous network is avoided, UL processing performance of the network is improved, and an lub transmission bandwidth of the macro cell is saved; and in addition, DL interference of the macro cell caused by CIO regulation is avoided.