Assisted Serving Cell Configuration for Heterogeneous Network Mobility
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Solution Overview
Problem
In heterogeneous networks, high-density small cells exacerbate mobility issues and interference, leading to increased handover failure rates and suboptimal capacity utilization, particularly for users with medium to high mobility, due to frequent handovers and differing radio conditions between macro and small cells operating on different frequency bands.
Innovation Solution
Implementing a method where a macro cell acts as the control serving cell, managing mobility, and small cells serve as assisted serving cells for user plane data, with enhancements in camping procedures, discontinuous reception, Layer 1 channels, and hybrid automatic repeat request (HARQ) processes to optimize handovers and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-density small cells are deployed within macro cells to improve capacity and cell edge performance, then capacity and cell edge performance are improved, but mobility performance deteriorates due to frequent handovers and increased handover failure rates
Solution Approach 1:
The patent segments the serving cell relationship by introducing assisted serving cells that provide user plane data services while the primary serving cell handles control plane functions. This segmentation allows the network to manage mobility through the primary serving cell while utilizing assisted serving cells for data transmission, thereby improving capacity without exacerbating mobility issues.
Solution Approach 2:
The patent introduces an intermediary mechanism where the primary serving cell coordinates with assisted serving cells through a coordination interface. This intermediary coordination allows the network to optimize handover decisions by considering both control plane and user plane conditions, reducing handover failure rates while maintaining high capacity through dense small cell deployment.
2Object-affected harmful factors
If small cells use different frequency bands from macro cells to relieve interference, then interference between macro and small cells is reduced, but device complexity increases due to inter-site carrier aggregation requirements
Solution Approach 1:
The patent implements a universal cell structure where cells can operate on different frequency bands while maintaining a standardized interface for coordination between primary and assisted serving cells. This multi-functionality allows the network to deploy small cells on different frequencies to relieve interference without requiring complex device modifications, as the coordination mechanism works across different frequency configurations.
3Productivity
If frequent handovers are implemented to optimize user connection to small cells, then capacity utilization is improved, but handover failure rates increase due to fast changing radio conditions at small cell edges
Solution Approach 1:
The patent applies preliminary action by establishing the assisted serving cell relationship before handover occurs. The primary serving cell pre-configures the assisted serving cell with necessary parameters and coordinates handover decisions in advance. This preliminary setup ensures that when handover is needed, the assisted serving cell is already prepared to receive user plane data, reducing handover failure rates while maintaining high capacity utilization.
Data Source
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AI summary
Methods, systems and apparatus are provided for camping, assisted serving cell addition or removal, and discontinuous reception (DRX) in networks having a macro cell and at least one assisted serving cell. In other aspects, enhancements to Layer 1 channels and uplink timing alignments are provided in networks having a macro cell and at least one assisted serving cell. In further aspects, assisted serving cell Layer 2 architecture and transport channels are provided in networks having a macro cell and at least one assisted serving cell. In further aspects, collaborated HARQ solutions are provided in networks having a macro cell and at least one assisted serving cell.