Heterogeneous Network Mobility Control via Macro-Assisted Small Cell Segmentation

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Solution Overview

Problem

In heterogeneous networks, high-density small cells within macro cells lead to mobility issues and interference, particularly for user equipment (UE) with medium to high mobility, resulting in increased handover failure rates and interference between high power and low power cells.

Innovation Solution

Implementing a method where the macro cell operates on a low frequency band for mobility control and handover management, while assisted serving small cells operate on a higher frequency band for user plane data communication, using almost blank subframes and coordinated resource sharing to mitigate interference and enhance handover efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high-density small cells are deployed within macro cells to improve capacity and cell edge performance, then network capacity and coverage are improved, but mobility management complexity and handover failure rates increase for user equipment with medium to high mobility

Engineering Contradiction:
Improvenetwork capacityVSAvoidhandover failure rate
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent segments the network into macro cells for mobility control and small cells for data communication. The macro cell handles control plane functions including handover management, while small cells handle user plane data transmission. This segmentation allows the macro cell to provide stable mobility management coverage while small cells provide high-capacity data services, reducing handover failures by preventing frequent handovers between small cells.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a dual-connectivity dimension where user equipment simultaneously connects to both macro cell and small cell. The control plane connection to macro cell and user plane connection to small cell operate in parallel, allowing data communication to occur without breaking the mobility management connection. This dimensional separation enables high-capacity small cell deployment while maintaining reliable macro cell-based mobility control.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If small cells use a different frequency layer from macro cells to remove interference, then interference between high power and low power cells is reduced, but device complexity and resource coordination overhead increase

Engineering Contradiction:
ImproveinterferenceVSAvoidresource coordination overhead
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent uses the macro cell as an intermediary for control plane communication between user equipment and the network. All control signaling including handover commands and mobility management messages are routed through the macro cell, even when data communication occurs with small cells. This intermediary role simplifies resource coordination by centralizing control functions at the macro cell level while allowing small cells to focus on data transmission.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments communication functions into control plane (handled by macro cell on one frequency layer) and user plane (handled by small cells on different frequency layers). This functional segmentation allows interference mitigation through frequency separation while reducing coordination complexity by assigning clear responsibilities: macro cell for control signaling and small cells for data transmission.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2936697B1Method and apparatus for hybrid automatic repeat request operation in a heterogeneous network architecture
Publication Date: 2018.10.31 BLACKBERRY LTD
  • EP2936697B1 patent drawingFigure 1
  • EP2936697B1 patent drawingFigure 2
  • EP2936697B1 patent drawingFigure 3

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.