Multi-Band Cell Border Shifting to Reduce Inter-Cell Interference

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Solution Overview

Problem

Existing distributed antenna systems face challenges in managing inter-cell interference and cell border interference, leading to poor Signal to Interference and Noise Ratio (SINR) and degraded user throughput, especially in high-capacity venues like airports and stadiums.

Innovation Solution

Implementing a method for cell border shifting by adjusting frequency band coverage areas and deploying at least three TRPs per cell, combined with a scheduler to assign users to bands with favorable SINR, and utilizing distributed MIMO to enhance performance at cell borders.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If distributed antenna systems are deployed to cover signal dead spots and increase system capacity, then coverage area and system capacity are improved, but inter-cell interference and cell border interference increase leading to poor SINR

Engineering Contradiction:
Improvecoverage areaVSAvoidinter-cell interference
Core Design Contradiction:
Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent segments the coverage area into multiple frequency bands (e.g., Band 1 and Band 2), each with its own cell border configuration. By dividing the single-cell system into multi-band operations, the patent can independently manage interference patterns for each band, reducing the impact of inter-cell interference on overall system performance while maintaining extended coverage area.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter of cell border position by applying cell border shifting specifically to Band 2 while keeping Band 1's cell border in its original position. This parameter modification allows the system to optimize SINR for cell edge users in Band 2 by relocating the interference boundary, thereby reducing the harmful effects of inter-cell interference without sacrificing coverage area.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If cell border shifting is applied to minimize common interference areas, then SINR is improved, but coverage area optimization becomes more complex

Engineering Contradiction:
Improvecommon interference areaVSAvoidcoverage area optimization
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies cell border shifting selectively only to Band 2 while maintaining the original cell border configuration for Band 1. This local application of the shifting technique allows optimization of SINR in specific interference-prone areas without requiring complete reconfiguration of the entire multi-band system, thereby reducing the complexity of coverage area optimization compared to a full-system approach.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

Instead of applying cell border shifting to all frequency bands simultaneously, the patent implements partial action by shifting only Band 2's cell border. This partial approach achieves the primary goal of reducing common interference areas and improving SINR for cell edge users without incurring the full complexity of optimizing all bands, making the solution more manageable and easier to implement.

Inventive Principle:
Principle #16Partial or excessive action

3Object-affected harmful factors

If multiple frequency bands are deployed with separate cell borders, then interference management is improved, but network configuration complexity increases

Engineering Contradiction:
Improveinterference managementVSAvoidnetwork configuration
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent performs preliminary cell border shifting configuration during network planning and deployment, specifically pre-configuring Band 2's cell border position to minimize common interference areas with Band 1. By establishing the optimal cell border positions in advance rather than dynamically adjusting them during operation, the patent simplifies real-time network configuration and reduces the complexity of interference management during system operation.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3804387B1Cell border shifting for multiple frequency bands
Publication Date: 2025.10.01 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3804387B1 patent drawingFigure 1
  • EP3804387B1 patent drawingFigure 2
  • EP3804387B1 patent drawingFigure 3

AI summary

According to certain embodiments, a method by a network node (860) for shifting cell borders of multiple frequency bands includes deploying at least two frequency bands. Each of the at least two frequency bands have at least two cells, and each cell have an associated cell coverage area within a common target coverage area. Each of the at least two frequency bands are associated with a respective interference area along a respective cell border, and each interference area is characterized by interference from an adjacent cell. The associated cell coverage area of at least one of the at least two frequency bands is adjusted such that the respective cell border of the at least one of the at least two frequency bands is shifted to reduce a common interference area of the at least two frequency bands. The common interference area is an area where the respective cell borders of the at least two frequency bands overlap.