Reference Signal Coordination for Interference Mitigation in LTE Networks

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Solution Overview

Problem

In wireless communication systems, particularly in LTE networks, the increasing number of mobile stations leads to interference issues due to inadequate bandwidth utilization and interference between semiautonomous base stations and macrocells, which existing technologies fail to effectively manage.

Innovation Solution

The method involves receiving transmission coordination information from a first wireless network node to control wireless transmissions from a second node, modifying receiver functionality based on the relationship between reference signals from multiple network nodes, and adjusting channel estimates to mitigate interference by selecting orthogonal cell IDs and restricting data/control signal transmissions during protected intervals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If multiple base stations transmit reference signals simultaneously, then network coverage and connectivity are improved, but interference between cells increases

Engineering Contradiction:
Improvenetwork coverageVSAvoidinterference between cells
Core Design Contradiction:
Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent implements periodic transmission of reference signals at specific time intervals (e.g., every 10ms or 20ms) rather than continuous transmission. This periodic action allows other base stations to remain silent during reference signal transmission periods, reducing interference while maintaining network coverage through scheduled repetitions.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system performs preliminary coordination between base stations to schedule reference signal transmissions in advance. By pre-coordinating which base station transmits reference signals during specific time intervals, the system prevents simultaneous transmissions that would cause interference, while ensuring all areas maintain coverage through planned signal sequences.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If semiautonomous base stations are deployed to manage small cells, then network capacity and flexibility are improved, but interference management complexity increases

Engineering Contradiction:
Improvenetwork capacityVSAvoidinterference management complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

Semiautonomous base stations automatically detect reference signal transmissions from neighboring cells and autonomously determine their own transmission schedules. The system enables base stations to self-configure their reference signal timing without manual intervention, reducing interference management complexity while maintaining high network capacity through distributed intelligence.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system implements feedback mechanisms where base stations monitor interference levels from neighboring cells and adjust their reference signal transmission timing accordingly. By continuously measuring interference and adapting transmission schedules, base stations automatically optimize network performance without requiring complex centralized coordination.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If reference signals are transmitted frequently for channel estimation, then receiver performance is improved, but bandwidth utilization decreases

Engineering Contradiction:
Improvechannel estimation accuracyVSAvoidbandwidth utilization
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system transmits reference signals at optimized intervals that provide sufficient channel estimation accuracy without excessive frequency. By determining the minimum necessary transmission frequency to maintain acceptable measurement precision, the system avoids over-transmission that would waste bandwidth while ensuring receiver performance remains adequate for reliable communication.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP2683105B1Methods and apparatus for coordination of sending reference signals from multiple cells
Publication Date: 2018.05.30 QUALCOMM INC
  • EP2683105B1 patent drawingFigure 1
  • EP2683105B1 patent drawingFigure 2
  • EP2683105B1 patent drawingFigure 3

AI summary

Methods and apparatus for coordination of sending reference signals in wireless network are disclosed. A network node may select a cell ID based on a measurement of adjacent cells so as to mitigate interference. A network node may communicate information to another network node to control transmitted resources in a protected interval so as to measure channel characteristics.