OFDM Carrier Spacing Optimization for Interference Reduction

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Wireless communication systems face challenges in maintaining orthogonality between tones from different carriers, leading to signal interference and separation issues due to varying OFDM symbol durations and time offsets.

Innovation Solution

Implementing a method that verifies and synchronizes OFDM symbol durations between carriers, ensures minimal time offsets, and calculates a carrier spacing that is an integer multiple of the tone spacing to maintain orthogonality and facilitate signal separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If carrier spacing is increased to reduce interference between OFDM carriers, then signal separation is improved, but frequency resource utilization deteriorates

Engineering Contradiction:
Improveinterference between carriersVSAvoidfrequency resource utilization
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent changes the carrier spacing parameter from arbitrary values to specifically optimized values that are integer multiples of the OFDM symbol duration reciprocal. This parameter optimization allows carriers to be spaced sufficiently to reduce interference while maintaining tight packing for efficient frequency resource utilization.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If OFDM symbol duration is extended to improve orthogonality between tones, then signal separation is improved, but transmission time increases

Engineering Contradiction:
Improveorthogonality between tonesVSAvoidtransmission time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent optimizes the OFDM symbol duration parameter to a specific value that is the reciprocal of the tone spacing. This optimization ensures that orthogonality is maintained between tones while minimizing the symbol duration and thus reducing transmission time.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If time synchronization is tightened to maintain orthogonality between carriers, then signal separation is improved, but system complexity increases

Engineering Contradiction:
Improveorthogonality between carriersVSAvoidsynchronization mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent optimizes the carrier spacing parameter to be an integer multiple of the reciprocal of the OFDM symbol duration. This parameter optimization creates a robust system where orthogonality between carriers is maintained even with relaxed time synchronization requirements, thereby reducing system complexity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2286563B1Interference reduction between OFDM carriers by carrier spacing optimization
Publication Date: 2022.10.05 QUALCOMM INC
  • EP2286563B1 patent drawingFigure 1
  • EP2286563B1 patent drawingFigure 2
  • EP2286563B1 patent drawingFigure 3

AI summary

Systems and methodologies are described that facilitate signal separation across different carriers within a wireless communications environment. The systems and methods can identify a carrier spacing that can be based upon a tone spacing associated with two or more carriers. Such carrier spacing can be employed within a network in order to mitigate signal separation with multiple carriers. The subject innovation can further evaluate a carrier raster associated with a network in order to identify a carrier spacing to ensure orthogonality between tones from different carriers.