Common Comb Reference Signal for OFDM and DFTS-OFDM

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Solution Overview

Problem

The use of different frequency division multiple access (FDM) technologies in downlink (DL) and uplink (UL) in wireless communication systems, such as OFDM and DFTS-OFDM, leads to issues in reference signal design and handling, particularly in LTE and the emerging NR standard, due to differing transmission schemes.

Innovation Solution

Implementing a common comb-based reference signal structure for both OFDM and DFTS-OFDM in uplink transmissions, allowing for symmetry and ease of handling across different FDM technologies, with the option to combine comb structures for increased density or leave resource elements empty to manage PAPR/CM differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If different FDM technologies (OFDM and DFTS-OFDM) are used for uplink transmissions, then transmission flexibility and adaptability are improved, but reference signal design complexity and handling difficulty increase

Engineering Contradiction:
Improvetransmission flexibilityVSAvoidreference signal design complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing a common reference signal structure that works for both OFDM and DFTS-OFDM transmissions. The comb-based reference signal pattern is defined in a waveform-independent manner, allowing the same reference signal design to serve multiple FDM technologies without requiring separate designs for each waveform type.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent segments the reference signal design into waveform-independent components (comb structure, resource element allocation patterns) and waveform-specific parameters (PAPR/CM constraints). This segmentation allows the common comb-based structure to be reused across different FDM technologies while accommodating their specific requirements through parameter adjustment.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If different FDM technologies are used, then transmission scheme diversity is improved, but reference signal handling symmetry and ease of operation deteriorate

Engineering Contradiction:
Improvetransmission scheme diversityVSAvoidreference signal handling symmetry
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The comb-based reference signal structure serves as a universal solution that maintains handling symmetry across different FDM technologies. By defining reference signals in terms of comb patterns rather than waveform-specific structures, the patent enables symmetric and unified reference signal processing for both OFDM and DFTS-OFDM transmissions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Quantity of substance

If comb structures are combined for increased density, then reference signal coverage is improved, but PAPR/CM management complexity increases

Engineering Contradiction:
Improvereference signal densityVSAvoidPAPR/CM management complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent applies local quality by allowing different comb configurations (single comb or combined combs) in different transmission scenarios based on local requirements. When high reference signal density is needed, multiple combs can be combined; when PAPR/CM management is critical, simpler single-comb structures can be used. This localized adaptation optimizes both density and complexity management.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3523911B1Common reference signal design for OFDM and DFTS-ofdm
Publication Date: 2025.12.03 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3523911B1 patent drawingFigure 1
  • EP3523911B1 patent drawingFigure 2
  • EP3523911B1 patent drawingFigure 3

AI summary

The present disclosure pertains to a terminal (10) for a Radio Access Network, the terminal (10) being adapted for transmission based on a first frequency division multiple access, FDMA, technology and for transmission based on a second frequency division multiple access technology. The terminal (10) is adapted for transmitting reference signaling having a comb structure for transmission based on either the first FDMA technology or the second FDMA technology. The disclosure also pertains to related devices and methods.