Terminal Cyclic Prefix Adaptation for Compressed FTN Transmission

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Solution Overview

Problem

The increase in phase noise and propagation loss in high frequency bands beyond 52.6 GHz, along with sensitivity to peak-to-average power ratio (PAPR) and nonlinearity of power amplifiers, poses challenges for efficient radio communication.

Innovation Solution

A terminal that combines Faster-Than-Nyquist (FTN) transmission with Discrete Fourier Transform-Spread Orthogonal Frequency Division Multiplexing (DFT-s-OFDM) and adjusts the cyclic prefix (CP) length based on the time-domain compression rate to improve frequency utilization efficiency and PAPR.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If FTN transmission is applied to improve frequency utilization efficiency, then spectral efficiency increases, but inter-symbol interference and sensitivity to PAPR increase

Engineering Contradiction:

Improvefrequency utilization efficiencyVSAvoidinter-symbol interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the cyclic prefix length based on the compression factor α. When FTN transmission with higher compression (lower α) is used to improve frequency utilization, the system compensates by extending the cyclic prefix length to mitigate the resulting inter-symbol interference, thus resolving the contradiction between spectral efficiency and ISI sensitivity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements dynamics by making the cyclic prefix length adaptive rather than fixed. The cyclic prefix length is dynamically adjusted according to the compression factor, allowing the system to optimize the balance between frequency utilization efficiency and inter-symbol interference mitigation for different transmission conditions

Inventive Principle:

Principle #15Dynamics

2Reliability

If cyclic prefix length is increased to mitigate inter-symbol interference, then signal quality improves, but time resource overhead increases

Engineering Contradiction:

Improvesignal qualityVSAvoidtime resource overhead

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent resolves this contradiction through dynamic adjustment of cyclic prefix length based on the compression factor. Instead of using a consistently long cyclic prefix, the system adapts the CP length to match the actual interference level, thereby maintaining signal quality while minimizing time resource overhead when high compression is applied

Inventive Principle:

Principle #15Dynamics

3Productivity

If compression factor is decreased to increase symbol density, then frequency utilization efficiency improves, but PAPR sensitivity increases

Engineering Contradiction:

Improvefrequency utilization efficiencyVSAvoidPAPR sensitivity

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by adjusting the cyclic prefix length in response to changes in compression factor. When a lower compression factor is used to improve frequency utilization efficiency, the system compensates by increasing the cyclic prefix length, which helps mitigate the increased PAPR sensitivity and maintains signal quality

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12457141B2Terminal

Publication Date: 2025.10.28 NTT DOCOMO INC

AI summary

A terminal transmits and receives a slot configured with a plurality of symbols. The terminal sets a length of a cyclic prefix added to each symbol based on a degree of compression of each symbol in time domain.