EHT-LTF Sequence Design for PAPR Reduction in Distributed Tone RUs

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Solution Overview

Problem

In 6 GHz low-power indoor (LPI) wireless communication systems, the distribution of small resource unit tones over a wider bandwidth results in high peak-to-average power ratio (PAPR) due to non-continuous subcarriers, limiting transmission power and coverage range.

Innovation Solution

The proposed solution involves generating and transmitting a 4×EHT-LTF sequence with a subcarrier spacing resolution of four times the regular spacing for uplink trigger-based physical-layer protocol data units with distributed-tone resource units, optimizing the EHT-LTF sequence per bandwidth and distributed-tone size to reduce PAPR.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If small resource unit tones are distributed over a wider bandwidth to achieve higher transmission power, then coverage range is improved, but peak-to-average power ratio increases

Engineering Contradiction:

Improvetransmission powerVSAvoidpeak-to-average power ratio

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent changes the subcarrier spacing parameter from regular spacing to 4× subcarrier spacing for EHT-LTF sequences in distributed-tone RUs. This parameter change reduces the PAPR by spreading the frequency components more sparsely, thereby lowering the peak power while maintaining the distributed-tone structure needed for coverage extension.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent segments the EHT-LTF sequence into distributed-tone structures with 4× subcarrier spacing, separating adjacent subcarriers to reduce constructive interference that causes high PAPR. This segmentation approach allows the system to maintain distributed-tone RUs for coverage extension while mitigating the PAPR increase through strategic spacing of frequency components.

Inventive Principle:

Principle #1Segmentation

2Device complexity

If EHT-LTF sequence of regular RU is directly reused for dRU transmission, then implementation complexity is reduced, but PAPR increases

Engineering Contradiction:

Improveimplementation complexityVSAvoidpeak-to-average power ratio

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by making the EHT-LTF sequence design specific to distributed-tone RUs rather than universally reusing regular RU sequences. The 4× subcarrier spacing is specifically applied to dRU configurations where PAPR reduction is needed, while maintaining standard spacing for regular RUs. This localized adaptation solves the PAPR issue only where distributed-tone structures are used.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11817985B2EHT-LTF sequence design for distributed-tone resource units with PAPR reduction

Publication Date: 2023.11.14 MEDIATEK SINGAPORE PTE LTD

AI summary

Various schemes pertaining to extremely-high-throughput long training filed (EHT-LTF) sequence design for distributed-tone resource units (dRUs) with peak-to-average power ration (PAPR) reduction in 6 GHz low-power indoor (LPI) systems are described. A communication entity distributes subcarriers of a RU with a resolution of four times (4×) subcarrier spacing to generate a 4×EHT-LTF of an uplink (UL) trigger-based (TB) physical-layer protocol data unit (PPDU) with a dRU. The communication entity then transmits the 4×EHT-LTF for the UL TB PPDU with dRU.