LTF Sequences for 320 MHz WiFi PAPR Reduction

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Solution Overview

Problem

Current Wi-Fi technologies face challenges in accurately estimating communication-channel characteristics for 320 MHz channels due to noise added by the wireless channel, which affects signal equalization, and existing LTF sequences do not efficiently manage peak-to-average power ratio (PAPR) for high-throughput channels.

Innovation Solution

The development of optimized long-training field (LTF) sequences for 320 MHz Wi-Fi channels and distributed resource unit (dRU)-LTF sequences for 20, 40, and 80 MHz channels, based on 80 MHz base sequences, which minimize PAPR and improve channel estimation by using specific algorithms and tone plans to reduce signal distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional LTF sequences are used for 320 MHz channels, then channel estimation can be performed, but the peak-to-average power ratio (PAPR) is high causing signal distortion

Engineering Contradiction:

Improvechannel estimation accuracyVSAvoidsignal distortion due to high PAPR

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the LTF sequence parameters by applying phase rotations and using optimized base sequences (e.g., Zadoff-Chu sequences with specific root indices) to reduce PAPR while maintaining channel estimation functionality. The phase rotation parameters are specifically designed to distribute signal energy more evenly across time and frequency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The 320 MHz channel is divided into multiple 80 MHz segments, each with its own optimized LTF sequence. This segmentation allows independent optimization of each segment's PAPR characteristics while maintaining overall channel estimation capability across the full 320 MHz bandwidth

Inventive Principle:

Principle #1Segmentation

2Productivity

If LTF sequences are designed for high-throughput 320 MHz channels, then data rate increases, but noise from the wireless channel degrades channel estimation accuracy

Engineering Contradiction:

Improvedata rateVSAvoidchannel estimation accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent incorporates feedback mechanisms where the receiver estimates channel characteristics using the optimized LTF sequences and feeds back channel state information to the transmitter. This feedback loop enables adaptive adjustment of transmission parameters to compensate for channel noise and maintain estimation accuracy at high data rates

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The LTF sequence design combines multiple mathematical sequences (Zadoff-Chu sequences, phase rotations, and interleaving patterns) to create a composite signal structure that provides both high data rate capability and robust noise resistance for accurate channel estimation

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS12107705B2LTF sequences for 320 MHz WiFi channels

Publication Date: 2024.10.01 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

A wireless communication device includes a communication interface and processing circuitry coupled to the communication interface. At least one of the communication interface or the processing circuitry can generate an orthogonal frequency-division multiple access (OFDMA) frame that includes a preamble that specifies allocation of at least one resource unit (RU) for a communication channel or nonallocation of the at least one RU for the communication channel. The preamble includes at least one long training field (LTF) to be used by a receiver for channel estimation. The LTF includes an extremely high-throughput (EHT)-LTF sequence.