OOK Cyclic Prefix Handling for Accurate OFDM Envelope Detection

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Solution Overview

Problem

In wireless communication systems, the conventional method of generating a cyclic prefix (CP) by duplicating the end of an OFDM symbol introduces false transitions at symbol boundaries in OOK waveforms, degrading envelope detection performance in ultra-low power devices, particularly under large sampling frequency offset conditions.

Innovation Solution

Generate the CP by duplicating samples from the beginning of the first OOK chip in an OFDM symbol, ensuring uniform length among all OOK chips to preserve chip-level timing alignment and avoid artificial edges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the CP is generated by duplicating the end of an OFDM symbol, then the CP effectively mitigates inter-symbol interference and facilitates synchronization, but false transitions are introduced at symbol boundaries that degrade envelope detection performance

Engineering Contradiction:

Improvesynchronization and ISI mitigationVSAvoidenvelope detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

Instead of duplicating samples from the end of the OFDM symbol (conventional approach), the patent inverts the approach by duplicating samples from the beginning of the first OOK chip. This reversal eliminates the false transitions at symbol boundaries that occur with end-duplication, while still providing the necessary cyclic prefix functionality for synchronization and ISI mitigation.

Inventive Principle:

Principle #13The other way round (Inversion)

2Measurement precision

If the CP is generated by duplicating samples from the beginning of the first OOK chip, then false transitions are avoided and envelope detection accuracy is improved, but the duration of the first OOK chip must be adjusted to maintain uniform timing alignment

Engineering Contradiction:

Improveenvelope detection accuracyVSAvoidchip duration adjustment complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the parameter of the first OOK chip duration to accommodate the CP insertion at the beginning. By adjusting the first chip's duration and accordingly modifying subsequent chip timing, the system maintains uniform timing alignment across all chips while enabling the beneficial beginning-duplication CP approach.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250343716A1System and method for cyclic prefix handling for OFDM based OOK waveform

Publication Date: 2025.11.06 SAMSUNG ELECTRONICS CO LTD

AI summary

A system and a method are disclosed for transmitting data in a wireless communication network. The method includes transmitting, by a network node, a bit stream comprising ambient Internet of things (A-IoT) data; generating an on-off keying (OOK)-1 or OOK-4 modulated waveform; generating a cyclic prefix (CP) by duplicating one or more samples of a first OOK chip in the waveform; appending the CP at the beginning of the first OOK chip in the waveform; and transmitting the waveform with the appended CP over a wireless channel to one or more A-IoT devices.