Multicarrier OOK Waveform Generation Using OFDM Symbol Mapping
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Solution Overview
Problem
Current implementations of On-Off Keying (OOK) signals in wake-up receivers face challenges in achieving low complexity and efficient power management, particularly in high data rate scenarios, due to the need for modifications in existing chipsets and the limitations of inverse Fast Fourier Transform (IFFT) in generating Manchester coded OOK waveforms.
Innovation Solution
The approach involves designing sets of complex-valued frequency domain symbols that, when transformed via IFFT and cyclic prefix insertion, produce Partial OOK (P-OOK) signals with reduced OFF power relative to ON power, allowing for power spectrum flattening and efficient transmission, even in legacy chipsets, by using specific symbol constellations like 256 QAM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional IFFT-based multicarrier OOK is used, then power consumption is reduced through wake-up receiver operation, but implementation complexity increases due to required modifications in existing chipsets
Solution Approach 1:
The patent changes the fundamental parameter of OOK signal generation from time-domain switching to frequency-domain symbol selection. By selecting specific complex-valued frequency domain symbols that map to desired OOK waveforms after IFFT transformation, the system achieves low-complexity implementation using existing OFDM transmitters without requiring additional time-domain switching hardware or modifications to the transmitter architecture.
Solution Approach 2:
The patent replaces the mechanical/time-domain switching approach (using switch arrangements to select between ON and OFF waveforms) with a frequency-domain computational approach. Instead of physically switching between signal states in the time domain, the system computes appropriate frequency domain symbols and uses the existing IFFT processor to generate the desired OOK waveform, substituting mechanical switching with mathematical transformation.
2Productivity
If multicarrier OOK with IFFT is implemented, then data transmission capability is improved, but power efficiency deteriorates due to high peak power requirements
Solution Approach 1:
The patent transforms the OOK signal generation problem from the time domain to the frequency domain by selecting appropriate complex-valued frequency domain symbols. This parameter transformation enables the system to control the time-domain waveform characteristics (including peak power) through frequency-domain symbol selection, allowing optimization of both data transmission capability and power efficiency simultaneously.
Solution Approach 2:
The patent performs preliminary computation of frequency domain symbols that are specifically designed to produce desired OOK waveforms with controlled peak power characteristics. By pre-calculating and selecting frequency domain symbols that map to efficient time-domain waveforms, the system avoids the need for high peak power transmission while maintaining data transmission capability.
3Ease of manufacture
If conventional OOK generation with switch arrangement is used, then signal generation is straightforward, but device complexity increases due to additional switching components
Solution Approach 1:
The patent eliminates mechanical/time-domain switching components by substituting them with frequency-domain computational methods. Instead of using switch arrangements to select between pre-generated ON and OFF waveforms, the system directly computes the appropriate frequency domain symbols and uses the existing IFFT processor to generate the OOK signal, removing the need for additional switching hardware.
Solution Approach 2:
The patent makes the existing OFDM transmitter infrastructure perform the additional function of OOK signal generation without requiring dedicated OOK-specific components. By utilizing the existing IFFT processor and frequency domain processing capabilities already present in OFDM transmitters, the system achieves multi-functionality where the same hardware can generate both OFDM data signals and OOK wake-up signals.
Data Source
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AI summary
A method and transmitter for transmitting an On-Off Keying, OOK, signal which comprises an ON waveform and an OFF waveform forming a pattern representing transmitted binary information as a Manchester code. For one binary value of information to be transmitted, a first set of complex -valued frequency domain symbols is provided to an inverse fast Fourier transformer, or for the other binary value of information to be transmitted, a second set of complex -valued frequency domain symbols is provided to the inverse fast Fourier transformer. The inverse fast Fourier transform is performed to form an orthogonal frequency division multiplex, OFDM representation, including a cyclic prefix, of the OOK signal of information to be transmitted. The OFDM representation is then transmitted.