Non-Coherent OFDM Wake-Up Modulation for Low-Power Detection
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Solution Overview
Problem
Existing wireless communication technologies face challenges in reducing power consumption during low-power modes, particularly when using wake-up signals (WUS) due to the need for costly synchronization and multi-carrier-based receivers, which are inefficient in scenarios with tight reachability requirements and extended DRX cycles.
Innovation Solution
Implementing a non-coherent modulation scheme, such as OOK or FSK, for wake-up signals, which are shaped and modulated onto OFDM subcarriers, allowing detection by a low-power receiver without requiring synchronization, and cutting and cropping the reference signal to fit within multiple OFDM symbols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional multi-carrier-based receivers are used for wake-up signal detection, then detection capability is improved, but power consumption increases
Solution Approach 1:
The wake-up signal is segmented into multiple orthogonal frequency division multiplexing (OFDM) symbols, each carrying a portion of the signal. This segmentation allows the receiver to process the signal in smaller, more energy-efficient units while maintaining detection capability through the cumulative information from multiple symbols.
Solution Approach 2:
The patent employs periodic transmission of wake-up signals across multiple OFDM symbols with specific periodicity patterns. This periodic structure enables low-power receivers to detect signals through correlation over time without requiring continuous high-power operation, thus reducing overall power consumption while maintaining reliable detection.
2Measurement precision
If synchronization procedures are implemented for wake-up signal detection, then detection accuracy is improved, but system complexity and power consumption increase
Solution Approach 1:
The patent incorporates preliminary synchronization information directly into the wake-up signal structure itself, rather than requiring separate synchronization procedures. The signal design includes inherent reference patterns and known sequences that enable automatic correlation-based detection without complex preliminary synchronization steps, thus maintaining accuracy while reducing complexity.
Solution Approach 2:
The wake-up signal uses repeated copies of known reference patterns across multiple OFDM symbols. This copying approach enables simple correlation-based detection at the receiver, where the known patterns are compared against received signals to achieve accurate detection without requiring complex synchronization mechanisms.
3Length of stationary object
If wake-up signal duration is extended to improve reachability, then coverage is improved, but power consumption during listening increases
Solution Approach 1:
The patent uses periodic transmission of wake-up signals across multiple OFDM symbols, allowing terminals to listen intermittently rather than continuously. The periodic structure enables energy-efficient detection where the terminal can correlate received signals with expected patterns at specific intervals, extending effective coverage without requiring continuous high-power listening.
Solution Approach 2:
The extended wake-up signal is divided into multiple segments across different OFDM symbols. This segmentation allows terminals to process information in discrete, energy-efficient units rather than requiring continuous processing of a long uninterrupted signal, thus extending reachability while controlling power consumption during listening periods.
Data Source
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AI summary
A method includes obtaining a reference signal waveform (b, b 1 -b 5 ) which is defined in accordance with a non-coherent modulation scheme. The method also includes - shaping the reference signal waveform (b, b 1 -b 5 ) to obtain at least one signal waveform (x~) associated with one or more subcarriers (K) of a plurality of subcarriers (301-303). The method further includes inputting the at least one signal waveform to at least one corresponding channel (1552) of a multi-channel orthogonal frequency division multiplex, OFDM, modulator (F, 1502, 1503, 1504) and transmitting an OFDM symbol (s) output by the OFDM modulator (F, 1502, 1503, 1504).