Low-Power Wake-Up Link Demodulation Using Non-OFDM Sync Symbols
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Solution Overview
Problem
Existing wireless communication systems face challenges in reducing power consumption, particularly in wake up links of terminals like wearable devices and wireless sensors, due to high power consumption in main links and wake up links, which affect battery life and production efficiency.
Innovation Solution
A method and apparatus for demodulating signals using non-orthogonal frequency division multiplexing (OFDM) symbols and cyclic prefixes (CPs) in low power links, allowing for reduced power consumption by determining time domain locations without precise time-frequency synchronization, and using simpler modulation schemes like FSK, ASK, or OOK.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM modulation is used in wake up link, then transmission efficiency is improved, but power consumption increases
Solution Approach 1:
The patent changes the modulation parameter from OFDM to non-OFDM (such as FSK, ASK, or OOK) for the wake up link, which simplifies the signal processing requirements and reduces power consumption while maintaining adequate transmission efficiency for wake up signals
Solution Approach 2:
The patent segments the communication system into two distinct links: a main link for high-efficiency data transmission and a wake up link for low-power synchronization and control signals, allowing each link to be optimized for its specific function
2Measurement precision
If precise time-frequency synchronization is performed, then signal demodulation accuracy is improved, but processing complexity increases
Solution Approach 1:
The patent uses simpler, less computationally intensive synchronization methods that do not require complex time-frequency synchronization, accepting adequate accuracy without the heavy processing overhead of precise synchronization algorithms
Solution Approach 2:
The patent extracts the essential synchronization function from the complex time-frequency synchronization process, achieving sufficient synchronization accuracy through simpler means that remove unnecessary processing complexity
3Use of energy by moving object
If non-OFDM symbols are used in wake up link, then power consumption is reduced, but transmission efficiency deteriorates
Solution Approach 1:
The patent applies different modulation qualities to different parts of the system: non-OFDM modulation is used specifically for the wake up link where power saving is critical, while OFDM can be used for the main data transmission link where transmission efficiency is prioritized
Data Source
AI summary
Embodiments of this application provide a method and an apparatus for demodulating a signal, and a method and an apparatus for sending a synchronization signal. A terminal device receives a synchronization signal over a low power link in at least two communication links, where the synchronization signal includes M first modulated symbols and N CPs, the M first modulated symbols are non-OFDM symbols, M is a positive integer greater than 1, and N is a positive integer. The terminal device determines time domain locations of the M first modulated symbols. The terminal device determines time domain locations of the N CPs based on the time domain locations of the M first modulated symbols. The terminal device demodulates, based on the time domain locations of the N CPs, a signal transmitted on the low power link.