Low-Power Wake-Up Signal Procedures for Time-Frequency Synchronization
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Solution Overview
Problem
Existing wireless communication systems face challenges in achieving power-efficient time and frequency synchronization during low-power wake-up signal procedures, as conventional methods like discontinuous reception (DRX) do not fully address the power consumption issues associated with maintaining synchronization.
Innovation Solution
Implementing a low-power wake-up receiver (LP-WUR) that can be switched on and off quickly to receive and process simple signals, such as those modulated using on-off keying (OOK), in addition to the main radio for receiving OFDM transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main radio is continuously activated to maintain time and frequency synchronization, then synchronization reliability is improved, but power consumption increases
Solution Approach 1:
The radio system is segmented into two functional parts: a low-power wake-up receiver that consumes minimal power for basic signal detection, and a main radio that handles full OFDM transmissions. This segmentation allows the main radio to remain off during idle periods while the wake-up receiver maintains basic synchronization capabilities, resolving the contradiction between continuous synchronization reliability and power consumption.
Solution Approach 2:
A wake-up signal acts as an intermediary between the network and the main radio. The low-power wake-up receiver detects this intermediate signal to trigger main radio activation only when necessary. This intermediary mechanism eliminates the need for continuous main radio operation while maintaining reliable synchronization through event-driven activation.
2Use of energy by moving object
If the UE enters sleep mode to save power, then power consumption is reduced, but ability to receive downlink communications deteriorates
Solution Approach 1:
The low-power wake-up receiver performs preliminary detection of downlink signals before the main radio is activated. By预先 detecting the presence of a wake-up signal, the system can transition the main radio from sleep mode to active state in time to receive the actual downlink communication, ensuring no data is missed while minimizing power consumption during idle periods.
Solution Approach 2:
The radio system dynamically switches between sleep mode and active mode based on the presence of wake-up signals. The low-power wake-up receiver continuously monitors for activation signals, and upon detection, triggers the main radio to wake up. This dynamic state transition optimizes the balance between power consumption and downlink reception reliability.
3Use of energy by moving object
If DRX procedures are used to reduce power consumption, then power savings are achieved, but synchronization maintenance capability is insufficient
Solution Approach 1:
The reception function is segmented into two layers: a always-on low-power wake-up receiver that maintains basic time and frequency synchronization by detecting wake-up signals, and a periodic DRX-mode main radio that handles full communications. This segmentation allows synchronization maintenance at the wake-up receiver level without requiring continuous main radio operation, achieving both power savings and synchronization reliability.
Data Source
AI summary
Aspects of the disclosure are directed to methods and apparatus for time and frequency synchronization during a low-power wake up signal (LP-WUS) procedure. For example, an LP-WUS procedure may include transmission of signaling modulated via on-off keying (OOK). Such a signal requires less processing relative to an orthogonal frequency division multiplexing (OFDM) modulated signal and can be used to notify a wireless node that the transmitting device has data to transmit to the wireless node via an OFDM transmission. Accordingly, in response to the LP-WUS signal, the wireless node may power-on a main radio capable of receiving and demodulating the OFDM transmission.