Receiver ADC Sleep-Wake Architecture for Fast OFDM Synchronization
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Solution Overview
Problem
In Orthogonal Frequency Division Multiplexing (OFDM) systems, receivers face delays in establishing or re-establishing control parameters, especially when in sleep mode, due to the lack of advance notification and the need for rapid re-acquisition upon wake-up, which complicates power management and synchronization.
Innovation Solution
Implementing an auxiliary reduced power ADC and processing chain during sleep periods to maintain up-to-date control parameters, allowing the main ADC and processing chain to be turned off, and quickly switched on at the end of sleep periods for immediate data reception, using a low dynamic range ADC for signaling information to reduce power consumption and wake-up time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the receiver employs sleep mode to save power, then power consumption is reduced, but wake-up time and synchronization delay increase
Solution Approach 1:
The patent segments the ADC into two distinct components: a main high-resolution ADC for full data reception and an auxiliary low-resolution ADC for signaling information only. This segmentation allows the receiver to maintain power savings during sleep mode while still acquiring control parameters, thereby reducing wake-up time without significantly increasing power consumption.
Solution Approach 2:
The auxiliary ADC performs preliminary action by acquiring control parameters (time offset, frequency offset, channel profile) during sleep mode before the main ADC is activated. This preliminary acquisition of synchronization information reduces the time required for parameter establishment upon wake-up, directly addressing the wake-up time delay problem.
2Use of energy by moving object
If the main ADC and processing chain are turned off during sleep mode, then power consumption is reduced, but control parameters become outdated
Solution Approach 1:
The patent divides the signal processing function between two ADCs with different resolutions. The auxiliary low-resolution ADC is sufficient for extracting control parameters from signaling information, while the main high-resolution ADC handles full data reception. This segmentation maintains parameter accuracy while enabling power savings.
Solution Approach 2:
The auxiliary ADC creates a simplified copy of the reception function, processing only signaling information to generate control parameters. This copy is sufficient for synchronization purposes and allows the main ADC to remain off during sleep mode without losing parameter accuracy.
3Measurement precision
If a high-resolution ADC is used continuously, then data reception accuracy is maintained, but power consumption increases
Solution Approach 1:
The patent segments the ADC functionality based on signal type: high-resolution for data reception, low-resolution for signaling information. This segmentation maintains measurement precision when needed while reducing power consumption during sleep mode.
Solution Approach 2:
The patent applies different quality levels (resolution) to different parts of the signal processing: high resolution for the main ADC handling data, low resolution for the auxiliary ADC handling signaling. This local quality differentiation maintains accuracy for critical functions while reducing power consumption overall.
Data Source
AI summary
An auxiliary reduced power analog-to-digital converter (ADC) is provided for use during sleep periods of a receiver. The auxiliary ADC has a reduced dynamic range but sufficient accuracy to allow demodulation of signaling information contained in an input signal and to update control parameters used for synchronization and channel estimation. As such, a main higher power, higher dynamic range ADC can be turned off during sleep periods, reducing receiver power consumption. The main ADC is turned on at the end of a sleep period, and the receiver can be ready for receiving data immediately using the main ADC because the control parameters are maintained up to date during the sleep period using the auxiliary ADC.