Wakeup Receiver Frequency Calibration for Low-Power Interference Rejection
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Solution Overview
Problem
Wakeup receivers in wireless communication systems face challenges with high power consumption due to limited filtering capabilities and vulnerability to interference, as they rely on free-running oscillators with inaccurate frequencies, leading to reduced signal-to-noise ratios and increased interference sensitivity.
Innovation Solution
A wireless communication device with a dual transceiver architecture, including a main transceiver and a wakeup transceiver, where the wakeup transceiver features a free-running digitally controlled oscillator for low power consumption, accompanied by an ultra-low power transmitter that periodically sends signals to a base station, allowing the base station to determine and adjust the oscillator frequency, thereby improving filtering and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a free-running oscillator is used in the wakeup receiver to minimize power consumption, then power consumption is reduced, but frequency accuracy deteriorates leading to vulnerability to interference
Solution Approach 1:
The patent introduces an intermediary frequency calibration mechanism where the wakeup receiver periodically measures the frequency offset of the free-running oscillator and reports it to the network. The network then provides compensation information to adjust the oscillator frequency, effectively mediating between the low-power free-running operation and the need for frequency accuracy.
Solution Approach 2:
The system implements periodic frequency calibration actions where the wakeup receiver occasionally activates to measure oscillator drift and communicate with the network for frequency correction. This periodic intervention maintains frequency accuracy without requiring continuous operation of power-hungry frequency control circuits.
2Use of energy by moving object
If modest filtering is applied prior to amplitude detection to maintain low power consumption, then power consumption is limited, but interference rejection capability deteriorates
Solution Approach 1:
The patent implements feedback mechanisms where the wakeup receiver periodically measures channel conditions and interference levels, reports this information to the network, and receives adjusted filtering parameters or frequency calibration data. This feedback loop enables adaptive interference rejection without continuously operating complex filtering circuits.
Solution Approach 2:
The system performs preliminary frequency calibration and interference assessment during periodic wakeup intervals before returning to sleep mode. This preliminary action prepares the system for better interference rejection in the next active period without requiring continuous power consumption.
3Speed
If the wakeup receiver operates regularly to achieve short response time, then response time is reduced, but power consumption increases
Solution Approach 1:
The wakeup receiver operates in periodic intervals rather than continuously, balancing response time requirements with power consumption. The system wakes up at predetermined intervals to check for signals, maintaining acceptable response times while significantly reducing average power consumption compared to continuous operation.
Solution Approach 2:
The system dynamically adjusts the wakeup interval based on operational requirements, traffic patterns, and power availability. This dynamic operation allows the receiver to be more frequent when fast response is critical and less frequent when power saving is prioritized, optimizing the trade-off between response time and power consumption.
Data Source
AI summary
A wireless communication device (100) comprises a first transceiver (110) comprising a first frequency synthesizer (112) which comprises a first digitally controlled oscillator (DCO1) and a crystal oscillator (XO). The wireless communication device (100) further comprises a second transceiver (120) comprising a wakeup receiver (Rx2), a second transmitter (Tx2) and a second digitally controlled oscillator (DCO2) connected to the wakeup receiver (Rx2) and second transmitter (Tx2). The wireless communication device (100) further comprises a control unit (170) configured to control operation of the wireless communication device. The second transmitter (Tx2) is configured to transmit periodically a signal to a base station. The signal is modulated by a code identifying the wireless communication device (100) and transmitted at a frequency set by the second digitally controlled oscillator (DCO2).