NFC Scan Oscillator Tuning for Reciprocal Mixing Errors
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Solution Overview
Problem
The IEEE 802.15.4 Scan process is prone to errors due to reciprocal mixing, where devices may incorrectly join or associate with unintended networks, leading to communication issues and increased power consumption, as they lack effective methods to differentiate between intended and unintended channels.
Innovation Solution
The proposed solution involves modifying the scan process by increasing the current of a voltage controlled oscillator (VCO) or digitally controlled oscillator (DCO), reducing or increasing the bandwidth of the phased locked loop, changing the reference frequency, or dithering the reference frequency to reduce phase noise and spurs, thereby improving the accuracy of channel detection and association.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the scan process uses standard oscillation parameters, then power consumption remains low, but phase noise and spurs increase causing reciprocal mixing and erroneous channel detection
Solution Approach 1:
The patent dynamically adjusts oscillation parameters (increasing VCO/DCO current, modifying PLL bandwidth, dithering reference frequency) specifically during the scan process to reduce phase noise and spurs, then returns to standard parameters afterward. This temporary dynamic adjustment during the critical scan window improves channel detection accuracy without permanently increasing power consumption.
Solution Approach 2:
The patent changes physical parameters of the oscillation system during scanning - specifically increasing the current of the VCO or DCO, adjusting the PLL bandwidth, and dithering the reference frequency. These parameter changes reduce phase noise and spurs during the scan, improving measurement precision for channel detection while the changes are temporary and localized to the scan operation.
2Reliability
If the scan process operates without parameter adjustments, then device complexity remains low, but reliability of network association decreases due to reciprocal mixing errors
Solution Approach 1:
The patent applies parameter adjustments (increasing VCO current, modifying PLL bandwidth, dithering reference frequency) as a preliminary action before and during the scan process to prevent reciprocal mixing errors before they occur. This proactive approach ensures reliable channel detection and network association by preparing the oscillation system in advance for the critical scanning operation.
3Ease of operation
If standard oscillation parameters are used during scanning, then device simplicity is maintained, but erroneous associations with unintended networks occur
Solution Approach 1:
The patent implements self-service by having the wireless device automatically adjust its own oscillation parameters during the scan process without external intervention. The device monitors its own scanning needs and applies appropriate parameter adjustments (VCO current increase, PLL bandwidth modification, reference frequency dithering) to eliminate reciprocal mixing errors, then automatically returns to standard operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the reliability of the scan process, reduces the likelihood of erroneous associations, and minimizes power consumption by effectively mitigating reciprocal mixing issues, leading to more successful and efficient near-field wireless communications.
Implementation Method 1
increasing a current of a voltage controlled oscillator (VCO)/digitally controlled oscillator (DCO) of the second wireless device
Implementation Method 2
reducing a bandwidth of the phased locked loop, increasing the bandwidth of the phased locked loop
Implementation Method 3
dithering the reference frequency
Data Source
AI summary
Exemplary systems, apparatus, and methods described herein may improve a scan process for near field communications, such as IEEE 802.15.4. The improvements may include, during the scan process, performing one of increasing a current of a voltage controlled oscillator (VCO)/digitally controlled oscillator (DCO) of a second wireless device, reducing a bandwidth of a phased locked loop, increasing the bandwidth of the phased locked loop, changing a reference frequency of the phased locked loop, or dithering the reference frequency.