Asymmetric Frequency Spreading With Dynamic Offset for Small Sub-Bands
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Solution Overview
Problem
Polar phase modulators introduce phase modulation errors that are difficult to eliminate completely, leading to residual impairments in radio frequency signals due to constraints on digitally controlled oscillators, which require large sub-bands to accommodate wide modulation bandwidths and environmental variations.
Innovation Solution
A communication device with a frequency spreading controller, accumulator, and subtractor is used to actively control frequency spreading by determining a frequency offset based on the margin between the signal frequency and sub-band limits, integrating this offset to generate a phase offset that is subtracted from the original phase modulation commands, thereby reducing phase-related errors without increasing sub-band size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If large sub-bands are used to accommodate wide modulation bandwidth and environmental variations, then the adaptability and reliability improve, but the phase noise and power consumption increase
Solution Approach 1:
The frequency spectrum is divided into multiple smaller sub-bands instead of using one large sub-band. The digitally controlled oscillator operates within a restricted frequency range corresponding to a small sub-band, while frequency spreading techniques spread the signal across a wider effective bandwidth. This segmentation reduces phase noise and power consumption while maintaining the ability to accommodate wide modulation bandwidth through spectral spreading.
Solution Approach 2:
The system dynamically adjusts the frequency offset parameter based on the margin between the signal frequency and sub-band limits. By changing the frequency offset parameter adaptively, the system maintains reliable operation within a small sub-band while effectively utilizing the available spectral space, thereby reducing power consumption and phase noise without sacrificing adaptability.
2Reliability
If large sub-bands are used to accommodate environmental variations, then the reliability improves, but the device complexity increases
Solution Approach 1:
The system continuously monitors the margin between the signal frequency and the sub-band limits, and uses this feedback to dynamically adjust the frequency offset. This closed-loop feedback mechanism ensures that the digitally controlled oscillator remains within the restricted frequency range while maintaining reliable operation under environmental variations, without requiring complex management of large sub-bands.
Solution Approach 2:
The frequency offset is made dynamic rather than static, allowing the system to adapt to environmental variations in real-time. The frequency spreading controller adjusts the offset based on current operating conditions, enabling the system to maintain reliability within a small, fixed sub-band without increasing device complexity.
3Manufacturing precision
If frequency spreading is used to reduce phase errors, then the manufacturing precision improves, but the device complexity increases
Solution Approach 1:
A frequency spreading controller acts as an intermediary between the modulator and the digitally controlled oscillator. This intermediary component generates the frequency offset and manages the spreading operation, simplifying the overall system architecture while achieving phase error correction. The intermediary absorbs the complexity of frequency spreading control, allowing the core modulation system to remain simple and precise.
Data Source
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AI summary
A wireless communication device for asymmetrical frequency spreading including a processor configured to receive a frequency band message comprising a maximum difference and a minimum difference, wherein the maximum difference is between a maximum frequency of a sub-band and a signal frequency, and wherein the minimum difference is between the minimum frequency of the sub-band and the signal frequency compare the maximum difference and the minimum difference with each other; and generate a frequency shift based on the comparison.