Frequency Hopping Using Relative Deviations for Low-Complexity Links
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Solution Overview
Problem
Existing frequency hopping techniques require high performance and energy-consuming radio stages with precise synchronization, making them unsuitable for low-cost, low-complexity devices like those used in very low bandwidth, long range radio frequency communication systems, which are limited by deep fading phenomena and high energy consumption.
Innovation Solution
A frequency hopping method where frequency jumps follow a pseudo-random temporal sequence, allowing the transmitter to randomly select a first frequency and subsequent frequencies with deviations, enabling transmission over a wideband channel while maintaining sensitivity, without requiring prior synchronization or complex oscillator stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional frequency hopping techniques are used to combat deep fading phenomena, then communication reliability is improved, but device complexity and energy consumption increase significantly
Solution Approach 1:
The patent changes the fundamental parameter of frequency hopping from requiring precise oscillator stability and synchronization to using simple frequency deviations from a center frequency. By transforming the frequency hopping mechanism from an absolute frequency sequence to a relative deviation sequence, the system achieves the same diversity gain against fading while reducing oscillator requirements to simple, low-cost components that can tolerate much greater stability variations.
Solution Approach 2:
The patent replaces expensive, high-precision oscillators with cheap, low-precision oscillators that have short-lived stability characteristics. The system accepts that these inexpensive oscillators will drift and vary in frequency, but compensates by using simple frequency deviations from a center frequency rather than requiring absolute frequency accuracy. This allows low-cost devices to achieve frequency hopping benefits without the burden of expensive precision components.
2Reliability
If bandwidth is reduced to increase receiver sensitivity for long-range communication, then receiver sensitivity is improved, but data rate decreases to very low levels
Solution Approach 1:
The patent segments the communication approach by separating the sensitivity-enhancing narrowband reception from the diversity-providing frequency hopping. The system uses narrowband Ultra-Narrow-Band technology for high sensitivity long-range reception, then overlays simple frequency deviations on top of this narrowband signal. This segmentation allows the system to maintain the high sensitivity of narrowband communication while adding frequency diversity to combat fading, avoiding the need to choose between sensitivity and data rate.
3Reliability
If precise synchronization is implemented to enable frequency hopping, then frequency hopping performance is improved, but energy consumption increases
Solution Approach 1:
The patent makes the frequency hopping system self-synchronizing by using simple frequency deviations that are inherently detectable without complex synchronization protocols. The receiver can automatically track the transmitter's frequency deviations using basic correlation techniques, eliminating the need for energy-intensive synchronization handshaking, timing alignment, and frequency calibration procedures. The system serves itself by making the hopping pattern obvious and trackable through simple signal processing rather than complex coordinated protocols.
Data Source
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AI summary
The invention relates to a method for data communication by frequency hopping in a first frequency band, wherein the frequency hops follow a predetermined time sequence, known at least to one data transmitter, characterised in that it comprises the steps implemented by said data transmitter: - Defining, from a pseudorandom selection, the successive values of the respective gaps in frequency (∆fs1, ∆fs2, ∆fs3, etc.; ∆fd1, ∆fd2, ∆fd3, etc.) to determine the time sequence of hops from a first frequency (f1), - Transmitting to at least one data receiver · at a first frequency (f1), said first frequency being chosen randomly (S1) in the first frequency band, · then at successive frequencies (S5), applying, as from the first frequency, said successive frequency gap values, said successive frequency gap values defining, upon reception, a series of frequencies for the reception of useful data to be received from said data transmitter.