Closed-Loop Data Rate Control for Covert Signal Transmission
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Solution Overview
Problem
Existing communication systems face challenges in maintaining signal covertness, as adversaries can detect and intercept signals using 'Jam, Blank and Observe' detectors by causing senders to increase power, making signals more detectable.
Innovation Solution
Implementing closed-loop rate control to dynamically adjust communication signal rates, keeping power constant or below a threshold, thereby preventing signal detectability by adversaries, even in the presence of jamming attempts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal power is increased to improve signal-to-noise ratio for decoding, then the receiver can detect and decode the signal, but the signal becomes detectable by adversaries
Solution Approach 1:
The patent changes the parameter being controlled from signal power to data rate. By dynamically adjusting the data rate instead of power, the system can maintain reliable communication while keeping the spectral flux density below detection thresholds. The receiver adapts its decoding process to the varying data rates, extracting sufficient signal information without requiring power increases that would make the signal detectable.
2Object-affected harmful factors
If closed-loop power control is used to maintain constant power, then signal detectability is reduced, but signal-to-noise ratio may be insufficient for reliable decoding
Solution Approach 1:
The patent substitutes data rate control for power control. Instead of adjusting power to maintain signal-to-noise ratio, the system adjusts the data rate to match the available signal quality. This allows the receiver to reliably decode signals at the constant power level by adapting its decoding expectations to the actual signal conditions, without requiring power increases that would compromise covertness.
Solution Approach 2:
The patent introduces dynamic adaptation at the receiver side, where the decoding process dynamically adjusts to varying channel conditions and data rates. This dynamic decoding capability enables reliable communication at constant power levels by optimizing the decoding strategy according to the actual signal quality, eliminating the need for power control loops.
3Reliability
If data rate is reduced to increase energy per bit, then signal-to-noise ratio improves, but communication efficiency decreases
Solution Approach 1:
The patent implements dynamic data rate adjustment based on channel conditions and adversary detection status. When covertness is required, the data rate is reduced to increase energy per bit and maintain signal-to-noise ratio. When covertness is less critical, the data rate can be increased to improve communication efficiency. This dynamic approach optimizes the trade-off between reliability and productivity based on operational requirements.
Data Source
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AI summary
Transmitting a signal from a transmitter. A method includes identifying a threshold spectral flux density for a given physical location. The method further includes, as a result of identifying the threshold spectral flux density, transmitting a signal at a power level causing the signal to be below the spectral flux density at the given physical location, the signal being transmitted at a data rate. The method further includes receiving feedback from a receiver indicating the signal-to-noise ratio of the signal at the receiver. The method further includes adjusting the data rate of the signal based on the feedback. The method further includes continuing transmitting the signal at the adjusted data rate and power level.