Orthogonal Pseudo-Random Waveforms for Covert Wireless Communications
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Solution Overview
Problem
Current wireless communication systems face challenges in providing low interference, high privacy, and cognitive flexibility due to increasing demand for multimedia broadband services, with existing LPI/LPD/LPE and JR communications systems being suboptimal in detecting and identifying spread-spectrum signals in changing noise environments.
Innovation Solution
A wireless communication system using waveforms devoid of cyclostationary signatures, generated through Gram-Schmidt Orthogonalization of Gaussian-distributed seed waveforms, to create orthonormal functions that reduce cyclostationary signatures and enhance covertness and privacy, allowing for Low Probability of Intercept, Low Probability of Detection, and Low Probability of Exploitation communications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hybrid spread-spectrum waveforms (FH/DSPN/TH) are used to increase covertness and resistance to jamming, then LPI/LPD/LPE performance is improved, but detectability by radiometric approaches remains insufficient in changing noise environments
Solution Approach 1:
The patent applies dynamics by making the waveform parameters adaptive to changing environments. The system dynamically adjusts the spread-spectrum waveform characteristics based on real-time noise and interference conditions, allowing the communication system to maintain optimal LPI/LPD/LPE performance across varying environmental conditions rather than using fixed parameters
Solution Approach 2:
The patent changes physical parameters of the waveform including amplitude, frequency, and temporal characteristics to eliminate cyclostationary features. By transforming the waveform parameters to create a Gaussian-distributed process without cyclostationary signatures, the system achieves better adaptability to changing noise environments while maintaining reliability
2Reliability
If waveform alphabets are generated based on statistical distributions responsive to keys and TOD values, then covertness and privacy are increased by eliminating cyclostationary signatures, but waveform generation complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-generating waveform alphabets based on statistical distributions and storing them for later use. The waveforms are prepared in advance responsive to keys and TOD values, eliminating the need for complex real-time generation while maintaining high covertness and privacy through the elimination of cyclostationary signatures
Solution Approach 2:
The patent uses copying by generating waveform alphabets that can be replicated and reused. Once waveforms are generated based on the statistical distributions and keys, they can be copied and transmitted without regenerating them, reducing computational complexity while maintaining the covert and private communication properties
Data Source
AI summary
An available signal space, whether it is a priori specified or is cognitively determined based upon an assessment of frequency utilization, serves to provide a number of signal dimensions which may be occupied by a number of pseudo-randomly generated waveforms. The number of pseudo-randomly generated waveforms may be based upon a key input to a pseudo-random number generator and a desired statistical distribution and may be subjected to an orthogonalization procedure to produce a respective number of orthogonal pseudo-random waveforms which may serve as a communications alphabet. A specific data sequence to be communicated may be associated with a respective specific element/member of the orthogonal pseudo-random waveforms and that specific element/member may be transmitted in lieu of the specific data sequence. Systems/methods of spread-spectrum communications that are substationally devoid of revealing signatures such as chipping and cyclostationarity are presented, offering increased privacy, reduced detectability and reduced exploitation of communications.