Coherent Chaos-Based Communication System
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Solution Overview
Problem
Current chaos-based communications systems face limitations in throughput due to analog chaos generator drift, leading to synchronization challenges and reduced data transmission rates, while non-coherent systems suffer from error rate performance and exploitability issues.
Innovation Solution
A coherent chaos-based communication system that uses digitally generated chaotic sequences and phase modulation to create a spread spectrum format, allowing for synchronized data transmission without constant state information exchange, and implements permission-controlled access for multiple users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If analog chaos generator circuits are used to generate chaotic signals, then chaotic properties are achieved, but drift occurs over time requiring constant state information exchange which reduces throughput
Solution Approach 1:
The patent replaces analog chaos generator circuits with a digital chaos generator implemented as a state machine in a field programmable gate array (FPGA). This substitution eliminates the drift problem inherent in analog circuits while maintaining chaotic signal properties, thereby resolving the contradiction between signal stability and data throughput.
2Measurement precision
If state information is exchanged frequently between transmitter and receiver to maintain synchronization, then synchronization accuracy is improved, but data transmission rate decreases
Solution Approach 1:
The digital chaos generator is designed to be self-synchronizing through the use of a synchronization word that is automatically recognized and processed by the receiver's state machine. This eliminates the need for continuous state information exchange, allowing the system to maintain synchronization accuracy while preserving high data transmission rates.
3Device complexity
If multiple pseudo-random number generators are used to generate chaotic-like sequences, then sequence complexity increases, but true chaotic properties are not achieved
Solution Approach 1:
The patent implements a digital chaos generator that uses a non-linear feedback function with specific parameters (a=3, b=7, c=0, d=11) to generate truly chaotic sequences. By carefully selecting these parameters, the system achieves genuine chaotic properties with deterministic behavior that is computationally efficient and suitable for spread spectrum communication applications.
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 throughput by reducing drift-related synchronization issues and maintains low probability of intercept and detection characteristics, while enabling secure, permission-based multiple access communication.
Implementation Method 1
Chaotic systems can generally be thought of as systems which vary unpredictably unless all of its properties are known. When measured or observed, chaotic systems do not reveal any discernible regularity or order. Chaotic systems are distinguished by a sensitive dependence on a set of initial conditions and by having an evolution through time and space that appears to be quite random.
Implementation Method 2
phase modulating a data signal including protected data symbols to form a phase modulated signal
Data Source
AI summary
Systems (100) and methods for selectively controlling access to multiple data streams which are communicated using a shared frequency spectrum and spreading code. The methods involve forming a global data communication signal (134) by amplitude modulating a global data signal (130) comprising global data symbols and forming a phase modulated signal (120) by phase modulating a protected data signal. The phase modulated signal represents protected data symbols. The methods also involve forming a protected data communication signal (126) by changing phase angles of the protected data symbols using a variable angle Ø determined by a random number source and combining the protected data signal with a spreading sequence (CSC). The methods further involve combining the global and protected data communication signals to form an output communication signal (140) having a spread spectrum format. The output communication signal is transmitted over a communications channel (104).