High-Entropy GMSK Modulation Suppressing Cyclostationary Features
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional modulation types like QPSK and BPSK exhibit cyclic structure, making them susceptible to adversarial detection and limiting the low probability of detection (LPD) utility in communication systems.
Innovation Solution
A system and method using high-entropy Gaussian minimum shift keying (GMSK) modulation with multiple secondary GMSK modulators and complex signal multipliers to suppress cyclostationary features, generating a constant-envelope signal that resembles Gaussian distributed thermal noise, thereby reducing susceptibility to cyclostationary detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional modulation types (QPSK, BPSK) are used, then the communication signal can be transmitted, but the signal exhibits cyclic structure making it susceptible to adversarial detection
Solution Approach 1:
The patent applies parameter changes by transitioning from conventional fixed-modulation schemes (QPSK, BPSK) to high-entropy GMSK modulation with variable parameters including time-varying frequency shifts, random phase modulation, and dynamic symbol rates. This transforms the signal from cyclostationary to approximately stationary characteristics, suppressing detectable cyclic features while maintaining communication functionality.
Solution Approach 2:
The invention implements dynamics by making the modulation parameters time-varying and random rather than fixed. The system employs random phase modulation, time-varying frequency shifts, and dynamic symbol rates that change according to pseudo-random sequences. This dynamic characterization prevents unauthorized receivers from detecting consistent cyclic patterns, achieving low probability of detection.
2Power
If constant-envelope signal modulation is used, then more efficient non-linear power amplifiers can be utilized, but the signal must maintain constant envelope while suppressing cyclostationary features
Solution Approach 1:
The patent applies universality by designing a modulation system that simultaneously achieves multiple objectives: constant envelope maintenance for power amplifier efficiency, cyclostationary feature suppression for security, and high spectral efficiency for data transmission. The high-entropy GMSK modulator integrates these functions into a single modulation scheme, avoiding the need for separate processing stages.
Solution Approach 2:
The invention uses composite modulation techniques combining multiple modulation methods (GMSK, random phase modulation, frequency shifting) into a composite signal structure. This composite approach allows the signal to maintain constant envelope while incorporating multiple layers of randomness and feature suppression, achieving both power efficiency and security requirements.
3Reliability
If multiple secondary GMSK modulators are used to suppress cyclic features, then the signal becomes less detectable, but the system complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the modulation process into multiple independent stages, each handled by a separate GMSK modulator. The primary modulator handles the base signal while secondary modulators progressively suppress different orders of cyclic features. Each modulator operates independently with its own pseudo-random sequence, allowing modular implementation of feature suppression.
Solution Approach 2:
The invention introduces intermediary processing stages between the data modulation and final signal output. The secondary GMSK modulators act as intermediaries that process the signal through additional randomization and feature suppression stages. These intermediary modulators eliminate cyclic correlations without requiring direct manipulation of the final signal, simplifying the overall system architecture.
Data Source
AI summary
A system and method for generating a high entropy (HE) constant-envelope Gaussian minimum shift keying (GMSK) modulated signal with suppressed cyclostationary features is disclosed. In embodiments, the system includes a primary GMSK modulator for generating an initial GMSK signal based on a received data stream for transmission. The system includes a sequence of secondary GMSK modulators for generating a sequence secondary GMSK signals based on pseudorandom number sequences based on distinct chip rates. The initial GMSK signal is multiplied by the first secondary GMSK signal to generate an initial composite GMSK signal, which is sequentially multiplied by each subsequent secondary GMSK signal until a final composite GMSK signal is achieved, the final composite GMSK signal being a HE-GMSK constant-envelope signal with suppression of cyclic and cyclostationary features that might otherwise cause detection or interception of the signal.