HE-CPM Demodulation via ISI Phase Removal
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Solution Overview
Problem
Conventional methods for demodulating high-entropy continuous phase modulation (HE-CPM) signals require extensive computational resources due to the need for a bank of matched filters and trellis demodulation, which is inefficient and increases complexity with the order of the TRANSEC-generated symbols.
Innovation Solution
A receiver system that uses complex multipliers to remove phase associated with inter-symbol interference (ISI) hypotheses, generating soft decisions by combining real parts of complex multiplier outputs, thereby eliminating the need for a bank of matched filters and trellis demodulation, reducing computational complexity by an order of magnitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional matched filters and trellis demodulation are used for HE-CPM demodulation, then demodulation accuracy is maintained, but computational complexity increases significantly
Solution Approach 1:
The patent extracts and removes the phase component associated with inter-symbol interference (ISI) from the received HE-CPM signal using complex multipliers. By isolating and eliminating the ISI phase effect, the system simplifies the demodulation process while maintaining accuracy, avoiding the need for computationally intensive matched filters and trellis demodulation
Solution Approach 2:
The patent changes the approach from traditional filter-based demodulation to phase-removal-based demodulation. By transforming the problem from filtering in the time domain to phase manipulation in the complex domain, the system achieves the same demodulation accuracy with significantly reduced computational complexity
2Reliability
If the order of TRANSEC-generated symbols increases, then security and entropy of HE-CPM signal improve, but computational resources required for demodulation increase
Solution Approach 1:
The patent extracts only the essential ISI phase component from the signal, ignoring less significant factors. This selective extraction allows the system to handle higher-order symbols efficiently by focusing computational effort only on the critical phase removal operation rather than processing all signal components through complex filters
Solution Approach 2:
Instead of building up the demodulation process from traditional filtering approaches that scale poorly with symbol order, the patent inverts the approach by directly removing the ISI phase effect. This inverted methodology achieves constant computational complexity regardless of the TRANSEC symbol order, enabling efficient demodulation of high-security signals
Data Source
AI summary
A receiver system for demodulating a high-entropy continuous phase modulation (HE-CPM) signal is disclosed. A plurality of complex multipliers is configured to receive the synchronized HE-CPM signal. Each of the complex multipliers removes a phase associated with a respective one of a plurality of inter-symbol interference (ISI) hypotheses and generates a respective one of a plurality of complex multiplier outputs. Each ISI hypothesis includes a previous chip hypothesis corresponding to a binary value for a previous chip, and a next chip hypothesis corresponding to a binary value for a next chip. A summer is configured to combine real parts of the plurality of complex multiplier outputs to generate a soft decision for a current chip of the HE-CPM signal.