NNPR Pulse-Shaping Filters for Spectral Efficiency Trade-Offs

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Solution Overview

Problem

Existing satellite communication systems face challenges in efficiently utilizing limited spectral resources due to interference and bandwidth constraints, particularly with conventional Nyquist-based pulse shaping filters, which often result in increased peak-to-average power ratio and sensitivity to timing jitters.

Innovation Solution

Implementing non-Nyquist partial response (NNPR) filters with tunable weighting factors to generate pulse-shaped signals, allowing controlled inter-symbol interference (ISI) for improved spectral efficiency and reduced adjacent channel interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional Nyquist-based pulse shaping filters are used, then inter-symbol interference is minimized, but peak-to-average power ratio increases and spectral efficiency is reduced

Engineering Contradiction:

Improveinter-symbol interference minimizationVSAvoidpeak-to-average power ratio

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the fundamental parameter of pulse shaping by transitioning from Nyquist-based filters to non-Nyquist partial response filters. This parameter change allows the system to accept controlled levels of inter-symbol interference in exchange for significantly reduced peak-to-average power ratio and improved spectral efficiency, directly resolving the technical contradiction

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If conventional Nyquist-based pulse shaping filters are used, then signal containment within spectrum is improved, but bandwidth efficiency is reduced

Engineering Contradiction:

Improvespectrum containmentVSAvoidbandwidth efficiency

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent employs parameter changes by adopting non-Nyquist partial response filtering with adjustable weighting factors. This allows optimization of the balance between spectral containment and bandwidth efficiency, enabling higher symbol rates and better utilization of available spectrum while maintaining acceptable interference levels through the tunable parameter

Inventive Principle:

Principle #35Parameter changes

3Productivity

If non-Nyquist waveforms are used without orthogonalization, then spectral efficiency is improved, but inter-symbol interference increases

Engineering Contradiction:

Improvespectral efficiencyVSAvoidinter-symbol interference

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies partial orthogonalization rather than complete orthogonalization. By using a weighting factor between 0 and 1, the system performs partial action that achieves a compromise: some reduction of inter-symbol interference is obtained while maintaining the spectral efficiency benefits of non-Nyquist waveforms, avoiding the full constraints of complete orthogonalization

Inventive Principle:

Principle #16Partial or excessive action

4Object-affected harmful factors

If pulse shaping filters are optimized for main lobe performance, then adjacent channel interference is reduced, but device complexity increases

Engineering Contradiction:

Improveadjacent channel interferenceVSAvoidfilter complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The non-Nyquist partial response filter serves multiple functions simultaneously: it provides spectral shaping for reduced adjacent channel interference, enables higher symbol rates for improved bandwidth efficiency, and offers tunable control over inter-symbol interference through the weighting factor. This multi-functionality reduces the need for separate optimization mechanisms, thereby managing device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12477392B2Pulse-shaping filters for improving the spectral efficiency of broadband satellite systems

Publication Date: 2025.11.18 HUGHES NETWORK SYST

AI summary

Systems and methods are described for generating and implementing pulse-shaping filters for efficient utilization of limited spectral resources in wireless communication systems. Wireless communication systems operating at high spectral efficiency conventionally use pulse shaping filters that rely on Nyquist waveforms for good main lobe performance with low inter-symbol interference (ISI) power. Conventional uses of non-Nyquist waveforms typically involve an orthogonalization process to convert those non-Nyquist waveforms to Nyquist waveforms for ISI free performance. Embodiments of pulse shaping filters described herein generate a non-Nyquist partial response (NNPR) transmit filter and/or matched receive filter based on applying a tunable second-weighted orthogonalization to a tunable first-weighted non-Nyquist waveform to obtain a pulse-shaping waveform with parametric control over throughput and power penalty.