PS-QAM Demodulation Using Maxwell-Boltzmann Distance Scaling
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Solution Overview
Problem
Existing wireless communication systems, particularly in 5G NR, face challenges in improving demodulation efficiency and reducing decoding complexity for probabilistically-shaped (PS) quadrature amplitude modulation (QAM) signals.
Innovation Solution
A method is introduced for demodulating probabilistically-shaped signals using a distance-based demodulation calculation adjusted based on a Maxwell-Boltzmann distribution, which involves receiving symbols with detected amplitudes and phases and applying input scaling before further demodulation operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If probabilistic amplitude shaping is applied to QAM signals, then the achievable information rate is improved, but the demodulation complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the distance-based demodulation calculation to incorporate Maxwell-Boltzmann distribution adjustments. Specifically, the demodulation metric is changed from standard Euclidean distance to a modified distance calculation that accounts for the non-uniform probability distribution of constellation points, thereby simplifying the demodulation process while maintaining the benefits of probabilistic amplitude shaping
Solution Approach 2:
The patent introduces an intermediary approach by using scaled constellation points and adjusted distance calculations as a bridge between the transmitted probabilistically-shaped signal and the demodulation process. The scaling factor derived from the Maxwell-Boltzmann distribution acts as an intermediary parameter that simplifies the relationship between transmitted and received signals, reducing computational complexity
2Ease of operation
If standard distance-based demodulation is used for PAS QAM, then the implementation is simple, but the decoding accuracy deteriorates
Solution Approach 1:
The patent modifies the demodulation parameter by incorporating Maxwell-Boltzmann distribution-based scaling into the distance calculation. The scaled distance metric D'(x) = D(x) - log(p(x)) where p(x) follows Maxwell-Boltzmann distribution, transforms the simple but inaccurate standard demodulation into a more accurate version while maintaining computational feasibility
Data Source
AI summary
The apparatus may be an apparatus for wireless communication at a decoding device, for decoding a probabilistically-shaped quadrature amplitude modulation (QAM) signal associated with a phase modulation and an amplitude modulation. The apparatus may be configured to receive, in association with the probabilistically-shaped QAM signal, at least one symbol associated with a first amplitude and demodulate the at least one symbol based on a distance-based demodulation calculation that is adjusted based on a Maxwell-Boltzmann distribution.