Non-Uniform Constellation Mapping for Lower PAPR WLAN Modulation
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Solution Overview
Problem
Current communication systems face challenges in maximizing coding and modulation capacity while reducing bit error rates and signal-to-noise ratio (SNR) requirements, particularly due to high peak-to-average power ratio (PAPR) in single carrier modulation, which affects power amplifier efficiency and battery life in wireless devices.
Innovation Solution
The implementation of non-uniform constellations (NUCs) optimized for both shaping gain and peak power, where constellation points are strategically located based on channel conditions and code rate, to enhance SNR gain and reduce PAPR, applicable to both single and multicarrier communication schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uniform constellations are used in BICM systems, then the system achieves reasonable decoding complexity and good performance through interleaver and FEC encoder, but the coding and modulation capacity is limited and the bit error rate remains high
Solution Approach 1:
The patent applies local quality by transitioning from uniform constellation points to non-uniform constellation points with different densities in different regions. The constellation points are strategically distributed with higher density in certain areas and lower density in others, optimizing the signal distribution to reduce bit error rate while maintaining decoding complexity
2Productivity
If higher order modulation schemes are used to increase coding and modulation capacity, then more data can be transmitted, but the required SNR increases and PAPR increases affecting power amplifier efficiency
Solution Approach 1:
The patent applies parameter changes by modifying the constellation point parameters from uniform to non-uniform distribution. The non-uniform constellation optimizes the amplitude and phase parameters of modulation symbols, achieving higher coding and modulation capacity while reducing PAPR and improving power amplifier efficiency
3Ease of manufacture
If conventional uniform constellations are used, then the system implementation is simple, but the SNR requirements remain high and power efficiency is reduced
Solution Approach 1:
The patent changes the constellation parameter distribution from uniform to non-uniform, optimizing the signal characteristics to reduce SNR requirements and improve power efficiency while maintaining implementation feasibility through standardized non-uniform constellation designs
Data Source
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AI summary
A coding and modulation apparatus and method are presented, particularly for use in a system according to IEEE 802.11. The apparatus comprises an encoder configured to encode input data into cell words according to a low density parity check code, LDPC, and a modulator configured to modulate said cell words into constellation values of a non-uniform constellation and to assign bit combinations to constellation values of the used non-uniform constellation, wherein said modulator is configured to use, based on the total number N of constellation points of the constellation and the code rate R, a particular non-uniform constellation, which has been optimized using the peak-to-average power ratio (PAPR).