Non-Uniform Constellation Modulation for Lower PAPR and BER
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Solution Overview
Problem
Current communication systems face challenges in maximizing coding and modulation capacity while minimizing bit error rates and signal-to-noise ratio (SNR) requirements, particularly due to high peak-to-average power ratio (PAPR) in single carrier (SC) modulation, which affects power amplifier efficiency and battery life in portable devices.
Innovation Solution
The implementation of a coding and modulation apparatus using non-uniform constellations (NUCs) optimized for both BICM capacity and peak power, where constellation points are strategically placed based on channel conditions and code rate, allowing for reduced PAPR and enhanced SNR gain, applicable to both single carrier and multicarrier communication schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform constellations are used in BICM systems, then the system achieves reasonable decoding complexity and good performance, but the coding and modulation capacity is limited and the bit error rate is higher
Solution Approach 1:
The patent applies asymmetry by transitioning from uniform constellations to non-uniform constellations (NUCs). The NUCs have asymmetrically distributed constellation points with varying distances from the origin, creating different signal energies. This asymmetric structure allows optimization of both reliability and capacity by strategically placing points to maximize information transmission while maintaining error performance.
Solution Approach 2:
The patent changes the fundamental parameter of constellation uniformity to non-uniformity. By varying the energy levels and positions of constellation points according to specific mathematical formulations, the system achieves improved coding and modulation capacity while maintaining acceptable bit error rates through optimized point distributions.
2Productivity
If high-order modulation schemes are used to increase coding and modulation capacity, then more data can be transmitted, but the signal-to-noise ratio requirements increase and bit error rate worsens
Solution Approach 1:
The patent applies local quality by creating regions of different densities and energies within the constellation diagram. Certain areas have higher concentration of constellation points with specific energy levels, allowing the system to transmit more information in favorable signal conditions while maintaining robustness in noisy conditions through strategically placed lower-energy points.
3Use of energy by moving object
If conventional uniform constellations are used, then the system is simple to implement, but the power efficiency is reduced due to high PAPR
Solution Approach 1:
The patent introduces dynamics by making the constellation structure adaptive rather than static. The NUCs are designed with flexible parameters that can be adjusted based on channel conditions, allowing the system to optimize power efficiency dynamically. The varying energy levels of constellation points enable better power amplifier utilization and reduced PAPR compared to fixed uniform constellations.
Data Source
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).