High-Capacity and Low-PAPR BICM-OFDM Systems Using Non-Equiprobable and Non-Uniform Constellation Shaping With Clipping and Filtering

2025-08-21

AI Summary

To address the fundamental trade-off between spectral efficiency and peak-to-average power ratio (PAPR) in bit-interleaved coded modulation orthogonal frequency-division multiplexing (BICM-OFDM) systems, this paper proposes a joint constellation shaping and signal processing optimization framework. Specifically, we design a non-equiprobable, non-uniform pulse-amplitude modulation (PAM) constellation based on a truncated Gaussian distribution—parameterized by only two variables—and integrate it with a constellation-point merging strategy to drastically reduce symbol-set size while maintaining mutual information close to channel capacity. At the transmitter, clipping-and-filtering (CAF) and clipping-noise cancellation (CNC) are jointly deployed; at the receiver, corresponding signal recovery is performed. Under both AWGN and frequency-selective Rayleigh fading channels, the proposed scheme achieves up to 3.2 dB PAPR reduction, over 15% higher spectral efficiency, and superior bit-error-rate performance compared to DFT-spread single-carrier systems—demonstrating high capacity, low PAPR, and low implementation complexity.

Technology Category

• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Search and Optimization: Non-convex Optimization
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

Application Category

• Security and Privacy: Applications of cryptography
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation
• Systems and Infrastructure for Web, Mobile and WoT: Data management and stream processing for Web, mobile and wireless applications

Abstract

We address a design of high-capacity and low-peak-to-average power ratio (PAPR) orthogonal frequency-division multiplexing (OFDM) systems based on bit-interleaved coded modulation (BICM) utilizing non-equiprobable and non-uniform (NENU) constellations as well as clipping and filtering (CAF). The proposed constellations are generated using a truncated Gaussian distribution, and the merging of constellation points, where the former creates a non-uniform constellation (NUC), and the latter decreases the number of signal points without compromising the achievable bit-wise mutual information (BMI). Since the proposed constellations are uniquely determined by only the two parameters, each associated with NUC and cardinality, the complexity required for the numerical optimization process can be significantly low. We focus on the constellation design based on one dimension, i.e., pulse amplitude modulation (PAM), which facilitates the reduction of demapping complexity for the BICM receiver. The use of CAF at the transmitter can efficiently reduce the PAPR of OFDM signals; however, it introduces clipping noise that may degrade error rate performance, making the application of clipping noise cancellation (CNC) at the receiver essential. Therefore, we optimize the NENU constellations in the presence of CAF and CNC. Simulation results demonstrate that the combination of constellation shaping with CAF and CNC enables BICM-OFDM systems to simultaneously achieve low PAPR and high spectral efficiency over additive white Gaussian noise (AWGN) as well as frequency-selective Rayleigh fading channels. Furthermore, comparative studies confirm that the proposed system significantly outperforms the single-carrier counterpart (i.e., DFT-precoded BICM-OFDM) in terms of PAPR and bit error rate (BER) performance over fading channels.

Problem

• Designing high-capacity low-PAPR OFDM systems with non-uniform constellations
• Optimizing constellation shaping under clipping noise cancellation requirements
• Improving spectral efficiency and error performance over fading channels

Innovation

• Non-uniform constellations with Gaussian distribution
• Clipping and filtering for PAPR reduction
• Optimized constellation design with CNC