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 adjusts the number of signal points for further improving the total bit-wise mutual information (BMI). Unlike other exhaustive search-based approaches, the proposed constellations are uniquely determined by only two parameters associated with NUC and cardinality. Due to this property of limited degrees of freedom, 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 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.

翻译：本文提出一种基于比特交织编码调制（BICM）、采用非等概率非均匀（NENU）星座成形以及限幅滤波（CAF）技术的高容量低峰均功率比（PAPR）正交频分复用（OFDM）系统设计方案。所提出的星座通过截断高斯分布与星座点合并生成，前者产生非均匀星座（NUC），后者通过调整信号点数量进一步优化总比特互信息（BMI）。与其他基于穷举搜索的方法不同，所提出的星座仅由与NUC和基数相关的两个参数唯一确定。由于这种自由度有限的特性，数值优化过程所需的复杂度可显著降低。我们专注于基于一维（即脉冲幅度调制（PAM））的星座设计，这有助于降低BICM接收端的解映射复杂度。在发射端采用CAF可有效降低OFDM信号的PAPR，但会引入可能恶化误码性能的限幅噪声，使得在接收端应用限幅噪声消除（CNC）技术至关重要。因此，我们在CAF与CNC并存条件下优化NENU星座。仿真结果表明，星座成形与CAF及CNC技术的结合，使得BICM-OFDM系统能够在加性高斯白噪声（AWGN）信道及频率选择性衰落信道上同时实现低PAPR与高频谱效率。此外，对比研究证实，在衰落信道下，所提系统在PAPR和误码率（BER）性能方面显著优于单载波方案（即DFT预编码BICM-OFDM）。