发表机构
Samsung Research America; University of Minnesota, Twin Cities; Indian Institute of Science; Duke University（三星美国研究所; 明尼苏达大学双城分校; 印度科学学院; 杜克大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对QPSK星座整形应用受限的问题，提出将短整形码融入LDPC编码QPSK系统，通过稀疏码字实现概率整形，联合优化码本、映射和星座，在5G NR LDPC编码QPSK和QAM-16上分别获得0.6 dB和0.53 dB增益。
AI 中文摘要
虽然星座整形能提高频谱效率，但其在正交相移键控（QPSK）中的应用仍然有限。我们通过将短整形码纳入低密度奇偶校验（LDPC）编码的QPSK系统来解决这一限制。具体来说，LDPC码字位的一个子集用作整形位，并由整形码映射到稀疏码字，通过控制低能量和高能量QPSK星座之间的非等概率选择来实现概率整形。由于稀疏码字中零占主导地位，低能量星座点被更频繁地传输，从而产生类似高斯的符号分布。通过利用整形位的信道编码保护，我们开发了接收机算法，利用LDPC解码器反馈来细化整形位的对数似然比（LLR）。整形码本、比特到符号映射和星座的联合优化使得所提出的整形方案在5G新空口（NR）LDPC编码QPSK和QAM-16上分别获得高达0.6 dB和0.53 dB的增益。
英文摘要
While constellation shaping improves spectral efficiency, its application to quadrature phase-shift keying (QPSK) remains limited. We address this limitation by incorporating a short shaping code into low-density parity-check (LDPC)-coded QPSK systems. Specifically, a subset of LDPC codeword bits is used as shaping bits and mapped by the shaping code to a sparse codeword that enables probabilistic shaping by controlling non-equiprobable selection between lower- and higherenergy QPSK constellations. Because zeros dominate the sparse codeword, lower-energy constellation points are transmitted more frequently, yielding a Gaussian-like symbol distribution. By exploiting the channel-code protection of the shaping bits, we develop receiver algorithms that refine shaping-bit log-likelihood ratios (LLRs) using LDPC decoder feedback. Joint optimization of the shaping codebook, bit-to-symbol mapping and constellations enables the proposed shaping scheme to achieve gains of up to 0.6 and 0.53 dB over 5G New Radio (NR) LDPC-coded QPSK and QAM-16, respectively.
