Rate-matching of low-density parity-check (LDPC) codes enables a single code description to support a wide range of code lengths and rates. In 5G NR, rate matching is accomplished by extending (lifting) a base code to a desired target length and by puncturing (not transmitting) certain code bits. LDPC codes and rate matching are typically designed for the asymptotic performance limit with an ideal decoder. Practical LDPC decoders, however, carry out tens or fewer message-passing decoding iterations to achieve the target throughput and latency of modern wireless systems. We show that one can optimize LDPC code puncturing patterns for such few-iteration-constrained decoders using a method we call swapping of punctured and transmitted blocks (SPAT). Our simulation results show that SPAT yields from 0.20 dB up to 0.55 dB improved signal-to-noise ratio performance compared to the standard 5G NR LDPC code puncturing pattern for a wide range of code lengths and rates.

翻译：低密度奇偶校验（LDPC）码的速率匹配使得单一码描述能够支持广泛的码长与码率。在5G NR中，速率匹配通过将基础码扩展（提升）至目标长度，并对特定编码比特进行穿孔（不传输）来实现。LDPC码及其速率匹配通常针对理想译码器的渐近性能极限而设计。然而，实际LDPC译码器为满足现代无线系统的吞吐量与时延要求，仅执行数十次或更少的消息传递译码迭代。本文提出一种称为“穿孔与传输块交换”（SPAT）的方法，可用于为此类少迭代约束译码器优化LDPC码的穿孔模式。仿真结果表明，在广泛的码长与码率范围内，相较于标准5G NR LDPC码穿孔模式，SPAT方法可获得0.20 dB至0.55 dB的信噪比性能提升。