面向高可靠低时延通信的顺序统计译码 (OSD) 关键技术综述

Ultra-reliable low-latency communications (URLLC) is one of the three key scenarios in 5G, and its en⁃hanced form, hyper-reliability low-latency communications (HRLLC), has been proposed as one of the six typical scenariosfor 6G. These services impose very stringent constraints on latency and reliability, presenting new opportunities and chal⁃lenges for the coding and decoding of short-blocklength codes. Ordered statistics decoding (OSD) is a universal near-maxi⁃mum-likelihood (Near-ML) decoding algorithm for short codes with strong potential in such scenarios, but its high computa⁃tional complexity severely limits practical deployment. This paper surveys recent advances in OSD with a focus on the design of test error pattern (TEP), including ordering rules, skipping mechanisms, and early termination strategies, and outlines future research directions. Specifically, we first examine Hamming-weight, soft-weight, and logical-weight TEP orderings, and show that logical-weight ordering achieves an effective balance between reliability and implementation complexity. We then review existing skipping and termination mechanisms, which exploit dynamic soft information or probabilistic decisions to avoid redundant re-encodings. Moreover, we concentrate on TEP generation, skipping, and termination schemes driven by soft metrics and additional parity checks, as well as their joint design. By combining structural constraints with hybrid decision strategies, such schemes can reduce the average number of re-encodings by one to two orders of magnitude with almost no loss in frame error rate. Simulation results show that, for the bose-chaudhuri-hocquenghem (BCH) code [127,64], a combined skipping mechanism requires only tens of re-encodings at an SNR of 4 dB, reducing the computational cost by more than 90% compared to the original OSD algorithm. Finally, we discuss open challenges related to nonbinary codes, time-varying channels, and hardware implementations for longer blocklengths and medium-rate codes, and outline several promising directions for future research.