This article reviews state of the art channel coding techniques for URLLC. The stringent requirements URLLC services, such as ultrahigh reliability and low latency, have made it most challenging feature 5G mobile networks. problem is even more services beyond promise, tele-surgery factory automation, which require latencies less than 1ms packet error rates 10-9. provides an overview compares them in terms performance complexity. Several important research directions are identified discussed detail.

Two classes of turbo codes constructed on high-order finite fields are introduced. The derived from a particular protograph sub-ensemble the (2,3) regular low-density parity-check (LDPC) code ensemble. first construction results in parallel concatenation two non-binary, time-variant accumulators. second consists serial non-binary differentiator with accumulator, and provides highly structured flexible encoding scheme for (2,4) LDPC codes. A cycle graph representation is also provided....

This paper investigates efficient maximum-likelihood (ML) decoding of low-density parity-check (LDPC) codes over erasure channels. A set algorithms, referred to as pivoting is developed. The aim limit the average number pivots (or reference variables) from which all other erased symbols are recovered iteratively. suggested algorithms exhibit different trade-offs between complexity phase and pivots. Moreover, a systematic procedure design LDPC code ensembles for ML proposed. Numerical results...

In this paper, a digital transmission scheme protected by packet-level forward error correction (FEC) coding technique is proposed for optical feeder links in satellite communication system. The architectures of the gateway and are defined, including building blocks interface between radio frequency (RF) front-end front-end, as well signal processor. system designed to cater Terabit/s high-throughput (HTS) applications. addition, turbulent atmospheric channel modeled different elevation...

SUMMARY Protograph‐based non‐binary low‐density parity‐check (LDPC) codes with ultra‐sparse matrices are compared binary LDPC and turbo (TCs) from space communication standards. It is shown that larger coding gains achieved, outperforming the competitors by more than 0.3 dB on additive white Gaussian noise channel (AWGN). In short block length regime, designed gain 1 respect to protograph recently proposed for next generation up‐link standard of Consultative Committee Space Data Systems....

The design of low-density parity-check (LDPC) codes under hybrid iterative / maximum likelihood decoding is addressed for the binary erasure channel (BEC). Specifically, we focus on generalized irregular repeat-accumulate (GeIRA) codes, which offer both efficient encoding and flexibility. We show that properly designed GeIRA tightly approach performance an ideal distance separable (MDS) code, even short block sizes. For example, our (2048,1024) code reaches a codeword error rate 10 <sup...

Low complexity decoding algorithms are necessary to meet data rate requirements in excess of 1 Tbps. In this paper, we study one and two bit message passing for belief propagation low-density parity-check (LDPC) codes analyze them by density evolution. The variable nodes (VNs) exploit soft information from the channel output. To decrease flow, messages exchanged between check (CNs) VNs represented or bits. newly proposed quaternary (QMP) algorithm is compared asymptotically finite length...

Recent works showed how low-density parity-check (LDPC) erasure correcting codes, under maximum likelihood (ML) decoding, are capable of tightly approaching the performance an ideal maximum-distance-separable code on binary channel. Such result is achievable down to low error rates, even for small and moderate block sizes, while keeping decoding complexity low, thanks a class algorithms which exploits sparseness matrix reduce Gaussian elimination (GE). In this paper main concepts underlying...

We investigate the performance of free-space optical communication systems in presence atmospheric turbulence to assess advantages that a coherent system can bring with respect conventional intensity modulation and direct detection (IM/DD) system. The perspective is an information-theoretic one, hence we evaluate mutual information corresponding outage probability both channels, various traditional symbol constellations, as pragmatic approximation capacity, or those channels. In addition,...

This paper investigates efficient maximum-likelihood (ML) decoding algorithms for low-density parity-check (LDPC) codes over erasure channels. In particular, enhancements to a previously proposed structured Gaussian elimination approach are presented. The improvements achieved by developing set of algorithms, here referred as pivoting aiming limit the average number reference variables (or pivots) from which erased symbols can be recovered. Four compared, exhibit different trade-offs between...

A ternary message passing (TMP) decoding algorithm for low-density parity-check codes is developed. All messages exchanged between variable and check nodes have a alphabet, the exploit soft information from channel. density evolution analysis developed unstructured protograph-based ensembles. For ensembles stability condition derived. Optimized TMP show asymptotic gains of up to 0.6 dB with respect optimized binary decoding. Finite length simulations TMP-optimized 0.5 under compared designed...

Summary In this paper, a packet‐level forward error correction coding technique and pre‐distortion adaptive optics technology are applied to digital transmission scheme for optical feeder links in geostationary Earth orbit satellite communication system. The architectures of the gateway defined, including building blocks interface between radio frequency front‐end front‐end, as well signal processor. system is designed cater Terabit/s high‐throughput applications. performance evaluated...

Short non-binary irregular repeat-accumulate (IRA) codes based on well-known Hamiltonian and Hypohamiltonian graphs with large girth are presented. The mapping of the code coordinates graph edges is discussed for graphs, two encoding methods introduced. performance presented order-256 finite fields (F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">256</sub> ) provided both additive white Gaussian (AWGN) channel binary erasure (BEC) under...

This work investigates protograph-based low-density parity-check (LDPC) codes for the additive white Gaussian noise (AWGN) channel with on-off keying (OOK) modulation. A non-uniform distribution of OOK modulation symbols is considered to improve power efficiency especially low signal-to-noise ratios (SNRs). To this end, a specific transmitter architecture based on time sharing proposed that allows probabilistic shaping (some) symbols. Tailored LDPC code designs outperform standard schemes...

This paper investigates the design of non-binary protograph low-density parity-check codes for Poisson channel with m-ary pulse position modulation. The field order over which code is constructed matched to modulation yielding a coded scheme. optimization structure performed via density evolution on surrogate erasure channel. illustrated be not only accurate, but also robust range practical values background noise and various orders. As result proposed show excellent performance...

This work considers the design of short non-binary low-density parity-check (LDPC) codes over finite fields order m, for channels with phase noise. In particular, m-ary differential phase-shift keying (DPSK) modulated code symbols are transmitted an additive white Gaussian noise (AWGN) channel Wiener At receiver side, non-coherent detection takes place, help a multi-symbol algorithm, followed by decoding step. Both detector and decoder operate on joint factor graph. As benchmark, length...

In the framework of error correction in space telecommand (TC) links, Consultative Committee for Space Data Systems (CCSDS) currently recommends short block-length BCH and binary low-density parity-check (LDPC) codes. Other alternatives have been discarded due to their high decoding complexity, such as non-binary LDPC (NB-LDPC) NB-LDPC codes perform better than counterparts over AWGN jamming channels, being great candidates communications. We show feasibility coding TC applications by...

This work considers the design of short parallel turbo codes (PTCs) with block lengths in order (a few) hundred code bits. In particular we aim at designing large minimum distance. To this end a structured approach is presented to find suitable component configurations, as well interleavers. As result proposed possess low error floors and outperform competing binary low-density parity-check (LDPC) by approximately 0:9 dB state-of-the-art 0:4 word rate (CER) about ≈10 <sup...

We consider high data rate free-space optical links between satellite and ground station, which are prone to strong variations of the received signal due atmospheric turbulence. The rates towards hundreds Gbit/s paired with channel coherence times a few milliseconds pose serious challenge for reliable transmission. On such non-ergodic channels, use appropriate diversity techniques combined coding schemes is must ensure required rates. There several ways tackle problem. A pragmatic approach...

In this paper, an overview of recent achievements in the design and decoding non-binary low-density parity-check (LDPC) codes is provided. Non-binary constructions based on ultra-sparse matrices are compared with binary turbo from satellite communication standards, to show that larger coding gains (outperforming competitors by at least 0.3 dB) can be achieved AWGN channel, especially moderate/short block regimes. Thanks excellent performance, LDPC represent appealing solution for space...

The design of moderate-length erasure correcting low-density parity-check (LDPC) codes over correlated channels is considered. Although the asymptotic LDPC code remains same as for a memoryless channel, robustness to channel correlation shall be guaranteed finite length code. This further requirement great importance in several wireless communication scenarios where packet represent simple countermeasure fade events (e.g., mobile broadcasting services) and coherence time often comparable...

An efficient decoding algorithm for low-density parity-check (LDPC) codes on erasure channels with sporadic errors (i.e., binary error-and-erasure error probability much smaller than the probability) is proposed and its performance analyzed. A general single-error multiple-erasure (SEME) first described, which may be in principle used any linear block code. The optimum whenever non-erased part of received word affected by at most one error, capable performing detection multiple errors. upper...