Block turbo codes : towards implementation

International audienceThis paper presents two implementations of the same block turbo decoding algorithm : on the one hand an elementary decoder in association with a sequencer performs the complete turbo decoding process, and on the other hand, the circuit contains one elementary decoder per half-iteration. The choice of different parameters for each algorithm implemented bring the results more or less close to the theoretical limit. We briefly describe the iterative process which creates the "turbo" effect and explain the essential choices in order to adapt the algorithm to an ASIC implementation

A low-complexity soft-decision decoding architecture for the binary extended Golay code

International audienceThe (24, 12, 8) extended binary Golay code is a well-known rate-1/2 short block-length linear error-correcting code with remarkable properties. This paper investigates the design of an efficient low-complexity soft-decision decoding architecture for this code. A dedicated algorithm is introduced that takes advantage of the code’s properties to simplify the decoding process. Simulation results show that the proposed algorithm achieves close to maximum-likelihood performance with low computational cost. The decoder architecture is described, and VLSI synthesis results are presented

Near maximum likelihood soft-decision decoding of a particular class of rate-1/2 systematic linear block codes

International audiencePresented is a soft-decision decoding algorithm for a particular class of rate-1/2 systematic linear block codes. The proposed algorithm performs successive re-encoding of both the data and parity bits, to produce a list of codewords among which the most likely candidate is chosen. Simulation results show that close to optimal performance can be obtained at reasonable complexity. They validate the potential of the proposed algorithm as a practical approach for soft-decision decoding

New architecture for high data rate turbo decoding of product codes

International audienceThis paper presents a new circuit architecture for turbo decoding, which achieves very high data rates when using product codes as error correcting codes. Although this architecture is independent of the elementary code (convolutional or block) used and of the corresponding decoding algorithms, we focus here on the case of product codes. This innovative circuit architecture stores several data at the same adress and performs parallel decoding to increase the data rate. It is able to process several date simultaneously with one memory (classical designs require m memories); its latency decreases when the amont of data processed simultaneously is large. We present results on block turbo decoder designs of 2-data, 4-date and 8-data decoders (where 2, 4 and 8 are the number of data symbos processed simultaneously). For each decoder circuit, the latency is decreased, the area of the processing unit is inscreased by a factor m and the critical path and memory size are constant (the data rate is increased by m2 if we have m paralel decoders)

Reed-Solomon turbo product codes for optical communications: from code optimization to decoder design

International audienceTurbo product codes (TPCs) are an attractive solution to improve link budgets and reduce systems costs by relaxing the requirements on expensive optical devices in high capacity optical transport systems. In this paper, we investigate the use of Reed-Solomon (RS) turbo product codes for 40 Gbps transmission over optical transport networks and 10 Gbps transmission over passive optical networks. An algorithmic study is first performed in order to design RS TPCs that are compatible with the performance requirements imposed by the two applications. Then, a novel ultrahigh-speed parallel architecture for turbo decoding of product codes is described. A comparison with binary Bose-Chaudhuri-Hocquenghem (BCH) TPCs is performed. The results show that high-rate RS TPCs offer a better complexity/performance tradeoff than BCH TPCs for low-cost Gbps fiber optic communications

Design and implementation of a soft-decision decoder for Cortex codes

International audienceCortex codes are a family of rate-1/2 self-dual systematic linear block codes with good distance properties. This paper investigates the challenging issue of designing an efficient soft-decision decoder for Cortex codes. A dedicated algorithm is introduced that takes advantage of the particular structure of the code to simplify the decoding. Simulation results show that the proposed algorithm achieves an excellent trade-off between performance and complexity for short Cortex codes. A decoder architecture for the (32,16,8) Cortex code based on the (4,2,2) Hadamard code has been successfully designed and implemented on FPGA device. To our knowledge, this is the first efficient digital implementation of a soft-decision Cortex decoder

A highly parallel Turbo Product Code decoder without interleaving resource

International audienceThis article presents an innovative turbo product code (TPC) decoder architecture without any interleaving resource. This architecture includes a full-parallel SISO decoder able to process n symbols in one clock period. Syntheses show the better efficiency of such an architecture compared with existing previous solutions. Considering a 6-iteration turbo decoder of a (32,26)2 BCH product code, synthetized in a 90 nm CMOS technology, the resulting information throughput is 2.5 Gb/s with an area of 233 Kgates. Finally a second architecture enhancing parallelism rate is described. The information throughput is 33.7 Gb/s while an area estimation gives A=10 mum2

Comparaison performances/complexité de décodeurs de codes BCH utilisés en turbo-décodage

Cet article propose une étude comparée entre algorithme et architecture en vue de l'implantation sur silicium et plus particulièrement sur FPGA d'un circuit de turbo-décodage de codes BCH(128,120,4). L'utilisation du langage C - pour les simulations - et du VHDL - pour la synthèse - permettent de comparer les performances et la complexité du circuit en fonction de quelques paramètres essentiels au déroulement de l'algorithme de décodage comme le nombre de bits de quantification, le nombre de concurrents et le nombre de vecteurs de tests

Conception d'un décodeur BCH (30,19,6) à entrées et sorties pondérées : Application au turbo décodage

- Cet article présente la conception d'un décodeur BCH (32,19,6) à entrées et sorties pondérées corrigeant 2 erreurs. La cible technologique choisie, circuit intégré programmable (FPGA XILINX), ainsi que sa faible complexité (20000 portes), a permis son insertion dans une maquette de turbo décodage qui autorise des mesures de taux d'erreurs de l'ordre de 10-9. Elle valide l'utilisation de turbo code produit obtenu à partir de codes BCH étendus de rendement proche de 0,5 et pour des blocs de la taille d'une cellule ATM

Conception d'un turbo décodeur de code produit

Cet article présente les derniers résultats concernant les turbo codes en blocs, obtenus à partir de codes BCH étendus. Après avoir rappelé l'algorithme itératif de décodage utilisé, nous évaluons la complexité des turbo décodeurs associés. Nous proposons des simplifications dans le calcul de la pondération et dans la mise en oeuvre de l'algorithme de Chase. Ces simplifications nous ont conduits à concevoir une maquette qui nous permettra à terme de valider complètement les nouveaux concepts liés au turbo décodage des codes produits. Cette réalisation à partir de circuits prédiffusés programmables ouvre la porte à de futures intégrations sur le silicium, plus denses et plus rapides