Laurent Schmalen

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Spatially coupled low-density parity-check codes show an outstanding performance under the low-complexity belief propagation (BP) decoding algorithm. They exhibit a peculiar convergence phenomenon above the BP threshold of the underlying non-coupled ensemble, with a wave-like convergence propagating through the spatial dimension of the graph, allowing to(More)
Iterative source-channel decoding (ISCD) exploits the residual redundancy of source codec parameters by using the Turbo principle. A powerful improvement for ISCD is the concept of redundant index assignments. In this letter we present new design and optimization guidelines for redundant index assignments. For block code based redundant index assignments,(More)
We address the optimization of joint source-channel coding schemes for iterative source-channel decoding of first- order Markov sources. Compared to the traditional design, we propose two novelties: (1) source encoders, providing code words with a minimum Hamming distance d<sub>min</sub>ges2, realized by linear block codes, and (2) irregular channel(More)
We implemented a flexible transmission system operating at adjustable data rate and fixed bandwidth, baudrate, constellation and overhead using probabilistic shaping. We demonstrated in a transmission experiment up to 15% capacity and 43% reach increase versus 200 Gbit/s 16-QAM. Introduction Future optical metro and long-haul networks require transceivers(More)
We present a system for iterative source-channel decoding (ISCD) using irregular index assignments: The concept of irregular codes is applied to the index assignment of a scalar quantizer. The optimization performed in the EXIT chart enables near optimum transmission. The irregular index assignments are constructed by using high-rate block codes. This(More)
Low-Density Parity-Check (LDPC) codes are very powerful channel coding schemes with a broad range of applications. The existence of low complexity (i.e., linear time) iterative message passing decoders with close to optimum error correction performance is one of the main strengths of LDPC codes. It has been shown that the performance of these decoders can(More)
Audio-visual source encoders for digital wireless communications extract parameter sets on a frame-by-frame basis. Due to delay and complexity constraints these parameters exhibit some residual redundancy which manifests itself in nonuniform parameter distributions and intraas well as interframe correlation. This residual redundancy can be exploited by(More)
Fo rward error correction (FEC) techniques are essential for optical core and optical access networks. In optical core networks, the emphasis is on high coding gains and extremely low output bit error rates, while allowing decoder realizations to operate at a throughput of 100 Gb/s and above. Optical access networks operate at 10 Gb/s or above and require(More)
Low-density parity-check (LDPC) codes based on structured parity check matrices are widely used due to their favorable implementation properties. Often, however, the convergence threshold is optimized based on the general LDPC code ensemble (i.e., the degree profile only) without taking into account the imposed structure, leading to a mismatch of(More)
In this paper, we compare different metrics to predict the error rate of optical systems based on nonbinary forward error correction (FEC). It is shown that the correct metric to predict the performance of coded modulation based on nonbinary FEC is the mutual information. The accuracy of the prediction is verified in a detailed example with multiple(More)