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In low signal-to-noise ratio (SNR) scenarios, image wireless transmission is often interrupted due to the "threshold effect" in traditional digital communication system. Fortunately, it can be avoided in analog communication system, owing to its feature of linear degradation to noise. And to design the efficient analog error correction codes is the key to achieve high fidelity image. Considering...
The current distributed storage systems mainly rely on data replication to ensure certain level of data availability and reliability. A recent trend is to introduce erasure codes into the distributed storage. Inspired by the RAID system, early attempts have been focused on designing Reed-Solomon (RS) based solutions and other block codes including Low Density Parity Check (LDPC) codes. This paper...
Luby Transform (LT) codes are the first realization of a class of erasure codes, usually known as universal erasure codes. LT codes were originally designed for Binary Erasure Channel (BEC), but for the sake of transmitting data reliably over the wireless broadcast channels, LT codes have to be combined with classical channel codes. This paper proposes a new model for LT code based wireless broadcast...
Low density parity check (LDPC) codes are one of the error-correction codes more versatile, promising and important, and have been adopted in most of the current communication standards. Given the actual and future relevance of these codes, we have developed a graphical interface for simulation and performance analysis considering several factors that affect their encoding and decoding. Thus, this...
Due to the existence of multiuser interference, codes optimized for point-to-point links may be unsuitable for multiuser networks. In this paper, we are concerned with the design of low-density parity-check (LDPC) codes for binary-input Gaussian interference channels (GIFC). We utilize a Monte-Carlo approach based on the downhill-simplex algorithm to obtain good LDPC degree distributions for GIFC...
The performance of Low-Density Parity-Check codes over symmetric alpha-stable impulsive noise channels is considered in this paper. Due to the lack of closed-form expressions for the probability density functions of almost all the alpha-stable distributions, an efficient non-linear approximation method for channel log-likelihood ratio is presented to achieve high decoding performance covering the...
In this paper, we focus on the behavior of the Belief Propagation (BP) algorithm when decoding the Low-Density Parity-Check (LDPC) code of rate 3/4 in the DVB-S2 standard. By studying the topological structure of its Tanner graph, we raise properties inherent to the degree distribution that turns out to be strongly correlated with the decoding failures. The irregularity of the degrees seriously damages...
In this paper, we present an efficient fault tolerant solution for multi-level per cell (MLC) flash memory that concatenates trellis coded modulation (TCM) with an outer low-density parity-check (LDPC) code. Traditional flash coding systems employ simple hard-decisions based codes, such as Bose-Chaudhuri-Hocquenghem (BCH) codes, that can correct a fixed, specified number of errors. Thanks to the Bahl,...
Quantum key reconciliation is an essential process of quantum key distribution (QKD). It aims to correct the transmission errors after the distribution of quantum objects over a quantum channel, where two legitimate parties use a classical public authenticated channel to disclose correlated bits for agreeing on their common key. This work proposes an alternative promising method employing LDPC-codes...
In this paper, a new fast convergence hybrid decoding algorithm based on multi-dimensional searhing is proposed for decoding LDPC codes. The main idea of this algorithm is flipping variable multi bits in each iteration, change in which leads to the syndrome vector with least hamming weight. To this end, the algorithm does multidimensional searching between all possible bit positions that could flip...
In this paper, we present a practical Dirty Paper Coding (DPC) scheme using sum codes based on LDPC codes. While a typical sum-code-based DPC scheme uses a constrained decoder as part of the encoding operation, such an approach fails in the case of LDPC codes since the constrained decoder based on a standard LDPC decoder tends to get stuck at highly suboptimal points in typical scenarios. We get around...
In this article, an iterative demodulation and decoding receiver for M-ary differential chaos shift keying (DSCK) modulation is proposed over Additive White Gaussian Noise (AWGN) channel. The Log-Likelihood Ratios (LLRs) of coherent DCSK demodulator and decoder are derived assuming that its perfect carrier synchronization happened. The simulation results show that the performance of our proposed iterative...
In this paper, a flexible architecture of multi-rate Low Density Parity Check (LDPC) decoder has been presented. It supports six different code-rates which are specified by IEEE 802.16e wireless standard. In the suggested decoder-architecture, column layered decoding technique has been employed to increase the convergence speed. Additionally, the decoder-design incorporates parallel architecture to...
LDPC codes can be constructed by tiling permutation matrices that belong to the square root of identity type and similar algebraic structures. We investigate into the properties of such codes. We also present code structures that are amenable for efficient encoding.
Quadrature Orthogonal Frequency Division multiple access (Q-OFDMA) has been renowned as a promising technique which provides a solution to the high PAPR (Peak to average power ratio), sensitivity to carrier frequency offset (CFO) problem and design complexity as introduced by the normal OFDMA systems. Exploiting this Q-OFDMA systems on the Multi-Input Multi-Output (MEMO) architecture, leads to a remarkable...
In this paper, we present a high throughput and low latency LDPC (low-density parity-check) decoder implementation on GPUs (graphics processing units). The existing GPU-based LDPC decoder implementations suffer from low throughput and long latency, which prevent them from being used in practical SDR (software-defined radio) systems. To overcome this problem, we present optimization techniques for...
This paper is concerned with Gaussian interference channels (GIFC) in which all transmitters are coded with binary low-density parity-check (LDPC) codes. We focus on the design of decoding algorithms. The main contributions of this paper include: 1) we present three types of iterative decoding algorithms (IDA), which are computing-decoding type, decodingcomputing type and computing-decoding-computing...
This work evaluates the robustness of Low-Density Parity-Check decoders against errors due to imprecise arithmetic. While the use of imprecise arithmetic is motivated by savings in energy, delay and area, it also causes errors during the decoding process. This is a new paradigm in coding theory, which traditionally assumes that an error correction decoder operates on exact hardware and errors can...
In this paper, we carry out a practical assessment of the performance of finite-length LDPC codes over the wiretap channel with fast Rayleigh fading. Classical metrics for physical layer security, like the secrecy capacity, are based on information theoretic arguments, and provide the ultimate security bounds for these schemes. However, it is difficult to design practical schemes, using some specific...
An improved normalized min-sum (IN-MS) algorithm is proposed for decoding low-density parity-check (LDPC) codes. In this algorithm, two normalized factors are used in check node computing, one for the minimum data and another for the second minimum data, and this algorithm achieves a better approximation to the BP algorithm. Simulation results show that the decoding performance of IN-MS algorithm...
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