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Low-density parity-check (LDPC) coded massive multiple-input and multiple-output (MIMO) scheme is getting increasingly popular and sophisticated in today's wireless communication systems, since it can highly improve the spectral efficiency, data rates, and error performance. In this paper, a novel iterative detection and decoding (IDD) method for LDPC-coded massive MIMO systems is proposed. Based...
LDPC code is a powerful error correcting code used in many communication systems. Efficient decoding algorithm and hardware implementation of LDPC code is an important issue. The paper proposes an improved version of the Normalized Min-Sum (NMS) decoding algorithm named “Girth-Aware NMS”. The principle of the GA-NMS is to determine “offline” the optimal normalisation factor of the extrinsic message...
This paper presents a linear model for the sum-product decoding of random low-density parity-check (LDPC) codes, specifically in the high signal-to-noise ratio (SNR) region. The sum-product algorithm is first approximated as the min-sum algorithm and then a linear model is estimated for the latter. To formulate the model, the dominant trapping sets of the particular code are found. We consider a criterion...
The throughput of a conventional rate-compatible code based hybrid automatic repeat request (HARQ) protocol is lower-bounded by the rate of the mother code used. The mother code rate along with the highest puncture rate determine the operation range of the protocol in terms of the average received signal-to-noise ratio (SNR). In this paper, we propose a new HARQ protocol based on rate-compatible punctured...
A protograph-based low-density parity-check (LDPC) code design technique for bandwidth-efficient coded modulation is presented. The approach jointly optimizes the LDPC code node degrees and the mapping of the coded bits to the bit-interleaved coded modulation (BICM) bit-channels. For BICM with uniform input and for BICM with probabilistic shaping, binary-input symmetric-output surrogate channels are...
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...
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...
A hybrid decoder (HD) for LDPC codes in the presence of additive white Gaussian noise is proposed. This HD employs a min-sum belief propagation (BP) decoding to correct errors, combined with erasure iterative decoding. Whenever BP decoding fails, its output is modified and artificially created erasures are introduced. The proposed HD employs an overall reduced number of iterations and achieves a similar...
For LDPC decoding, a class of weighted bit-flipping algorithms is much simpler than a belief propagation algorithm. This work proposes a modified Gradient Descent Bit-Flipping algorithm based on Reliability Ratio with an adaptive threshold to address trade-off between performance and latency. From numerical results, the proposed algorithm achieves lower latency without an expense of performance. It...
This paper considers maximum a posteriori (MAP) decoding of the maximum transition run (MTR) codes, over two-head digital magnetic recording system. Decoding is based on Bayesian algorithm and computes a posteriori log-likelihood ratios (LLR) from codewords of the MTR code. In this paper we present simulation results for performance of the joint soft detection-decoding of a concatenation of MTR code...
Codes on graphs have become the most important way to reach channel capacity. A new problem for High Performance Computing has been constructed with this work. The graph search problem as posed in this work is the coarsest version of the problem which corresponds to the exhaustive search case. The coarse grain graph search (CGGS) problem chooses an optimal parity-check matrix, based on minimum value...
This paper presents an improvement of the reliability-based iterative majority-logic decoding algorithms for regular low-density parity-check (LDPC) codes proposed by Huang et al. We improve the computation of the extrinsic information that is used to update the reliability measure of each received bit in each iteration with some kind of reliability measures of the check-sums that are orthogonal on...
The hybrid auto repeat request (HARQ) is an efficient retransmission technique which can guarantee highly reliable communication over noisy channels, and nowadays it has been widely adopted in packet-based data communication systems. In this paper, we propose an improved Type-II Hybrid-ARQ scheme that can degrade the average number of the iteration and improve the performance. In this scheme, the...
Low-density parity-check (LDPC) codes are promising for low code rate applications, however its competitiveness over BCH codes in the high code rate region is not well studied. In this work, we compare the Euclidean geometry (EG) LDPC and BCH codes of the length 1,023, 4,095, and 16,383 that have the code rates of 0.75~0.85. Hard-decision input data are applied to both decoders, and the EG-LDPC codes...
The error-correcting performance of non-binary LDPC codes has been shown to be better than most codes currently used for a variety of applications. However, due to the very high complexity of decoding these codes, they are not ubiquitously used. Moreover, an SPA decoder is so prohibitively complex, that a fully parallel implementation is not feasible even with simplified algorithms. In this paper...
Modern VLSI decoders for low-density parity-check (LDPC) codes require high throughput performance while achieving high energy efficiency on the smallest possible footprint. In this paper we present a valuable optimization to the processing step known as syndrome check. After each decoding iteration the updated posterior values are used to verify the validity of the codeblock and halt the decoding...
Stopping criteria for the iterative decoding of low-density parity-check codes are considered. For a successful decoding task an inherent stopping criterion is used: the fulfillment of all parity-check constraints. For an unsuccessful task the decoder usually completes a preset maximum number of iterations. Proper iteration control is required to save energy and time on unnecessary decoder operation...
In this paper, we employ to provide a method which combines Turbo codes and Low-Density Parity-Check (LDPC) codes based on Orthogonal Frequency Division Multiplexing (OFDM) system by adaptive encoding. The technique of channel estimation is used. The code rate and encoding scheme are all adaptive selection in the light of different channel conditions, so that we can make good use of these two types...
Message-Passing is the main decoding algorithm for Low-Density Parity Check (LDPC) Codes, in which Logarithmic Belief Propagation (Log-BP) algorithm is the most popularly used one. Particle Swarm Optimization (PSO) can also be regarded as an optimization algorithm by message-passing, which makes it possible to combine Log-BP algorithm with PSO. PSO was introduced into Log-BP algorithm by regarding...
We derive the log-likelihood ratio for iterative decoding of low-density parity-check codes transmitted using binary phase-shift-keying (BPSK) with pilot-symbol-assisted modulation. This is done with the aid of a reference phasor formed from the received pilot signals. We compare our metric with the existing Gaussian metric for differential BPSK transmission and also show that our metric converges...
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