Modern error correcting codes for 4G and beyond: Turbo codes and LDPC codes

2015 ◽  
Author(s):  
Pradeep M. Shah ◽  
Prakash D. Vyavahare ◽  
Anjana Jain
Keyword(s):  
Turbo Codes ◽  
Ldpc Codes ◽  
Error Correcting Codes

scholarly journals UEP Concepts in Modulation and Coding

2010 ◽  
Vol 2010 ◽  
pp. 1-14 ◽  
Author(s):  
Werner Henkel ◽  
Khaled Hassan ◽  
Neele von Deetzen ◽  
Sara Sandberg ◽  
Lucile Sassatelli ◽  
...  
Keyword(s):  
Turbo Codes ◽  
Arbitrary Number ◽  
Ldpc Codes ◽  
Unequal Error Protection ◽  
Multicarrier Modulation ◽  
Multimedia Data ◽  
Turbo Coding ◽  
Bit Loading ◽  
Check Node ◽  
Number Of Classes

First unequal error protection (UEP) proposals date back to the 1960's (Masnick and Wolf; 1967), but now with the introduction of scalable video, UEP develops to a key concept for the transport of multimedia data. The paper presents an overview of some new approaches realizing UEP properties in physical transport, especially multicarrier modulation, or with LDPC and Turbo codes. For multicarrier modulation, UEP bit-loading together with hierarchical modulation is described allowing for an arbitrary number of classes, arbitrary SNR margins between the classes, and arbitrary number of bits per class. In Turbo coding, pruning, as a counterpart of puncturing is presented for flexible bit-rate adaptations, including tables with optimized pruning patterns. Bit- and/or check-irregular LDPC codes may be designed to provide UEP to its code bits. However, irregular degree distributions alone do not ensure UEP, and other necessary properties of the parity-check matrix for providing UEP are also pointed out. Pruning is also the means for constructing variable-rate LDPC codes for UEP, especially controlling the check-node profile.

scholarly journals A Hybrid Statistical and Prioritised Unequal Error Protection Scheme for IEEE 802.11n LDPC Codes

2017 ◽  
Vol 8 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Tulsi Pawan Fowdur ◽  
Madhavsingh Indoonundon
Keyword(s):  
Ldpc Codes ◽  
Ldpc Code ◽  
Error Correcting Codes ◽  
Code Word ◽  
Unequal Error Protection ◽  
Node Degree ◽  
Error Protection ◽  
Ieee 802.11N ◽  
Protection Scheme ◽  
Power Region

The combination of powerful error correcting codes such as (LDPC) codes and Quadrature Amplitude Modulation (QAM) has been widely deployed in wireless communication standards such as the IEEE 802.11n and DVB-T2. Recently, several Unequal Error Protection schemes which exploit non-uniform degree distribution of bit nodes in irregular LDPC codes have been proposed. In parallel, schemes that exploit the inherent UEP characteristics of the QAM constellation have also been developed. In this paper, a hybrid UEP scheme is proposed for LDPC codes with QAM. The scheme uses statistical distribution of source symbols to map the systematic bits of the LDPC encoded symbols to the QAM constellation. Essentially, systematic symbols having highest probabilities of occurrence are mapped onto the low power region of the QAM constellation and those with a low probability of occurrence are mapped onto the high power region. The decrease in overall transmission power allows for an increased spacing between the QAM constellation points. Additionally, the scheme uses the distribution of the bit node degree of the LDPC code-word to map the parity bits having the highest degree onto prioritised QAM constellation points. Simulations with the IEEE 802.11n LDPC codes revealed that the proposed scheme can provide gains of up to 0.91 dB in Eb/No compared with other UEP schemes for a range of Bit Error Rate (BER) values

scholarly journals A Robust and High Capacity Data Hiding Method for H.265/HEVC Compressed Videos with Block Roughness Measure and Error Correcting Techniques

Symmetry ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1360
Author(s):  
Kusan Biswas
Keyword(s):  
Video Coding ◽  
Data Hiding ◽  
Turbo Codes ◽  
High Capacity ◽  
Error Correcting Codes ◽  
Human Vision ◽  
Embedding Technique ◽  
Payload Capacity ◽  
Capacity Data ◽  
Jensen Shannon Divergence

Recently, the H.265/HEVC video coding has been standardised by the ITU-T VCEG and the ISO/IEC MPEG. The improvements in H.265/HEVC video coding structure (CTU, motion compensation, inter- and intra-prediction, etc.) open up new possibilities to realise better data hiding algorithms in terms of capacity and robustness. In this paper, we propose a new data hiding method for HEVC videos. The proposed method embeds data in 4 × 4 and some selected larger transform units. As theory of Human Visual System suggests that human vision is less sensitive to change in uneven areas, relatively coarser blocks among the 8 × 8 and 16 × 16 blocks are selected as embedding destinations based on the proposed Jensen-Shannon Divergence and Second Moment (JSD-SM) block coarseness measure. In addition, the SME(1,3,7) embedding technique is able to embed three bits of message by modifying only one coefficient and therefore exhibits superior distortion performance. Furthermore, to achieve better robustness against re-compression attacks, BCH and Turbo error correcting codes have been used. Comparative studies of BCH and Turbo codes show the effectiveness of Turbo codes. Experimental results show that the proposed method achieves greater payload capacity and robustness than many existing state-of-the-art techniques without compromising on the visual quality.

Asymmetric quantum codes: constructions, bounds and performance

2009 ◽  
Vol 465 (2105) ◽  
pp. 1645-1672 ◽  
Author(s):  
Pradeep Kiran Sarvepalli ◽  
Andreas Klappenecker ◽  
Martin Rötteler
Keyword(s):  
Ldpc Codes ◽  
Finite Geometry ◽  
Explicit Construction ◽  
Error Correcting Codes ◽  
Quantum Codes ◽  
Asymmetric Quantum ◽  
Asymmetric Quantum Codes ◽  
Central Result ◽  
And Performance ◽  
Css Construction

Recently, quantum error-correcting codes have been proposed that capitalize on the fact that many physical error models lead to a significant asymmetry between the probabilities for bit- and phase-flip errors. An example for a channel that exhibits such asymmetry is the combined amplitude damping and dephasing channel, where the probabilities of bit and phase flips can be related to relaxation and dephasing time, respectively. We study asymmetric quantum codes that are obtained from the Calderbank–Shor–Steane (CSS) construction. For such codes, we derive upper bounds on the code parameters using linear programming. A central result of this paper is the explicit construction of some new families of asymmetric quantum stabilizer codes from pairs of nested classical codes. For instance, we derive asymmetric codes using a combination of Bose–Chaudhuri–Hocquenghem (BCH) and finite geometry low-density parity-check (LDPC) codes. We show that the asymmetric quantum codes offer two advantages, namely to allow a higher rate without sacrificing performance when compared with symmetric codes and vice versa to allow a higher performance when compared with symmetric codes of comparable rates. Our approach is based on a CSS construction that combines BCH and finite geometry LDPC codes.

Correctness of Local Probability Propagation in Graphical Models with Loops

2000 ◽  
Vol 12 (1) ◽  
pp. 1-41 ◽  
Author(s):  
Yair Weiss
Keyword(s):  
Graphical Models ◽  
Turbo Codes ◽  
Error Correcting Codes ◽  
Analytical Relationship ◽  
Theoretical Understanding ◽  
Single Loop ◽  
Joint Distributions ◽  
Probability Propagation ◽  
Local Propagation ◽  
Local Probability

Graphical models, such as Bayesian networks and Markov networks, represent joint distributions over a set of variables by means of a graph. When the graph is singly connected, local propagation rules of the sort proposed by Pearl (1988) are guaranteed to converge to the correct posterior probabilities. Recently a number of researchers have empirically demonstrated good performance of these same local propagation schemes on graphs with loops, but a theoretical understanding of this performance has yet to be achieved. For graphical models with a single loop, we derive an analytical relationship between the probabilities computed using local propagation and the correct marginals. Using this relationship we show a category of graphical models with loops for which local propagation gives rise to provably optimal maximum a posteriori assignments (although the computed marginals will be incorrect). We also show how nodes can use local information in the messages they receive in order to correct their computed marginals. We discuss how these results can be extended to graphical models with multiple loops and show simulation results suggesting that some properties of propagation on single-loop graphs may hold for a larger class of graphs. Specifically we discuss the implication of our results for understanding a class of recently proposed error-correcting codes known as turbo codes.

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