Low Density Parity Check Codes Codes Research Articles

Improving security of 5G networks with multiplicative masking method for LDPC codes

5th Generation (5G) mobile networks are gradually being used all over the world. However, channel-coding security has become one of the most important challenges, especially in the face of new attacks such as side-channel attacks. To protect 5G against side-channel attacks, the multiplicative masking method for low-density parity check code (LDPC) codes is exploited in this study. First, a multiplication algorithm in finite fields is proposed for LDPC codes. Second, to secure LDPC codes, a multiplicative masking method based on a multiplication algorithm is put forward. Third, based on the multiplicative masking method, a secure coding method of LDPC for 5G is advanced. Based on the above designs and other improvements, the security of 5G networks is improved owing to the randomization of the channel-coding process and protection of important information against side-channel attacks.

Predictive Syndrome Based Low Complexity Joint Iterative Detection-Decoding Algorithm for Non-Binary LDPC Codes

This paper addresses the problem of decoding non-binary low density parity check codes(LDPC) over finite field GF(q) using symbol flipping approach. To achieve low complexity reliable communication, three new algorithms for improving the bit error rate performance of the non-binary LDPC decoder are presented. The first type is the symbol flipping decoding algorithm using a flipping function based on the channel reliability to identify the least reliable symbol position. In this algorithm, if the predicted symbol value satisfies the check sum, then the value is declared as correct otherwise the value is adjusted and sent back to the QAM detector. Algorithms 2 in this paper is an improvement to iterative joint detection-decoding algorithm by using the method of iterative hard decision based majority logic to select the new candidate symbol value. The feedback value to the QAM detector is adjusted by using Euclidean distance between the current symbol and the newly selected symbol value. Algorithm 3 is a low complexity version of Algorithm 2 which is derived by applying a majority voting scheme. In the majority voting scheme, symbols are short listed first by voting and all the computation are carried out only for the short listed least reliable symbols which significantly lowers the processing complexity. Numerical results and complexity analysis show that the proposed methods have good bit error rate versus complexity trade-off for various applications when compared with some existing algorithms.

Performance Analysis of Regular and Irregular LDPC Codes on SPIHT Coded Image Data

The LDPC (Low Density Parity Check Code) has Shown interesting results for transmitting embedded bit streams over noisy communication channels. Performance comparison of regular and irregular LDPC codes with SPIHT coded image is done here. Different Error Sensitive classes of image data are obtained by using SPIHT algorithm as an image coder. Irregular LDPC codes map the more important class of data into a higher degree protection class to provide more protection. Different degree protection classes of an LDPC code improves the overall performance of data transmission against channel errors. Simulation results show the superiority of irregular LDPC over regular LDPC codes.

Алгоритмы итеративного приёма кодов-произведений на основе низкоплотностных кодов проективной геометрии

The focus of this paper is directed towards the investigation of the characteristics of symbol-by-symbol iterative decoding algorithms for error-correcting block product-codes (block turbo-codes) which enable to reliable information transfer at relatively low received signal/noise and provide high power efficiency. Specific feature of investigated product codes is construction with usage of low-density parity-check codes (LDPC) and these code constructions are in the class of LDPC too. According to this fact the considered code constructions have symbol-by-symbol decoding algorithms developed for total class LDPC codes, namely BP (belief propagation) and its modification MIN_SUM_BP. The BP decoding algorithm is iterative and for implementation the signal/noise is required, for implementation of MIN_SUM_BP decoding algorithm the signal/noise is not required. The resulted characteristics of product codes constructed with usage of LDPC based on project geometry (length of code words, information volume, code rate, error performances) are presented in this paper. These component LDPC codes are cyclic and have encoding and decoding algorithms with low complexity implementation. The computer simulations for encoding and iterative symbol-by-symbol decoding algorithms for the number of turbo-codes with different code rate and information volumes are performed. The results of computer simulations have shown that MIN_SUM_BP decoding algorithm is more effective than BP decoding algorithm for channel with additive white gaussian noise concerning error-performances.

Research of Multi-Rate LDPC Decoding in Optical Communication System

Low-density parity-check code (LDPC) not only has good performance approaching the Shannon limit, but also has low decoding complexity and flexible structure. It is a research hot-spot in the field of channel coding in recent years and has a wide range of application prospects in optical communication systems. In this paper, the decoding aspects and performance of LDPC codes are analyzed and compared according to the bit error rate (BER) of LDPC codes. The computer simulation was carried out under additive white Gaussian noise (AWGN) channel and binary phase shift keying (BPSK) modulation. Through theoretical analysis and simulation results, this paper explores the way of multi-rate LDPC decoding.

LDPC-based Joint Source Channel Coding and Decoding Strategies for single relay cooperative communications

This paper investigates new cooperative communication strategies based on Low-Density Parity-Check codes (LDPC) with Joint Source-Channel (JSC) coding and decoding algorithms to efficiently deliver a correlated content to a destination node. The proposed strategies rely on double LDPC codes where the source and the channel coding are similar to standard LDPC operations, and can be mapped on Tanner graphs for message-passing decoding. Three coding strategies are proposed where different LDPC source and channel coding setups are applied at the source node and the relay node. For each transmission strategy, we propose a graph mapping the whole network, over which iterative message-passing decoding is applied, and where the probability of errors in the source–relay link are taken into account. We showed, based on computer simulations, that the proposed strategies can provide substantial improvements compared to equivalent rates point-to-point systems. Simulation results also showed that the system performance depends on the relay position, and that adapting the source and the relay channel coding rates accordingly can enhance the overall system performance for a time-varying network.

Research On LDPC-DFH Code Modulation And Demodulation System Based On Hard Decision Decoding

In order to reduce the bit error rate of differential hopping transmission, differential frequency hopping (DFH) is combined with low density parity check code (LDPC). On the basis of not adding more system complexity, the hard decision bit inversion algorithm (BF) and weighted error check based bit inversion algorithm (WVBF) are proposed to decode LDPC-DFH system. The check matrixes of different generation methods are used respectively. The BF decoding method and WVBF decoding method are used to simulate the Gaussian channel and Rician channel. The influence of different decoding methods on the bit error rate is discussed. The simulation results show that the BER of the DFH system with LDPC code is lower than that of DFH without LDPC, and the WVBF algorithm is better than the BF algorithm.

Program realization of simulation tools of low-density codecs: effective architecture of a decoder for massive parallel computations on graphic processors

The article deals with the peculiarities of modeling the characteristics of low-density parity-check codes (LDPC) in terms of their decoding. When decoding low-density parity-check codes in various communication standards, the iterative belief propagation algorithm (BP) and its various modifications - Pearl’s algorithm, sum-of-products algorithm - are widely used. In the article, special attention is given to this algorithm. The BP algorithm is a message-passing algorithm on a graphical model and consists of two basic messaging procedures between the nodes in the Tanner graph for LDPC code. The issues of constructing an effective architecture for an iterative decoder operating on the belief propagation algorithm in a heterogeneous system with massively parallel computing on a graphics processing unit are considered. It is shown that the use of the GPU allows to achieve a significant gain in decoding time with a sufficient size of the test matrix (a sufficient number of code and test nodes), obtained due to the parallelism of the architecture. Expressions for calculation of the size of the “working group” are given. The benefit of using a modified decoder architecture is estimated.

Implementation of Low density Parity Check system using Probabilistic Gradient Descent Bit Flipping Decoder

This paper represents the concept of hard decision decoder in which PGDBF is suitable decoder for the basic model of hard-choice decoder as long as low-density parity check code (LDPC) which is increase the error correction. This design introduced dynamic architecture which reduce the capability of random disarrangement of the PGDBF. The design is working on the Short Random Sequence (SRS) that is replica cover on the PGDBF decoding guidelines. In each iteration flipping number of bits these are focusing on improvement in performance and decoding delay. The best SRS is essential to manage the well-known decoding achievement of PGDBF, we introduced two kind of access with same hardware categories, but various LDPC codes are perform different behaviors. In this design we are modifying small hardware decoding unit for obtaining a good decoding explanation for present and further purpose.

Digital image information hiding algorithm research based on LDPC code

LDPC (low-density parity-check code) is a parity check code, and its performance is very close to Shannon limit. It is a sort of good channel code which has good ability of error correction. The coding can be introduced to an information-hiding algorithm because of its functional advantages. This way can improve robustness of a system in the process of information hiding, and it has a good application prospect. In this paper, a new algorithm is proposed which concludes two steps. Firstly, the encryption information needs to be implemented scrambling dispose; secondly, LDPC codes and modulation are used in the algorithm, and the encryption information is embedded into the carrier image, so the process of watermark embedding is completed. The method realizes the double encryption of information, and it improves the system’s stability and security. Under the test of MATLAB emulation, the application of LDPC code in encryption algorithm is fully verified.

Research on the application of LDPC code in chaotic sequence image encryption

Low density parity check code (LDPC) is a linear block code whose performance is close to Shannon’s limit. Compared with other decoding algorithms, it has low decoding complexity and flexible structure. So it becomes people’s research hotspots. In recent years, LDPC code codec algorithm has been improved, and is widely used in deep space communications, optical fiber communications, mobile communications and underwater and other fields. Using chaotic sequence single-layer mapping plus pixel scrambling can complete chaotic image encryption, because some chaotic sequence is poor robust, in the process of channel transmission, it is difficult to ensure that the information can be destroyed after the attack In this paper, LDPC codes are introduced, and in the chaotic image encryption, block coding is used to form error protection to improve the stability of the image transmission process and improve the transmission quality.

On CS Image Reconstruction Using LDPC Code Over Radio Mobile Channel

In this work, the effect of additive white Gaussian noise and fading channel on the compressed sensing or compressive sampling (CS) image reconstruction process are demonstrated. First, the work suggests encoding of the sensed samples by low density parity check code (LDPC) before transmission. It is well known that longer is the length of the LDPC codes better (lower) is the bit error rate (BER) performance. Thus to improve CS reconstruction a method to construct a larger length but 4 cycle free irregular LDPC code structure is also proposed. The code construction is based on the LDPC code in IEEE WiMAX standard. The proposed CS-LDPC structure is then extended for $$4^n$$ -QAM to find an optimal set of thresholds by minimizing BER (equivalently symbol error rate) using differential evolution (DE). The algorithm works on the log likelihood ratio values obtained by LDPC decoding. Extensive simulation results show the efficacy of the use of LDPC codes and the trade-off in code rate and measurements on reconstruction quality. Improved performance with the proposed DE based demodulation is also demonstrated.

Re-jagged AR4JA LDPC codes and their applications

This work investigated the performance of a newly developed protograph-based low-density parity-check code (LDPC) families belonging to accumulate-repeat-4-jagged-accumulate codes. The proposed code has hierarchical irregularity and quasi-cyclic property that retains it to be suitable for fast encoder and decoder implementation. The code used in this work is a rate-compatible linearly punctured code. The modified iterative decoding algorithm as mentioned in the literature is used along with a newly proposed encoder and simulation has been done for proposed LDPC coded orthogonal frequency division multiplexing (OFDM) link over wireless and optical wireless channels with hard- and soft-decision decoding. The code relates to new methods for designing rate-compatible families of protographs of different rates, all having the linear minimum distance property showing small performance degradation compared with the threshold. The parity-check matrix is composed of small identical modules to reduce the routing complexity of the decoder. The main essence of this code lies in the fact that LDPC codes of arbitrarily large size can be built by expanding from individual protographs or rate-compatible protograph families.

Bipolar chaotic pulse position modulation communication system based on cyclic LDPC

To overcome the error propagation and improve the communication efficiency of the chaotic pulse position modulation (CPPM) system, the bipolar chaotic pulse position modulation (BCPPM) communication system is proposed here. In BCPPM, every two-bit data are set as a group. The first bit and the discrete chaotic map determine the position of sent pulse, while the second bit determines the polarity of sent pulse. Each pulse in the channel contains two-bit information, so this scheme improves the communication efficiency. A (255,175) cyclic low-density parity-check code (LDPC) was designed, and its generator matrix and parity check matrix are cycled. Furthermore, the constructed BCPPM communication system is utilized in the cyclic LDPC aiming to mitigate the effect of noise. In the transmitter, it uses the encoder structure of cyclic codes while the min-sum algorithm is deployed to decode in the receiver. The analysis indicates that the proposed system is secure, insensitive to the channel distortion and convenient for multiple access communication. The simulation results show that in the additive white Gaussian noise (AWGN) channel, multipath channel, multiuser model, and hybrid communication environment, the BCPPM system has lower bit error rate (BER) compared with those of the CPPM and chaotic pulse on-off-keying (CPOOK). In addition, using cyclic LDPC codes, the system is more suitable for hardware implementation.

PERFORMANCE ANALYSIS OF HIGH EFFICIENCY LOW DENSITY PARITY-CHECK CODE DECODER FOR LOW POWER APPLICATIONS

In this study, we propose a low power, high efficient Low Density Parity-Check Code (LDPC) Decoder Architecture for error detection and correction applications. LDPC codes have been adopted in latest wireless standards such as satellite and mobile communications since they possess superior error-detecting and correcting capabilities. As technology scales, memory devices become larger and more powerful and low power consumption based error correction codes are needed. This study discuses the design and analysis of check node unit and variable node unit in LDPC decoder. The architecture is synthesized on Xilinx 9.2i and simulated using Modelsim, which is targeted to 90 nm device. Synthesis report shows that the proposed architecture reduces the hardware utilization and power consumption when compared to the conventional architecture design.

Design of Hard and Soft Decision Decoding Algorithms of LDPC

The demand for satellite communication and a wide-ranging objective, however, is often to achieve maximum data transfer, in a minimum bandwidth while maintaining an satisfactory quality of transmission. The transmission quality is basically concerned with the probability of bit error at the receiver here with respect to communication. This is an attempt to achieve highest capacity with minimum error rate by implementing modern codes named as LDPC(Low Density Parity Check codes) and it is represented here various decoding schema to decode and encode them At the present time LDPC codes has received a superior interest because their error correction performance and their functional world wide applications. The paper represents LDPC significance ,its characteristics and encoding and iterative decoding approaches to achieve channel capacity. Thus we need some technology that utilizes this available bandwidth by providing good error correction capability. We can also achieve it by using FPGA spartan 3e’s VHLD implementation. General Terms Iterative decoding, LDPC, encoding.

A joint encryption and error correction method used in satellite communications

Due to the ubiquitous open air links and complex electromagnetic environment in the satellite communications, how to ensure the security and reliability of the information through the satellite communications is an urgent problem. This paper combines the AES(Advanced Encryption Standard) with LDPC(Low Density Parity Check Code) to design a secure and reliable error correction method ? SEEC(Satellite Encryption and Error Correction). This method selects the LDPC codes, which is suitable for satellite communications, and uses the AES round key to control the encoding process, at the same time, proposes a new algorithm of round key generation. Based on a fairly good property in error correction in satellite communications, the method improves the security of the system, achieves a shorter key size, and then makes the key management easier. Eventually, the method shows a great error correction capability and encryption effect by the MATLAB simulation.

AID: An Energy Efficient Decoding Scheme for LDPC Codes in Wireless Body Area Sensor Networks

One of the major challenges in Wireless Body Area Networks (WBANs) is to prolong the lifetime of network. Tra- ditional research work focuses on minimizing transmit power; however, in the case of short range communication the consumption power in decoding is significantly larger than transmit power. This paper investigates the minimization of total power consumption by reducing the decoding power consumption. For achieving a desired Bit Error Rate (BER), we introduce some fundamental results on the basis of iterative message-passing algorithms for Low Density Parity Check Code (LDPC). To reduce energy dissipation in decoder, LDPC based coded communications between sensors are considered. Moreover, we evaluate the performance of LDPC at different code rates and introduce Adaptive Itera- tive Decoding (AID) by exploiting threshold on the number of iterations for a certain BER (10−4). In iterative LDPC decoding, the total energy consumption of network is reduced by 20 - 25%.

Security, Reliability in the Networks 4G, Using Elliptic Curve, Irregular LDPC Code and Interleavers of Block

A new system of transmission and reception with security and reliability requests for the networks of fourth generation (4G) is proposed. The security is provided by elliptical curve encryption, system reliability is given by the encoding of irregular low density parity check code (LDPC) and the interleaver. The construction of the irregular LDPC used a technique of low level error, the decoding utilized is the algorithm sum product, and the simulated channel is Additive White Gaussian Noise. According to the results of the proposed system enables transmission and reception achieve a great reliability, because for signal to noise ratio of 4 decibels is 100% of messages received without error

Design of low-density parity check codes for MIMO systems with doubly-iterative receivers

In this paper, the Multiple Input Multiple Output (MIMO) doubly-iterative receiver which consists of the Probabilistic Data Association detector (PDA) and Low-Density Parity-Check Code (LDPC) decoder is developed. The receiver performs two iterative decoding loops. In the outer loop, the soft information is exchanged between the PDA detector and the LDPC decoder. In the inner loop, it is exchanged between variable node and check node decoders inside the LDPC decoder. On the light of the Extrinsic Information Transfer (EXIT) chart technique, an LDPC code degree profile optimization algorithm is developed for the doubly-iterative receiver. Simulation results show the doubly-receiver with optimized irregular LDPC code can have a better performance than the one with the regular one.