Turbo Codes Research Articles

Joint Decoding Technique for Collision Resolution in Non-orthogonal Multiple Access Environment

Multiple access technologies have grown hand in hand from the first generation to the 5th Generation (5G) with both performance and quality improvement. Non-Orthogonal Multiple Access (NOMA) is the recent multiple access technology adopted in the 5G communication technology. Capacity requirements of wireless networks have grown to a large extent with the penetration of ultra-high-definition video transmission, Internet of Things (IoT), and virtual reality applications taking ground in the recent future. This paper develops the Physical Layer Network Coding (PNC) for collision resolution in a NOMA environment with two users. Traditionally NOMA uses Successive Interference Cancellation (SIC) for collision resolution. While additionally a decoding algorithm is added along with SIC to improve the performance of the collision resolution. MATLAB-based simulation is developed on the NOMA environment with two users using Viterbi coding, Low-Density Parity Check (LDPC), and Turbo coding. Performance parameters of Bit Error Rate (BER) and throughput are compared for these three algorithms. It is observed that the Turbo coding performed better among these three algorithms both in the BER and throughput. The BER obtained from the SIC- Turbo is found to be performing well with an increase of about 14% from the ordinary SIC implementation. The performance of the collision resolution has increased by 13% to 14% when joint decoding techniques are used and thus increasing the throughput of the NOMA paradigm.

Parallel Implementation of the CCSDS Turbo Decoder on GPU

This paper presents a software turbo decoder on graphics processing units (GPU). Unlike previous works, the proposed decoding architecture for turbo codes mainly focuses on the Consultative Committee for Space Data Systems (CCSDS) standard. However, the information frame lengths of the CCSDS turbo codes are not suitable for flexible sub-frame parallelism design. To mitigate this issue, we propose a padding method that inserts several bits before the information frame header. To obtain low-latency performance and high resource utilization, two-level intra-frame parallelisms and an efficient data structure are considered. The presented Max-Log-Map decoder can be adopted to decode the Long Term Evolution (LTE) turbo codes with only small modifications. The proposed CCSDS turbo decoder at 10 iterations on NVIDIA RTX3070 achieves about 150 Mbps and 50 Mbps throughputs for the code rates 1/6 and 1/2, respectively.

Enhancing medical image security through machine learning and dual watermarking-based technique

ABSTRACT As the world becomes increasingly digital, healthcare is no exception. With the ease of sharing e-healthcare records over open networks, smart healthcare systems have become a popular way to manage patient information. But as the popularity of these systems has grown, so has the concern for their security. That's where image security techniques come in. In this paper we have developed a new approach to secure e-patient records like DICOM images. By combining the redundant discrete wavelets transform (RDWT), Hessenberg Decomposition (HD), and randomized singular value decomposition (RSVD). We developed a robust and dual watermarking scheme. This scheme uses multiple watermarks, including Electronic Patient Record (EPR) as text and images, to ensure high-level authentication. In order to attain a balance between imperceptibility and robustness, a PSO-based optimization of scale factor is employed and Turbo code is utilized to encode the EPR and minimize channel noise. Additionally, the marked image undergoes encryption using a 3D chaotic-based encryption technique, and the extracted watermark is denoised through a deep neural network. The result shows that the proposed scheme is both secure and reliable. With this dual watermarking scheme, we have made great strides in securing e-patient records.

Distributed Symmetric Turbo Coded OFDM Scheme Incorporated with STBC-MIMO Antennas for Coded-Cooperative Wireless Communication under Wideband Noise Jamming Environment

Distributed Symmetric Turbo Coded OFDM Scheme Incorporated with STBC-MIMO Antennas for Coded-Cooperative Wireless Communication under Wideband Noise Jamming Environment

A History of Channel Coding in Aeronautical Mobile Telemetry and Deep-Space Telemetry.

This paper presents a history of the development of channel codes in deep-space telemetry and aeronautical mobile telemetry. The history emphasizes "firsts" and other remarkable achievements. Because coding was used first in deep-space telemetry, the history begins with the codes used for Mariner and Pioneer. History continues with the international standard for concatenated coding developed for the Voyager program and the remarkable role channel coding played in rescuing the nearly-doomed Galileo mission. The history culminates with the adoption of turbo codes and LDPC codes and the programs that relied on them. The history of coding in aeronautical mobile telemetry is characterized by a number of "near misses" as channel codes were explored, sometimes tested, and rarely adopted. Aeronautical mobile telemetry is characterized by bandwidth constraints that make use of low-rate codes and their accompanying bandwidth expansion, an unattractive option. The emergence of a family of high-rate LDPC codes coupled with a bandwidth-efficient modulation has nudged the aeronautical mobile telemetry community to adopt the codes in their standards.

Implementation of turbo decoding for VDES signal data segments

Abstract The International Telecommunication Union (ITU) mandates the use of turbo coding for VDES signal data segments. Previous studies primarily focused on turbo decoding for a specific link in VDES, often neglecting its applicability to all links. This paper proposes an FPGA-based implementation method for turbo code decoding, aiming to achieve fast and accurate turbo decoding of VDES signal data segments, while also ensuring compatibility with different links. The resulting turbo decoder can adapt to the different code rates and data segment lengths specified in the VDES. A comparison of the decoding speeds between DSP and FPGA confirms that the parallel computing capability of FPGA can significantly improve the decoding speed. Finally, the main onboard resources required for FPGA implementation of turbo decoding were provided.

Advanced channel coding schemes for B5G/6G networks: State‐of‐the‐art analysis, research challenges and future directions

SummaryAs a consequence of continuing demand for additional capacity and higher quality data transmission, channel coding as a key component of a digital communication network has progressed from a classical single pair, point‐to‐point information theoretic application to a class of coding techniques with diverse parameters. The heterogeneous requirements of B5G/6G networks technology have made flexibility of code parameters the main desired feature while designing channel codes. Owing to this, channel coding techniques have evolved to support enabling applications that depend on different factors such as latency, reliability, energy efficiency and throughput. We review and discuss the application of new techniques, modifications in the design and construction of modern channel coding schemes, including block, convolutional, rateless and space‐time codes. Further, the error correction performance of mainstream channel decoders for LDPC, polar and turbo codes is compared and analysed for their attainable error rate. The aim of this study is to highlight the adaptability of the discussed coding schemes for the forthcoming cellular network landscape. This article also addresses the implementational challenges of high throughput, low latency and machine type communication scenarios. Moreover, some recent studies exploring the role of machine learning for optimisation of B5G/6G networks are classified and discussed. Concluding, research areas pertaining to the scalability of error control coding for next generation networking are addressed.

TURBO CODE RE-ANALYSIS USING DIFFERENT ALGORITHMS

Turbo codes are a novel type of forward error correcting codes that have proved to give a perfor- mance close to the channel capacity as proposed by C. Shannon. The parallel concatenation of two identical recursive convolutional encoders that are spaced apart by an interleaver results in a turbo code encoder. The two cascaded decoding blocks used by the turbo code decoder pass along a priori knowledge generated by each block in turn. The decoding approach has the advantage of working iteratively, allowing for an increase in total performance. This study does a performance analysis of turbo codes. The performance study includes two decoding methods: the soft output Viterbi algo- rithm (SOVA), which uses the log-likelihood ratio to produce soft outputs, and the log maximum a posteriori probability (Log-MAP) algorithm. Both punctured and unpunctured codes are studied to determine the impact of utilizing various decoding algorithms. The performance of the two various decoding techniques is then contrasted in terms of bit error rate. MATLAB tools are utilized to per- form simulations.

Evaluating Puncture and Non-puncture for the Turbo Code Model based the on AWGN Channel with 16-QAM

In general, a 5G new radio network is defined by three primary utilization situations, namely upgraded versatile broadband, ultra-reliable, and low latency interchanges of information, as well as huge machine-type correspondences. These utilizations require improved throughput, inertness, dependability contrasted, and a 4G framework. As a coding plan for information, 5G Turbo codes attain high throughput, a variable code rate, and length, and crossover programmed rehash with good error-detecting capability. The execution boundaries of 5G advancements are normal and are tens and thousands of times better compared with 4G. In this paper, the evaluations of puncturing and non-puncturing for turbo code depending on the minimization of penetrating of efficient pieces are discussed. It also provides penetrating of equality pieces considering additive white Gaussian noise (AWGN) Channel with 16 quadrature amplitude modulation (QAM) to attain high spectral efficiency. In addition to this, the super encoder encodes the separated progression with a code speed of 1/3. The code block association progressively connects the yields from the super encoder. The sign mapper employed in this paper adjusts the progression using a 16-QAM balance. Also, the mapper takes effective pieces, one uniformity bit from the upper encoder, and the deinterleaved equity bit from the base encoder. The Orthogonal frequency-division multiplexing (OFDM) mapper parts into more modest equivalent channels, named subcarriers and the information is sent on these equivalent channels at a reduced rate.

Hybrid Multi Kernel Polar Code Construction and Optimized Decoding Algorithm for 5G Mobile Communications

5G mobile communications faces difficulty in channel coding to satisfy user requirements. This paper evaluates flexibility, reliability and complexity for different channel coding schemes(Turbo codes, Low Density Parity check codes, mother polar codes, Multi Kernel-polar codes) on regular channel AWGN with BPSK modulation of code rate R=1/2. The proposed hybrid Multi Kernel-polar codes will have greater flexibility and reliability for short and large code words. The optimized decoding of Multi Kernel polar codes reduces the number of computations by using repeated LLR’s of sub-kernel matrices.

An Efficient Design for the DVB-S2 Forward Link System Outer Layer Encoding Based on PCC Turbo Coding Across Fading Channel

The most significant challenges wireless broadcasting systems face are channel effects and Inter Symbol Interference (ISI). Many different kinds of channel coding are employed to get around these issues. Digital Video Broadcasting for Satellite Telecommunication Second Generation (DVB-S2) uses a serial concatenation of Bose, Ray-Chaudhuri, and Hocquenghem (BCH) code and Low-Density Parity-Check (LDPC) code as a Forward Error Correction (FEC) for error detection purpose and correction. In this work, a MATLAB code (m-files) is constructed to simulate the standard DVB-S2 Bit-Interleaved Coded Modulation (BICM) system according to the ETSI Technical Report (EN 302 307 1). Then, the traditional design is redesigned with a Parallel Concatenation Convolutional (PCC) Turbo coding in concatenation with LDPC coding to enhance the (FEC). The two approaches have been tested under the official modulation types QPSK, 8PSK, 16APSK, and 32APSK with 2/3, 3/4, 3/5, 4/5, and 5/6 code rates (RC). Over a Rayleigh Fading channel, the two models are compared. The proposed model performed better than the standard model regarding bit error rate (BER) mitigation when operating at varying signal-to-noise ratio (SNR) levels, especially in 8PSK 3/5 MODCODE. The proposed model achieved (2.6272×10-3) BER mitigation value with power gain equal to 4 dB.

Advanced hybrid algorithms for precise multipath channel estimation in next-generation wireless networks

Multipath channels continue to present challenges in wireless communication for both 5G and 6G networks. A multipath channel is a phenomenon in wireless communications where signals traverse from the sender to the receiver along various paths. This end occurs due to the reflection, diffraction, and refraction of signals of various objects and structures in the environment. Such pathways can cause symbol interference in the transmitted signal, leading to communication issues. To this end, our paper proposes the integration of three algorithms: teaching-learning-based optimization (TLBO), particle swarm optimization (PSO), and artificial neural networks (ANN). This combination effectively analyzes and stabilizes the transmission channel, minimizing symbol interference. We have developed, simulated, and evaluated this hybrid approach for multipath fading channels. We apply it to various coding schemes, including tail-biting convolutional code, turbo codes, low-density parity-check, and polar code. Additionally, we have explored various decoding methods such as Viterbi, maximum logarithmic maximum a posteriori, minimum sum, and cyclic redundancy check soft cancellation list. Our study encompasses new channel equalization schemes and coding gains derived from simulations and mathematical analysis. Our proposed method significantly enhances channel equalization, reducing interference and improving error correction in wireless communication systems.

Method of assessing the information reliability of in 5G wireless transmission systems

The article proposes a method of assessing information transmission reliability by using the output normalized logarithmic ratio of the likelihood function (LRLF) of the decoder. Based on the evaluation, the method allows adapting system parameters with turbo codes (TC) or LDPC code. This method can be used in combination with other methods of parametric and structural adaptation using turbo codes or LDPC codes.

A tactical data link model based on CCSK-FMSK

In collaborative combat operations, the challenges brought by the communication adversities of tactical data links are becoming increasingly prominent. Ensuring the reliable connection of tactical data links has always been a key issue, especially considering the increasing impact of external interference on the signal at the receiving end of the system, which in turn affects the bit error rate (BER) of the tactical data link system. To address this challenge, this paper proposes a tactical data link anti-interference scheme based on cyclic code shift keying (CCSK) spread spectrum and minimum shift keying (MSK) modulation fusion frequency hopping technology, named CCSK-FMSK, and introduces turbo code and cyclic redundancy check (CRC) coding to construct a tactical data link model based on CCSK-FMSK. Specifically, CCSK-FMSK disperses interference power by expanding the signal spectrum, enhancing the anti-interference ability of tactical data links. CRC coding and Turbo coding achieve error detection and correction by introducing supervised symbols. In addition, this paper proposes a soft despreading and a soft demodulation algorithm corresponding to CCSK spread spectrum and MSK modulation to achieve cascade with Turbo decoder and improve the error rate performance and robustness of the model. Compared with existing models, the tactical data link based on CCSK-FMSK has better BER performance.

Hardware-Level Secure Coding

In this letter, a combined encryption and error-control coding scheme based on Turbo Codes (TC) is proposed to enhance the security of the transmission. It relies on Convolutional Encoders that operate over Galois Fields GF(4) and include variable encryption polynomials, whose coefficients are randomly selected every L steps from a set of optimal polynomials. This type of encoder has been studied in previous papers, where a certain correspondence between the randomness of the encoded sequence and the performance of the TC was conjectured. In this work, a scheme with a varying length L is proposed to increase the output randomness and, therefore, the security of the sequence to be transmitted. That is to say, the number of steps L, over which one of the polynomials is iterated, is a random variable. The randomness of the output and the security of the TC are quantified using differential block entropy, showing that it is possible to improve the security of the transmitted data without compromising the corresponding Bit Error Rate (BER).

Study of the block and convolutional code decoding efficiency using a turbo code decoder

An urgent task is to correct errors that occur during the transmission and storage of information. To solve this problem, various noise-resistant codes have recently been increasingly used. Turbo codes have the best correcting ability in data transmission channels with a high probability of an erroneous bit. To obtain the necessary characteristics, various combinations of codes and encoding and decoding methods are used. If another block of information bits is added to the codeword of a systematic block or systematic convolutional code, then it will be possible to implement decoding of such a codeword by a turbo code decoder. The disadvantage of the resulting combined code is its extremely low correcting ability in the presence of errors in the check bits of the codeword. The article shows that the correcting ability of the presented code can be significantly increased by multiplying the decoded values of the check bits by reduction factors.

The Comparison of RS Codes, LDPC Codes, And Turbo Codes

Error correction codes have been widely used in various fields in recent years, including the communication field, storage field, digital media field, computer network field, and so on. In this paper, the development history of error correction codes is briefly summarized; and the principles and performance of three kinds of error correction control codes are systematically summarized starting from RS codes, LDPC codes, and Turbo codes. Three types of error correction codes are compared and analyzed in the field of wireless optical communication, and the error correction characteristics of different codes in three different weather conditions are compared and summarized for the applicable environments. The error correction codes are also compared in the field of aviation flight telemetry, and which codes are suitable for uplink and downlink telemetry in flight telemetry are summarized. At the same time, the paper provides an outlook on the future development trend of error correction codes.

CRGAN-based turbo code interleaver for underwater acoustic communications

This paper proposes a channel response generative adversarial network (CRGAN)-based turbo code interleaver that estimates a channel response and interleaver indices at a transmitter by using a sound speed profile (SSP) and the ocean environments without feedback from a receiver. The interleaver indices are designed to allocate important bits from the turbo code to subcarriers with great channel gains, which reduces them from being affected by deep fading. Computer simulations and practical ocean experiments demonstrate that the proposed method estimates the channel response with low mean squared errors (MSEs) and improves bit error rate (BER) performances compared with the conventional method.

Turbulence mitigation in FSO based on turbo coding and equalization

Abstract Free space optical (FSO) communication has gained considerable interest for various applications because of its high speed, security, and low power consumption, which seem like promising advantages for the future. FSO systems are severely constrained by turbulence produced by air temperature and density fluctuations, resulting in scattered and distorted light beams. The capacity and bit error rate (BER) of an FSO link can be influenced by fading brought on by turbulence. Turbulence raises the BER, especially under conditions of moderate and high turbulence. The proposed model suggests using a turbo encoder with an intensity modulator at the FSO transmitter and combining maximum likelihood estimation (MLE), zero-forcing equalization (ZFE), and a turbo decoder for the direct detection receiver. However, MLE does an accurate channel estimate, which minimizes fading and turbulence. ZFE improves the quality of the link even further, while turbo coding lowers the bit error rate by increasing redundancy and greatly enhancing error-correcting capability. The Gamma–Gamma turbulence model simulation showed the proposed system’s superiority over other techniques, which achieved a BER of 10−5 with a signal-to-noise ratio (SNR) of 16 dB for moderate and strong turbulence, respectively. Consequently, even though turbo coding adds redundancy to the signal, it can achieve substantial coding gains that increase FSO capacity.

Formalization and modeling of turbocode encoding/decoding processes for 5G communication systems

Improving the energy characteristics in 4G and 5G mobile communication systems is provided by the use of adaptive control technology for encoding, modulation and power parameters. The paper considers promising adaptive coding schemes in mobile communication systems. The article formalizes the process of optimizing the operation of the turbo code encoder and decoder by using adaptive selection of the size of state diagrams based on the proposed decoding uncertainty indicator. In contrast to the known methods of TC adaptation, the size of the TC encoder/decoder state diagram is adaptive depending on the signal-to-noise ratio in the channel and the values of the normalized number of changes in the sign of the a posteriori-a priori logarithmic relations of the likelihood functions about the transmitted data bits of the turbo code decoder. Analysis of the simulation results shows that the reliability of transmission is increased by choosing a rational size of the TC encoder/ decoder state diagram. The proposed formalization of the model of the TC functioning process is a further development of adaptive coding technologies while preserving the transmission system bandwidth and differs from those known in that various TC MLRS polynomials are used for adaptation, which determine the necessary structure and size of the TC encoder and decoder state diagram. The interleader parameters are selected as fixed. Simulation modeling was used to analyze the efficiency of optimizing the operation of the encoder and decoder of the turbo code by using adaptive size selection of state diagrams. For comparison, the fourth-generation LTE-Advanced Mobile Communication Standard was chosen. The simulation was carried out in Visual Studio 2019 the data transmission system with Turbo codes, modulator (demodulator) OFDM, channel with additive Gaussian white noise (ABGN) was modeled. The results of the work can be used in conjunction with other adaptation methods, such as coding rate adaptation, based on polynomials of TC component codes, in systems with multiparametric adaptation that function under conditions of complete or partial a priori uncertainty.