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In data communication the process of sending data in the form of information is susceptible to theft, destruction, modification or repetition of the data sent which causes information to be changed / corrupted according to the original data. One way to guarantee authenticity can be done by utilizing security techniques in the process of sending data, one of which is by using a combination of cryptographic and error correction techniques, namely AES and Turbo Code. This study aims to combine the two techniques and apply them to text data by evaluating based on the length of AES encryption keys. Performance results indicate that AES-Turbo cryptographic combination algorithms can work optimally at SNR greater than or equal to 15 dB, for the best test value for avalanche effects is 24.77 % at 256-bit key lengths and the testing data execution time with an average time of 9.19 seconds, the time required for decryption is longer than the time needed for encryption, and the longer the key the longer it takes for encryption and decryption. For selection of keys length of AES more efficiency and effectiveness that is by using 128-bit key.

This paper presents the design of an interleaver for short Parallel Turbo Codes (PTC) with short block lengths in the order of 64, 128, and 256 bits. In particular, the objective is to design an interleaver that generates decorrelation in the external input information to parallel recursive convolutional encoders, with sufficient data propagation to reduce the Bit Error Rate (BER). Experimental tests are designed and implemented −by numerical calculations− using the MatLab/Simulink software. The S-random interleaver, which applies circular displacement and a propagation constraint, is employed. An excellent reduction in BER is achieved for the three short block lengths, according to the quality indicator defined by the International Telecommunication Union (ITU).

This paper investigates the turbo coded-spatial modulation (TC-SM) scheme based on code matched interleaver (CMI) for multiple input multiple output (MIMO) antenna system. The information bits for the selection of transmit active antenna and for the M-QAM modulated symbols are protected by a forward error correcting turbo code. In this work, we demonstrate that parallel encoding and decoding construction of the TC-SM scheme enabled us to effectively extend the TC-SM scheme to a turbo coded-cooperative spatial modulation (TCC-SM) scheme with CMI placed at the relay node. Numerical results based on Monte Carlo simulations revealed that the TCC-SM and TC-SM schemes outperform state of the art polar coded-cooperative spatial modulation (PCC-SM) and polar coded spatial modulation (PC-SM) schemes, respectively, under identical conditions. This performance improvement in bit-error rate (BER) of the proposed TCC-SM and TC-SM schemes occurred due to the joint soft input soft output log maximum a posteriori probability (SISO-Log-MAP) iterative decoding at the receiver. Furthermore, the mathematical error performance of the TC-SM scheme has also been presented. The numerical results demonstrate that the proposed TCC-SM scheme offers robustness not only in BER performance over the practical (non-ideal) source to relay channel but also presents less encoding and decoding complexity as compared to the PCC-SM scheme.

Multiple‐Input Multiple‐Output Orthogonal Frequency Division Multiplexing (MIMO‐OFDM) is an essential technology in the wireless communication system. However, its performance is significantly affected by Carrier Frequency Offset (CFO), which leads to inter‐carrier interference (ICI). The CFO estimation and compensation techniques are used to mitigate the Doppler effect. In addition, the confidentiality of data is a key factor of the system. This paper proposes a Turbo‐based encryption and coding scheme to improve reliability and security for the MIMO‐OFDM wireless communication systems affected by the Doppler frequency offset. In our proposed scheme, the secret key is produced from channel parameters between legitimate users and it is used as a seed for generating a pseudo‐random bit sequence using an Advanced Encryption Standard (AES) generator with variable key lengths. The Turbo code's puncturing mechanism is controlled by this pseudo‐random bit sequence. The proposed method is applied to the system with different modulation schemes through the Rayleigh channel. The simulation results show that the system affected by the Doppler effect would obtain the best performance when using the highest key length of the AES generator, the BPSK, and a great number of receive antennas. Furthermore, the proposed solution outperforms several previous approaches for the MIMO‐OFDM systems. This paper proposes a Turbo‐based encryption and coding scheme for the MIMO‐OFDM wireless communication systems affected by Doppler frequency offset. The simulation results show that the system affected by the Doppler effect would obtain the best performance when using the highest key length of the AES generator, the BPSK, and a great number of receive antennas. Furthermore, the proposed solution outperforms several previous approaches for the MIMO‐OFDM systems .

The term Block Turbo Code typically refers to the iterative decoding of a serially concatenated two-dimensional systematic block code. This paper introduces a Vector Turbo Code that is irregular but with code rates comparable to those of a Block Turbo Code (BTC) when the Bahl Cocke Jelinek Raviv algorithm is used. In BTC’s, the horizontal (or vertical) blocks are encoded first and the vertical (or horizontal) blocks second. The irregular Vector Turbo Code (iVTC) uses information bits that participate in varying numbers of trellis sections, which are organized into blocks that are encoded horizontally (or vertical) without vertical (or horizontal) encoding. The decoding requires only one soft-input soft-output decoder. In general, a reduction in complexity, in comparison to a BTC was achieved for the same very low probability of bit error (10-5). Performance in the AWGN channel shows that iVTC is capable of achieving a significant coding gain of 1.28dB for a 64QAM modulation scheme, at a bit error rate of 10-5over its corresponding BTC. Simulation results also show that some of these codes perform within 0.49dB of capacity for binary transmission over an AWGN channel.

Design of interleavers with a compromise between reliability and complexity of implementation is a challenging code design problem. This paper deals with the design of chaotic interleavers for secure turbo codes using a novel generalized 2D chaotic map. Compared with random interleavers, the proposed interleavers improve the performances while reducing the complexity of implementation. Furtheremore, parameters of chaotic maps can be used to jump from a map to the other which improve the security against decoding attacks. The proposed interleavers enhance the reliability and physical layer security.

A neural network-based decoder, based on a long short-term memory (LSTM) network, is proposed to solve the problem that large decoding delay and performance degradation under non-Gaussian noise due to poor parallelism of existing turbo decoding algorithms. The proposed decoder refers to a unique component coding concept of turbo codes. First, each component decoder is designed based on an LSTM network. Next, each layer of the component decoder is trained, and the trained weights are loaded into the turbo code decoding neural network as initialization parameters. Then, the turbo code decoding network is trained end-to-end. Finally, a complete turbo decoder is realized. The structural advantage of turbo code component coding is fully considered in the design process, and the problem of decoding delay caused by the existence of interleaver is cleverly avoided. The introduction of deep learning technology provides a new idea to solve the traditional communication problems. Simulation results show that the performance of the proposed decoder is improved by 0.5–1.5 dB compared with the traditional serial decoding algorithm in Gaussian white noise and t-distribution noise. When BER performance is close, the LSTM decoder requires half or even less than that of BCJR. Moreover, the results demonstrate that the proposed decoder is adaptive and can be applied to communication systems with various turbo codes. The LSTM decoder shows lower bit error rate, computational complexity and higher decoding efficiency under the same conditions. Therefore, it is necessary to study the turbo code decoding technology based on deep learning combined with the actual channel environment.

This article presents the performance analysis and comparison of turbo codes for several interleavers with short blockchains. According to the symmetry concept, turbo codes consist of two symmetric convolutional codes preceded by an interleaver. Some interleavers can be described by symmetric 3 × 3 generator matrices, whereas others are represented through symmetric matrices in which the nonzero terms in the matrix are monomials. Interest in short blockchains has grown over the years because of their use in emerging applications that require the transmission of data units in the order of hundred bits. In this research, interleavers used are random interleaver, semi-random interleaver, quadratic polynomial permutation (QPP) interleaver, and chaotic Lozi map interleaver. For each interleaver, the turbo code is assessed with at least two short data distances; then, the interleavers are compared against each other. The performance of turbo codes is assessed based on bit error rate, particularly with lengths between 64 and 512 bits. Additionally, an interleaver based on Duffing chaotic maps is proposed, whose deterministic nature provides an advantage, and the performance results are presented, achieving excellent BER values for 64 bits. With these results, the effect of the interleaver on turbo codes and particularly on short block length interleavers, is studied.

This paper investigates the design of a modified matrix interleaving algorithm as a way to improve the performance of turbo codes. This proposed solution, known as the matrix-dithered golden (MDG) interleaver, utilizes the characteristics of a matrix interleaver combined with the golden section theory. The performance of the proposed interleaving method is compared with that of matrix (M), random (R), and dithered golden (DG) interleavers. The comparison is made in terms of bit error rate (BER), frame error rate (FER), computational complexity, and storage memory requirement. The turbo coded system is implemented and simulated using Matlab/Simulink software. Results of simulations performed both in the additive white Gaussian noise (AWGN) channel and the Rayleigh fading channel demonstrate the effectiveness of the proposed interleaver. The MDG interleaver is an effective replacement for random interleavers, as it improves BER and FER performance of the turbo code and is also capable of reducing the storage memory requirement without increasing the system's complexity.

Thought provoking “Turbo Code” (TC) is found to be as one of the competent error control coding schemes not only for its amazing “Bit Error Rate” (BER) act but also for its proficiency in secured data transmission with least errors. However, “TC” is incapable of lessening the knocking down effect because of low “Minimum Hamming Distance (MHD)” d min . This problem can be resolved either by designing greater memory driven “TCs” or by conniving a coding system driven by higher number of encoding units. Moreover, the evaluation of “constricted and accurate upper bound” on “BER” can be considered as another interesting scope of research in this regard. Inspired by this research orientation, in this article, the Moment based Simplified Augmented State Diagram (MSASD) has been proposed to evaluate the “Transfer Function” for the assessment of the “upper bound” on the “BER” act of the “4D-TC” scheme. For this purpose, “BER” act of the two memories driven “4D-TC” model has been inspected using “simulation”, “Augmented State Diagram” (ASD) and “MSASD” techniques. Moreover, a qualified investigation has been done on the “BER” performances of the “4D-TC” for different code rates. Furthermore, the “BER” behavior of the “4D-TC” has been compared with “3D-TC” using three different approaches namely, “simulation”, “ASD” and “MSASD”. Finally, a comprehensive BER comparison among different forms of TCs has been performed in LTE system under different fading channel conditions.