Performance Of Turbo Codes Research Articles

Performance of the Duo-Binary Turbo Codes in DVB-RCS2 system

Performance of the Duo-Binary Turbo Codes in DVB-RCS2 system

Performance Analysis of Turbo Codes, LDPC Codes, and Polar Codes over an AWGN Channel in the Presence of Inter Symbol Interference.

This paper discusses the results of simulations relating to the performances of turbo codes, low density parity check (LDPC) codes, and polar codes over an additive white Gaussian noise (AWGN) channel in the presence of inter symbol interference, denoting the disturbances that altered the original signal. To eliminate the negative effects of inter symbol interference (ISI), an equalizer was used at the level of the receiver. Practically, two types of equalizers were used: zero forcing (ZF) and minimum mean square error (MMSE), considering the case of perfect channel estimation and the case of estimation using the least square algorithm. The performance measure used was the modification of the bit error rate compared to a given signal to noise ratio; in this sense, the MMSE equalizer offered a higher performance than the ZF equalizer. The aspect of channel equalization considered here is not novel, but there have been very few works that dealt with equalization in the context of the use of turbo codes, especially LDPC codes and polar codes for channel coding. In this respect, this research can be considered a contribution to the field of digital communications.

SP-DSTS-MIMO Scheme-Aided H.266 for Reliable High Data Rate Mobile Video Communication

With the ever growth of Internet users, video applications, and massive data traffic across the network, there is a higher need for reliable bandwidth-efficient multimedia communication. Versatile Video Coding (VVC/H.266) is finalized in September 2020 providing significantly greater compression efficiency compared to Highest Efficient Video Coding (HEVC) while providing versatile effective use for Ultra-High Definition (HD) videos. This article analyzes the quality performance of convolutional codes, turbo codes and self-concatenated convolutional (SCC) codes based on performance metrics for reliable future video communication. The advent of turbo codes was a significant achievement ever in the era of wireless communication approaching nearly the Shannon limit. Turbo codes are operated by the deployment of an interleaver between two Recursive Systematic Convolutional (RSC) encoders in a parallel fashion. Constituent RSC encoders may be operating on the same or different architectures and code rates. The proposed work utilizes the latest source compression standards H.266 and H.265 encoded standards and Sphere Packing modulation aided differential Space Time Spreading (SP-DSTS) for video transmission in order to provide bandwidth-efficient wireless video communication. Moreover, simulation results show that turbo codes defeat convolutional codes with an averaged Eb/N0 gain of 1.5 dB while convolutional codes outperform compared to SCC codes with an Eb/N0 gain of 3.5 dB at Bit Error Rate (BER) of . The Peak Signal to Noise Ratio (PSNR) results of convolutional codes with the latest source coding standard of H.266 is plotted against convolutional codes with H.265 and it was concluded H.266 outperform with about 6 dB PSNR gain at Eb/N0 value of 4.5 dB.

Design of Chaotic Interleaver Based on Duffing Map for Turbo Code

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.

Design of a Modified Interleaving Algorithm Based on Golden Section Theory Enhancing the Performance of Turbo Codes

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.

On the performance of chaotic interleaver for turbo codes

It is well known that the interleaver plays a critical role in the performance of turbo codes and its design using random and deterministic permutations. In this paper, we present a new method to design a deterministic interleaver with random-like behavior based on two-dimensional chaotic map, so called lozi map. The designed interleaver is called chaotic interleaver. The statistical properties and the performance of such interleaver have been investigated and compared with random interleaver and dithered golden interleaver. Chaotic interleaver results in lowering the latency and the complexity of implementation and enhance the reliability and the security of the communication system.

Filtered-OFDM with channel coding based on T-distribution noise for underwater acoustic communication

Bit error rate (BER) is typically high in underwater acoustic (UWA) channel, which is characterized by high propagation delay and poor quality of communications. UWA noise statistics do not follow the standard Gaussian distribution. It has been proven through field tests that the noise follows the t-distribution in Malaysian shallow-water. In this paper, a study on UWA error performance is presented based on t-distribution. Furthermore, the expressions of error performance are derived using binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) modulations order. Moreover, the new waveform filtered orthogonal frequency division multiplexing (F-OFDM) in UWA with turbo and convolution code is adopted. The simulation results show that at BER 10–3, the Signal-to-Noise Ratio (SNR) is 6 dB and 11 dB for BPSK and QPSK, respectively. The turbo code performance appears to be superior over the convolution code. Furthermore, the results indicate that F-OFDM significantly improves the power spectral density to approximately 120 dBW compared with OFDM.

Performance Analysis of Reliability-Based Decoding Algorithm for Short Block Length Turbo Codes

Demand for transmission using short block length messages has been increased recently in applications including satellite communication, mobile communication, wireless sensor networks, and machine type communications. Unacceptable performance degradation associated with the short block length Turbo codes restricted its use for applications requiring communication with short block length codewords. A novel performance improved reliability-based decoding algorithm for short block length Turbo codes has been formulated and proposed by the authors. The proposed algorithm has a coding gain of 2.45 dB at a BER of 10−3 over AWGN channel with BPSK modulation for a code rate of . The algorithm has a channel adaptive complexity and has shown nearly 82% reduction in the decoding time complexity for the rate Turbo code at 3 dB SNR. As an extension of this earlier work, a detailed performance analysis of the algorithm on different Turbo codes has been carried out. A four-state Turbo encoder has been used to bring out the key aspects of the level based algorithm which is driven by reliability as the key parameter. The formulated algorithm has been applied to different Turbo encoder structures namely 3GPP LTE and CCSDS Turbo codes and a detailed analysis has been carried out in this paper. Simulation results show a significant improvement in the error correction performance of short block length Turbo codes. The algorithm also leads to a marked improvement in time complexity at high SNRs. The algorithm is an attractive solution for applications requiring communication with short block lengths.

Channel Coding for Multi-Carrier Wireless Partial Duplex

In order to leverage the spectrum resources, several forms of wireless duplex have been introduced and investigated in recent years. In Partial Duplex (PD) schemes, part of the band is transmitted in Full-Duplex (FD) and the rest in Half-Duplex (HD); therefore, some transmitted symbols will be characterized, at the receiver, by high SNR (Signal-to-Noise Ratio) and others by low SNR because of the residual self-interference (SI) in the FD part. Combining properly the patterns of these high and low SNR symbols affects the performance of the encoding schemes used in the system; in order to overcome this issue, different encoding and allocation schemes can be adopted for achieving a satisfactory solution. This paper investigates the performance of Low-Density Parity-Check (LDPC), turbo, polar codes for wireless PD. Orthogonal Frequency Division Multiplexing (OFDM) is an efficient multicarrier modulation technique, used in 4G and in the upcoming 5G, and it can be exploited for realizing a proper symbol allocation according to the SNR on each subcarrier. In this context, performance of LDPC, polar, and turbo codes derived from existing specifications has been studied when the system faces a mixture of high and low SNRs on the bits and hence on the symbols coming from the same codeword and this unbalanced SNR distribution is known a-priori at the transmitter, a condition associated with a scheme in which part of the symbols is subject to FD interference.

Performance Analysis of High Throughput MAP Decoder for Turbo Codes and Self Concatenated Convolutional Codes

The effect of parallelism on Bit Error Rate (BER) performance of Turbo Code (TC) and Self Concatenated Convolutional Code (SECCC) with different levels of parallelism and frame sizes is investigated. Next Iteration Initialization (NII) method is employed for mitigating the BER degradation resulting from increased parallelism. In order to analyze and compare the architectural performance of both schemes, this paper presents the Very High Speed Integrated Circuit Hardware Description Language (VHDL) design of Maximum Aposteriori Probability (MAP) decoder for TC and SECCC, both employing the same constituent code. The simulation results show that for BER of 10−4, without parallelism, TC is 0.4 dB superior to SECCC, whereas, with parallelism of 64, the difference in performance between both schemes reduces to 0.25 dB. It is found that SECCC outperforms TC for frame sizes less than or equal to 2048 bits, when invoking a parallelism of 16, 32 and 64. The BER performance of both schemes shows that SECCC outperforms TC at parallelism of 256 by 0.3 dB at BER of 10−4. Hence, for high throughput architectures employing higher parallelism (beyond 64 and 128) without significant degradation in BER performance, SECCC performs better than TC. The synthesis results of VHDL design of the MAP decoder obtained using Xilinx ISE verify that both schemes have equal clock frequency and resource consumption. It is demonstrated that the MAP decoder achieves the clock frequency of 86.3 MHz which is capable of producing a throughput of 691 Mbps using parallelism of 64.

Performance Evaluation of Encoded Opportunistic Transmission Schemes

The performance of encoded opportunistic transmission schemes in wireless channels affected by Rayleigh fading and additive white Gaussian noise (AWGN) is analyzed. In opportunistic transmission, the information is transmitted only when the fading amplitude is above a threshold. For this, the receiver with the knowledge of the channel state information notifies the instants the transmitter should transmit. Opportunistic systems with convolutional error correcting codes or with trellis coded modulation are analyzed in terms of closed-form bit error rate (BER) expressions. Nevertheless, the approach presented can be employed with any kind of error correcting codes. Hence, the performance of turbo codes is also presented in the simulations. Monte Carlo simulations verify the accuracy of the derived expressions and provide insights on the system performance. Performance results show that uncoded and encoded opportunistic systems are superior to uncoded and encoded ordinary systems (non-opportunistic), respectively. In particular, the BER curves of the opportunistic system decay exponentially when the signal-to-noise ratio (SNR) increases. On the other hand, BER curves for ordinary transmission decay linearly, where the slope is proportional to the diversity that depends on the error correcting code. Thus, opportunistic systems require less SNR to guarantee the same BER of ordinary transmission. The BER gain increases as the SNR increases. It is also observed that uncoded opportunistic systems are even superior to encoded ordinary ones. The results are validated guaranteeing the same spectral efficiency for all the scenarios. Finally, due to the exponential decay of the BER curves, coding gain expressions, used in ordinary systems over AWGN, can be used as approximations for opportunistic transmission in fading channels.

Performance of Turbo Code in CDMA under AWGN Channel

Carrier Division Multiple Access is considered as an efficient technique in wireless communication due to its high possibility to serve an unlimited number of users. CDMA uses the same frequency concurrently with wireless communication. In this paper, the performance and evaluation of turbo code are duly presented followed by the examination of CDMA under AWGN channel was highlighted. The simulation estimated to achieve bit error rate of less than 10-2 frame size. To this end, the results of the simulation show that the Bit Error Rate is inversely proportional to the size of the frame and directly proportional the number of iteration in the decoder.

Multi-level quantization and blind equalization based direct transmission method of digital baseband signal

The direct transmission of digital baseband signals has practical significance in the field of Ethernet terminal connection, high-speed digital communication, data transmission of various types of information peripherals. The signal amplitude gradually decays while the transmission distance increases. Also the attenuation is proportional to the signal frequency, resulting in signal distortion and receiving error. It is a common method for digital baseband signal transmission to use pre-emphasis chip and equalizer chip to improve the transmission quality with a wide range of mature applications. This paper describes a new type of digital signal transmission method, as the receiver using analog-to-digital converter, instead of equalizer chip, to achieve the multi-level quantization of receiving time-domain data waveform. The waveform of the transmitted digital high and low level signal is sampled into multi-bit values. Then, the paper realizes adaptive frequency domain equalization based on soft threshold and makes use of multi-level quantization soft information for error correction. Error correcting code is mainly used to correct the error caused by the channel bandwidth limit, external noise or interference in the process of data transmission, so as to improve the stability and reliability of the transmission. The paper uses the two-stage error correcting codec system based on both Turbo and BCH coding, to achieve the high performance of Turbo code, and good characters of respond time and complexity. The transmitter outputs 12.5 MHz pseudo-random sequence through a 199.93 meter unshielded balanced twisted pair transmission medium. And the receiver circuit using a 62.5MSPS analog-to-digital converter over-samples the waveform to 8-level quantity. The output error of a 65536 bit pseudo-random sequence is less than 8 bits, and the error correction can be further improved by 8b-10b codec. Compared with the traditional pre-emphasis and balanced interface ICs connection, the method described in this article has the advantages of longer transmission distance, better flexibility and wider scope of use.

Turbo Codes Performance Optimization over Block Fading Channels

In this paper, the best achievable performance of a turbo coded system on a block fading channel is obtained, assuming binary antipodal modulation. A rate 1/3 turbo code is considered, obtained by concatenating, through a random interleaver, an 8-states rate 1/2 and a rate 1 convolutional codes (CC). The block fading channel model is motivated by the fact that in many wireless systems the coherence time of the channel is much longer than one symbol interval, resulting in adjacent symbols being affected by the same fading value. The fading blocks will experience independent fades, assuming a sufficient separation in time, in frequency, or both in time and in frequency. This channel model is suitable for analyzing, forinstance, wireless communication systems employing techniques such as slow frequency-hopping, as is done in the Global System for Mobile communications (GSM).In such systems, coded information is transmitted over a small number of fading channels in order to achieve diversity. The best coded information allocations over a certain number of fading channels are evaluated, using the Eades-McKay algorithm to generate distinct permutations of a multiset. Bounds on the achievable performance due to coding are derived using information-theoretic techniques. In particular, in the paper an analytical method is proposed, based on the sphere-packing bounding technique, to assess the achievable performance. Moreover, simulation results are obtained and compared with the theoretical ones.

Non‐binary turbo‐coded physical‐layer network coding on impulsive noise channels

Non-binary turbo codes promise excellent performance for a wide range of applications and environments, but research in this area is sparse. The performance of a non-binary turbo code defined in GF(4) on a two-way wireless relay channel (TWRC) employing physical-layer network coding, which is affected by impulsive noise is investigated. Simulation results for binary and non-binary turbo codes are presented and validated with an error floor analysis at the relay of the TWRC and it is observed that non-binary turbo codes significantly outperform binary turbo codes at low signal-to-noise ratios.

Lowering the Error Floor of Turbo Codes With CRC Verification

Decoding performance of turbo codes can flatten at moderately high signal-to-noise ratio. This letter proposes a low complexity method for lowering this error floor. This method rests on the observation of the extrinsic information during the iterative decoding process. A set of $ {q}$ most unreliable bits are identified based on their associated extrinsic information. A total of $ {2^{q}}$ test patterns are then built by inverting the most unreliable bits. The decoded codeword is identified thanks to a cyclic redundancy check detector. This method keeps the turbo coding scheme unchanged as long as an error detection code is serially concatenated with the turbo code. Simulations were performed on a rate-1/3 long-term evolution turbo code and show an improvement of at least one decade in terms of frame error rate in the error floor region. This low complexity method paves the way for further improvements in lowering the error floor of turbo codes.

수중 실험 데이터 기반 터보 부호 성능 분석

The performance of underwater acoustic communication systems is sensitive to inter-symbol interference caused by delay spread developed from multipath signal propagation. The multipath nature of underwater channels causes signal distortion and error floor. In order to improve the performance, it is necessary to employ an iterative coding scheme. Of the various iterative coding schemes, turbo code and convolutional code based on the BCJR algorithm have recently dominated this application. In this study, the performance of iterative codes based on turbo equalizers with equivalent coding rates and similar code word lengths were analyzed. Underwater acoustic communication system experiments using these two coding techniques were conducted on Kyeong-chun Lake in Munkyeong City. The distance between the transmitter and receiver was 400 m, and the data transfer rate was 1 Kbps. The experimental results revealed that the performance of turbo codes is better for channeling than that of convolutional codes that use a BCJR decoding algorithm.

Improve the BER Performance of Turbo Codes with Large Size Based on BER Distributions

Improve the BER Performance of Turbo Codes with Large Size Based on BER Distributions

Turbo Codes: Analysis and Design

This paper studies briefly the design and performance of turbo codes. It focuses on studying the effects of three parameters beside the termination process on the performance of turbo codes. These parameters include, number of iterations, frame size and code rate. Simulation results show that the performance proportional to these three parameters, in addition, the termination process improves the performance.

Decreasing the BER of turbo codes with short frame by optimising the energy allocation

Turbo codes have been shown to approach the Shannon limit for error correcting capability at low signal-to-noise ratios SNR given large sized frames. In standard turbo codes, all bits are transmitted with equal energy. Extensive research efforts have been examining ways to enhance the performance of turbo codes for short frames. One way is to optimise the energy allocated to each bit stream to achieve the best performance possible. In this paper, a novel scheme to improve the bit error rate BER performance of turbo codes with short frame size is presented. Theoretically, a formula is derived to optimise the bit energy and experimentally, an adjustable parameter is employed so that the proposed scheme can be used over a wide range of SNR. A case study verifies the efficiency of the scheme. It shows that the improvements of BER for turbo codes with short frame size are significant.