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In this paper we are interested to the decoding of blocks turbo codes constructed from Reed Solomon (RS) codes. We have modified the iterative algorithm proposed by Chase in order to exploit the a priori information provided by a correlated source. Indeed, some sources such as images have a strong correlation. A simple iterative decoding algorithm does not take this feature into account. The choice...
The continuing trend towards higher data rates in wireless communication systems will, in addition to a higher spectral efficiency and lowest signal processing latencies, lead to throughput requirements for the digital baseband signal processing beyond 100 Gbit/s, which is at least one order of magnitude higher than the tens of Gbit/s targeted in the 5G standardization. At the same time, advances...
The degree to which Turbo-Code decoder architectures can be parallelized is constrained by requirements for flexibility with respect to code block sizes and code rates. At the same time throughput requirements are expected to increase by a factor of up to 20x for 5G networks, which are currently undergoing standardization. The limiting factors for the throughput of a Turbo-Code decoder are maximum...
In this paper we propose a model for the generation of error patterns at the output of a turbo decoder. One of the advantages of this model is that it can be used to generate the error sequence with little effort. Thus, it provides a basis for designing hybrid concatenated codes (HCCs) employing the turbo code as inner code. These coding schemes combine the features of parallel and serially concatenated...
Weight distribution of code is very important for error correction in the use of Turbo coding program in optical fiber communication. Input sequence need to pass convolutional encoder, Therefore, it is necessary that the weight of the output should be kept as large as possible. Although the interleaver can help to improve the output code weight, the higher the complexity of interleaving, the iterative...
Quadrature Amplitude Modulation (QAM) is an important modulation scheme with many practical applications, including current and future wireless technologies. The performance of a mobile communication system can be improved by using a doubly iterative decoding scheme for space-time turbo codes with a large number of transmit and receive antennas, where the decoder uses preliminary soft values of the...
This paper proposes a parallel double Gray mapping scheme that is suited to circular quadrature amplitude modulation (QAM) constellations using partial channel coding associated with collaborative decoding. Using the proposed scheme, We compare the bit error rate (BER) performance of circular 1024QAM and 2048QAM schemes to that of rectangular 1024QAM and cross 2048QAM schemes, respectively. Computer...
In the paper, we will discuss the powerfull class of channel codes referred to as turbo codes. We commence with a brief discussion for MAP and log-MAP decoding algorithms. Then we work with proposed turbo decoding method, which is called as PL-log-MAP. Some numerical results and research experiments, such as simulation for bit error rate estimation and images transmission have been presented. It is...
State-of-the-art LTE Turbo-Code decoder architectures support throughputs of several Gbps by employing parallelism on different architectural levels. However, a very high flexibility with respect to code block sizes and code rates must also be retained. Sophisticated techniques are used to maintain communications performance at high code rates which are critical. In this paper, we propose new techniques...
The paper explores the background and development of Turbo code, and analyzes the basic principle of coding and decoding in Turbo code. Based on CCSDS standard, the implementation and simulation of Turbo coding and decoding is presented. The article analyzes some factors which may influence BER performance such as iteration times, code rate, and decoding algorithm.
In an energy-efficient receiver employing iterative decoders, phase synchronization errors reduce much of the gains that can be achieved at low SNRs. To address this problem, the concept of an iterative receiver has received much attention in the past. In such a framework, signal degradation at low SNR is overcome by repeated phase synchronization executed over the soft symbols generated by the iterative...
Since the introduction of turbo codes in 1993, researchers have turned their attention to the design, performance evaluation and practical application of these codes. The practical implementation of turbo decoding algorithms faces two major challenges: (1) heavy computations for the α and the β values, and (2) huge memory requirement. Using powerful fast processors, which are in hand nowadays, one...
Filter bank multi-carrier with offset quadrature amplitude modulation (FBMC/OQAM) is considered as a promising alternative to orthogonal frequency division multiplexing with the cyclic prefix insertion (CP-OFDM). In this paper, a MIMO-FBMC using turbo code is proposed and a comparison is made between turbo coded MIMO-OFDM and turbo coded MIMO-FBMC systems. The evaluation of bit error rate and signal-to-interference...
Polar codes under cyclic redundancy check-aided successive cancellation list (CA-SCL) decoding can outperform the turbo codes and the LDPC codes at the cost of high complexity and decoding delay. In order to reduce the decoding complexity, in this paper we propose a hybrid parity-check and CRC aided SCL decoding scheme for polar codes. Simulation results under the binary input additive white Gaussian...
In this paper, the performance of iterative turbo coding with nonlinearly distorted orthogonal frequency division multiplexing (OFDM) signal is analyzed. System level implementation in Simulink is performed and bit error rate (BER) performance is analyzed. Initially, we have implemented both, the series turbo coder and iterative turbo coder, compared the performance and then using better performed...
In this paper we investigate the impact of puncturing on a given information set. This study is necessary to design a good rate-compatible puncturing pattern for hybrid automatic repeat request based on incremental redundancy (HARQ-IR) since an information set should be unchanged during retransmission. We first identify that for an information set, there exist the so-called catastrophic puncturing...
In this paper, we propose the encoding and list decoding method of polar codes based on the four-dimensional Reed-Solomon (RS-4) kernel. In specific, an encoding table based method is employed to reduce the computational complexity of both encoder and decoder. In addition, a simplified method to update log-likelihood ratios (LLRs) which employs additions instead of exponential calculations is also...
Turbo codes are well known error-correcting codes used in many communication standards. However, they suffer from error floors. Recently, a method - denoted as the flip and check algorithm - that lowers the error floor of turbo codes was proposed. This method relies on the identification of the least reliable bits during the turbo decoding process. Gains of about one order of magnitude were reached...
In order to support the very high code rates and challenging throughput demands of the LTE/LTE-A standard, sophisticated Turbo-Code decoder architectures are required. Two types of architectures for the commonly used Max-Log-MAP algorithm are suited to fulfil throughput and frame error rate (FER) performance requirements. One is the more common parallel serial MAP architecture (PSMAP) and the other...
This paper presents three new ensembles of low density generator matrix (LDGM) codes, all of which are systematic codes. We prove that, under the maximum likelihood (ML) decoding, these codes can achieve the capacity of binary-input output-symmetric (BIOS) memoryless channels in terms of bit-error rate (BER). The proof technique is different from that for totally random block code ensembles. The recently...
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