Binary shaping for low-duty-cycle communications

We develop a coding method called binary shaping that generates a binary channel input of arbitrary duty-cycle with Bernoulli statistics, which is useful for laser communications using generalized on-off keying. We couple binary shaping with a serially concatenated turbo code for forward error correction, and show by simulation that the performance of this scheme with iterative decoding approaches the capacity of generalized on-off keying on the Poisson channel for medium duty cycles, significantly exceeding the performance of pulse-position modulation (PPM) in this regime. Analogous to trellis shaping for the AWGN channel, binary trellis shaping utilizes a convolutional shaping code to which we apply the Viterbi algorithm at the encoder to minimize Hamming weight. We show how low-duty-cycle communications is a special case of information embedding and discuss how binary shaping relates to information embedding methods.

In this paper, we focus on the design of optimized binary convolutional codes (CCs) and serially concatenated convolutional codes (SCCCs) in the presence of a-priori information (API) at the receiver. For large signal-to-noise ratios (SNRs), we first propose a CC design criterion based on the minimization of a union bound on the bit error probability (BEP). In this case, relevant performance gains, with respect to previously proposed CCs, are obtained. These gains persist even in the presence of estimation errors on the API. Then, we apply the same union bound-based design criterion to SCCCs. Since the BEP of SCCCs is characterized by a typical waterfall shape, the proposed union bound-based design criterion is accurate only at large SNR, to estimate the BEP floor. In order to complement this analysis, we propose a density evolution-based approach to optimize the SCCC design in terms of minimization of the SNR of the knee of the BEP curve. The obtained simulation results show substantial gains with respect to previously proposed parallel concatenated convolutional coding (PCCCing) schemes optimized under the assumption of no API at the decoder. Moreover, in the presence of strong API the proposed SCCCs allow to approach the Shannon limit (SL) more than any previously proposed turbo coding scheme.

The paper proposes an analytical method to solve the rate allocation problem in serial concatenated convolutional codes (SCCCs). The goal is to find the best rate allocation between the inner and the outer constituent convolutional codes of an SCCC for constant overall code rate, interleaver size and complexity. Simulation results are shown in the paper to demonstrate the optimum and superior design criteria. In addition, the ‘density evolution’ model is shown to verify the proposed rate allocation method, while indicating that a high rate inner code should not be used for SCCCs. Finally, it is also shown that the upper bounds on BER of ML decoded SCCCs do not provide good design criteria for allocating the rate in iteratively decoded SCCCs.

A coded wideband MC-CDMA system is considered for high-bit-rate data transmission in a typical outdoor environment with Rayleigh multipath fading. First, two powerful interleaved concatenated coding techniques, turbo and serially concatenated convolutional codes (SCCC) codes are applied in the downlink system and important conclusions are derived on their relative performance behavior in this type of system. Simulation results indicate some of the relative merits of SCCC on achieving very low error rates, with relative mitigation of error floor behavior at the typical BER range of interest for wireless data applications. Next, the more critical uplink system is considered, which requires a multiuser detection technique in combination with powerful coding to achieve similar performance. Successive interference cancellation with SCCC coding is presented, with computation of optimal log-likelihood ratios required for this type of interference cancellation followed by SCCC decoding. Application of SCCC coding and interference cancellation has improved the system performance significantly even in the fully loaded case. Based on these results, the combination of SCCC coding and successive cancellation is found to be attractive for high-rate data transmission in the uplink MC-CDMA.

An analysis of performance of Serially Concatenated Convolutional Codes (SCCC) is evaluated on Additive White Gaussian Noise model channel, which is used as a basis, and actions of SCCC on Raleigh flat slow and flat fast faded channels are evaluated in this research work. In DCS the SCCC are utilized to reduce the bit error rates. SCCC encoder consists of RSCC. The major thrust is iterative decoding. This research has utilized BCJR and TDA decoding algorithms. This research analyzed SCCC with interleaved scheme. The BPSK modulation was considered. Performance metric for SCCC over Memory less AWGN channel, and memory based channels i.e. Rayleigh slow and fast Faded Channel is BER verses SNR.

International audience

Error control coding improves reliability and efficiency of wireless communication systems. This research delves into the latest advancements in error control coding schemes for wireless communication systems, with a specific focus on their application within the domain of Low Power Wide Area Networks (LPWANs) such as Narrowband Internet of Things (NB-IoT) systems, LoRa energy-efficient hardware design, random access control systems, and wireless sensor networks. In the context of LPWANs, particularly NB-IoT systems, we investigate the adaptive coding and modulation (ACM) in NB-IoT systems, which adapts coding rates and modulation techniques to changing channel circumstances. Comprehensive analysis of the literature review shows that the proposed approaches are more energy efficient and less error-prone than fixed coding and modulation schemes. Using Cell Design Methodology (CDM), Single Error Correction (SEC) codes are optimized for energy efficiency. Power and energy efficiency have improved in standard CMOS and CDM logic systems. This impacts IoT devices, memory storage, and security systems. Next, Forward Error Correction (FEC) is examined for ALOHA-based random-access control systems wherein packet loss rate and spectral efficiency metrics are mathematically calculated. FEC is beneficial, especially when time and frequency synchronization diverge. Monte Carlo simulations studied in the literature shows that FEC improves satellite communication systems. This review establishes benefits of FEC, notably in satellite communications systems. In addition, Wireless Sensor Networks (WSNs) error control techniques and network reliability and performance are examined along with Convolutional, Turbo, Low density parity check codes(LDPC), and Polar error correction coding (ECC) methods. We learn about their benefits, drawbacks, and implementation challenges by assessing their efficacy, efficiency, and applicability in wireless sensor networks (WSN) applications. This study further highlights advancements of energy-efficient error control coding when, integrated into network designs alongwith the trade-offs between efficacy and intricacy to help improve wireless communication networks. Finally, this study summarizes current error control coding approaches for wireless communication systems. We provide insights into improving reliability, energy conservation, and efficacy by examining ACM, CDM, FEC, and error correction coding (ECC) across varied domains including LPWAN and IoT technologies with earnest hope to facilitate researchers, engineers, and professionals working in the field of error control coding in wireless communication.

Forward Error Correction code (FEC) is important for Wireless Communication and Cryptography applications to perform the Error Detection and Correction (EDC) mechanisms. FEC codes are classified into two types such as Convolutional code and Block code. Various FEC codes can be used in Wireless Communication likes Viterbi code, Reed Solomon code, Golay, BCH, Multidimensional parity, Hamming code and LDPC codes. In this paper, an analysis between Reed Solomon code, Bose, Chaudhuri, and Hocquenghem (BCH) code and LDPC codes are presented. A Low Density Parity Check (LDPC) code provides low area and high speed than all other codes. Simulation is carried out by ModelSim6.3C and Synthesis is carried out by Xilinx10.1.

Today, Forward Error Correcting (FEC) codes are mainly implemented in hardware, and many believe that their complexity prohibits their software implementation. This paper presents in detail how the performances of a software implementantion can be significantly improved. Different levels of optimization which are independent of the working environment are presented and discussed. The coding throughput of 100 Mbps on an UltraSparc 1 shows that FEC codes can be easily added to multimedia applications without requiring dedicated hardware support. As a case study, we use FEC codes to protect AAL5-PDUs from cell losses in ATM networks.

In this letter, we propose and compare some new rate-compatible serially concatenated convolutional code (SCCC) families. To obtain them, inner coded bits only are punctured. However, and this is the novelty proposed in the letter, the puncturing is not limited to inner parity bits, but extended also to inner systematic bits, thus obtaining high rate SCCCs (i.e., beyond the outer code rate). The two main applications of this technique are its use in hybrid Automatic-Repeat-reQuest/Forward-Error Correction (ARQ/FEC) schemes and to achieve unequal error protection (UEP) of an information sequence.

Forward error correction (FEC) coding, modulation formats like differential phase shift keying (DPSK) and adaptive electronic equalization to mitigate, e.g. polarization mode dispersion (PMD) are some of the methods applied in current direct-detection optical communication systems, which are limited to a spectral efficiency of 1 bit/s/Hz. Coherent single-carrier QPSK systems with polarization multiplexing (PolMUX) allows to attain an spectral efficiency of up to 4 bit/s/Hz. However, to guarantee a bit error rate (BER) <; 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-15</sup> adaptive multiple-input multiple-output (MIMO) equalization as well as outer FEC coding has to be included which results in less than 4 bit/s/Hz in commercial 40 Gbit/s systems. From wireline and wireless systems it is well known that larger symbol alphabets in combination with FEC coding (denoted as coded modulation) and orthogonal frequency division multiplexing (OFDM) can significantly enhance the spectral efficiency. However, in order to exploit the channel capacity of the fiber the modulation itself needs to be capacity achieving. In this contribution we apply capacity achieving constellations in an optical OFDM system and jointly design mapping and low-density parity-check (LDPC) codes for an iterative decoding scheme, namely bit-interleaved coded modulation with iterative decoding (BICM-ID). The authors expect this coding scheme to be most appropriate for future optical transponders to utilize long haul communications close to channel capacity.

The growth of high-density television (HDTV) systems, along with the development of peripheral devices, depends on the development of transmission systems. The authors have constructed an HDTV digital transmission system for the purpose of supporting secondary distribution of HDTV signals and developed an HDTV codec intended for application in this system. The HDTV digital transmission system is a transmission system that utilizes a single (36 MHz) channel of a Kuband transponder of a communication satellite, employs a rate 3/4 convolutional code and a (255,239) Reed-Solomon block code for forward error correction, and uses quadriphase-shift keying (QPSK) as the modulation format. The HDTV codec developed for application in this system is a coding method that is based on discrete cosine transform (DCT) and motion compensated prediction, which provides 40 Mb/s coded video signal. In this paper, the structure of the HDTV digital satellite transmission system and the HDTV codec are described. The video coding method of the HDTV codec is also described. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80 (1): 35–51, 1997

The area of digital communications has undergone a significant transformation in the last twenty years due mostly to the discovery of iterative forward error correction (FEC) codes (such as turbo codes) and iterative demodulation techniques (such as turbo equalization). Waveforms developed for the High Frequency (HF) band typically place an interleaver between the FEC scheme and the transmitted symbols. The purpose of this interleaver is to decorrelate the errors caused by slow fading multipath channels encountered on HF. If no interleaver is used, most standard EEC schemes become ineffective (e.g. convolutional codes). Although HF waveforms were not designed with the notion of iterative demodulation techniques in mind, it turns out that these techniques can be applied to single-carrier HF waveforms which utilize FEC and interleaving by iteratively exchanging soft information between the equalizer and the FEC decoder. This paper will investigate the benefits of applying iterative demodulation techniques to the 3200 and 9600 bit per second waveforms defined in STANAG 4539 as a function of the Doppler spread and multipath spread encountered on HF channels.

We compare the asymptotic performance of parallel concatenated codes (PCCs) and serial concatenated codes (SCCs) over GF(4). We construct such codes using optimal nonbinary convolutional codes where optimality is in the sense of achieving the largest minimum distance for a fixed number of encoder states. Code rates of the form K/sub 0//(K/sub 0/ + 1) for K/sub 0/ = 1, 8, and 64 are considered. For all of these code rates, we find the minimum distance and its multiplicity for both concatenated code systems. This is accomplished by feeding the encoder with all possible weight-two and weight-three input information patterns and monitoring, at the output of the encoder, the weight of the corresponding codewords and their multiplicity. Our analytical results indicate that the SCC codes outperform their counterpart PCC codes with much lower complexity.

In this paper, performance of COFDM (Coded Orthogonal Frequency Division Multiplexing) which is OFDM with a forward error correction code, is studied in frequency selective fading underwater acoustic communication channel. The OFDM is a multiplexing technique resistant to frequency selective multipath channel. In OFDM, a broadband information signal is transformed into several narrow band signals and transmits narrow band signals whose bandwidths are less than the channel coherence bandwidth. However, its performance is degraded in a specific narrow band signal due to its deep fading by multipath. To mitigate this degradation, COFDM which is OFDM with convolution code as a forward error correction code, is evaluated. The performance of COFDM is found to be better than that of OFDM in multipath channel.