Error Propagation Phenomenon Research Articles

Virtual Space-Time DiversityTurbo Equalization Using Cluster Sparse Proportional Recursive Least Squares Algorithm for Underwater Acoustic Communications

The oceanic positioning, navigation and timing (PNT) network requires high-quality underwater acoustic message transmission. Turbo equalization technology has exhibited superior performance for underwater acoustic (UWA) communications compared with conventional channel equalizers. To overcome the performance reduction caused by severe doubly selective UWA channels, the virtual space-time diversity soft direct-adaptation turbo equalization is proposed for UWA communications. The proposed scheme improves the ability of the typical turbo equalizer to deal with both Doppler and multipath effects for time varying channels. We utilize a fractionally spaced soft interference cancellation equalizer (FS-SE) instead of a hard decision to constitute the soft-input soft-output (SISO) equalizer. Combined with another virtual time-reversal mirror equalizer component, we can obtain virtual space and time diversity with only a single receiving transducer and mitigate the error propagation phenomenon of the feedback filter. To satisfy the sparse UWA channel, the ℓp,q-PRLS algorithm is applied to adaptive updates for FS-SE. In the proposed scheme, an adjustable interpolator and digital phase-locked loop are embedded into the equalizer to overcome the residual Doppler frequency shift and recover the timing distortion. Results of simulations and field lake trial show that the proposed scheme achieves better performance than existing ones under the same equalizer order.

Three-dimensional shape measurement method based on composite cyclic phase coding.

Phase coding is widely used in 3D measurement due to its good anti-interference and robustness. However, the measurement accuracy is affected by the limitation of the number of codewords. To solve this problem, we propose a 3D shape measurement method based on composite cyclic phase coding. The traditional phase coding is quantized cyclic without adding extra patterns, further adopting composite coding, using the composite cyclic phase coding grayscale values to distinguish the same cyclic codewords, and finally integrating them into a new fringe order sequentially for phase unwrapping to achieve effective expansion of codewords. The related experimental results show that the proposed method stably achieves high accuracy 3D reconstruction, which overcomes the misjudgment of codewords caused by traditional phase coding under high-frequency fringes due to system nonlinearity and noise. Meanwhile, compared with the improved phase coding method of temporal domain combined with spatial domain information, such as the method of quantized phase coding and connected region labeling, it can effectively avoid the phenomenon of error propagation, with high robustness and low algorithm complexity.

Blind Signal Estimation Using Structured Subspace Technique

This brief addresses the blind signal estimation of a single input multiple output (SIMO) finite impulse response (FIR) system. The proposed method estimates directly the input signal with no need for the channel estimation stage or estimation of the second-order statistics. This is achieved by exploiting the Toeplitz structure inherent in the signal’s linear model, to build a quadratic cost function. Such methods are needed to lessen the latency and wave the error propagation phenomena. The simulation results are compared to other methods and are shown to highlight appealing advantages under adverse scenarios, specifically, short-burst communications and poor channel diversity.

Autonomous Power Decision for the Grant Free Access MUSA Scheme in the mMTC Scenario.

Non-orthogonal multiple access schemes with grant free access have been recently highlighted as a prominent solution to meet the stringent requirements of massive machine-type communications (mMTCs). In particular, the multi-user shared access (MUSA) scheme has shown great potential to grant free access to the available resources. For the sake of simplicity, MUSA is generally conducted with the successive interference cancellation (SIC) receiver, which offers a low decoding complexity. However, this family of receivers requires sufficiently diversified received user powers in order to ensure the best performance and avoid the error propagation phenomenon. The power allocation has been considered as a complicated issue especially for a decentralized decision with a minimum signaling overhead. In this paper, we propose a novel algorithm for an autonomous power decision with a minimal overhead based on a tight approximation of the bit error probability (BEP) while considering the error propagation phenomenon. We investigate the efficiency of multi-armed bandit (MAB) approaches for this problem in two different reward scenarios: (i) in Scenario 1, each user reward only informs about whether its own packet was successfully transmitted or not; (ii) in Scenario 2, each user reward may carry information about the other interfering user packets. The performances of the proposed algorithm and the MAB techniques are compared in terms of the successful transmission rate. The simulation results prove that the MAB algorithms show a better performance in the second scenario compared to the first one. However, in both scenarios, the proposed algorithm outperforms the MAB techniques with a lower complexity at user equipment.

Analysis of a Fault-Tolerant Framework for Reliability Prediction of Service-Oriented Architecture Systems

Service-oriented architecture (SOA) has become an increasingly popular choice for building software application in the last years. An SOA system is an elastic structure that utilizes services discovery and integrates these services to perform specified functions. In general, reliability is a critical system attribute when evaluating the quality of a well-built software applications. But it has to be noted that the phenomenon of error propagation could have significant impacts on system reliability. Propagated errors may be masked or propagated to the system interface, which can thereby lead to a system failure. Much research on reliability evaluation for SOA systems have been proposed in the past. However, most of these studies have neglected the phenomenon of error propagation and the issue of link failure. In this article, we take a different view of error propagation, fault tolerance, and the failure behavior of links between services and try to develop an enhanced SOA reliability prediction model incorporating error propagation and fault tolerance (EP–FT). Different fault tolerance techniques will be selected and integrated into the SOA systems. Additionally, sensitivity analysis is also presented and discussed to determine the critical services in the system. Experiments are performed based on four real-world case studies. We will show and discuss the experimental results of the proposed EP–FT reliability model and simulation-based approach in detail. Our experimental results show that the impact of error propagation on system reliability is not negligible, and the SOA systems with fault tolerance demonstrate higher reliability than those that do not.

An Error Resilience and Concealment Method for Line-based Wavelet Image Compressions

Recently, some wavelet-based line compression methods for low-cost high-resolution image transmission have been studied. With these line compression methods, which are a combination of the multilevel discrete wavelet transform, predictive coding, and entropy coding, communications errors on the transmission channel can cause an image quality–degradation phenomenon of various line shapes. In this paper, we analyze image degradation patterns of wavelet-based hybrid line compression techniques caused by communications errors. Then, we propose an image quality–improvement method including a low-cost resynchronization technique by using a periodic reset to prevent the error propagation phenomenon of predictive coding, as well as an error concealment technique that uses only one additional line memory in the variable reference line–based decoder to improve degraded image quality. Experimental results showed that the proposed method achieved better image quality than the conventional techniques at the small expense of compression ratio while satisfying low-cost design conditions pursued by existing line compression systems.

Partly systematic Luby transform codes based on improved progressive edge-growth algorithm for Mars communications

The Luby transform code is a forward error correction code and was originally designed for the erasure channel. In this paper, the Luby transform codes over the Mars communication channel are investigated. To guarantee the reliable data transmission over the Mars communication channel which are usually affected by fading and noises, the progressive edge-growth algorithm is improved and used in for encoding the Luby transform codes. And then a partly systematic Luby transform code with an improved progressive edge-growth algorithm is designed to improve the error propagation phenomenon in Mars communications. Performance evaluations of the designed partly systematic Luby transform code based on the random graph, PEG and improved progressive edge-growth algorithms, respectively, are conducted through a series of simulations. Simulation results show that the performance of the partly systematic Luby transform code based on the improved progressive edge-growth algorithm outperforms those of the partly systematic Luby transform code based on two other algorithms and has the lower bit error rate and overhead.

Feedback Acquisition and Reconstruction of Spectrum-Sparse Signals by Predictive Level Comparisons

In this letter, we propose a sparsity promoting feedback acquisition and reconstruction scheme for sensing, encoding and subsequent reconstruction of spectrally sparse signals. In the proposed scheme, the spectral components are estimated utilizing a sparsity-promoting, sliding-window algorithm in a feedback loop. Utilizing the estimated spectral components, a level signal is predicted and sign measurements of the prediction error are acquired. The sparsity promoting algorithm can then estimate the spectral components iteratively from the sign measurements. Unlike many batch-based compressive sensing algorithms, our proposed algorithm gradually estimates and follows slow changes in the sparse components utilizing a sliding-window technique. We also consider the scenario in which possible flipping errors in the sign bits propagate along iterations (due to the feedback loop) during reconstruction. We propose an iterative error correction algorithm to cope with this error propagation phenomenon considering a binary-sparse occurrence model on the error sequence. Simulation results show effective performance of the proposed scheme in comparison with the literature.

PN-PAM scheme for short range optical transmission over SI-POF \u2014 an alternative to Discrete Multi-Tone (DMT) scheme

BackgroundHow to deal with the time-dispersive channel is the main challenge faced by the short-range optical communication systems. In this work a novel pseudo-noise sequence (PN) assisted pulse-amplitude modulated (PN-PAM) transmission scheme for short-range optical communication systems is proposed in this work. With the help of the PN based channel estimation, minimum-phase pre-filter and reduced-state sequence estimation based equalizer, the proposed PAM transmission scheme can significantly reduce the training overhead for channel estimation in the classical PAM systems using decision feedback equalizer (DFE). In addition, the proposed PAM transmission scheme can effectively avoid the error propagation phenomenon in the classical DFE.ResultsTheoretical study shows that the proposed PAM scheme can achieve a 1.5 dB SNR gain with PAM-8 modulation over 50 m step-index polymer optical fiber (SI-POF) channel at a desired BER level of 1×10−3 and 1.2 Gbps transmission rate. Furthermore the hardware experiment using commercially available components proves the improvements in the proposed PAM transmission scheme.ConclusionThe novel PAM transmission scheme is compared to the optimized discrete multi-tone (DMT) transmission with bit-loading. The experimental results show that for a transmission distance less than 50 m over SI-POF, DMT systems outperform the PAM systems. However, for a SI-POF transmission over the distance longer than 50 m, the proposed scheme can reach a better performance than the DMT systems thanks to the advantage of a lower peak-to-average-power ratio.

Weighted Selection Combinings for Differential Decode-and-Forward Cooperative Networks

Two weighted selection combining (WSC) schemes are proposed for a differential decode-and-forward relaying system in Rayleigh fading channels. Compared to the conventional selection combining scheme, the decision variable of the relay link is multiplied by a scale factor to combat the error propagation phenomenon. Average bit-error rate (ABER) expressions of the two proposed WSC schemes are derived in closed-form and verified by simulation results. For the second WSC scheme, asymptotic ABER expression and diversity order are derived to gain more insight into this scheme. Moreover, it is demonstrated that both WSC schemes can overcome the extra noise amplification induced by the link adaptive relaying scheme. The first WSC scheme is slightly inferior to the second one, which has a higher complexity. Both proposed WSC schemes outperform the conventional selection combining scheme.

The Error Propagation Analysis of the Received Signal Strength-Based Simultaneous Localization and Tracking in Wireless Sensor Networks

Simultaneous localization and tracking (SLAT) in wireless sensor networks (WSNs) involves tracking the mobile target while calibrating the nearby sensor node locations. In practice, localization error propagation (EP) phenomenon will arise, due to the existence of the latest tracking error, target mobility, measurement error, and reference node location errors. In this case, the SLAT performance limits are crucial for the SLAT algorithm design and WSN deployment, and the study of localization EP principle is desirable. In this paper, we focus on the EP issues for the received signal strength-based SLAT scheme, where the measurement accuracy is assumed to be spatial-temporal-domain doubly random due to the target mobility, environment dynamics, and different surroundings at different reference nodes. First, the Cramer–Rao lower bound (CRLB) is derived to unveil both the target tracking EP and the node location calibration EP. In both cases, the EP principles turn out to be in a consistent form of the Ohm’s Law in circuit theory. Second, the asymptotic CRLB analysis is then presented to reveal that both EP principles scale with the inverse of sensor node density. Meanwhile, it is shown that, the tracking and calibration accuracy only depends on the expectation of the measurement precision. Third, the convergence conditions, the convergence properties, and the balance state of the target tracking EP and the location calibration EP are examined to shed light on the EP characteristics of the SLAT scheme Finally, numerical simulations are presented to corroborate the EP analysis.

Partially Block Markov Superposition Transmission of a Gaussian Source With Nested Lattice Codes

This paper studies the transmission of Gaussian sources through additive white Gaussian noise channels in bandwidth expansion regime, i.e., the channel bandwidth is greater than the source bandwidth. To mitigate the error propagation phenomenon of conventional digital transmission schemes, we propose in this paper a new capacity-approaching joint source channel coding (JSCC) scheme based on partially block Markov superposition transmission (BMST) of nested lattice codes. In the proposed scheme, first, the Gaussian source sequence is discretized by a lattice-based quantizer, resulting in a sequence of lattice points. Second, these lattice points are encoded by a short systematic group code. Third, the coded sequence is partitioned into blocks of equal length and then transmitted in the BMST manner. The main characteristics of the proposed JSCC scheme include: 1) entropy coding is not used explicitly and 2) only parity-check sequence is superimposed, hence, termed partially BMST. This is different from the original BMST. To show the superior performance of the proposed scheme, we present extensive simulation results which show that the proposed scheme performs within 1 dB of the Shannon limits. Hence, the proposed scheme provides an attractive candidate for transmission of Gaussian sources.

Distributed model predictive control with hierarchical architecture for communication: application in automated irrigation channels

ABSTRACTThis paper is concerned with a distributed model predictive control (DMPC) method that is based on a distributed optimisation method with two-level architecture for communication. Feasibility (constraints satisfaction by the approximated solution), convergence and optimality of this distributed optimisation method are mathematically proved. For an automated irrigation channel, the satisfactory performance of the proposed DMPC method in attenuation of the undesired upstream transient error propagation and amplification phenomenon is illustrated and compared with the performance of another DMPC method that exploits a single-level architecture for communication. It is illustrated that the DMPC that exploits a two-level architecture for communication has a better performance by better managing communication overhead.

A Bidirectional Successive Detection Technique for Asynchronous OFDMA-Based Wireless Mesh Networks

In this correspondence, a minimum-mean-square-error bidirectional successive detection (MMSE-BSD) technique is proposed to mitigate the effects of interferences caused by time difference of arrivals (TDoAs) in wireless mesh networks (WMNs) based on orthogonal frequency-division multiple access (OFDMA). The proposed BSD technique can successfully reduce the error propagation phenomenon in successive detection with low computational complexity by exploiting the subframe structure used in WMNs. It is shown by simulation that the proposed MMSE-BSD technique is robust to multipath channels and can be effectively used in asynchronous OFDMA-based WMNs.

On-line multiple component analysis for efficient quantitative bioprocess development

On-line monitoring devices for the precise determination of a multitude of components are a prerequisite for fast bioprocess quantification. On-line measured values have to be checked for quality and consistency, in order to extract quantitative information from these data.In the present study we characterized a novel on-line sampling and analysis device comprising an automatic photometric robot. We connected this on-line device to a bioreactor and concomitantly measured six components (i.e. glucose, glycerol, ethanol, acetate, phosphate and ammonium) during different batch cultivations of Pichia pastoris. The on-line measured data did not show significant deviations from off-line taken samples and were consequently used for incremental rate and yield calculations. In this respect we highlighted the importance of data quality and discussed the phenomenon of error propagation. On-line calculated rates and yields depicted the physiological responses of the P. pastoris cells in unlimited and limited cultures. A more detailed analysis of the physiological state was possible by considering the off-line determined biomass dry weight and the calculation of specific rates.Here we present a novel device for on-line monitoring of bioprocesses, which ensures high data quality in real-time and therefore refers to a valuable tool for Process Analytical Technology (PAT).

BINARY TREE BASED CLASSIFICATION METHOD FOR THE MATERIAL LAYER AND MULTILINK CONVERSION MODEL OF SIGNAL PROPAGATION PROCESS OF INFORMATION ACQUISITION

This research proposed a binary tree based classification method, which classifies sensory mechanisms according to material movements. This classification is a beneficial attempt that tries to explain the working mechanisms of sensors from a global view for the material layer of the discipline of information acquisition science and technology. Almost all types of mechanisms have been expressed with the Boolean symbol. The binary expression method presented in the paper also describes the deference of sensors' performances, including accuracy and dynamic performance. One actual application was analyzed to verify the reliability of the relation concluded from the binary classification presented in this paper. The results showed that this method could be used to forecast the performances of new sensor to a certain extent, especially in the inertial sensor field. A multilink conversion conception of sensing mechanisms is put forward to characterize the error propagation phenomenon. Corresponding mathematical expressions have been set up, which indicates a way to decrease total error by reducing signal conversion links. This deduction is supported by the binary tree based classification method.

Soft-Decision Feedback Turbo Equalization for Multilevel Modulations

Error propagation phenomena is the major drawback for existing hard-decision feedback turbo equalizers. In this paper, we propose a new soft-decision feedback equalizer (SDFE) suitable for multilevel modulation systems employing turbo equalization. The proposed SDFE offers a low computational complexity growing only linearly with the number of equalizer coefficients, as opposed to the quadratic complexity of MMSE-based linear turbo equalizer with time-varying coefficients (Exact-MMSE-LE). The performance and convergence property of the proposed SDFE are analyzed using extrinsic information transfer (EXIT) chart and verified by simulations in a severe intersymbol interference channel set by Proakis. Results show that our approach performs close to Exact-MMSE-LE for BPSK/QPSK modulation. And for 8PSK/16QAM modulations, the proposed SDFE performs much better. It exhibits lower SNR threshold (SNR required for “waterfall” BER) and much faster convergence than Exact-MMSE-LE.

An efficient blind decision feedback equalizer

Efficient and fully blind Decision Feedback Equalizer (DFE) remains an open issue, mainly because of the potential errors in the decision loop. Based on the Weighted Decision Feedback Equalizer (WDFE), our previous work aiming at decreasing the error propagation phenomena, we propose a new blind DFE called Blind Weighted Decision Feedback Equalizer. The main idea of the WDFE was to commute between Linear Recursive Equalizer (LRE) and DFE for the error computation at the decision device. In this paper, we extend this idea in order to commute also both the algorithms and the filtering structure. This commutation is performed softly and blindly.

DTV 방송 시스템 환경에서 동일 채널 중계기를 위한 다중 레벨 상관 LMS 기법

본 논문에서는 8VSB 기반의 DTV 방송시스템에서 동일 채널 중계기에 적용 가능한 등화기 알고리즘에 대해 분석하고, 이를 통해 궤환신호에 의한 에러 전파를 감소 시키는 동시에, 수신 성능을 향상 시킬 수 있는 있는 등화기 구조를 제안한다. 궤환 신호의 효율적 제거 여부를 확인하기 위하여 LMS (Least Mean Square) 기반의 DFE (Decision Feedback Equalizer) 와 Correlation LMS 등의 알고리즘 분석을 통해, 이와 연동할 수 있는 다중레벨의 상관 LMS 기법을 제안하고, 이를 기존 방식들과 비교해 봄으로써 효율적으로 에러전파 현상을 크게 감소 시키는 것을 확인할 수 있었다. 컴퓨터 모의실험 수행시, DTV 방송 시스템 환경에 널리 사용되는 브라질 채널 모델을 적용하여 등화기 알고리즘을 서로 비교 분석하여 그 결과를 도출하였다. DTV 방송시스템에서 동작 수신 SNR 값인 15~25dB 까지 범위에서의 심볼 에러율 및 MSE (Mean Square Error) 등을 살펴보았다. 기존의 방식들과 비교해 본 결과 제안방식이 동일한 비트 에러 오류 정정 성능을 유지하는데 필요한 신호대 잡음비가 약 2~5 dB 정도 감소 했고, MSE 를 통한 수렴속도 측면에서도 필요시간이 감소하였음을 알 수 있었다. In this paper, the equalizer techniques that is able to adopt the digital on-channel repeater for 8VSB-based DTV system has been analyzed and we propose an effective equalizer structure which can reduce the error propagation phenomenon by the feedback signal and improve the receiver performance at the same time. In order to confirm the effective cancellation of the feedback signal, the multi-level Correlation LMS scheme is proposed through the analysis of conventional basic LMS based DFE and Correlation LMS algorithm and as compared with the conventional method, we can confirm the reduction of error propagation. When performing the computer simulation, as the Brazil channel model which is very popular for DTV broadcasting system is adopted, the result is drawn by comparing and analysing the equalizer algorithm. We have examine the symbol error rate which is in the range of 15~25dB of operation receipt SNR and MSE(Mean Square Error) in the DTV broadcasting system. As a result of comparing with the existing method, the signal-noise ratio which is necessary for maintain the bit error correction ability that the means of proposal is same is reduced by about 2~5dB, and in the rate of convergence through the MSE, we found the reduction of needed time.

MMFSK-EOD System Using Binary Hopping Pattern in FH/SS Communications

In this paper a detailed explanation of our newly proposed frequency hopped spread spectrum system named “MMFSK-EOD System Using Binary Hopping Pattern” is presented. First, to make clear the concept of FH/M-ary Multilevel FSK modulation (abb. FH/ MMFSK or MMFSK), the waveform and the spectrum differences between MFSK and FH/MFSK or FH/MMFSK are reviewed. Next, to understand the error propagation phenomena from the first demodulation stage to the second demodulation stage, system principle of FH/MMFSK using EOD is explained of some length. In an EOD system, a hopping pattern is synthesized from a group A hopping pattern and a group B hopping pattern, which are different properties on even and odd levels. Finally, to prevent the error propagation novel binary hopping pattern method is proposed, and its effectiveness on improving error performance is shown by illustrative computer simulations. Some additional improving method in the design of group A hopping pattern are also shown.