Forward Error Correction Algorithm Research Articles

Modelling of Timestamp Processing within Transport Network Equipment

The modern telecommunication networks are forming on the basis of different transmission and data processing technologies. High load on the transport layer nodes demands quality synchronization of equipment that works on it. The transport network is an important element which delivers the time scale to slave nodes. Using the time-division multiplexing for the high-speed channel processing with the use of wavelength division multiplexing (OTN, Optical Transport Network) and classic Ethernet networks as a transport layer systems needs the precision time synchronization which can be achieved with the use of Precision Time Protocol (PTP). The modeling apparatus of PTP messages exchanging within OTN multiplexers and IP-network based on the routers are suggested. The packet transferring through the network are given as sequence of simple processing steps. The impact of a network load on PTP information processing capacity on the routers and efficiency of the Forward Error Correction algorithm for OTN equipment are analyzed. The experimental distribution of variable delays on that network elements are given.

Bağlantı Seviyesi Simülasyon Üzerinde LLRnet'in 5G-NR'ye Uygulanması

Modern receivers apply smooth demodulation and demapping processes to received symbols, using bit log-likelihood ratios (LLRs). Known as “LLRnet" demodulator architecture is offered that is a global educatable neural network attributed in this paper. The calculation of the optimal LLR algorithm includes the calculation of each bit in the LLR value and requires the assessment of whole lattice points as high dimensional which is unpractical for the QAM modulation. Known the most in the literature the Maximum Likelihood (ML) detector shows very high computational complexity that is used in the QAM scheme. Besides LLRnet developed achievement importantly, all calculational complexity is also reduced. Via estimating exact log-likelihood, how to create symbols, and channel corruptions for training a neural network LLRNet is shown in this paper. New and contemporary radio communication systems, such as 5G- NR (New Radio) and DVB (Digital Video Broadcasting) for satellite, DVB (S.2 Second Generation) utilize the LLR approach that calculates soft bit values with FEC (Forward Error Correction) algorithms and utilizes demodulated smooth bit values. This article aims a link-level simulation study to implement of LLRnet to DVB S2 and 5G-NR. The motivation of this study is seen that performing machine learning techniques on physical layer scheme, makes LLRNet a powerful example for practicability. This paper offers to compare Max-Log Approximate LLR, Exact LLR, and LLRNet methods for 16, 32 and 128 QAM.

A comparison analysis on forward error correction technology: a future perspective for GNSS

PurposeThe main aim of this study is to elaborately examine the error correction technology for global navigation satellite system (GNSS) navigation messages and to draw a conceptual decision support framework related to the modernization of the GNSS and other systems.Design/methodology/approachThe extensive simulation model developed in Matrix Laboratory (MATLAB) is used to evaluate the performance of forward error correction (FEC) codes such as Hamming, Bose–Chaudhuri–Hocquenghem, convolutional, turbo, low-density parity check (LDPC) and polar codes under different levels of noise.FindingsThe performance and robustness of the aforementioned algorithms are compared based on the bit length, complexity and execution time of the GNSS navigation message. In terms of bit error rate, LDPC coding exhibits more ability in the robustness of the navigation message, while polar code gives better results according to the execution time.Practical implicationsIn view of future new GNSS signals and message design, the findings of this paper may provide significant insight into navigation message modernization and design as an important part of GNSS modernization.Originality/valueTo the best of the authors’ knowledge, this is the first study that conducts a direct comparison of various FEC algorithms on GNSS navigation message performance against noise, taking into consideration turbo and newly developed polar codes.

Phase Noise Impact and Scalability of Self-Homodyne Short-Reach Coherent Transmission Using DFB Lasers

We investigateon a two-fiber short-reach self-homodyne coherent transmission system without optical amplification,where the same transmission laser is used to generate a modulated signal carrying useful data and a continuous wave signal, which serves as a local oscillator at the receiver side. Target of the work is to determine by experiments and theoretical models under which conditions DFB lasers can be used instead of more expensive ECL lasers. After careful characterization of lasers phase noise in terms of linewidth as a function of the mismatch between the optical paths of the signal and of the local oscillator, the performance of two laser technologies is investigated in the proposed transmission setup, showing that commercial DFB laser can be used, provided that the optical path mismatch between the two fibers is kept below 1.8 m for 28 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$GBaud$</tex-math></inline-formula> PM-QPSK and 0.8 m for PM-16QAM modulation format in combination with a soft-decision forward error correction algorithm. After an experimental demonstration, we theoretically investigate the scalability laws of the proposed systems in different configuration flavours.

An Adaptive Fuzzy based FEC Algorithm for Robust Video Transmission over Wireless Networks

Forward Error Correction (FEC) is a commonly adopted mechanism to mitigate packet loss/bit error during real-time communication. An adaptive, Fuzzy based FEC algorithm to provide a robust video quality metric for multimedia transmission over wireless networks has been proposed to optimize the redundancy of the generated code words from a Reed-Solomon encoder and to save the bandwidth of the network channel. The scheme is based on probability estimations derived from the data loss rates related to the recovery mechanism at the client end. By applying the adaptive FEC, the server uses the reports to predict the next network loss rate using a curve-fitting technique to generate the optimized number of redundant packets to meet specific residual error rates at the client end. Simulation results in the cellular system show that the video quality is massively adapted to the optimized FEC codes based on the probability of packet loss and packet correlation in a wireless environment.

Low latency LDPC hard‐decision algorithm for 5G NR

In this study, the authors demonstrate the potential of hard-decision algorithm in industrial 5G NR channel coding. This study aims to show different forward error correction algorithms that can be expected in the context of cloud radio access network. Based on low density parity check (LDPC) min-sum (MS) algorithm, an improved hard-decision algorithm is proposed. The decoding process and performances are shown and compared with MS algorithm. To identify the advantage of this proposal, a test bench is launched in Cisco server using X86 chipset. Its results show a good trade-off between latency and performance.

An application layer forward error correction method of wireless network broadcasting communication for smart video surveillance system

Aiming at the wireless channel in which the state of video surveillance communication network changes dramatically, to ensure the video impact under a restricted channel bandwidth condition, an application layer forward error correction system for wireless video communication is proposed. This scheme is an improved forward error correction algorithm. The most appropriate redundancy amount is implemented for each FEC block by constantly altering the redundancy in FEC blocks. Firstly, the system describes and implements the optimum video transmission. Then, the RCPC code and Raptor code are used as forward error correction codes in physical layer and application layer respectively, in this way, the optimal system solution can be acquired. In the forward error correction technology, a feedback mechanism is then developed between the receiver and the sender, which will acknowledge that the receiver can extract the packet loss rate from the received speech signal in the current network state in real time, and then the packet loss rate will be transferred back to the sender by the feedback mechanism. The sender can modify the forward packet loss rate according to the packet loss rate. The error-correcting schema can help the next speech signal have the most appropriate forward error-correcting redundancy, reducing bandwidth waste, significantly improving the adaptability and efficiency of forward error-correcting technology in the wireless network. The simulation results show that the average video quality of the proposed scheme is 0.5–4 dB higher than that of the equal error protection scheme and the extended window unequal error protection scheme.

Prototype of KIOSK Data Downloading System at 300 GHz: Design, Technical Feasibility, and Results

Recent advances in semiconductor device technologies and the ever growing worldwide traffic explosion have focused great attention on THz frequencies, which had long been considered a forbidden region in the electromagnetic spectrum. The huge bandwidth, perhaps much larger than the total bandwidth used on Earth for all wireless systems, is now believed to be the only way to handle incredibly large amounts of data instantaneously by wireless means. In this article, we describe the development of a KIOSK data downloading system prototype designed for touch-and-go use. Implementation of the 300 GHz THz front-end components and the performance are briefly summarized. A preliminary investigation of the LoS channel responses and a simple comparison of the forward error correction algorithms in the given THz channel are presented as well. Finally, an experimental demonstration of instant data transfer with the prototype is described to confirm the feasibility of using the THz wave band for future wireless applications.

Computational Complexity Analysis of FEC Decoding on SDR Platforms

The computational complexity evaluation is necessary for software defined Forward Error Correction (FEC) decoders. However, currently there are a limited number of literatures concerning on the FEC complexity evaluation using analytical methods. In this paper, three high efficient coding schemes including Turbo, QC-LDPC and Convolutional code (CC) are investigated. The hardware-friendly decoding pseudo-codes are provided with explicit parallel execution and memory access procedure. For each step of the pseudo-codes, the parallelism and the operations in each processing element are given. Based on it the total amount of operations is derived. The comparison of the decoding complexity among these FEC algorithms is presented, and the percentage of each computation step is illustrated. The requirements for attaining the evaluated results and reference hardware platforms are provided. The benchmarks of state-of-the-art SDR platforms are compared with the proposed evaluations. The analytical FEC complexity results are beneficial for the design and optimization of high throughput software defined FEC decoding platforms.

A 64 fJ/step 9-bit SAR ADC Array With Forward Error Correction and Mixed-Signal CDS for CMOS Image Sensors

A 9 b Successive-Approximation-Register (SAR) Anglog-to-Digital Converter (ADC) with pilot-Digital-to-Analog Converter (pDAC) technique for image sensor applications is described in this paper. Its Forward Error Correction (FEC) improves its robustness against device mismatch. It performs mixed-signal Correlated-Double-Sampling (CDS) using only the ADC's built-in capacitor array without any additional amplifier or memory. The ADC measures 490μm×7.4μm and is demonstrated in a low-power CMOS image sensors with column parallel ADCs. Measurement results from the prototype image sensor in 0.18 μm technology shows that the ADC's Differential Non-Linearity (DNL) is reduced from 3.5 LSB to 1.2 LSB by its mixed-signal FEC algorithm, making its Figure-of-Merit (FoM) 64 fJ/step. Furthermore, when combined with the ADC's mixed-signal Correlated-Double-Sampling, the column FPN is reduced from 3.2% to 0.5% without any additional circuit.

Hardware Acceleration of Hamming Code: Design of Runtime Reconfigurable FPGA Prototype

Digital communications has helped us achieve two way conversations in digital domain, in which messages are encoded into the communication channel and then decoded at the receiver end. During the transfer of message, the data might get corrupted due to disturbances in the communication channel. Hence, it is necessary that the decoder has an in-built function of detecting and correcting the errors that might occur.This project deals with channel coding with an objective of error correction and detection using a forward error correction algorithm viz. Hamming Code, which is basically a linear block code. The implementation of this code is done on ACTEL-ProASIC3 FPGA (250Kgates), and programmed in VHDL. The HDL entry is made in LIBEROIDE CAD tool , Synplify tool is used for synthesis, Netlist Viewer for generation of Netlists and Timer for Static Timing Analysis. The unit testing of each module and integration testing of the system is performed by simulation in MODELSIM 6.6d and by actual hardware implementation on Actel ProASIC3 FPGA. The code rate achieved here is 57.1%.FPGA is preferred over microcontroller development boards because variable frequency and dedicated pathways comprised of programmable logic blocks in FPGA’s allow high speed implementation of large data streams. The aim of this project is to implement a semiconductor IP Core. The FPGA Prototype we designed serves as a predecessor for ASIC. General Terms Error correction and detection, Field Programmable Gate Array, Hardware acceleration, FPGA Prototype, Functional prototyping, HDL

Adaptive Cooperative FEC Based on Combination of Network Coding and Channel Coding for Wireless Sensor Networks

The data delivery over wireless links with QoS-guarantee is a big challenge because of the unreliable and dynamic characteristics of wireless sensor networks, as well as QoS diversity requirements of applications. In this paper, we propose an adaptive cooperative Forward Error Correction algorithm based on network coding, in the hope quality of experience could be satisfied on receivers with high quality. The algorithm, based on wireless link and distance, adjusts the RS coder parameter and selects the optimal relay nodes. On the other hand, we combine the channel coding and network coding technology at the data link layer to fulfil the requirements of QoS diversity. Both mathematical analysis and NS simulation results demonstrate the proposed mechanism is superior to the traditional FEC and cooperative FEC alone at the reliability, real time performance and energy efficiency. In addition, the proposed mechanism can significantly improve quality of media streaming, in terms of playable frame rate on the receiving side.

Enhanced forward error correction algorithm supporting H.264 video transmission in wireless networks

In order to support H.264 video traffic transmission in wireless networks,an enhanced Forward Error Correction(FEC) algorithm called Enhanced Forward Error Correction(EFEC) was proposed,and the performance of EFEC was analyzed.EFEC will decide whether the forward error correction transmission should be used or not if the sender receives feedback information and the sender would not stop transferring data due to the loss of the feedback information.EFEC would adjust the additional length of data according to the BER of wireless networks.Detailed simulation results prove that according to network status EFEC can adaptively adjust coding strength and redundancy to improve video quality obviously.

Improving end-to-end quality-of-service in online multi-player wireless gaming networks

In this paper, we present a novel, scalable multi-player gaming architecture that can incorporate mobile nodes. Next we propose an adaptive forward error correction (FEC) and rate-control technique to improve service quality in such a wireless gaming environment. We consider only last-hop wireless links in this paper. It is assumed that the game server and clients (mobile devices) can switch between different prediction levels having different data rates. We introduce a new scheme for estimating the packet loss rates due to congestion and wireless channel conditions and use this information in a cross-layer design to improve the overall service quality. The congestion packet loss probability is used to devise a simple TCP-friendly rate-control algorithm for sending downlink data packets from the game server. We also propose a novel adaptive FEC and dynamic packetization algorithm to alleviate the effects of wireless channel packet losses based on this chosen data rate. Extensive NS-2 simulation results show the efficacy of our scheme in achieving higher throughput.

무선 센서 네트워크에서 전송 효율과 에너지 소비에 대한 블록 FEC 심볼 크기 영향 분석

본 논문에서는 저속의 무선 센서 네트워크(WSN: Wireless Sensor Network)에서 블록 FEC(Forward Error Correction) 알고리즘의 심볼 크기의 변화에 따른 802.11 MAC 프로토콜의 전송 효율과 전송 에너지를 해석적으로 분석한다. 블록 FEC 알고리즘은 심볼(symbol) 단위로 오류를 복원하므로, 주어진 무선 센서 채널에서 같은 FEC 체크 비트(check bit) 량을 사용하더라도 블록 FEC 알고리즘의 오류 패킷 복원률은 블록 FEC 심볼 크기에 의존적이다. 즉, 같은 양의 FEC 체크 비트를 사용하는 경우에, 연속된 군집 오류 길이는 작으면서 군집 오류가 자주 발생하는 채널에서는 작은 FEC 심볼이, 이에 반해 군집 오류의 길이는 크고 군집 오류 개수가 작은 군집적 분포를 보이는 채널에서 큰 FEC 심볼이 효율적이다. 심볼 크기의 영향을 평가하기 위해서 본 논문에서는 센서 노드 TIP50CM을 사용하는 WSN에서 수집한 패킷 트레이스를 기반으로 WSN 채널을 Gilbert 모델로 모델링하고, 심볼 크기가 다른 RS(Reed-Solomon) 코드를 생성하고 해석하기 위한 에너지를 측정하였다. 이러한 모델링된 채널과 각 RS 코드 생성과 해석 에너지를 이용하여 FEC 심볼 크기에 따른 RS FEC 코드를 채택한 802.11 MAC 프로토콜의 전송 효율과 전송 에너지를 계산하였다. 실제 측정 데이터와 해석적으로 계산한 데이터를 결합한 계산에 의하면 비슷한 FEC 체크 비트 량을 사용하더라도 FEC 심볼 크기에 따라 전송 효율은 최대 4.2%, 그리고 소요 에너지는 최대 35%의 차이가 발생한다. This paper analytically evaluates the FEC(Forward Error Correction) symbol size's effect on the performance and energy consumption of 802.11 protocol with the block FEC algorithm over WSN(Wireless Sensor Network). Since the basic recovery unit of block FEC algorithms is symbols not bits, the FEC symbol size affects the packet correction rate even with the same amount of FEC check bits over a given WSN channel. Precisely, when the same amount of FEC check bits are allocated, the small-size symbols are effective over channels with frequent short bursts of propagation errors while the large ones are good at remedying the long rare bursts. To estimate the effect of the FEC symbol site, the paper at first models the WSN channel with Gilbert model based on real packet traces collected over TIP50CM sensor nodes and measures the energy consumed for encoding and decoding the RS (Reed-Solomon) code with various symbol sizes. Based on the WSN channel model and each RS code's energy expenditure, it analytically calculates the transmission efficiency and power consumption of 802.11 equipped with RS code. The computational analysis combined with real experimental data shows that the RS symbol size makes a difference of up to 4.2% in the transmission efficiency and 35% in energy consumption even with the same amount of FEC check bits.

An adaptive FEC code control algorithm for mobile wireless sensor networks

For better performance over a noisy channel, mobile wireless networks transmit packets with forward error correction (FEC) code to recover corrupt bits without retransmission. The static determination of the FEC code size, however, degrades their performance since the evaluation of the underlying channel state is hardly accurate and even widely varied. Our measurements over a wireless sensor network, for example, show that the average bit error rate (BER) per second or per minute continuously changes from 0 up to 10−3. Under this environment, wireless networks waste their bandwidth since they can't deterministically select the appropriate size of FEC code matching to the fluctuating channel BER. This paper proposes an adaptive FEC technique called adaptive FEC code control (AFECCC), which dynamically tunes the amount of FEC code per packet based on the arrival of acknowledgement packets without any specific information such as signal to noise ratio (SNR) or BER from receivers. Our simulation experiments indicate that AFECCC performs better than any static FEC algorithm and some conventional dynamic hybrid FEC/ARQ algorithms when wireless channels are modeled with two-state Markov chain, chaotic map, and traces collected from real sensor networks. Finally, AFECCC implemented in sensor motes achieves better performance than any static FEC algorithm.

이동 무선 네트워크의 전송 성능 향상을 위한 적응적 FEC 알고리즘

무선 이동 네트워크에서 대부분의 패킷 손실은 네트워크 체증(congestion)보다는 전송(propagation) 오류에 의해 발생된다. 이러한 전송 오류에 의한 패킷 손실을 방지하여 전송 효율을 향상하기 위해 무선 네트워크에서는 FEC(Forward Error Correction)알고리즘을 채택하고 있다. 그러나 정적인 FEC방식은 연속적으로 변화하는 무선 채널의 전송 오류율에 알맞은 정정 코드(check code)를 채택하지 못해 도리어 전송 효율이 저하되는 문제가 있다. 이러한 문제를 개선하기 위해서는 채널의 상태에 따라 FEC를 동적으로 변경하는 것이 필요하다. 본 논문은 무선 채널 특성의 이론적 분석과 저 출력 라디오파를 이용하는 센서(sensor) 네트워크상에서의 실험적 측정을 통해서, 적응적 FEC 기법이 무선 네트워크의 전송 성능을 향상시킬 수 있다는 것을 보여준다. 또한 전송 에러률이 <TEX>$10^{-3}$</TEX> 정도로 상당히 오류가 많은 무선 네트워크에서 적용할 수 있는 적응적 FEC 기법, FECA(FEC-level Adaption)기법을 제안한다. 마지막으로 FEC 알고리즘의 성능 비교를 위해 패킷 시뮬레이션에서 비트 레벨(bit-level) 오류를 시뮬레이션할 수 있는 통합 시뮬레이션 기법을 소개한다. 통합 시뮬레이션을 통해 FECA는 정적 FEC에 비해서 지속적으로 무선 채널 오류률에 알맞는 FEC 정정 코드를 채택하여 성능을 향상시키는 것을 확인하였다. Wireless mobile networks tend to drop a large portion of packets due to propagation errors rather than congestion. To Improve reliability over noisy wireless channels, wireless networks can employ forward error correction (FEC) techniques. Static FEC algorithms, however, can degrade the performance by poorly matching their overhead to the degree of the underlying channel error, especially when the channel path loss rate fluctuates widely. This paper investigates the benefits of an adaptable FEC mechanism for wireless networks with severe packet loss by analytical analysis or measurements over a real wireless network called sensor network. We show that our adaptive FEC named FECA (FEC-level Adaptation) technique improves the performance by dynamically tuning FEC strength to the current amount of wireless channel loss. We quantify these benefits through a hybrid simulation integrating packet-level simulation with bit-level details and validate that FECA keeps selecting the appropriate FEC-level for a constantly changing wireless channel.

Adaptive link layer strategies for asymmetric high-speed wireless communications

A forward error correction (FEC) strategy and a medium access control (MAC) protocol that are thoroughly tailored to complement and support a high-speed asymmetric physical layer design based on equalization and precoding is presented and fully discussed. Both proposals exhibit a high degree of adaptability and flexibility, which allows for increased data throughput while providing a wide range of quality-of-service requirements. Fast link layer adaptation is made possible through the joint design of link and physical layers. The adaptive FEC algorithm is based on the use of variable-rate trellis coded modulation with fast channel estimation, while the MAC protocol employs a centralized, dynamic slot allocation technique. The overall system design is shown to achieve high spectral efficiency, while minimizing energy consumption at the portable unit.