Use Of Forward Error Correction Research Articles

Performance Evaluation of LoRa Communications in Harsh Industrial Environments

LoRa technology is being integrated into industrial applications as part of Industry 4.0 owing to its longer range and low power consumption. However, noise, interference, and the fading effect all have a negative impact on LoRa performance in an industrial environment, necessitating solutions to ensure reliable communication. This paper evaluates and compares LoRa’s performance in terms of packet error rate (PER) with and without forward error correction (FEC) in an industrial environment. The impact of integrating an infinite impulse response (IIR) or finite impulse response (FIR) filter into the LoRa architecture is also evaluated. Simulations are carried out in MATLAB at 868 MHz with a bandwidth of 125 kHz and two spreading factors of 7 and 12. Many-to-one and one-to-many communication modes are considered, as are line of sight (LOS) and non-line of Sight (NLOS) conditions. Simulation results show that, compared to an environment with additive white Gaussian noise (AWGN), LoRa technology suffers a significant degradation of its PER performance in industrial environments. Nevertheless, the use of forward error correction (FEC) contributes positively to offsetting this decline. Depending on the configuration and architecture examined, the gain in signal-to-noise ratio (SNR) using a 4/8 coding ratio ranges from 7 dB to 11 dB. Integrating IIR or FIR filters also boosts performance, with additional SNR gains ranging from 2 dB to 6 dB, depending on the simulation parameters.

Analytical Model of ALOHA and Time- and Frequency-Asynchronous ALOHA with Forward Error Correction for IoT Systems.

The blooming of internet of things (IoT) services calls for a paradigm shift in the design of communications systems. Short data packets sporadically transmitted by a multitude of low-cost low-power terminals require a radical change in relevant aspects of the protocol stack. For example, scheduling-based approaches may become inefficient at the medium access (MAC) layer, and alternatives such as uncoordinated access policies may be preferred. In this context random access (RA) in its simplest form, i.e., additive links on-line Hawaii area (ALOHA), may again become attractive as also proved by a number of technologies adopting it. The use of forward error correction (FEC) can improve its performance, yet a comprehensive analytical model including this aspect is still missing. In this paper, we provide a first attempt by deriving exact expressions for the packet loss rate and spectral efficiency of ALOHA with FEC, and extend the result also to time- and frequency-asynchronous ALOHA aided by FEC. We complement our study with extensive evaluations of the expressions for relevant cases of study, including an IoT system served by low-Earth orbit (LEO) satellites. Non-trivial outcomes show how time- and frequency-asynchronous ALOHA particularly benefit from the presence of FEC and become competitive with ALOHA.

Error-free PAM-4 transmission by a high-speed plastic optical fiber without forward error correction.

This Letter reports, to the best of our knowledge, the first study in which error-free four-level pulse-amplitude modulation (PAM-4) transmission has been achieved using a graded-index plastic optical fiber (GI POF) without the use of forward error correction (FEC) techniques, at a high data rate (>50Gb/s), for short-reach applications (10 m). The GI POF that is developed has the characteristic microscopic heterogeneities in the fiber core material, which provide distinct mode coupling and significantly stabilize PAM-4 data transmission. The results of the study in this Letter indicate that the GI POF achieves highly stable PAM-4 transmission without the need for the current FEC techniques, which seriously increase the communication delay and power consumption of the transmission systems. Our GI POF material is paving the way for "material changes the system" approaches for achieving unprecedented optical interconnects in real time at a high speed and with low power consumption.

Data transmission at 1300 nm using optical interposer comprising hybrid integrated silicon waveguide and dilute nitride electroabsorption modulator

High speed back-to-back transmission of NRZ data at 12.5 Gbit/s was achieved over a repeaterless optical network without the use of forward error correction or optical clock recovery using a hybrid integrated silicon photonics optical interconnect. The interconnect comprises an electroabsorption modulator based on dilute nitride multiple quantum well material on GaAs substrate optically coupled to large core silicon waveguide using passive alignment and flip-chip bonding.

AMCC Superimposition and Extraction With Interference Elimination for 5G Mobile Fronthaul

Wavelength-division multiplexing passive optical network (WDM-PON) is an attractive technique for 5G mobile fronthaul (MFH) due to the large bandwidth and low latency. Auxiliary management and control channel (AMCC) is required for WDM-PON to achieve an efficient network deployment. In this letter, we experimentally demonstrated up to 10-Mbps baseband over modulated AMCC superimposition on 10-Gbps WDM-PON. We proposed a low-complexity interference elimination (IE) method for AMCC extraction which significantly decreases the bit error rate of AMCC signal by suppressing the interference caused by the WDM-PON signal. With the help of the proposed IE method, over megabits-per-second AMCC implementation can be achieved with different modulation indexes which is prospective for future 5G MFH. For large modulation index, AMCC can even be transmitted without the use of forward error correction.

Efficient high-resolution video delivery over VANETs

The adoption of video-equipped vehicles in Vehicular ad-hoc networks (VANETs) is experiencing a rapid growth. It is also anticipated a substantial increase in the video content distribution with the arrival of self-driving cars as both passengers and vehicles will be able to produce and consume this type of media. This unveils a set of challenges, especially in VANETs where the network resources tend to be scarce and the connections suffer from time-varying error conditions. Taking everything into consideration, a Quality of Experience (QoE)-driven mechanism is desirable to enhance the video delivery over error-prone networks. To this end, the combined use of forward error correction and unequal error protection has proven its efficiency in delivering high-quality videos with low network overhead. The proposed intelligent quality-driven and network-aware mechanism (AntArmour) uses an ant colony optimization scheme to dynamically allocate a precise amount of redundancy. This allows AntArmour to safeguard, in real-time, the live transmission of high-resolution video streams. This operation is performed according to specific high efficiency video coding details and the actual network conditions such as the signal-to-noise ratio, the network density, the vehicle’s position, and the current packet loss rate (PLR) as well as the prediction of future PLR. The experiments were performed using real map’s clippings and actual video footage. The assessment was performed with the aid of two well-known objective QoE metrics, as well as the measure of the network overhead. The results showed that the proposed mechanism outperformed all its competitors in both video quality improvement and network overhead decrement.

Reducing Latency for Multimedia Broadcast Services Over Mobile Networks

Multimedia services over mobile networks pose several challenges, such as the efficient management of radio resources or the latency induced by network delays and buffering requirements on the multimedia players. In Long Term Evolution (LTE) networks, the definition of multimedia broadcast services over a common radio channel addresses the shortage of radio resources but introduces the problem of network error recovery. In order to address network errors on LTE multimedia broadcast services, the current standards propose the combined use of forward error correction and unicast recovery techniques at the application level. This paper shows how to efficiently synchronize the broadcasting server and the multimedia players and how to reduce service latency by limiting the multimedia player buffer length. This is accomplished by analyzing the relation between the different parameters of the LTE multimedia broadcast service, the multimedia player buffer length, and service interruptions. A case study is simulated to confirm how the quality of the multimedia service is improved by applying our proposals.

Layered multicast for reliable event notification over large-scale networks

Nowadays, several advanced ICT infrastructures demand multicast services able to jointly provide a high degree of reliability and good performances despite of failure occurrences. The current practice to tolerate failures in such services mainly consists in the adoption of methods based on temporal redundancy, where messages are successfully delivered to all the interested destinations by means of retransmissions. However, in such methods, a high degree of reliability is typically obtained at the expenses of severe performance fluctuations and instability. On the contrary, approaches that make use of forward error correction imply a more performance-friendly behavior; however, the effective tuning of such approaches is a critical and challenging task, which has limited their applicability in large-scale multicast services. This paper is aimed at presenting a solution to resolve this issue by effectively tuning the redundancy degree to be applied, so as to be able to tolerate the losses affecting the multicast communications without an excessive, and un-needed, workload imposed over the network. To this aim, we drawn from the experience of layered multicast, commonly applied to multimedia content delivery, for addressing such tunability problem. Specifically, we detail how to apply layered multicast within the context of a well known multicast service and how to determine the correct redundancy degree to be applied. We also make use of extensive simulations to evaluate the quality of the proposed approach in terms of reliability, performance and overhead, and to compare it with the best retransmission-based approach available in the literature.

Deploying AL-FEC protection with online algorithms for multicast services over cellular networks

Reliability control is a key concern on the evolution of mobile multicast services. To this direction, the use of forward error correction (FEC) on the application layer is widely adopted in several mobile multicast standards. FEC is a feedback free error control method, where the transmitter introduces in advance redundant information within the source data to enable receivers recovering arbitrary data erasures. On multicast delivery where retransmission-based error recovery methods are not efficient, the most suitable error control method is the use of application layer forward error correction (AL-FEC) codes. In this work, we introduce novel AL-FEC deployment policies over mobile multicast environments utilizing online algorithms. We aim at the efficient application of AL-FEC protection with RaptorQ codes over multicast delivery in the context of competitive analysis. We provide a competitiveness analysis model of AL-FEC application over mobile multicast environments. Furthermore, we propose two online algorithms adjusting the introduced redundancy of AL-FEC protection according to several FEC encoding parameters and constraints of mobile multicast delivery.

Optimized cross-layer forward error correction coding for H.264 AVC video transmission over wireless channels

Forward error correction (FEC) codes that can provide unequal error protection (UEP) have been used recently for video transmission over wireless channels. These video transmission schemes may also benefit from the use of FEC codes both at the application layer (AL) and the physical layer (PL). However, the interaction and optimal setup of UEP FEC codes at the AL and the PL have not been previously investigated. In this paper, we study the cross-layer design of FEC codes at both layers for H.264 video transmission over wireless channels. In our scheme, UEP Luby transform codes are employed at the AL and rate-compatible punctured convolutional codes at the PL. In the proposed scheme, video slices are first prioritized based on their contribution to video quality. Next, we investigate the four combinations of cross-layer FEC schemes at both layers and concurrently optimize their parameters to minimize the video distortion and maximize the peak signal-to-noise ratio. We evaluate the performance of these schemes on four test H.264 video streams and show the superiority of optimized cross-layer FEC design.

Demonstration of a WDM/TDM hybrid PON based on a colorless frame-level reach extender

We propose a hybrid passive optical network (PON) consisting of a 2.5Gb/s reflective semiconductor optical amplifier (RSOA)-based 32 channel loopback wavelength division multiplexing-passive optical network (WDM–PON) and a colorless OEO-based frame-level reach extender (RE). This hybrid PON is designed to support a 128-way split over a 50km transmission distance per single wavelength channel. We experimentally demonstrate the feasibility of this design through downstream and upstream packet transmission with a commercial gigabit-capable PON (GPON) product. Even if the colorless frame-level RE uses active devices at the remote node, it is still possible to increase the optical link budget through backward compatibility with existing GPON products. This design also provides wavelength conversion and an upstream burst-to-continuous mode conversion between the WDM–PON and GPON. The proposed hybrid PON can satisfy a packet loss ratio (PLR) of 10−10 at the downstream and upstream transmission including the use of forward error correction (FEC).

안정적 Wi-Fi 방송 서비스를 위한 무선 랜 전송 특성 분석

무선 랜 기술을 방송 분야에 응용하기 위해서는 IEEE 802.11 방송 패킷에 대한 이해가 필요하다. 현재 IEEE 802.11 방송 패킷 전송 기술은 Unicast 패킷 전송 기술에 비해 컨텐츠 전달의 신뢰성을 보장 할 수 없다는 단점이 있다. 이러한 무선 랜 방송 기술의 손실률 제어를 위한 기법으로 FEC가 주로 사용되고 있다. 무선 랜 방송 기술에 FEC 기법을 활용함에 있어서 핵심은 복구를 위한 여분의 패킷 양을 결정하는 것이다. 이에 본 논문은 먼저 다중 무선 랜 전송률-(1-54Mbps) 이 지원되는 방송 테스트베드를 구성하였다. 그리고 방송 패킷의 길이, 무선랜 전송률, 주변 환경에 따른 손실률을 구하고 손실률을 최소화 할 수 있는 인자들의 값을 도출 하였다. 나아가 구해진 손실률을 이용하여 FEC 여분 패킷 양을 결정하였다. To apply Wi-Fi technique to the Broadcast field, we have to study features of IEEE 802.11 Broadcast packet. IEEE 802.11 Broadcast technique cannot guarantee successful packet delivery than IEEE 802.11 Unicast. A promising solution to this problem is the use of FEC(Forward Error Correction) mechanisms. However, the adjustment of the FEC redundancy rate is not a trivial issue due to the dynamic wireless environment. In order to explore the above issues we conducted an experimental study of the packet loss behavior of the IEEE 802.11g protocol. In order to study, we implemented a broadcast test bed. Based on the experimental results, we provide guidelines on wireless lan parameters(packet size, transmission rate(11g), background traffic). From this experimental study, we provide FEC redundancy rate.

Reliable and Low Latency Transmission in Industrial Wireless Sensor Networks

The major advantages with Industrial Wireless Sensor Networks (IWSNs) in process automation are cable cost reduction, enhanced flexibility and enabling new emerging applications such as wireless control. However, transmission over the wireless channel is prone to noise and interference which causes packets to be erroneous received at the receiver node. To improve the link reliability in lossy channels, error correcting codes are commonly used. In this paper we discuss the use of forward error correction (FEC) codes in IWSN in order not only to improve the link reliability but also to reduce the number of retransmissions in harsh industrial environments. We propose a FEC scheme suitable for MAC level protection where the packet is divided into groups and encoded using systematic FEC codes. We have implemented different FEC codes in a typical IWSN chip to evaluate memory consumption and to ensure that we are not violating the strict timing rules for acknowledgment. Our results show that some FEC codes are suitable to be implemented in a typical IWSN node while several fails due to large memory footprint or to long encoding and decoding time.

A study of forward error correction for mobile multicast

Abstract3rd Generation Partnership Project (3GPP) has standardized the use of forward error correction (FEC) for the provision of reliable data transmission in the mobile multicast framework. This error control method inevitably adds a constant overhead in the transmitted data. However, it is so simple as to meet a prime objective for mobile multicast services; that is scalability to applications with thousands of receivers. In this paper, we present a study on the impact of application layer FEC on mobile multicast transmissions. We examine whether it is beneficial or not, how the optimal code dimension varies based on network conditions, which parameters affect the optimal code selection, and how this can be done. Additionally, we focus on one of the most critical aspects in mobile multicast transmission, which is power control. The evaluation is performed with the aid of a novel scheme that incorporates the properties of an evolved mobile network, as they are specified by the 3GPP. Copyright © 2010 John Wiley & Sons, Ltd.

Hybrid ARQ Error-Controlling Scheme for Robust and Efficient Transmission of UWB Body Area Networks

This paper presents hybrid type-II automatic repeat request (H-ARQ) for wireless wearable body area networks (BANs) based on ultra wideband (UWB) technology. The proposed model is based on three schemes, namely, high rate optimized rate compatible punctured convolutional codes (HRO-RCPC), Reed Solomon (RS) invertible codes and their concatenation. Forward error correction (FEC) coding is combined with simple cyclic redundancy check (CRC) error detection. The performance is investigated for two channels: CM3 (on-body to on-body) and CM4 (on-body to a gateway) scenarios of the IEEE802.15.6 BAN channel models for BANs. It is shown that the improvement in performance in terms of throughput and error protection robustness is very significant. Thus, the proposed H-ARQ schemes can be employed and optimized to suit medical and non-medical applications. In particular we propose the use of FEC coding for non-medical applications as those require less stringent quality of service (QoS), while the incremental redundancy and ARQ configuration is utilized only for medical applications. Thus, higher QoS is guaranteed for medical application of BANs while allowing coexistence with non-medical applications.

Reliable Multicast with Local Retransmission and FEC Using Group-Aided Multicast Scheme

In reliable multicast, feedback and recovery traffic limit the performance and scalability of the multicast session. In this paper, we present an improvement to the many-to-many reliable multicast protocol, Group-Aided Multicast protocol (GAM), with a local-group based recovery by making use of forward error correction (FEC) locally in addition to NACK/retransmission. In contrast to the original GAM, which only makes use of NACK-based recovery, our scheme produces FEC packets and multicasts the packets within the scope of a local group in order to correct uncorrelated errors of the local members in each group of the multicast session, which reduces the need for NACK/retransmission. By using our scheme, redundancy traffic can be localized in each group within a multicast session, and the overall recovery traffic can be reduced.

Forward error correction in 10 Gbits/s Ethernet passive optical networks

The use of forward error correction (FEC) codes in future deployments of access networks is quite foreseeable and requires an analysis of the proper code for this purpose. Therefore, an overview of the most important classes of FEC codes is presented, assessing the most suitable to be used in time-division multiple access networks. Concerning the traffic characteristics and the properties of such networks, the Reed-Solomon codes were found to be the most appropriate, and an analysis of the performance improvement obtained with these codes is reported. The upstream performance of 10 Gbits/s Ethernet passive optical network systems employing the selected FEC code is evaluated and the benefits of introducing FEC are assessed, aiming for the minimization of characteristic impairments of such networks.

Reed-Solomon Codes for Low Power Communications

Power consumption is a critical issue for many applications running on autonomous battery operated devices. In the context of low power communications, the use of Forward Error Correction (FEC) schemes shall therefore not only be considered as a way to improve communication robustness but also as a way to reduce transmit power. The benefits of this approach can be assessed by analyzing the tradeoff between the additional performance gained and the power consumption overhead resulting from extra computations.In this paper, a selection method is described to size the parameters of a low power Reed-Solomon (RS) code. The rationale highlights the influence of code parameters on computational complexity and performance of the code. An efficient set of code parameters can be deduced from this analysis to reduce the global power consumption of the system. Among the RS codes considered, the shortened RS(40,32,4) code over GF(28) is selected for further implementation analysis. Several design improvements are investigated step by step, and the relative power savings achieved with each enhancement are quantified. These results tend to illustrate the improvements that can be reached with only little design efforts.

A Hybrid FEC Method Using Packet-Level Convolution and Reed-Solomon Codes

Efficient real-time contents distribution services on the Internet are only possible by suppressing the influence of packet losses. One solution for UDP transmission is the use of Forward Error Correction (FEC) based on Reed-Solomon codes. However, a more efficient method is required since this causes the increase of network traffic and includes the weakness to burst packet losses. In this paper, we propose a data recovery method that generates redundant data with the combination of Reed-Solomon codes and convolution of neighboring blocks. We realize the small amount of redundancy and the high reliability in data transmission compared with using only Reed-Solomon codes in the environment that burst packet losses are occurred frequently. We implement proposal method into the network bridge and confirm its efficiency from the viewpoint of data reconstruction from burst packet losses.

Scalability of spectrum-sliced DWDM transmission and its expansion using forward error correction

This paper clarifies the scalability of spectrum-sliced dense wavelength-division-multiplexing (DWDM) transmission systems primarily intended for metro access applications. A theoretical analysis elucidates the tradeoff between the loss budget and the sliced bandwidth (i.e., the number of channels with assuming light sources with a fixed bandwidth). Moreover, the use of forward error correction (FEC) to expand scalability is studied. Based on the analysis, two spectrum-sliced DWDM transmission schemes are introduced. One demonstrates 1.25-Gb/s, eight channel spectrum-sliced DWDM transmission through the use of directly modulated super-luminescent diodes (SLDs), and the other confirms 10-Gb/s, eight channel spectrum-sliced DWDM transmission with the channel spacing of 200 GHz through the use of FEC