Copyright © 2020 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0) Simulation Study of Video Transmission by OpticalFiber 1 Nadira BOUKHATEM, 1Salah TOUMI,2El-Bey BOURENNANE, 1 Abdelghani REDJATI, 1Abderraouf FARES 1 Laboratory LERICA Department of Electronics, BadjiMokhtar University, Annaba,Algeria E-mail:boukhatemnadira@yahoo.fr, salah.toumi@univ-annaba.org, redjati@yahoo.fr,faresabderraouf93@gmail.com, 2 Laboratory ImVIA Burgundy University, Dijon, France, E-mail:ebourenn@u-bourgogne.fr Abstract: The migration to the use of optical fiber has wirelinenetwork and on the wireless network [4], i.e. required several developments, because nowadays it is the compression is a viable part of video communication. A most widely used transmission medium in vast fields, wide variety of codecs are available, none of which are particularly video transmission. The work carried out made suitable for all situations. it possible to study, evaluate and analyze the implementation The first section is devoted to the theoretical study of of this transmission system. We examined the characteristics of the operating techniques of each channel of the video optical fiber. In the second we studied the video transmission chain and found several problems, one of which transmission by optical fiber and the different treatments is the performance of error-correcting codes based on coding that video undergoes. Finally, the third section was and decoding algorithms, optical fiber and these several devoted to the simulation of video transmission by optical criteria for which we have the rate, propagation distance and fiber taking into account: compression, decompression, good transmission quality, which implies that there is always attenuation and length. And will conclude with a research and improvements in this area. conclusion. Keywords: Telecommunications networks; optical fiber; video II. OPTICAL FIBER, ITS EVOLUTION AND USE coding; video transmission. With the advent of the Internet, bandwidth requirements have become increasingly important in order to convey the I. INTRODUCTION growing mass of information on the various networks, The last decade has been marked by the rapid evolution of with reliability and while maintaining a good quality of the information and communication technology (ICT) service. Indeed, this has required the development of sector, including telecommunications and the Internet. communication systems that are efficient and reliable Solutions have been developed by allowing devices to enough to interconnect a constantly growing number of connect to the Internet from an access point without the users around the globe. Researchers and industrialists were need for a cable connection [1]. The rapid increase in able to propagate a deformation-free pulse at the speed of video applications on wired (optical fiber...) and wireless light over very long distances and with a wide bandwidth. (LTE, wimax...) standards allowing real-time video The door to the transport of information in optical and transmission for various applications such as video binary form was broken and this was the starting point of conferencing, telemedicine, video streaming, digital the race for speed, which led to pharaonic progress in just terrestrial television [2]. Thus the production of 20 years [5]. multimedia content has become accessible to all audiences A.Description and evaluation of optical fibers and at a low cost. This development makes it possible to achieve better video quality, from the digital that is The fiber is nothing more than fused silica glass beginning to grow, to HD TV and then to 8k. Current filament[6] that can accept electrical signals as an input researchers are working on a thorough analysis of video and convert them into optical signals (light) that are characteristics on different types of networks to optimize converted back into electrical signals at destination[7].The transmission and to efficiently and adaptively route video main element of the fiber is the central conductor called data from the source to the destination that requires a the fiber core or core. This conductor is surrounded by an transport protocol. A network path includes a succession of optical sheath with a refractive index lower than that of the links, each with its own bandwidth [3] which is not the core. The whole will then be covered with a protective only factor that affects network performance. The error coating to mechanically protect the fiber; it plays no role in rate in channels must be minimized by designing an guiding light (Fig.1). The fiber optic cabling system is based on cabling with an even number of fibers (one for appropriate transmission means that allows specific transmission, one for reception) [8]. treatment for losses between connection on the distortion of the received signal, in order to ensure maximum reliability of the transfer of information by using a physical medium such as cable, optical fiber, etc. The heterogeneity of computer networks requires the implementation of a common network access interface to manage interoperability between the equipment of different manufacturers. The ISO organization has therefore specified a common structure describing the Fig.1.Optical fiber structure architecture of a network, called the OSI model (Fig. 2). B. Types of Optical fiber The following section will be the subject of the To understand the applications of optical fiber, it is presentation of the OSI model in a transmission context necessary to understand each type and its characteristics. [11]. Optical fibers can be classified into two categories according to their diameters and wavelength propagation. The dispersion phenomenon results in a widening of the pulses at the heart of their propagation; this widening limits the bandwidth of the optical fiber channel. The (Table 1.) provides a comparative summary of the advantages, disadvantages and practical application between the different types of optical fibers TABLE I. COMPARISON BETWEEN THE DIFFERENT TYPES OF FIBER OPTIC Fig. 2.Layered structure of the OSI model Number of single mode multi-mode modes The telecommunications network is a set of connected Refractive / Index jump Gradient equipment that can be defined as an extensible web of index fiber index fiber interconnected nodes by physical lines: optical fibers in Corediamete 8à10 50 à 62.5 50 à r (μm) 62.5 some places and, in others, by copper electrical wires; so Sheathdiame 125 125 125 we talk about afixed network. ter (μm) Data Processing Terminal Equipment or any other source Attenuation 0.1 à 0.5 3 1.5 à 3 (Transmitter) of digital data is called DTE. They (dB / Km) Bandwidth In the order of <60 MHz. Km De l'ordre de communicate with each other through a data circuit that THz.Km GHz.Km consists of Data Circuit Termination Equipment (DCTE). Dispersion Chromatic: Axial modal: Total modal: Forms All the functions necessary for the management of the data propagation reflection on a sinusoidal circuit by each DTE constitute the physical layer of the fiber shape latter or it is carried out by joins or interfaces DTE/DCT. Spectral 1300nm 1550nm 850nm 1330 850nm 1330 Windows of nm nm use Practical Long-distance Short distance Short and applications communications communication mediumdista s, local nce networks communicati ons C.Optical fiber in telecommunications networks At present the most efficient and widespread technology is based on the fiber optic transmission system. These offer a low attenuation physical support that is virtually Fig.3.Basic component of a data link insensitive to electromagnetic noise, easy to install and has a high transmission capacity. The optical fiber as we A DTE is characterized by its rate (bits/s), the transmission currently use it is the result of intensive research on new mode (synchronous or asynchronous), and the type of low-dissipative waveguides. Like all other transmission transmission line, the operating mode of the circuit media, optical fiber has disadvantages but also offers many (simplex, duplex... etc.), the coding method, the advantages for telecommunications [9][10]. modulation speed and the type of interface with the DTE (Fig.3). An optical fiber telecommunications network can be Ⅲ QUALITY CRITERIA FOR FIBER OPTIC VIDEO divided into three categories according to their size (in TRANSMISSION terms of number of machines), data transfer speed and The principle of any data transmission is to convey extent [6]: information from the source to the recipient (between a transmitter and a receiver) by minimizing the risks of  The access network - LAN (local area network) returned to its original form; a reconstructed video or local network, covering dimensions ranging (Fig.5)[14]. from a few kilometers to a few tens,  the metropolitan area network (MAN), with dimensions of the order of one hundred kilometers,  The wide area network (WAN) or broadband network, the best known WAN is the Internet, extending over several hundred kilometers. It includes terrestrial or underwater systems. Fig.5.Schematic diagram of an optical link A. Error problems on transmission networks Although these networks have deployment advantages The source: The message source transmits the information and user mobility, real-time video transmission over these in digital form and will be encoded on "n bits". networks for various applications such as Telemedicine, Source encoding/decoding: Source encoding consists of videoconferencing and video streaming is a challenging transforming the source message into a sequence of task[12] and that is why it is often necessary to implement information. By reducing the redundancy (lossy or devices to detect errors and if possible to correct them, lossless) contained in the message and thus minimizing the however, if the high binary error rate ,error-resistant amount of information useful for its representation. The techniques are needed to protect encoded video bit streams source decoding performs the dual operation; the For more information, the works[4],[13], detail all these information message is decompressed in order to find its aspects.Various Error Detection Codes (EDC) or Error equivalent from the substitution sequence before Correcting Codes (ECC) have been used for years to transmission. It should be noted that the theoretical limits increase the reliability of transmission systems [14].AlSo, of source coding are set by Shannon's first it is necessary to provide in a transmission chain theorem[16][17].The performance of a source coder is techniques for detecting and correcting errors within evaluated by the compression ratio parameter which codecs. The figure below gives a simple summary of the represents the ratio between the size of the information large coding family. In the first category (block codes), let before and after source coding (the principle of source us mention the most famous codes such as BCH, Reed coding for still image and video, commonly called Muller, Reed Solomon and Goppa, Golay and Hamming. compression). The second category (trellis codes) is less rich in variety Channel encoding/decoding: Channel encoding is an but offers much more flexibility, especially in the choice operation that reduces errors and protects transmitted of available parameters and decoding algorithms. For information from transmission channel interference. To example, binary convolutional codes widely used in coded combat these transmission errors, it is necessary to add modulations (TCM) and parallel concatenated codes redundancy in order to detect and possibly correct errors (Turbo Codes). during reception. It is therefore possible to improve the signal-to-noise ratio (SNR), which defines the difference between the power of the transmitted signal and the noise of the propagation channel. This is expressed in decibels (dB). The signal strength is derived from the energy required to emit an Es modulation symbol. The noise power depends on the density of the noise spectrum N0, so the SNR is defined according to the relationship (1.1). 𝐸 𝑆𝑁𝑅 = 𝑆 (1) Fig.4.Hierarchy of correction codes [15] 𝑁0 𝑬 𝑺𝑵𝑹𝒅𝒃 = 𝟐𝟎. 𝒍𝒐𝒈𝟏𝟎 (𝑵𝑺 )(2) In the case of optical fiber transmission and since the 𝟎 information is presented in multimedia form (text, still Modulation/demodulation: Digital modulation allows the image, video), the video is first coded or modulated in a coded information to be adapted to the transmission known sequence but the result is the same: the information medium. The transmitter is in charge of the modulation then consists in transmitting bit streams, which can be operation which associates one or more binary elements controlled upon reception. This signal is injected into the with a symbol characterized by its amplitude and phase. optical fiber through the transmitter; there may be losses Modulation acts on the parameters of a carrier signal to and degradation of the signal, caused mainly during transmit the encoded data. There are several types of dispersion within the fiber. At the output of the fiber, the modulations that can be applied to optical channels [18], signal is received and amplified before being decoded, (Fig.6) The demodulator plays the dual role of the however the signal will undergo reverse processing to be modulator and thus transforms the received signal into a bitstream. The simulation is carried out for reference values for the attenuation: 0.17, 0.22, 0.50 associated with the single mode fiber F: (λ = 1550nm) for lengths ranging from 40km to 110km.In this part we tried to implement a Matlab code that allowed us to get as close as possible to the theoretical results. First we created a video file and saved it (the video must be in the same path as the Matlab code backup), then we started processing the video to send Fig. 6. Modulation techniques [18] it correctly on the fiber. We will study the influence of The transmission channel: It represents the link between transport with optical fiber, indeed we will see the the transmitter and the receiver and can be of different influence of the attenuation on the quality of the video and natures depending on the type of quantity it allows to convey. The transmission channel is characterized by its the losses it will cause. The results obtained are capacity and bandwidth. Note that the input of the summarized in table Ⅱ: transmission channel processes binary elements, while the output produces probabilistic information associated with TABLE II. ATTENUATION ACCORDING TO the binary elements. There are several theoretical models LENGTH of the transmission channel depending on the most frequent types of errors. The most commonly used Att 0.17 0.22 0.50 channels in information theory are the Symmetric Binary Length (Km) Channel (CBS) and the Gaussian White Additive Noise 40 0.8350 0.7135 0.3266 Channel (BBAG) [19]. 50 0.6680 0.5708 0.2613 60 0.5566 0.4756 0.2177 IV. STUDY AND SIMULATION OF THE 70 0.4771 0.4077 0.1866 PARAMETERS OF A TRANSMISSION 80 0.4175 0.3567 0.1633 CHAIN WITH THE MATLAB / 90 0.3711 0.3171 0.1452 SIMULINK SOFTWARE 100 0.3340 0.2854 0.1306 In this section, we describe the motivation to better 110 0.3036 0.2594 0.1188 choose the components of an optical telecommunication chain; we need to calculate the optical link balance [20] which is summarized in the calculation of the energy balance and the bandwidth balance of the link. Two effects limit the transmission capacity: attenuation and dispersion. First of all, this paper provides an overview of the transmission chain and program architecture, each of the above blocks is used in the code as a subprogram. The script used for the simulation will therefore only pass the variables from one subprogram to another and calculate it. A. Attenuation Or loss of transmitted power, during propagation in the Fig.7. Attenuated video for Att= 0.17: [1- L=40km, 2- L=50km, 3 - fiber, the power decreases as a function of the length of the L=60km, 4 - L=70km, 5-L=80km, 6-L=90km, 7- L=100km, 8- fiber at a defined wavelength ʎ, according to the law: L=110km] 𝑃𝐿 = 𝑃0 𝑒 (−𝛼𝐿) (3) Instead, the attenuation is defined in dB/km: 𝑃 𝐴(𝑑𝐵/𝐾𝑚) = 10𝑙𝑜𝑔 𝑃0 (4) 𝐿 A: AttenuationP0: Power of light at the entrance of the fiber L: Length (Km) PL: Power of light at the fiber output : absorption factor in Neper/m. For practical reasons 𝐴 = −4,34 𝛼𝐿 (5) Fig.8. Attenuated video for Att= 0.22: [1- L=40km, 2- L=50km, 3 - L=60km, 4 - L=70km, 5-L=80km, 6-L=90km, 7- L=100km, 8- L=110km] L=60km, 4 - L=70km, 5-L=80km, 6-L=90km, 7- L=100km, 8- L=110km] Fig.9.Attenuated video forAtt= 0.50: [1- L=40km, 2- L=50km, 3 - L=60km, 4 - L=70km, 5-L=80km, 6-L=90km, 7- L=100km, 8- L=110km] Fig.13. Video noisy for Att= 0.22: [1- L=40km, 2- L=50km, 3 - L=60km, 4 - L=70km, 5-L=80km, 6-L=90km, 7- L=100km, 8- L=110km] Fig.10. Absorption factor by attenuation value Fig.14. Video noisy for Att= 0.50: [1- L=40km, 2- L=50km, 3 - L=60km, 4 - L=70km, 5-L=80km, 6-L=90km, 7- L=100km, 8- L=110km] C. Calculation of PSNR The signal-to-noise ratio is often used as a measure of quality between the original image and a compressed image. For this fact, the square error (MSE) Fig.11. Absorption coefficient by length and the peak signal-to-noise ratio (PSNR) are the two error B. Noise measures used to compare the quality of image The optical signal is propagated along the fiber as compression. The MSE represents the cumulative squared well as in the different components of a transmission error between the compressed image and the original chain, the latter will be assigned to the various types of image, while the PSNR represents a measure of the noise so attenuation is not the only disadvantage there is maximum error.It is calculated using two equations: also the influence of noise that distorts the video signal, 𝑀𝑆𝐸 = 𝑚𝑒𝑎𝑛(𝑚𝑒𝑎𝑛(𝑐𝑜𝑚𝑝_𝑣𝑖𝑑é𝑜 − 𝑠)2(7) such as the Gaussian additive noise channel. We present: 𝑃𝑆𝑁𝑅 = 10 ∗ 𝑙𝑜𝑔10(2552 ⁄𝑀𝑆𝐸 (8) the Gaussian model which is the most common in the literature for optical fibers. It is a rather simplistic model, The results obtained are summarized in (table Ⅲ) it is the reference channel to study error-correcting codes and their decoding algorithms. The AWGN assumes that a noise element Bn is added to the emitted element: Hence: 𝑌𝑛 = 𝐵𝑛 + 𝑋𝑛 (6) TABLE III. CALCULATION OF PSNR Yn :received signal Bn : noisy signalXn : emitted signal Att PSNR (dB) 0.17 22.3 0.22 17.11 0.50 10.02 Fig.12. Video noisy for Att= 0.17: [1- L=40km, 2- L=50km, 3 - [4] A. Nafaa, T. Taleb, and L. Murphy, “Forward error correction strategies for media streaming over wireless networks,” IEEE Communications Magazine, vol. 46, pp. 72–79, January 2008. [5] A.Hamouda , K.Saouchi ,“Breves generator of pulses has different flow rates(40 Ghz, 80 Ghz and 160 Ghz),”, journal of JNTM, Vol. 7(01), 27-32. 2017. [6] P.G. Kokaje, Dr. R. S. Kawitkar, M. Selva Balan,“ Review of Recent Development in Optical Fiber Technology,”International Journal of Advanced Research in Electrical,Electronics and Instrumentation Engineering (An ISO 3297: 2007 Certified Organization)Vol. 4, Issue 3, March 2015. Fig.15. Calculation of PSNR [7] I. S. Chibueze, O. N. 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