Release time:

2023-08-16

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Optical communication (OpTIcal CommunicaTIon) is a communication method using light waves as a carrier. There are two ways to increase the optical path bandwidth: one is to increase the single-channel transmission rate of the optical fiber; the other is to increase the number of wavelengths transmitted in a single optical fiber, that is, wavelength division multiplexing (WDM). Detailed explanation of optical communication, optical communication structure principle and its advantages and advantages Broadband Metropolitan Area Network (BMAN) is the hot spot of China's information construction, DWDM (dense wavelength division multiplexing) of the huge bandwidth and transmission data transparency, is undoubtedly the technology of today's optical fiber applications. However, MAN has the characteristics of short transmission distance, flexible topology and many access types, such as copying DWDM, which is mainly used for long-distance transmission, is bound to cost too much, while the early DWDM is also difficult to adapt to the flexible diversity of MAN and so on. In the face of this low-cost metro-wide broadband demand, CWDM (Coarse Wavelength Division Multiplexing) technology came into being and soon became a practical device. For optical communication, its technology is basically mature, and the business demand is relatively insufficient. In FTTH, which is known as the "ultimate goal of broadband access", for example, its implementation technology EPON has been fully mature, but due to the low bandwidth required by ordinary users to access the Internet, the commercial use of FTTH is limited to some pilot areas. However, in 2006, with the development of triple-play services such as IPTV, the bandwidth provided by operators can no longer meet the requirements of users for high-definition TV, and the deployment of FTTH has also been put on the agenda. Coincidentally, ASON has flexible control over the transmission network and can provide personalized services for enterprise customers. Many operators do not hesitate to invest heavily in the construction of ASON in order to develop and maintain enterprise customers. The ultimate goal of the future transmission network is to build an all-optical network, that is, to fully realize "optical fiber transmission instead of copper wire transmission" in the access network, metropolitan area network and backbone network ". The backbone network and metropolitan area network have basically realized all-optical, and some areas with rapid network development have also realized the optical advance and copper retreat of some access layers. Optical communication is the technology of using light to transmit information to each other. Detailed explanation of optical communication, optical communication structure principle and its advantages and advantages Basic structure of optical communication Computers and mobile phones around us send messages through electrical signals "0 and 1. Optical communication is composed of a "transmitter" that converts electrical signals into optical signals, a "receiver" that converts optical signals into electrical signals, and a "fiber" that transmits light. Detailed explanation of optical communication, optical communication structure principle and its advantages and advantages Advantages of Optical Communication 1. Long transmission distance, economical and energy saving 2. One-time transmission of massive information 3. Fast communication speed (1) Long transmission distance, economical and energy-saving Assuming that 10Gb of information (10 billion signals) is to be transmitted in 1 second, if electrical communication is used, the signal must be adjusted every 100 meters. In contrast, when optical communication is used, the required adjustment interval may be 100 kilometers or more. The fewer the number of times the signal is adjusted, the fewer the number of machines used, so it has an economic and energy saving effect. Detailed explanation of optical communication, optical communication structure principle and its advantages and advantages For example, when talking to friends abroad or chatting online, it feels like talking at home. Not like before the sound will lag. In the era of only electronic communication, the distance that can be transmitted at one time is short and the amount of information transmitted is small. International communication is mainly transmitted by artificial satellites as relays. However, if optical communication is used, the distance of one-time transmission is long and the amount of information transmitted is large. Therefore, by using optical fiber cables laid on the seabed, natural and smooth communication with overseas can be realized. (The speed of radio waves and light is the same. However, because the transmission path will be longer through satellites, the signal will arrive slower. The distance of submarine cables is much shorter, so the signal will arrive faster.) Detailed explanation of optical communication, optical communication structure principle and its advantages and advantages (2) one-time transmission of massive amounts of information A large number of users can receive the required information (movies or news, etc.) at the same time. In 1 second, electrical communication can only transmit up to 10Gb(10 billion 0 and 1 signals) of information. Compared with this, optical communication can transmit up to 1Tb(1 trillion 0 and 1 signals) of information. Detailed explanation of optical communication, optical communication structure principle and its advantages and advantages (3) Fast communication speed Electrical communication may cause errors due to electrical noise, resulting in a decrease in communication speed. However, optical communication is not affected by noise, so signals can be transmitted quickly. Detailed explanation of optical communication, optical communication structure principle and its advantages and advantages Optical communication is to light wave carrier communication. There are two ways to increase the bandwidth of the optical path: one is to increase the single-channel transmission rate of the optical fiber; the other is to increase the number of wavelengths transmitted in a single optical fiber, that is, wavelength division multiplexing (WDM). In fact, optical communication equipment is only suitable for use in the last few kilometers. The most basic optical fiber communication system consists of data source, optical transmitter, optical channel and optical receiver. The data source includes all signal sources, which are signals obtained by source coding for voice, image, data and other services. Optical transmitters and modulators are responsible for converting signals into optical signals suitable for transmission on optical fibers. The used light wave windows have 0.85, 1.31 and 1.55. The optical channel includes the most basic optical fiber, as well as the relay amplifier EDFA, etc., while the optical receiver receives the optical signal, extracts the information from it, and then converts it into an electrical signal, and finally obtains the corresponding voice, image, data and other information. Detailed explanation of optical communication, optical communication structure principle and its advantages and advantages Four Optical Communication Technologies Based on the above all-optical network architecture, there are many core technologies, which will lead the future development of optical communication. The following focuses on ASON, FTTH, DWM, RPR, the four most important technologies. (1)ASON No matter from the domestic research and development progress, commercial trial situation, or from the development experience of foreign countries, it will be an inevitable trend for domestic operators to introduce ASON technology on a large scale in the transmission network. ASON(AutomaTIcally Switched OpTIcal Network, Intelligent Optical Network) is an optical transport network technology. The current product and market conditions show that ASON technology has reached a commercial maturity. With the large-scale deployment of 3G and NGN, business requirements will further drive the development of transmission network technology. It is expected that ASON will be more widely commercialized in 2007. In 2006, major equipment providers such as Huawei, ZTE, FiberHome and Lucent have launched commercially available ASON products. China Telecom, China Netcom, China Mobile, China Unicom and China Railcom have successively carried out ASON application testing and small-scale commercial use. The successful commercial experience of ASON in foreign countries shows that ASON will play an irreplaceable role in the backbone transmission network. For example, AT&T's 140 nodes cover the backbone transmission network in the United States. BT has set up 21CN network and currently has 40 ASON nodes. The Vodafone 131 nodes cover the ASON backbone transmission network in Britain, etc. However, the standardization of ASON in routing, automatic discovery, ENNI interface and other aspects is not perfect, which has become an important factor restricting the development and commercialization of ASON technology. In the future, China will participate in more ASON standardization work. At the same time, the standardization of ASON, especially the standardization of ENNI, will make breakthrough progress in recent years. (2)FTTH FTTH(Fiber To The Home) is the ultimate goal of next-generation broadband access. At present, EPON will become the mainstream technology in China in the future, and GPON has the most development potential. EPON uses Ethernet encapsulation, so it is very suitable for carrying IP services, in line with the rapid development of IP networks. At present, the state has taken EPON as a major project of the "863" plan, and has taken the initiative in the commercial operation. GPON pays more attention to multi-service support than EPON, so it is more suitable for the development of future converged networks and converged services. But it is not mature enough and the price is too high to be popularized in China. China's FTTH is still in the market start-up stage, and there is still a long way to go from large-scale commercial deployment. In the future industrialization development, the operator's monopoly on the "last mile" of the local network is an important factor restricting the development of FTTH. It is more conducive to the healthy development of FTTH industry by adopting the form of "cooperation between user resident network operators and real estate developers. Judging from the FTTH development experience of Japan, the United States, Europe, South Korea and other countries, the core driving force of FTTH lies in the rich content provided by the network, and the government's monitoring and management policies for applications and content will also restrict the development of FTTH. (3)WDM WDM breaks the limit of traditional SDH network capacity and will become the core transmission technology of future optical networks. According to the different channel spacing, WDM(Wavelength Division Multiplexing, wavelength division multiplexing) can be divided into DWDM (dense wavelength division multiplexing) and CWDM (sparse wavelength division multiplexing) these two technologies. DWDM is the technology in the field of optical fiber transmission today, but CWDM also has its place. In 2006, equipment manufacturers such as FiberHome and Huawei launched their own DWDM systems, and domestic operators also carried out related tests and small-scale commercial use. In the future, DWDM will play an irreplaceable role in networks with demanding transmission rates, such as using DWDM to build backbone networks. Compared with DWDM,CWDM has the advantages of low cost, low power consumption, small size and low requirements for optical fiber. In the next few years, telecom operators will strictly control the cost of network construction. At this time, CWDM technology has its own living space. It is suitable for fast and low-cost multi-service network construction, such as metropolitan and local access networks, and small and medium-sized cities. Metropolitan core network, etc. (4)RPR Resilient Packet Ring (Resilient Packet Ring,RPR) will become an important optical metropolitan area network technology in the future. In recent years, many domestic and foreign transmission equipment manufacturers have developed MSTP devices with embedded RPR function, and RPR technology has been supported and participated by a large number of chip manufacturers, equipment manufacturers and operators. In terms of standardization, the RPR standard of IEEE802.17 has been recognized by the whole industry, and the relevant standardization work in China is still in progress. In the future, RPR will be mainly used in the backbone and access of metropolitan area networks, and can also be applied in decentralized government networks, enterprise networks and campus networks, as well as IDC and ISP. Optical communication advantages Optical fiber communication has received great attention because it has unparalleled superiority compared with other means of communication. (1) Large communication capacity In theory, a fiber with only the thickness of a hair can transmit 100 billion channels at the same time. Although it is far from reaching such a high transmission capacity, the experiment of transmitting 240000 channels with one optical fiber has been successful, which is dozens or even thousands of times higher than the traditional open wire, coaxial cable, microwave, etc. The transmission capacity of an optical fiber is so huge, and an optical cable can include dozens or even thousands of optical fibers. If wavelength division multiplexing technology uses an optical fiber as several or dozens of optical fibers, its communication capacity is even more amazing. (2) Long relay distance Because the optical fiber has a very low attenuation coefficient (the current commercial silica fiber has reached below 0.19dB/km), if equipped with appropriate optical transmission and optical receiving equipment, the relay distance can reach hundreds of kilometers. This is the traditional cable (1.5km), microwave (50km) and so on can not be compared. Therefore, optical fiber communication is particularly suitable for long-distance 1. secondary trunk communication. It is reported that the experiment of transmitting 240000 channels simultaneously with one optical fiber and 100 kilometers without relay has been successful. In addition, the ongoing optical soliton communication experiments have reached the level of transmitting 1.2 million channels and 6000 kilometers without relay. Therefore, it is entirely possible to achieve global trunkless fiber optic communication in the near future. (3) good confidentiality performance When the light wave is transmitted in the optical fiber, it is only carried out in its core region, and basically no light "leaks" out, so its confidentiality performance is excellent. (4) strong adaptability It means that it is not afraid of the interference of strong external electromagnetic fields, corrosion resistance, and strong flexibility (its performance is not affected when the bending radius is greater than 25cm). (5) Small size and light weight It is convenient for construction and maintenance. It is convenient for construction and maintenance. The laying method of optical cable is convenient and flexible, which can be directly buried, pipeline laying, and underwater and overhead. (6) Rich sources of raw materials and potential low prices The most basic raw material for the manufacture of quartz optical fiber is silica or sand, which is almost inexhaustible in nature. So its potential price is very low.

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