Abstract
Optical fiber communication has always been the main means of information transmission, since 70 years, optical fiber communication technology have made great progress in China. Although after \affect the major trends. This paper reviews China's optical fiber communication (including the related system equipment, fiber optic cable and optical device technology) in the core, metro and access network applications , current research and development of the next step.
1 Preface
For now, China has a total length of cable laid over 4.05 × 106 km, approximately 7.582 × 107 core km. The microwave line length is only 2 × 105 km, and the transmission capacity is much lower than the fiber-optic cables, consequently more than 90% information capacity transmission through the fiber-optic cables, optical fiber communication is the primary means of information transmission. Chinese optical fiber communication technology began the study from the 20th century 70s , it made great progress over 30 years. Today, chinese optical fiber communications equipment and systems, not only to satisfy the domestic network construction. And has a large number of services in international communication networks, optical communication become the smallest gap in the levels of high-tech fields in the international level. The man who concerned with optical communications in China often ask people what level do we have in the optical fiber communication? The next step Whether there is no room for development or not? This article attempts to answer these questions in the optical fiber communications of China (including the related systems equipment, fiber optic cable and optical device technology) in the core , metro and access network's application , current research and development in the next step , in particular, that the optical fiber communication technology in China still has good development prospects.
2 optical communication technique
With the growing information needs of society, we are progressing rapidly in core transmission network . In standard terms, from the PDH is major before 1995 to the SDH become predominant at present. In light mode, multi-mode transmission was introduced did not take a long time to replace the entire single-mode. In channel, mainly from the initial development of single-channel system to the present multi-channel DWDM system. In the rate, gone from 34 Mbit / s, 140 Mbit / s, 565 Mbit / s to 622 Mbit / s, 2.5 Gbit / s upgrade process, and gradually evolved into dominate in the current long-distance network with 10 Gbit / s based DWDM systems. In the network of structure, from simple point to point system to a ring-shaped chain structure , and evolution in grid-shaped network, cable networks are now the backbone of our country is no longer a simple \vertical and eight horizontal\but rather a nationwide, including the roof of the world, including the Tibetan Plateau, a relatively complete mesh network. In addition, as single frequency network and
management network of such networks has been relatively in place. But the whole
communication network is in a transition at this time, faces from the circuit-based networks to packet-based network’s evolution, the current network evolution to next-generation networks, fixed network and mobile network’s integration, telecommunications networks, computer networks and wide’s integration. The development of transmission network proposed new requirements. Transmission network is also facing to the ultra-high speed, large capacity, ultra-long haul and intelligent development, transmission and switching capabilities’s combined , electric layer network has become optical layer networks, so the problem is that criss-cross. For simplicity, here we were only discuss the technical aspects of optical communication itself.
The rapid development of Internet traffic made the the core network rapid growth, according to CNNIC \Internet Development Statistics Report (2006 / 1),\pointed out that China's Internet broadband access ports are 4.8359 × 107. The total bandwidth of the network exit are 136.106 Gbit / s. Also, according to the Ministry of Information Industry, at the end of 2005, China's mobile network plus fixed network 2 Mbit / s long-distance business circuit are 70.6775 million. These data indicate that in our core network ,increase the rate of transfer for each channel, that is transmitted by large particle size is necessary. In addition, as 10 Gbit / s Ethernet gradually into the business, 40 Gbit / s Ethernet has emerged (these in the 10 Gbit / s based on the network load is more difficult), and now people studying the next step is 80GE or 100GE, that following the 40 Gbit / s Ethernet (referred to as 40GE) achieved, what the next step of ethernet rates should be development ,is that multiplied 2 times into 80GE, or simply jump to 100GE, there is no conclusion. Specification ITU-T has also stepped up 40 Gbit / s at the same time,and began to explore the next step to 160 Gbit / s (STM-1024) possibility of development, so the core network based of 10 Gbit / s develop to 40 Gbit to / s is an inevitable trend. In the \period by focusing on technological breakthroughs, have mastered the 40 Gbit/s SDH optical communication equipment and the basic technical, G.652 and G.655 fiber in the non-renewable transmission distance reached 560 km, as upgrade our network to lay the technical foundation.
The growth of the total flow of information. Make the network transmission capacity must also increase. Rate of increase in a single channel, based on the increase with a total capacity of DWDM is also very important initiative. The current capacity of the largest transmission network in the system is 160 × 10 Gbit / s, 1.6 Tbit / s DWDM. In the \\major projects, China has mastered the basic technology of the 80 × 40 Gbit / s, 3.2 Tbit / s DWDM system, non renewable distance is 800 km long, and that the system has been successfully in 3TNet broadband trial network in Shanghai to Hangzhou section of the opening run. The results obtained make the technical preparations for the expansion of the transport network .
With the demand for large capacity and high efficiency direct circuit urgent increase , in ultra long distance transmission (ULH) technology as the core network development become another direction. Particular, China's vast territory, the distance
between major cities from four to five hundred kilometers to more than one thousand kilometers or even thousands of kilometers widespread. Therefore, one thousand kilometers level to achieve ultra-long haul transmission is necessary means of direct transmission between large cities. In the %under the arrangement, China has mastered the 160 × 10 Gbit / s system from the 3 040 km without regeneration technology, and the system still has great margins, according to theoretical calculations, it can be achieved without electricity relaying transmissio in the 5 000 km. Technology research and development in the ULH technology, about the research of modulation code pattern, the applications of EDFA, and ROA (Roman optical amplifier, Raman optical amplifiers) and the technology of EFEC (Enhanced FEC) / SFEC (super-FEC) have been developed, ROADM (reconfigurable optical add and drop multiplexer, configurable of the optical add-drop multiplexer) technology has become ture, which in real networks have begun to be applied, driven by demand in the network, there will be further promotion.
The intellectualization has been the optical networks development targets, ASON increased the control plane in the foundation of original transport network's transmission plane and in the management plane, made great strides forward a stride to the light network's intellectualized aspect, is also transmission technology and the switching technology combined with a reflection. ASON has two most appealing characteristics: it can starts highly effective, the quick connection ability by the user or the operators; The complete, the fast protection restore the performance. Under “863” the plan deployment, our country present not only developed based on 10 Gbit/s SDH ASON system. But also has many applications in the domestic and foreign networks. Achieves the international advanced level in the performance aspect, some targets are also in are in the lead. In fact, in the laboratory, we had already grasped based on 40 Gbit/s SDH ASON technology, this as the next network's promotion, has built the foundation in advance. Next step develops the direction is based on ASON of OTN (optical transport network), will enable the optical network to further approach to the all-optical network. If we achieve all-optical network's goal, must has the significant breakthrough in the optical logic and the optical Storage aspect to realize the genuine optical Switching. This only then possibly becomes the genuine entire all-optical network.
While the rapid development of the system and equipment technology, optical devices and optoelectronic devices has also been rapid development. In the 40 Gbit / s SDH optical communication equipment and systems research projects, also arranged for the corresponding components of the subject, and it has made gratifying progress. For example: research and development the suitable high-speed signal amplification of the EDFA and the ROA and used for the system; developed for 40 Gbit / s transmitter module of the laser modulation driver and PIN / TIA (positive intrinsic negative junction / trans-impedance amplifier, PIN-based photodetector / transimpedance amplifier) component, also successfully developed 40 Gbit / s optical transceiver module; developed high-speed fiber grating dispersion compensator and used for the system; independent innovation polarization state based on the main track of the PMD compensator checked the system .
我国光纤通信技术发展的现状和前景(英文译文)
