Abstract
CONTENT
- Introduction
- 1. Theme urgency
- 2. Goal and tasks of the research
- 3.The concept of construction of broadband optical access networks of new generation
- Conclusion
- References
Introduction
The current stage of social development is closely related to the movement along the path of building a global information society. This trend is largely achieved through the development and improvement of the network architecture and telecommunications systems, substantial improvement in their performance, which primarily include the characteristics of the quality of service of all classes of the transmitted traffic on these networks. If until recently the basic media service provided by a wide range of subscriber data network, have access to the resources of the Internet, at the present time, this popular service is often complemented by the services of sound and television broadcasting, IP-telephony, high-speed communications between users and a number of others. The introduction of these services through modern multifunctional multimediaterminaly, accompanied by a transition to multi-network infrastructure of a new type, based on the principles of NGN NGN (Next Generation Networks). An important part of this packet network infrastructure is a broadband access network (SHSD) realizing the connection of user terminals and LAN users to the access points.
1.Theme urgency
Constant expansion of the range of network services, technology transfer, display, video, expanding user base covered by broadband services, and many other factors have led to the ongoing need to improve the data rate at the level of access. This fact contributes to the widespread adoption of fixed sector access network (AN) broadband fiber-optic technology. Engineering advances in the field of diabetes are significantly ahead of the development of scientific methods for analyzing the performance of this part of the EEC. In this connection it is relevant to develop scientific principles and methods for the creation and implementation of optical SHSD (OSHSD), their modeling and theoretical analysis of the quality of service of all types of traffic sent through this part of the network, as well as the development of scientific methods of analysis and reliability in such networks . Since OSHSD are expensive facilities that cover extensive, including rural areas, it is urgent to develop scientific methods and algorithms to create structures and topologies OSHSD optimal from the point of view of minimizing the reduced costs for the construction of these networks, while providing the required level of performance and, in particular, the reliability.
2. Goal and tasks of the research
The purpose of research is to study and modernization of the existing methods of construction of broadband optical access networks. Because with this were as follows:
1.Issledovat methods of building network infrastructure access technology based passive optical networks and hierarchical ring networks.
2. Develop a methodology to assess the quality of service of all classes
traffic flowing through the network access.
3. Analyze the existing techniques to estimate propagation delays
multiply-connected network, taking into account the nature of the alternative routes of signal propagation and modernize them.
4. Propose a methodology to assess the reliability and quality of service
Traffic in the ring optical access networks.
3. The concept of construction of broadband optical access networks of new generation
3.1 Next Generation Network NGN
Currently, the main income of the operators bring telephone services - mobile, long distance / international, fixed (for business customers). This trend will continue in the near future. Therefore, the construction of networks need to consider not only the possibility of providing additional services, but also the economic efficiency of communications networks. Thus reasonable to focus not on the explosive growth in revenues from the operation of the network in the future, and to generate new revenue now.
Thus, the modern requirements for Next Generation Network (NGN - Next Generation Network) is the ability of optimal voice traffic, data traffic, create and deliver new services, reduce the cost of capital construction and operating costs compared to existing communication networks.
Currently deployed in a significant number of traditional networks, so the construction of NGN useful to consider the possibility of existing equipment e e and an evolutionary transition to next-generation communications networks.
3.2 The concept of FTTx
The idea of using a fiber-optic communication lines (fiber optic) to provide services to residential and business users is not new. It is implemented in the concept of FTTx (Fiber to the x - "fiber-to ..."). At present, the provision of broadband and multimedia services are usually used mixed copper-optical access networks. There are several concepts of access network deployment of mixed type. One is called the HFC (Hybrid Fiber Coaxial) and involves bringing optics to the point of concentration, with the distribution network of the subscriber based on the coaxial cable. This architecture is not common and is usually used only by operators of cable television. Another concept is a kind of concept is known as FTTx and FTTB (Fiber To The Building - «fiber to the building," that is bringing fiber optic to an office building). Under the concept of distribution of signals on FTTB subscribers in the building is over twisted copper pairs using primarily technology VDSL.
Here are some other options for the concept of FTTx:
FTTH - Fiber To The Home (FOL bring to the residential home);
FTTP - Fiber To The Premises (generalized concept that brings together, in fact, the options FTTH and FTTB);
FTTO - Fiber To The Office (a concept similar to FTTB);
FTTC - Fiber To The Curb (FOL bring to the place in which you installed the wiring closet);
FTTCab - Fiber To The Cabinet (a concept similar to FTTC);
FTTR - Fiber To The Remote (bring fiber optic to the remote unit, hub);
FTTOpt - Fiber To The Optimum (FOL bring to optimal from the point of view of the operator, points).
Along with FTTx there is this, the concept of organization of the distribution network in the building - FITB (Fiber In The Building).
Any fiber optic cable core theoretically has unlimited bandwidth. Experiments on the transmission of information over fiber at speeds of the order of terabits per second were demonstrated time and again. It is well known that the transmission rate is limited to active equipment at both ends of the fiber-optic cable. Currently, the network based on copper pairs are ubiquitous in most regions remain the dominant cable infrastructure. However, fiber-optic networks are more simple, reliable, and require less maintenance when compared to copper networks. Taking into account these and the above arguments, it can be concluded that investment in fiber optic infrastructure are effective and long-lasting, and the introduction of FTTx technologies is feasible and very promising area
3.3. PON technology
PON - a family of rapidly developing the most promising technologies of broadband multi-service multi-access over optical fiber. The technology of passive optical networks, which follows from its name, is that its distribution network is constructed with no active components: a branching optical signal is carried by passive optical power dividers - splitters. The consequence of this advantage is the lower cost of access, reduction of necessary network management, high transmission range and no need for further modernization of the distribution network.
Structurally, any passive optical network consists of three main elements - optical terminal station OLT, passive optical splitters and optical network user terminal / device ONT / ONU.
Terminal OLT PON network interacts with external networks, splitters perform branching optical signal path in the area PON, and ONT / ONU have the necessary interface to the subscriber side. PON technology can be used for various versions of the concept FTTx
The arrival of GEPON, allowing direct Ethernet traffic on optics, was a logical development of the concept of a comprehensive, through the use of equipment for Ethernet networks operators. The procedures of the technology described in the standard IEEE 802.3ah, released in 2004. This technology is used for traffic Ethernet packets at speeds up to 1 Gbit / s in both directions. GEPON network topology can be any: bus, star, or even a combination of them ring for redundancy, which is accomplished with the use of automatic optical switches. Among the advantages of this technology is a low cost point solutions based on it. There are currently about 20 million installed ports GEPON, mostly in South-East Asia.
Another standard Gigabit PON, describing technology GPON, adopted ITU-T in 2005, and got a room G.984. It is based on the use of a specialized protocol that is based on standards SDH. In this case, to ensure the effective use of the communication channel, supported by dynamic reallocation of bandwidth while maintaining the frame structure SDH. The standard allows traffic to pass in both symmetric and asymmetric velocity ratio, reaching values ??of up to 2.5 Gbit / s. The advantages of GPON include a built mechanisms to ensure QoS for video and audio. This technology is the most widespread in North America and Europe.
Requirements for broadband, and especially its capacity to grow so rapidly that the capacity of GPON become insufficient. Therefore, in the work plan, Study Group 15 Studied Group ITU-T as part of question 2 (SG15 Q2) for the period 2009 ... 2012 was included work on the standards of the new generation NGPON with a capacity of 10 Gbit / s or more.
It is assumed that the development NGPON will have two stages. In the first phase XGPON1, which is almost completed ITU-T as a family of standards G.987.x, will be implemented PON transmission rate of 10 Gb / s. In the second, a long phase XGPON2 rate is expected to increase by at least 4 times.
At present, and equipment suppliers, and network providers are working intensively on implementing XGPON1.
Conclusion
Access networks are perhaps the most expensive element of operator networks. Currently in the access used predominantly copper cables (twisted pair). Bandwidth and channel capacity of these cables would not fully realize the modern multi-services, ie services of voice, data and multimedia traffic, including video information. To provide new multi-service requires bandwidth, usually broader than that which can provide the existing technology in the copper-cable infrastructure. Therefore, to provide access to broadband services often have to lay cables with high bandwidth. The most effective in such cases is to build a fiber-optic cable infrastructure.
References
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