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Communication Dans Un Congrès Année : 2012

Optical networks : today and tomorrow

Résumé

Fiber is the major material used in fix communication networks. In past decades, optical lines are used in backbone networks. Now optic infrastructures are in all types of fix network types "backbone, metropolitan, access and even in LANs". While it is mandatory to use the optical fiber in backbone infrastructure because of its capacity and long-haul access aspects, optical fiber start to take place also in access networks in last decade (like APON, GPON, EPON etc.). Even though, optical fiber suppose amazing bandwidth capacity and long-haul access availability compared to electronic, copper based approaches like xDSLs, according to the developments in ICT, optical network systems also have to get through an evaluation. Nowadays, the evaluation trend has changed from static to dynamic reconfigurable networks, from separate to integrated management layers, from unbalanced to balanced link utilization. Both academia and industry tend to the new trends and developing new devices and techniques. The main purpose of developing novel technologies is to gain benefit for humanity. In this context, one of the prior aspects in technological development in optics like performance left its place to QoS supporting and energy efficient design. Besides the user experience of internet usage and demands from network services changed among the developments in ICT. In early times of communication networks, voice constitutes the major amount of the carried traffic. Today it mostly changes to data, video, and P2P traffic. It is an inevitable result that optical networks evaluate in the same order to catch the development trend. In backbone networks, from beginning to today, in 1970's SONET/SDH, FDDI were used over fiber lines, then in 1990's WDM started to be used to increase line capacity, in 2000 optical cross-connects and optical add-drop-multiplexers and DWDM takes place in network infrastructures, in 2005 opto-electronic techniques as "Optical Burst Switching(OBS)" and "Optical Packet Switching(OPS)" came front. For the future communication systems, it is thought to be all optical packet switching networks are going to be used. However, lack of effective optical buffering solutions in industry is the major obstacle in front of the all optical solutions in backbone networks. As a middle step through to all optical networks, OBS and OPS techniques seem to be promising solutions for new network infrastructures. In metropolitan networks, novel developments must be compatible with old circuit-based transport infrastructure and has a scalable architecture to support increasing bandwidth demand and versatile QoS requirements and user behavior. Ring topology is widely used in metropolitan networks because of the advantages like; bidirectional rings can inherently provide fast restoration, statistical multiplexing of data traffic flowing from different nodes over the shared medium, efficient utilization of optical fiber, and reduces the infrastructure cost. There are challenges in WAN rings as; choosing best packet format to carry incoming traffic, communication issues among multiple rings, variable packets vs. fix packets etc. At 90's optical lines thought to be used in access network solutions, which was before totally based on electronic carry methods as twisted pair, and coaxial lines. APON appeared as a first standard in access networks, which is based on ATM cells packet format and used TDMA approach for medium sharing. It has been followed by GPON and EPON standards. GPON can carry any types of packet formant inside GEM slots. On the other hand, EPON is based on Ethernet frame structure. Now EPON has 10Gbps up/down stream capacity and next generation PON standard seems to follow EPON architectural design. In addition, WDMA is seems to be a promising solution for future access network to increase maximum subscriber capacity and range. Hybrid solutions, TDM-WDM combined PONs are also aspect to develop cost and energy efficient solutions for future access networks. Two main problems (accessing more users over longer distances and increasing the bandwidth) are focused on for next generation PON standards. Also, one of the other studying topics is the increasing number of mobile devices and mobile networks and design of optical-wireless convergence system to satisfy the bandwidth demands of these devices. By the increase of global warming energy consumption turns to one of the major problem for all the countries have to face with. Recent researches show that a huge amount of the energy consumption in ICT is caused by network equipment and it is going to increase in percentage in the following years. Therefore, new network technologies have to keep energy efficiency driven design in high priority. To decrease energy consumption, selectively turn off, green routing, sleep modes and similar methods are used in every kind of optical network.
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Dates et versions

hal-00784956 , version 1 (05-02-2013)

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  • HAL Id : hal-00784956 , version 1

Citer

Tülin Atmaca. Optical networks : today and tomorrow. CN '12 : The International Science Conference : Computer Networks, Jun 2012, Szczyrk, Poland. ⟨hal-00784956⟩
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