標準號：BS PD CLC/TR 50510-2007
中文標準名稱：用戶終端的纖維光學通路.FTTX纖維光學網絡的建設指南
英文標準名稱：Fibre optic access to end-user — A guideline to building of FTTX fibre optic network
標準類型：M33
發布日期：2007/11/30 12:00:00
實施日期：2007/11/30 12:00:00
中國標準分類號：M33
國際標準分類號：33.180.99
適用范圍：This Technical Report describes the FTTX-network. As a guideline other parts of the fibre optic infrastructureare given in this clause.First some basics: sound, pictures, voice, data carried by networks are digital data expressed in terms of bit,bytes and their multiples (kilo (k), mega (M), giga (G), tera (T)). A bit (binary digit) is the smallest digital unitand has only two values: 0 or 1. A byte includes 8 bits and defines the size of a data file. Transmissioncapacity of networks and terminals is not expressed by using bytes, but using bit per second (bps). When adata file is transferred in a network two supplementary bits are necessary. It means that 10 bits are requiredfor 1 byte.In the case of a VDSL subscriber with 10 Mbit/s, who wants to upload a pdf data file, the Web providerindicates for instance the following size: 20 Megabytes. It should then take 20 s. However, for any Mbit/ssubscription the fact is that the real final data flow is about a quarter of the notified data flow, because thedata flow is shared between subscribers and its quality depends on the activity of the other subscribers. Itmeans that the 20 Megabytes data file will need 1 min 20 s to be uploaded. For instance a 15 Mbit/s ADSLsystem gives only 1 Mbit/s for uploading. The following table gives some further examples of transmissiontimes for uploading a quality DVD-movie, if there is no data flow sharing.We do not know the new tools that will be created by the real high bit rate networks. New applications (notinvented today) will appear and applications originally dedicated to professionals will be extended to all in asimilar way as it happened with the mobile phone.It is important to define the meaning of ? low, medium and high bit rate transmission ?. One possibleclassification is presently the following:? low bit rate transmission: up to 1 Mbit/s? medium bit rate transmission: 1 up to 10 Mbit/s? high bit rate transmission: 10 up to 100 Mbit/s and more.