Final Report Chapter 4 Trend on Communication Technology Exchange IP DSLAM Metallic Cable ADSL Modem Data Speed depends on the distance between Exchange and Residence. Edge Router PSTN DSLAM: Digital Service Line Access Multiplexer Source: prepared by Survey Team Figure 4.2-1 ADSL Configuration (2) VDSL (Very high-bit-rate Digital Subscriber Line) VDSL provides very high speed transmission services for a short distance. It is mostly used in combination with FTTC and FTTB configurations. Moreover, it has become last one mile solution for FTTB. (3) SDSL（Symmetric Digital Subscriber Line） Its data speed on down link and up link is the same, at 2Mb/s. Its other characteristics are the same as those of ADSL, which is recommended as ITU-T G.991 standard. 4.2.3 FTTx Solution FTTｘ is a term for any broadband network architecture that uses fiber optic cable to replace all or part of the usual metallic local loop sued for last one mile communications. The terms most widely used are described below: (1) FTTH (Fiber To The Home) Fiber optic cable is laid until the subscribers’ home and ONU (Optical Network Unit) is nstalled. FTTH is realized with the technology of PON (Passive Optical Network). It consists OLT (Optical Line Terminal), ONU and optical splitter as shown in Figure 4.2-2. 4-4