ires the expense of a phone company visit and installation. However, it is possible to manage the splitting remotely from the central office. Next a DSL modem is required for modulation. DSL modems are using Discrete Multitone Technology (DMT), Carrierless Amplitude Modulation (CAP) and Multiple Virtual Line (MVL) for modulating. To interconnect multiple DSL users to a high-speed backbone network, the telephone company uses a Digital Subscriber Line Access Multiplexer (DSLAM). The DSLAM connects to an asynchronous transfer mode (ATM) network that aggregates data transmission at gigabit rates. At the other end of each transmission, a DSLAM demultiplexes the signals and forwards them to the appropriate individual DSL connections.x.DSL presents numerous opportunities to the home consumer. Features such as high speed Internet access, software on demand (SOD), videoconferencing, streaming video and voice signals, are all very attractive to the common dial-up customer. One example where SOD is a key feature, is a CD-ROM Shim developed on the Mpowered platform (by MTT). This is a customer designed software layer that lets end users who do not have CD-ROM equipped computers run CD-ROM dependent applications. The SOD platform will also offer users access to real-time billing information. What’s even more attractive is the fact that DSL presents a nailed circuit in which one is continuously connected. Also unlike cable, DSL works over existing phone lines and because each user has their own dedicated circuit, there is no competing for bandwidth with neighbors in your area. The most widely used form of X.DSL is ADSL (Asymmetric Digital Subscriber Line). ADSL is called "asymmetric" because most of its duplex bandwidth is devoted to the downstream direction, sending data to the user. Only a small portion of bandwidth is available for upstream or user-interaction messages. However, most Internet and especially graphics- or multi-media inte...
