engleski

Asymmetric Dsl Technology Of Signal Transmission

Asymmetric flow of information is the key feature of the ADSL (Asymmetric Digital Subscriber Loop) technology, i. e. higher data transmission rate towards the user than from the user towards the network. Characteristic is the short message sending by the user with a certain request to the server. The server responds to the request by a significantly longer message of various electronic forms (data, digitized speech, pictures or video). Therefore, this technology is most often used by small and medium users. ADSL is currently the only commercially available DSL technology which is still experiencing the breakthrough on the service market. It enables faster access to the Internet, LAN (Local Area Network), videoconferencing, VoD (Video on Demand) and interactive multimedia. In order to standardize such services, the ITU (International Telecommunications Union) G. 992.1 (standardized DMT-discrete multi-tone line coding technology) and ANSI (American National Standards Institution) T1.413-95/98 are used for ADSL. DMT (Discrete Multi Tone), as the more popular one, uses the line coding technique, which splits a certain frequency range into several sub-channels. Most of these sub-channels are used for upstream and downstream transmission of speech and data, whereas some are used as pilot signals or kept in reserve. Such modulation technique expands the frequency spectrum, allowing the usage of broadband services per one pair of wires. In this way the sharing of speech and data service transmission is realized.

asymmetric transmission; distance of the user; broadband access network; standardization; modulation techniques; voice and data services

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