●ADSL( Asymmetric Digital Subscriber Line)“ ADSL” is an asymmetric service that is capable of high-speed data communication by taking advantage of the unused bandwidth of a telephone line( analog line). The service is asymmetric in that the upstream( computer to network) and downstream( network to computer) communication speeds are not equal. Upstream speeds range from around 512kpbs to 12Mpbs, while downstream speeds range from around 1Mpbs to 50Mpbs. This line service is particularly suited to activities that involve a high volume of download communications such as viewing Internet Web pages and downloading files.
●FTTH( Fiber To The Home) or optical communication“ FTTH” is a method of high-speed communications in which optical signals are carried over optical fibers. In order to use FTTH, it is necessary to install fiber optic lines inside the building that receives the service. FTTH has a maximum speed of one gigabit per second, making it the fastest communication service among the methods of communication that are available to an individual user.
●CATV( Cable television)“ CATV” is a data communication service that takes advantage of the unused bandwidth of a cable television line used to send video. Depending on the cable television company that is used, the service can provide highspeed communications of around several tens of megabits per second.
●ATM( Asynchronous Transfer Mode)“ ATM” is a method of communication for transferring cells that are frames of a fixed length. It was originally developed as a communication technology for WANs to make it possible for a single network to carry various types of information such as voice calls, data communication, and video. ATM is utilized in order to effectively use high-speed data lines such as fiber optic lines.
Reference Broadband“ Broadband” refers to a communication service that is capable of high-speed, large bandwidth communications such as ADSL and FTTH. The opposite of broadband is“ narrowband,” which refers to low-speed communication services provided over an analog line( telephone line).
Reference
ADSL Abbreviation for“ Asymmetric Digital Subscriber Line.”
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FTTH Abbreviation for“ Fiber To The Home.”
Chapter 9 Technology element
●Mobile communications“ Mobile communications” is a service for providing data communication by using a data communication card paired with a mobile terminal such as a laptop computer, PDA, mobile phone, or PHS handset. Since the service relies on wireless communications, it is possible to conduct data communication anywhere within the service range.
●Packet communications“ Packet communications” is a method of communication that sends and receives data by dividing data into small blocks of a fixed size. Dividing the data into small blocks enables multiple persons to share and effectively use a single communications line. It is widely used as it is not prone to problems such as line interruption.
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