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Chapter 2Overview of current CATV network p• The Interactive STB configuration serves a very different function to the first twoconfigurations. The STB is not really designed to connect to a computer, although itfunctions in a similar way to a cable modem. Its primary role is to provide moretelevision channels on the same limited number of frequencies. This is made possibleby using Digital Video Broadcasting (DVB) technology. STBs also provide two-waycommunication. This two-way communication allows the user access to Enhanced-TV, Interactive TV, Web-browsing, email, etc., directly on the TV screen.2.4.2 Next generation servicesThe services that modern CATV networks would provide are listed in Table 2.1(Sources from [16], [36] and [25]). Not all of these services have to be supported in thenear future, but the network infrastructure should be able to support all of them as andwhen demand rises. Most of these new services are graphics, audio and video oriented,and contrary to the simple text-oriented first generation application, they demand ahigh-speed communications infrastructure.In addition, the requirement of ‘real-time’ interactivity makes the need for multimegabit-per-secondhigh-speed communications even greater. Since voice and videotransmission are inherently time sensitive (isochronous) applications, the network has toexhibit deterministic behaviour, and there has to be an upper limit for the transmissionAnalogue and DigitalTV and AudioTable 2.1 – Next generation of CATV services.TelecommunicationsServicesMultimedia ServicesLocal ServicesPay-per-channel Telephony Online-services Local-channelsPay-per-view Video Phone Services Interactive games Local TVAudio-on-demand Videoconferencing Distance Learning Local RadioVideo-on-demand Fax Interactive Video Local online servicesHigh-definition TV Telemetry Interactive MultimediaInformation ServicesNear-video-on-demandTele-banking/shoppingTele-teaching learningShopping and bill payingservicesHigh-speed Internet accessLAN interconnection(Leased Lines D1/E1)GamblingRemote-control andmonitoring2-9