IPTV Networking Technologies
IPTV technology is part of a new breed of services designed to facilitate access to video entertainment. It provides access to digital TV over the IP transport medium from a head-end device to the end user’s TV set-top box (STB). Most service providers use a dedicated transport network to support IPTV.IP Distribution to the STB via DVB IPI
DVB has had a technical ad-hoc committee (TM-IPI) dedicated to IP distribution to the STB since 2000. It has a responsibility to provide a standard for the IP interface connected to the STB. The
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IPTV related activities of selected standardization bodies
• DLNA (Digital Living Network Alliance) for the home network• HGI (The Home Gateway Initiative) for the standards surrounding the residential gateway between the broadband connection and the in-home network
• ISMA (The Internet Streaming Media Alliance) for the transmission of AVC video over IP
• DSL Forum for the standards surrounding DSL and remote management of in-home devices including STBs and residential gateways
• ITU which, via the IPTV Focus Group, is standardizing the distribution and access network architecture
• ETSI which, via the NGN initiative, is standardizing the IP network carrying the IPTV
• ATIS which, via the ATIS IPTV Interoperability Forum (ATIS-IIF), is standardizing the end-to-end IPTV architecture including contribution and distribution.
IPTV over DSL versus DVB over satellite and cable
In contrast to other technologies, the difference in IPTV over DSL is that the client-server architecture used for IPTV sits between the provider backbone and the IPTV home. The difference here is that not a single program goes automatically into the IPTV home. A simplified comparison of IPTV over DSL with the DVB-S and DVB-C is shown in Figure.
The colored lines represent the different television programs of a digital bouquet
that are bundled together in one or more multiplexes. Each of these carries a multi-program
transport stream (MPTS). Similar to Broadband cable head-end, the DSL head-end picks up
the satellite signals and converts them to IPTV signals. But the difference is that when we press
the button of an IPTV remote control, it is communicated back via the return channel to the
service provider. Then the server routes the requested program as a single program
transport stream (SPTS), over the backbone to the point of presence (PoP) at the DSL access
multiplex (DSLAM). The technical challenge for IPTV is the short time delay during channel
hopping
