IPTV is not a well-defined term and may be a source of ambiguity and sometimes
confusion. This article describes the basic building blocks in order to clarify the
difference between “IPTV” and what is increasingly being called “WebTV”. A
comparison between IPTV and the DVB transmission schemes for satellite and cable
is also made, providing some insight into the similarities between these delivery
systems but also revealing subtle differences.
The IPTV requirements for retransmitting live broadcast signals and on-demand
services are outlined, and some approaches for meeting these requirements are
The penetration of households with broadband internet access and downstream data rates of
several Megabit per second (Mbit/s) is making steady progress. For example, in Germany, the
number of DSL households rose from about 7.6 million in March 2005 to more than 12 million in
June 2006 , and is growing rapidly. Thus an increasing number of households are getting used to
video streaming and download, using the Internet Protocol (IP) to enable interactive retrieval of
video content (including TV programmes, either live or on-demand) from the Web. This type of IP
video may be termed WebTV. WebTV is getting increasingly popular among the audience and
many broadcasters have started to offer such services on their websites.
However, unlike conventional television, WebTV does not provide a guaranteed quality of service.
Telephone companies are now making an attempt to overcome the deficiencies of WebTV and are
launching so-called IPTV. The take-up of mobile communications and the resulting decline in
telephony on fixed-line networks has stimulated the need for new revenue streams. IPTV is a new
buzz word to fill the broadband networks with a compelling high-bandwidth application. Hype and
short-lived expectations are not excluded. For example, not all of the above-mentioned DSL house-
holds will have access to IPTV, as the first phase of the rollout will concentrate on selected urba