Editing Broadband (section)

== Differences from old telephony ==
Conventional [[telephony]] communication used:
* the voice medium only,
* connected only two telephones per [[telephone call]], and
* used circuits of fixed bit-rates.

Modern services can be:
* [[multimedia]],
* multi-point, and
* multirate.

These aspects are examined individually in the following three sub-sections.<ref name=QoS>{{cite book|author1=Ferguson P. |author2=Huston G. |title=Quality of Service: Delivering QoS on the Internet and in Corporate Networks|publisher=John Wiley & Sons, Inc.|year=1998|isbn=0-471-24358-2}}</ref>

=== Multimedia ===
A multimedia call may communicate audio, data, still images, or full-motion [[video]], or any combination of these media. Each medium has different demands for communication quality, such as:
* [[bandwidth (computing)|bandwidth]] requirement,
* signal [[Latency (engineering)|latency]] within the network, and
* signal fidelity upon delivery by the network.

The information content of each medium may affect the information generated by other media. For example, voice could be transcribed into data via voice recognition, and data commands may control the way voice and video are presented. These interactions most often occur at the communication terminals, but may also occur within the network.<ref name=Saito/><ref name=Hui/>

=== Multipoint ===
Traditional voice calls are predominantly two party calls, requiring a point-to-point connection using only the voice medium. To access pictorial information in a remote database would require a point-to-point connection that sends low bit-rate queries to the database and high bit-rate video from the database. Entertainment video applications are largely point-to-multi-point connections, requiring one way communication of full motion video and audio from the program source to the viewers. Video teleconferencing involves connections among many parties, communicating voice, video, as well as data. Offering future services thus requires flexible management of the connection and media requests of a multipoint, multimedia communication call.<ref name=Hui/><ref name=Broadband/>

=== Multirate ===
A multirate service network is one which flexibly allocates transmission capacity to connections. A multimedia network has to support a broad range of bit-rates demanded by connections, not only because there are many communication media, but also because a communication medium may be encoded by algorithms with different bit-rates. For example, audio signals can be encoded with bit-rates ranging from less than 1&nbsp;kbit/s to hundreds of&nbsp;kbit/s, using different encoding algorithms with a wide range of complexity and quality of audio reproduction. Similarly, full motion video signals may be encoded with bit-rates ranging from less than 1&nbsp;Mbit/s to hundreds of&nbsp;Mbit/s. Thus a network transporting both video and audio signals may have to integrate traffic with a very broad range of bit-rates.<ref name=Hui/><ref name=QoS/>