ATM and Broadband Networks
Currently under development, ATM (Asynchronous Mode Transfer) Broadband networks
guarantee the high speed and delay free requirements of real time video and audio.
They are also capable of handling other time critical applications such as live
video conferencing and medical applications. At ANSPAG (Advanced Network Systems
Performance and Applications Group), there is a video on demand (VOD) trial being
conducted over an experimental ATM network. This trial delivers real time video
and audio to client PCs at campus libraries in MPEG-1 (Motion Pictures Experts
Group) format via multi-megabit optical fibre links and Telstra’s EBN (Experimental
Broadband Network). The optical fibre technology uses ultra-thin fibres made of
silica material and information are sent through the fibres in the form of light
(Figure 0-4). An optical fibre offers a great deal more bandwidth than coaxial cables, which
makes it an ideal transmission medium for high speed networks (a larger bandwidth means data can
be sent down a transmission line faster).
Figure 0-4 Optical Fibre
Optical fibres are connected to ATM switches
via Optical Fibre Line Transmission Equipment (OLTE). The OLTEs converts optical
signals to the electrical signals that the switches can understand. Currently,
ANSPAG is also exploring the feasibility of delivering video via residential networks
using cable modems.