An MPEG-2-encoded high definition television (HDTV) program consumes 10-19 Mbit/s of bandwidth, compared to 128 kbps for a digital voice connection to a household, writes Magda Engelbrecht, Nortel country manager.

And it is estimated that YouTube, the web-based personal video-sharing service and one of the fastest growing websites today, serves upward of 100-million videos daily, generating more than 200Tb of Internet traffic.  In comparison, the world’s largest government libraries contain only about 20Tb of information.
These rapidly growing bandwidth demands will have a significant impact on networks, especially wireless access networks. Current 3G systems, although well-suited for voice and adequate for data, are simply not up to the task of meeting the huge bandwidth demands required for video services. While mobile video is possible on today's 3G networks, it can be delivered to only a limited number of subscribers or it can transmit only a basic broadcast service.
Video is rapidly emerging as the key driver of network performance as consumer and business use of video on IP networks explodes.
This includes content from services like mainstream high-definition TV services, streaming clips to mobile handsets, IP-based digital video surveillance or video teleconferencing systems.
Delivering video and converged applications present significant challenges. Video is ushering in a new era of innovation, user value and business opportunity.
Organisations, for example, are deploying desktop video as part of their unified communications systems, complementing their video conferencing systems. The entry of cable companies into voice services is driving business interest in offering entertainment TV services to customers.
Wireless operators are looking to mobile video streaming and downloads to improve their average revenue per user and to reduce customer churn. And global security threats and public safety concerns are driving a strong interest in surveillance video applications.
Increasing speeds of broadband access networks, particularly 4G wireless networks like WiMAX, will provide the bandwidth needed to support extensive video delivery.
And powerful new video compression and processing technologies are now reducing bandwidth and storage requirements while retaining the high quality of the video streams.
While we often tend to speak of "video" as a generic whole, in reality it is a broad application space, where each application has different characteristics and performance requirements at the service, application and network layers.
Moreover, within each of these video applications, individual deployments can vary widely based on the type of encoding used as well as the resolution and bandwidth required. The range of applications includes:
* Entertainment TV services, for example Internet Protocol television (IPTV) and video-on-demand.
* Security such as surveillance systems.
* Realtime communications – video telephony and conferencing.
* Interactive applications – interactive TV and gaming.
* Internet sharing and streaming – user-created video content and web-based streaming to a desktop PC or mobile device.
* Corporate enterprise training videos.
* Professional applications – broad-cast contribution networks where an aggregator repackages video feeds, and TV production networks.
The common thread across increasingly availability video applications is that, more than any other application to date, they fundamentally drive converged network and services performance requirements. The most obvious network requirement is the need for substantially increased bandwidth to support video applications, compared to voice or other data applications.
Nortel is focused on leading the move to 4G technologies, such as WiMAX, CDMA Long Term Evolution (LTE), and Ultra Mobile Broadband (UMB, the new name for CDMA EV-DO Rev C), in order to achieve the spectrum efficiencies and cost advantages needed to deliver the bandwidth required by new high-value services.
All the 4G technologies being developed are based on a combination of orthogonal frequency division multiplexing (OFDM) and multiple-input, multiple-output (MIMO) antenna technology, where Nortel has leadership positions. Nortel is also the first vendor to deliver a true Wave 2 WiMAX solution based on OFDM-MIMO.
Bandwidth is not the only factor that has an impact on network requirements for supporting video applications. Others include video's high sensitivity to packet loss, real-time constraints for interactive video services, audio-visual synchronisation and storage requirements.
The overall success of video service requires an end-to-end solution view and careful engineering to meet the quality of experience (QoE) expectations of end users. This can vary depending on the video application.
User expectations and performance parameters required for a video-on-demand HDTV customer will differ considerably from those of a mobile user sending a multimedia message and corporate video telephony user.