Each drop in video-streaming costs shortens the time it takes to recoup investments. Harmonic believes the servers, QAM modulation and RF upconversion functions should be centralised in the headend. Using this strategy, the video streams can move to the hub via DWDM transport. This would mean that the video can be transported in set-top ready format from the headend and would require no processing at the hub. Harmonic tested a 16 wavelength DWDM system over a 100 Km fibre link carrying QAM256.
Open systems stimulate competition and keep costs down.
Trail and Emms say. However, certain specifications need to be adhered to before VOD can be run effectively over today s cable systems. Wall believes that the use of larger nodes improves performance. Of course, we are well into the era of cable plant being subdivided into relatively small nodes, meaning that operators can use more frequencies, with a different programme for each node. Wall also says that operators will have to learn how to deal with a peak VOD usage.