ACT has developed adaptive push/pull technology using Direct
Broadcast Satellite Systems (DBS) and Unicast networks (terrestrial
or wireless). In such hybrid
networks, we deploy algorithms which rapidly adapt the content of the broadcast
based on the "misses" obtained from the explicit (on-demand) data
requests on the unicast channels. This technique has a distinctive
regular scheduling algorithms which are solely dependent on a priori
complete knowledge of the need. Such knowledge is often not available and
even when it is, it does not cover "panic situations" during which the
demand for information is growing at an exponential rate.
Examples of such a panic behavior have been observed on the
Internet during the Oklahoma bombing, the summer Olympic games in
Atlanta, and the winter Olympic games in Japan. The demand during
these situations by far surpasses the capacity of the media (server
In panic or high volume situations, there is no
time to analyze the demand and obtain optimal or near-optimal schedules of data
dissemination. Instead, rapid adaptive algorithms are necessary.
The techniques we developed take advantage of DBS for the massive data dissemination while they serve the less popular items through the unicast channels. The latter channels are,used at the same time, to adapt the broadcast content based on popularity.