Since WiMAX is a two-way BWA, it can offer bidirectional
operations in interactive services, in which most
of mobile TV broadcasting techniques such as DVB-H
[12][13] and MediaFLO [14][15] cannot provide, for WiTV
users very well. However, interactive WiTV services
usually deliver content via unicast. Content delivery via
unicast cannot provide scalable access to WiTV services
because network bandwidth and server resources are
consumed proportionally to the number of active users. For
example of interactive VoD on WiTV service, the resource
capacity of one WiMAX base station may allow less than
dozens of users to access at the same time.