Technical Reports - DIT-02-076
Cristina Maria Pinotti, Navrati Saxena
Keywords: Broadcast on the air, push and pull hybrid systems
Abstract:A hybrid scheduling that effectively combines broadcasting for very popular data (push data) and dissemination upon-request for less popular data (pull data) in asymmetric communication environments is introduced. In this solution, the server continuously broadcasts one push item and disseminates one pull item. The clients send their requests to the server, which queues-up them for the pull items. At any instant of time, the item to be broadcast is designated applying a pure-push scheduling, while the item to be pulled is the one stored in the pull-queue, which has accumulated, so far, the highest number of pending requests. The value of the average expected waiting time spent by a client in the hybrid system is evaluated analytically, and the cut-off point between push and pull items is chosen so that such a waiting time is minimized. It is found out that by doing so the cut off point decreases to a value, which is much less than the total number of items present in the system, improving upon the average waiting time spent by a client in a pure push system and also on that spent in some of the hybrid systems already proposed in literature.