Threshold-based admission policies for video services

In a video system, a central server stores all the files of interest to a large number of geographically distributed users. In order to lower the network transmission cost, the service provider may set up local servers to cache the video contents dynamically according to their local demands; thus forming a distributed video system. To lower the transmission cost further, the local servers can batch users together before presenting their video requests to the central server. In this case, if a video request to the central server is accepted, the provider enjoys the income collected by the batch while incurring a certain network transmission cost to the local servers. Due to the limited capacity at the central server, if video requests were accepted indiscriminately, the server may run out of channels too soon, which subsequently leads to the rejection of more profitable batches (and hence low profit). In order to better utilize the server channels, we consider admission policies which accept requests according to a threshold depending on the number of available channels at that time. We demonstrate that such admission policies can substantially increase the system profit while still meeting a certain user loss objective