Enforcing application-level QoS by frame-induced packet discarding in video communications

Abstract

Advances in networking are making it feasible to support a wide spectrum of video services over fast packet-switched networks. In this paper, we investigate the problem of providing efficient QoS guarantees for video communication, when they are expressed at the application-level, in terms of video frames, rather than at the network-level, in terms of packets. We propose a simple to implement, yet effective, strategy called frame-induced packet discarding (FIPD), in which, upon detection of loss of a threshold number (determined by an application's video encoding scheme) of packets belonging to a video frame, the network attempts to discard all the remaining packets of that frame. We present extensive, trace-driven performance simulations that demonstrate the efficacy of the FIPD strategy. Networks employing the FIPD strategy exhibit significant increase in the number of video channels that they can support. Towards such networks, using a discrete time Markov chain model of the FIPD strategy, we devise a method for computing the frame loss probabilities of video applications, which then serves as the criterion for admission control: the network admits an incoming application only if the predicted frame loss probability (in the event of admission) does not exceed the frame loss bounds of any of the applications being serviced.