Feedback Flow Control with Hysteresial Techniques for Multimedia Retrievals

The objective of this paper is to demonstrate the advantages of using hysteresial techniques in flow control mechanisms. The work scenario consists of a server transmitting video information to a group of clients. Each client stores the information in a buffer and then plays it back at a set consumption rate. To avoid “overflow” or “underflow” in the buffer, the client sends control messages (feedbacks) to the server which order adjustments in the transmission rate. Hysteresial techniques allow the minimization of this signaling traffic, even when there are rapid fluctuations in the buffer occupation. As a first step, an analytical model is developed using Markovian processes. This produces expressions of the most relevant parameters and allows the evaluation of the proposed flow control mechanism. The Markovian model has been compared with the performance of a multimedia application for video distribution, running in a real scenario. The results show that the model represents qualitatively the real scenario and consequently validates the model usefulness.