A Flow Control Algorithm for Multimedia Network Applications Raffaele Bolla, Alessandro Iscra, Mario Marchese, Sandro Zappatore Department of Communications, Computer and System Science (DIST) University of Genoa, Italy lelus, iscra, dama, zap @dist.unige.it Abstract: A flow control mechanism operating at the application level and aimed at controlling audio/video flows in order to provide a sufficient level of perceived quality of service (P-QoS) to each user is presented. Compression parameters and techniques are varied to dynamically adapt the output bit rate of the application to the network load, according to a mechanism based on feedback information from the receiver. The novelty of the paper is, more than the algorithm itself, the proposed integration of audio and video and the effects of p-loss on the MOS of the audio and video streams. The results show that the algorithm yields not only a drastic reduction of the video packet loss but also a significant improvement for the audio streams, due to the reduction of the congestion over the network while MOS of the multimedia applications are substantially unchanged. The implicit improvement of the P-QoS in the video flow is an important result, that highligths the effectiveness of an end-to-end control mechanism for best-effort traffic. • Introduction • The Experimental Setup • The Control Scheme • Experimental Results • Packet-Loss VS MOS • Conclusions • Bibliography • About this document ... Introduction Internet is characterized by heterogeneity of algorithms and management, as well as of physical links. It hosts high speed channels like ATM, FDDI, low speed phone links, wireless multi-access channels. The formulation of a flow control problem is very difficult in this context, since an algorithm suited to a high speed, guaranteed service network, cannot be applied in a low-speed best effort environment. Moreover, Internet is a mix of many organizations and providers and its development will be incremental and independent as concern the resources management policy. Meanwhile, the number of services and applications is growing faster and faster and the danger of network collapse due to congestion is real. The Internet research community is very active to find countermeasures, and various groups are working on Internet control and performance guarantees. Pagina 1 di 12 Packet Video 2000 18/01/2015 file:///C:/Users/Mario/Mario/Mario/paperi/PacketVideo2000/pv2000/main.html