A Fluid Model for a Packet-size Adaptation Protocol

In the last few years an increasing amount of attention has been paid to more efficient QoS (Quality of Service) tech- niques for real-time voice communications on the Internet. So as not to mutually penalize voice, for which Variable Bit Rate (VBR) coding standards have recently been proposed, and TCP sources, which share the same bandwidth, it is necessary to define appropriate rate control mechanisms that can link the coding level to the current network load. In addition, in the presence of a high network load and congestion, in order to prevent UDP sources from captur- ing most of the bandwidth, thus strongly penalizing TCP sources, the new congestion control mechanisms for voice sources have to be "TCP-friendly". In this paper a new TCP-Friendly algorithm called PSAP (Packet Size Adaptation Protocol) is proposed. The PSAP adapts the rate of VBR sources by varying the size rather than the number of packets in a given reference period.