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The current Internet is not designed for real-time applications. There are at least three major problems in developing real-time applications on the Internet: insufficient bandwidth, transmission performance unpredictability, and no support for quality of service. Current research efforts in providing better services on the Internet fall into two approaches. One focuses on enhancing the application layer, and the other modifies the network layer. This paper is based on the first approach, which seems more feasible. Real-time applications have to take adaptive strategies based on the dynamics of network status. The effectiveness of an adaptive strategy depends on whether it can accurately find out the current available bandwidth. A good estimate of the bandwidth can be obtained through a valid flow and congestion control protocol. In a rate-based feedback scheme, the receiver continuously monitors the quality of data stream such as data loss rate and sends back the information to the sender. The sender will then adjust the sending rate based on this information with the goal of minimizing the data loss rate. However, this scheme has at least two potential drawbacks. It may cause network buffer overflow since it controls the data rate rather than buffer size, and it is not easy to select a loss ratio threshold. This paper proposes a new Internet video flow control protocol (IVFCP) which adjusts data sending rate based on the combination of the receiver buffer length, packet loss ration, and current data rate. The flow control protocol runs every round trip instead of periodically or when congestion happens. It can control the rate more directly and precisely. This rate-based feedback control protocol is evaluated through simulation, and its performance is compared with that of other protocols.
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