Rate Control with Resource Metering for H.323 Multimedia Transmission

Abstract

H.323 defines the components, procedures, and protocols necessary to provide multimedia communications over packet-switched networks which provide best-effort services. Compared with data-oriented applications, multimedia applications require considerable bandwidth and have very large rate fluctuations. Network congestion will thus occur and affect delivery qualities such as packet delay and loss. H.323 does not provide any mechanisms for guaranteeing delivery qualities and thus requires a transmission mechanism for real-time multimedia services with quality of service (QoS) guarantees. In this paper, an adaptive rate control mechanism based on resource metering is proposed for improving the quality of multimedia communications. The sending rates of H.323 terminals are smoothed and are adaptive to the following two factors which affect communication qualities in H.323 conferences: the bandwidth in the network and the queue size at the multipoint control unit (MCU). From the simulation results, we found that increasing the weight on the bandwidth available in a low-bandwidth network will I improve communication qualities. In contrast, increasing the weight of the queue occupancy will reduces the loss rate; due to the queue overflow.