Integration of VBR video and ABR data sources at a DSL-based access node

ATM over xDSL allows integrated access of video, voice and data services into the Internet with QoS support. In this paper, we study the integration of MPEG video calls and high-speed data calls at an ATM DSL access multiplexer (DSLAM). The interactivity in video calls requires a stringent delay QoS (but relaxed cell loss). In contrast, data calls have a stringent cell loss QoS requirement (but relaxed delay). We study an access strategy which allocates separate buffers to the 2 types of traffic and assigns priority to video in accessing the channel. We first present a Markov-modulated fluid model for the video sources based on measurements performed on a large number of MPEG sequences. Then, we present a computationally efficient fluid analysis of multiplexed video calls. Finally, we provide a fluid analysis of the low-priority data buffer. We derive a model for the output fluid process of the video buffer and approximate it with a two-state model. We use both the full and approximate models to calculate the cell loss for data. We compare the performance of these two methods to a commonly-used approximate method. The study shows that: (1) our two-state approximation is fairly accurate while computationally very efficient; (2) the commonly used method is overly inaccurate compared to the first two methods.