The QoS-capable DSLAM for broadband services over the DSL access networks.

摘要

Telecommunication providers have been offering digital multimedia applications including broadcast video, video on demand (VOD) and multimedia teleconferencing over the existing twisted-pair telephone lines by using Digital Subscriber Line (DSL) technologies. However, there are some problems with broadband services over the DSL access networks, e.g. the limitation of DSL bandwidth and the existing DSL Access Multiplexers (DSLAMs) do not support QoS guarantees for broadband services. In this thesis, we propose a solution to deal with the limitations of the DSL access networks. In the proposed scheme, a single buffer created by the logical buffers is setup in the DSL port of the DSLAM in the Central Office (CO), which is connected directly to the customer. Each traffic class coming in the DSL port is fed into its own logical buffer and guaranteed by a service rate. The different traffic classes are treated separately according to their respective QoS requirements instead of as a common traffic class. To evaluate the performance of this scheme, the probability distributions of overflow and delay are derived by using the analytical method of fluid-flow queueing. Traffic classes are all modeled as Markov Modulated Fluid Process (MMFP) from the practical H.264/AVC (MPEG4-Advanced Visual Coding or MPEG-4 part 10) video, voice, data and FTP sources. The results of the performance evaluation show that with our proposal, the DSLAMs can provide QoS guarantees for broadband services over the DSL access networks. We can call it as the QoS-capable DSLAM for broadband services over the DSL access networks.