Architecture study and performance evaluation of ATM telephone system in broadband ISDN

Abstract

The Asynchronous Transfer Mode ( ATM ), as an international standard multiplexing and switching procedure, is the basic of the universal broadband network ( B-ISDN ) of the future. It is intended that this ATM-based broadband network will integrate all services, such as data, video, and voice transmission, in one common ( universal ) network. Thus ATM has been deployed far either as adjunct technology for high speed data or as a platform for high powered workgroups. From the beginning of 1990's, ATM has been quite successful in the high speed data communication in both private and public networks. But until ATM supports the voice traffic that still and continuously dominates both carrier and corporate networks, it will not become the network transport technology that its developers envision and dream about. Many within the industry have been realized the situation and some approaches and techniques are developed for voice over ATM, such as the circuit emulation, voice compressing, silence suppression and signal translation to ATM SVCs. And most current ATM switches can carry voice traffic using AAL 1 circuit emulation approach with different implementation methods. As we analyze in this thesis, all above approaches or techniques are the transitional solution but not the final solution for voice over ATM in a long term view point. Since all of them need the current telephone exchanges ( PABXs ) to do some of the call control functions. We argue that new approaches for voice over ATM are required. In this thesis, we propose a new approach, which is an end-to-end pure ATM solution, called ATM Telephone System approach. The premises of this approach are the ATM switch can support SVCs with ITU-T Q.2931 signaling ( DSS 2 signaling ) capability, and the ATM switch may need to terminate the low speed subscriber lines by itself. Our contributions for such an approach in this thesis are: We first define the functional requirements of an ATM-ready telephone set, which is considered to be able to connect to the ATM switch directly; And secondly, we design the functional modules of the ATM-ready telephone set; The rough logical ASIC design consideration according to above functional modules is also given. Finally, as ATM introduces extra processing delays which will increase the end-to-end delay of a connection, and it may make the echo becomes more sensitive during the conversation and degrades the quality of service. A performance analysis focusing on end-to-end delay and echo control according to ITU-T recommendations is presented in the thesis, which indicates that, echo control is always required in most ATM-PSTN interworking cases and those connections with very long transmission distance