Performance evaluation of ATM/AAL2 as switching technology in 3G mobile access networks

In this article we focus on the transport and switching part of third generation mobile access networks. At the moment, the second generation of mobile systems is sufficiently extended everywhere and can provide services to all mobile users. The next challenge in the development of digital mobile networks is the integration of data and voice services in a unique platform. It seems to be that Asynchronous Transfer Mode technology (ATM) will be the transport technology candidate to support both types of services (voice and data) and can therefore offer the flexibility required by the Third Generation Mobile Systems. ATM supports the very-low-bit-rate applications, which are typical of voice services. Used directly, however, it is inefficient. Therefore it is needed an adaptation level for ATM that provides an efficient transmission of variable length packets at low bit rate. The ATM Adaptation Layer type 2 (AAL2) has been chosen for the Third Generation Mobile Systems. This article identifies issues related to AAL2 as the gain obtained by multiplexing voice packets from different users on a single ATM connection, buffers requirements and both cell assembly and end-to-end delay.