Applying ATM/AAL2 as a switching technology in third-generation mobile access networks

In this article we focus on the transport and switching part of third-generation mobile access networks and outline some important aspects of applying ATM in these networks. In particular, we argue that in order for the mobile access network to support low-bit-rate delay-sensitive traffic consisting of short packets, the standardization of a new ATM adaptation layer, AAL2, and associated signaling protocol has been necessary. The AAL2 protocol has been designed to support low-bit-rate delay-sensitive services (typically compressed voice) where other adaptation layers fail to deliver the required QoS and maintain efficient resource utilization at the same time. Furthermore, in order to provide mobility and soft handover support in W-CDMA-based mobile networks such as UMTS or IMT-2000, there is also a strong demand for fast connection establishment and release. Therefore, when designing ATM-based cellular access networks some specific architectural and traffic management issues need to be addressed.