ATM adaptation layer 2 (AAL2) for low bit rate speech and data: issues and challenges

A new ATM adaptation layer (AAL2) to support low bit rate and delay sensitive applications in an ATM environment has been approved by ITU-T. AAL2 allows multiplexing of voice/data packets (minicells) from different users in a single ATM connection thus improving the utilization of the network resources. This paper identifies issues related to AAL2 such as the application environment, the gain obtained by multiplexing voice packets from different users on a single ATM connection, buffer requirements and cell assembly delay. To analyze these issues, we modeled and simulated ATM trunking between a base transceiver station (BTS) and the mobile switching center (MSG). The performance simulations show that the multiplexing gain obtained by AAL2 is significant and the output buffer requirement at the ATM node is small. In addition, AAL2 level packet switching and the current activities on AAL2 signaling are described.