Written by: Bo Karlander, Szilveszter Nádas, Sandor Rácz and Jonas Renius

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New switching technologies are needed in the access network of third-generation mobile networks to provide a cost-effective transmission of different kinds of services, such as AMR-coded voice and large bandwidth data. The use of ATM and AAL2 switching techniques in the traffic concentration nodes can significantly reduce the need for link capacity in the access network. The most important sources of these savings are the statistical fluctuation of the number of AAL2 connections, the fluctuation of the number of users at a base station due to mobility, and the granularity of the ATM virtual channel cell rate. Ericsson's offering of AAL2 switching technology enables operators to maximize these gains in the WCDMA radio access network. Indeed, in large networks, this technology has the potential to triple the capacity of the transmission link.

The authors describe the advantages of AAL2 switching in the WCDMA radio access network. They also include results from a study comparing bandwidth requirements when traffic between node B and the RNC is aggregated either at the ATM layer, by means of switching AAL2 paths using ATM cross-connect, or at the AAL2 layer, by means of dynamically switching AAL2 connections. The authors also describe the general architecture for terminating and switching AAL2 connections in Ericsson's WCDMA RAN node products.

[First published in Ericsson Review no. 03, 2002]