Base station subsystem#Transcoder

The Transcoder and Rate Adaptation Unit ( TRAU; German: transcoding unit ) is part of the infrastructure of a GSM mobile network and has to convert the task of working with a low data rate traffic channels of the radio interface in 64 kbit / s channels of fixed network infrastructure and vice versa. It will do everything from the mobile stations ( Base Transceiver Station | (BTS ) ) is controlled, it is assigned to logical.

The transcoding units are physically located in the GSM network in the Base Station Controller (BSC ) and the UMTS network in the mobile switching center ( Mobile -services Switching Centre ( MSC) ) and can it use in Submultiplex the 64 kbps channels, for example with 4 voice full rate channels per one 64 kbit / s channel.