TRAU is an element placed between MSC and BSC, if you are talking about TRAnscoder Unit. TRAU is used for speech channel rate adaptation and submultiplexing between A-if and Ater-if.
If you are talking about TRAnsmission Unit, it can be located sowhere else.
can any one tell me what is purpose of using transcoder?
I mean i know it converts 16k to 64k and works as multilexer.
is it the only functionality of transcoder?if it is then why we dont use multiplexer which will be more cheap then transcoder?
Thanks in advance.
yes the transcoder in GSM is hardware on the BSC. It allocates the EFR and halfrate channels to calls. If it goes down will affect drops on all cells on that BSC.
Pix sorry i should have said it contains the EFR HR codec hardware, if it is faulty it could lead to drops on the BSC, but there are several EFh and HR modules to choose from so if one goes board goes faulty. The drops will average out.