E1 links

[guess.who]

can someone elaborate how E1s travel between MSC , BSC and BTS.... ie Mapping of E1s in these entities... And does someone have pictures of how E1 are patched at MSC , BSC and BTS.

Please guyz help me in this regard coz i have had a great confusions about it...

[elche]

I recommend reading it completely but you can Look at slides 8, 61 , 62, 63, 83, 84 to have an idea of how E1 are connected in the network.
an E1 is just 30 pcm channels (PCM= a 64k stream or normal calls)+ 2 for signaling. for a total of 2048km or 2MB.
A TRAU simply changes coding between msc-bsc so that 4 GSM calls can fit into a single 64kb stream, so instead of 30 calls you have 30x4=120 calls simultaneously.
Hope this helps, and reputation is always welcome.:)