Network Elements

Hello friends, could you write brief introduction of the functions for the following NE?

MS:
Antenna:
TRX:
CDU:
BTS:
BSC:
TRAU:
MSC:
MGW:
GMSC:
PCU:
SGSN:
GGSN:

Thanks in advance, just 2-3 sentences for each network element. About their functions.