What is the antenna type used in the GSM BTS and the MS ?

For Base Station the most common are P@tch Array and Vertical Dipoles Array.
For mobile the most common are PIFA and Helix.

Some X-polarization base station antennas have dipole-pairs in two configurations:

1) in X (cross-shaped) providing 90deg HPBW in horizontal plane
2) in <> (rhombic) providing 65dge HPBW...

Take a look at some very interesting articles from Kathrein (with pictures):

/http://www.kathrein.com

mog.