With more and more exhibition halls opening up, it can be confusing to know which one. Here are some points of interest:

GPS:

Doha Exhibition Centre (Probably this one-also referred by above poster):
25.350154,51.522228

Qatar National Convention Centre (has an exhibition hall in the back):
25.322266,51.437466

Huge Conference Centre (still under construction):
25.322945,51.531381

Good luck.