WIRELESS NETWORK PROBLEM. I HAVE ONE WI FI LOCAL NETWORK , BUT THE PROBLEM IS I M NOT

Question

I HAVE ONE WI FI LOCAL NETWORK , BUT THE PROBLEM IS I M NOT SETISFIED WITH WI FI ACESS POINT (AP).MANY TIME  I FACE TO SIGNAL PROBLEM...CAN U SUGGEST ME WHICH ONE  AP WILL GOOD FOR LOCAL LAN I HAVE  UP TO 50 COMPUTER  WITH IN 3 FLOOR.

tHANK