The reason that your phone performs relatively poorly on a current 802.11n or 802.11ac wireless access point is down to its design. The MIMO implementation in these access points will use multiple antennas to transmit independent data streams. But those antennas require more electrical power. Phones can’t usually afford that overhead, so they generally stick with one antenna against MIMO’s two, three, or four antennas.
If you’ve got a three-antenna access point, it’ll be great for your laptop which may have three antennas. Not so much for your phone, with one antenna, because the access point will use all three antennas to communicate with the phone, but the phone will only be able to receive a signal from one. Of course, the receiving side is the one that will affect your download speed.
Matthew Gast, director of advanced technology for Aerohive Networks, likens it to driving on a three-lane motorway but never being able to leave the inside lane.
“Even if you have an 802.11ac phone, it supports one stream. So no matter how good that phone is, it can only use one third of the spatial stream,” he said.