The newer WiFi Access Points use MIMO technology that has multiple antennae for transmitting and receiving data. These antennae enable beam-forming where constructive and destructive interference are user to increase the energy transmitted in a certain direction is preferential increased, or preference is given to signals received form a certain direction is increased. This allows the range of WiFi to be significantly increased to a couple of hundred meters in certain environments.
Unfortunately the underlying MAC protocol used by WiFi to determine which transmitter gets priority has been shown to manifest significant capture effects that mean the strongest signal pairing (read closest) links tend to get preference.
So in practice to get the most range for your WiFi dollar do the following:
- Buy a MIMO enabled AP (802.11n)
- Choose the lowest possible unused channel number OR failing that the one that has the least competition in terms of other APs on the same or the immediately adjacent channels.
Like it was stated previously a mimo router could improve performance however depending on the location of the router it could be dramatically decreased the maximum for most is about 230ft indoors/820ft out doors for wireless n wireless B/G has 35ft indoors 123ft outdoors. Wireless A as sanctioned by FCC for a lot of different purposes can have ranges up to 16,000 ft. Wireless A is impractical for indoor use since it has a hard time going through walls. Most major public places that supply wifi will choose wireless A as one of their frequencies for this reason and that it has less issues with interference from other wireless bands.