As WLANs have evolved from a standards prospective, they have additionally evolved in how they are utilized. Originally, WLANs were deployed using Access Points at maximum power to ensure every area was provided some level of usable signal. While this design worked fine for traditional bandwidth limited applications, the move to high client densities and multimedia applications calls for a new approach in designing WLANs.
When designing for capacity rather than coverage, aim to have APs closer together at lower power output settings (this can be handled dynamically via Radio Resource Management) and globally disable any legacy data rates that you can afford to disable. In this manner, fewer clients will be loaded onto each Access Point, thus allowing each client to utilize a greater portion of the wireless medium.
The problem with clients operating at low data rates (example, 1Mbps) is that each packet takes up more `airtime' compared to clients utilizing high data rates such as 36Mbps to 54Mbps. In simpler terms, a client utilizing a 1Mbps rate is essentially `talking' slower than other clients and therefore drags down aggregate performance. Since WLANs operate with the guideline that only one device, be it AP or client, can utilize the channel at any one moment, overall system performance drops when a large percentage of low data rate frames monopolize the airtime. By designing Access Point density for capacity and disabling lower data rates, aggregate system capacity can be increased.
