The wireless link is still the bottleneck in 802.11 WLAN systems, especially in a public WLAN deployment with high-demand users. The most common way of improving the system performance is by accurate site planning, but this still does not cope with dynamic demand from users, such as in hotspots at an airport where travellers with WLAN laptops tend to gather at different gates at different times. In this paper, a novel intelligent radio resource management system for WLANs with low-cost semi-smart antennas is proposed and evaluated. The access points can re-configure their radio coverage patterns to balance hot-spot traffic. Using a global optimisation algorithm, significant performance improvement is discovered over traditional configurations by simulations.