This paper extends recent researches on using intelligent agents to improve 802.11 WLAN systems performance. Agent-controlled semi-smart antennas and multi-agent systems are used. The use of agent negotiation and change antennas' radiation patterns can dramatically improve overall data rates for WLAN users, especially for geographically non-uniform distributed users (so called "hot spot" traffic). Distributed agents can negotiate with each other resulting mutual changing radio patterns to re-balance traffic at hot spot area. As most WLAN systems are deployed in in-door environment severely affected by multi-path effects, a network planning tool is used to create path loss models based on building structures and floor plans. The design and building of prototype semi-smart antennas and their control units are also discussed. With limitations of the standard and more rapidly growing wireless application demand, the air interface acts as bottleneck even in high-speed WLAN systems such as 802.1 la and 802.11g. To improve overall performance of 802.11 WLAN under large deployment and heavy application demand environment, an novel agent-based Radio Resource Management is proposed with the help of proposed low-cost sectored semi-smart antennas. With dynamically changing radio cover patterns of AP and agent negotiation, simulation results show great dramatic system performance improvement over traditional configurations. Issues of implementation are also discussed in this paper.