This paper presents enhancements in the physical layer of 802.11a wireless local area networks (WLANs) to support multiple-input multiple-output (MIMO) communication. In this approach, spatial diversity is exploited at the radio-frequency (RF) front-end by weighting the transmitted and the received signals using integrated circuits (ICs). Their optimum weight settings are derived by baseband algorithms based on the estimated MIMO channel response. Prototyping platforms are designed for baseband signal processing and RF transmission, which contain all key components for the RF-MIMO technique and 802.11a data transmission, respectively. The developed algorithms, computing platforms and ICs are successfully verified with respect to the RF-MIMO concept and their compatibility to 802.11a devices.