The most advanced form of smart-antenna technology available--and the technology that's likely to be integral to the next generation of WLANs--is MIMO (multiple input/multiple output). MIMO's approach can be applied in many ways. One of the most interesting applications is found in new chipsets and reference systems from Airgo Networks. Airgo's MIMO implementation relies on multipath to increase signal level and range, thereby letting Airgo deliver a 108-Mbps data rate in a single 20-MHz 802.11 channel.
It's unlikely that Airgo's implementation of MIMO will be adopted by the 802.11n working group as the foundation for a next-generation WLAN standard. Understanding that, Airgo has gone to great lengths to ensure backward compatibility with legacy standards using creative approaches similar to those employed by Motia. In a recent demo in our labs, Airgo's products not only delivered the fastest TCP throughput we've seen in a single-channel WLAN (in excess of 40 Mbps), they also provided the best range of any 802.11a-compliant access points we've tested--significantly outperforming Cisco Systems' 1200 access point, as well as others from Airespace and Aruba Wireless Networks.