What is a MIMO? 

MIMO (multiple-input multiple-output)

A technique for enhancing wireless throughput  and range by taking advantage of new multiplexing technique. 

MIMO  send information out over two or more antennas. The radio signals reflect off many objects, creating multiple paths that in conventional wireless cause interference and signal fading, while MIMO uses these paths to carry more information, which is recombined on the receiving side by the MIMO algorithms.

a lot of  wireless-LAN vendors expect that some form of MIMO will be the basis of work starting in the IEEE 802.11n Task Group, creating a specification for WLANs having at least 100M bit/sec throughput. The 3rd Generation Partnership Project, is a collaboration of telecom standards groups, also is considering  MIMO techniques for use in cellular mobile networks.

MIMO doubles the spectral efficiency compared with that of today's Wireless LANs. The maximum data rate for 802.11g and 802.11a networks is 54M bit/sec, while actual throughput is as low as  20M to 30M bit/sec. Current MIMO techniques can reach constant throughput of 108M bit/sec.

MIMO Additional Resources

Multiple Input Multiple Output (MIMO) Systems for Wireless Communications

MIMO Research at UT-Austin
Describes different types of MIMO uses.

Where to find MIMO products?  

D-Link DI-634M Super G with MIMO Wireless Router

NetGear Range Max, Ultimate Range and Speeds MIMO products

ZyXEL XtremeMIMO^TM X-550 Wireless Broadband Router, Say Goodbye to Lag Time and Dead-spots

LinkSys WRT54GX4 Wireless Broadband Router