How They Work: Inside the New MIMO Technologies
All of them are called MIMO, but that's where the similarities end among the multiple-antenna technologies that most of the products in this roundup use.
Standard 802.11g Wi-Fi
The antennas on standard 802.11g devices send and receive data in all directions on one of eleven channels at the 2.4-GHz frequency used by 802.11b and g Wi-Fi.
Airgo Network's True Mimo
Used by: Belkin Wireless Pre-N Router, Linksys Wireless-G Broadband Router with SRX, and Netgear Pre-N Wireless Router
Test report: The most consistent performer in our tests--and, at longer ranges, the fastest.
Airgo Networks' patented True MIMO technology exploits what is known as spatial multipath characteristics of radio waves. Airgo-based products simultaneously use two radios to send two unique streams of data over a single 2.4-GHz channel. At the receiving end, three antennas and radios decode these disparate data streams, which are recombined into one. The extra antennas and other transmission enhancements improve speed and coverage for nona??True MIMO devices that don't otherwise benefit from spatial multipath technology.
Used by: D-Link Super G MIMO Wireless Router
Test report: Strongest results occurred at middle range.
In products that use beamforming antenna technology, the transmitting unit aims data streams directly at the antennas on the receiving devices. D-Link's MIMO products use a smart-antenna chip set from Atheros to add beamforming to Atheros's Super G Wi-Fi chip. The antennas sense the location of clients and focus data streams accordingly.
Used by: Netgear RangeMax Wireless Router
Test report: Produced the fastest throughput of any MIMO product at midrange distances, but results overall were inconsistent.
Netgear's RangeMax line uses Video54's patent-pending BeamFlex Smart MIMO Technology. Instead of employing the usual sticklike external antennas, the RangeMax router uses seven internal antennas that can be arrayed in different combinations optimized to transmit data based on the location of client devices and environmental obstacles. RangeMax clients also benefit from their multiple antennas and their BeamFlex-optimized software.
Belkin F5D8230-4 Wireless Pre-N Broadband Router
D-Link Super G MIMO Wireless Router
Linksys by Cisco Wireless-G Broadband Router with SRX - WRT54GX
Netgear Pre-N Wireless Router
Netgear WPN824 RangeMax Wireless Router
US Robotics Wireless MAXg Router with integrated USB Print Server