MIMO Wi-Fi (Wireless) Standards

Get ready for a new generation of Wi-Fi so powerful it can carry broadband Internet phone calls, HDTV, and music with its eyes closed and one hand tied behind its back. Well, almost.  According to some, the technology behind wireless data networks in homes and businesses is on the verge of a makeover that promises to fix long-standing complaints of spotty coverage, flaky connections and inconsistent speeds.

MIMO: A New Wireless Standard

Another in the long line of Wi-Fi technical standards, 802.11n is based on a new radio technology called MIMO (multiple input/multiple output) that allows the transmission of up to 100 Mbps over a much wider range than the earlier versions. In a general sense, MIMO uses multiple antennas and radios in the same frequency to transmit data, and is the basis for the 802.11n spec. MIMO promises dramatically improved capacity and range for wireless networks.

However, the impending 802.11n wireless standard and the rash of new products that manufacturers say use 802.11n technology are sowing confusion among many IT professionals.

Controversy over MIMO Wi-Fi

The new MIMO market breaks down into three camps:

• Belkin and Linksys offer MIMO gear based on Airgo's chipset
• Netgear has partnered with smart antenna vendor Video54 and plans to ship gear this spring
• D-Link (and soon SMC) is using Atheros' new Super G with MIMO chipset in products available now.

The confusion stems from different definitions of MIMO.  On the one hand, Airgo says true MIMO requires multiple antennas and radios to transmit and receive plus the ability to do spatial multiplexing. In spatial multiplexing, multiple distinct datastreams are transmitted over multiple radios in the same band at the same time to multiply the amount of data that can be sent.

On the other, other companies would like to see the definition of MIMO not strictly require spatial multiplexing, just multiple antennas and paths for the same data, which strengthens the signal. With fewer lost packets and errors, performance and distance are increased even without multiplexing.

Everyone agrees that MIMO uses multiple antennas. Airgo insists that without different data streams, spatial multiplexing, it’s not MIMO. Atheros muddies the water by adding another radio but only to supplement the single data flow. Which definition will triumph probably depends on both price and performance.