The rapid adoption of 802.11n has become a significant milestone in the history of wireless LANs. The MIMO-based technologies used in most 802.11n systems provide enough throughput, reliability, and rate vs. range performance to effectively remove the last major barriers to the broad adoption of WLANs in the enterprise.
But there is a broad range of options specified in 802.11n, and, consequently, many products with highly varying performance are on the market. A given 802.11n product is usually categorized by the number of spatial streams, with nominally 150Mbps of throughput possible per stream, assuming a 40 MHz. channel and a short guard interval.
Today, 600Mbps, via four streams, is the upper bound of the 802.11n standard, with two-stream implementations at nominally 300Mbps the effective norm. But we're starting to see a significant number of three-stream access points promising up to 450Mbps coming into the market.