802.11n (Pre-N and MIMO)
802.11n is an upcoming standard that will add throughput enhancement to existing 802.11 standards. The goal is to have an IEEE standard (instead of the current proprietary enhancements) that supports wireless throughput over 100Mbps.
11n will be DSSS-based and, like 802.11g, use OFDM as part of its speed-boosting arsenal of tricks. But it will also use Multiple Input Multiple Output (MIMO) technology to boost speeds well above the 100Mbps target.
This much-awaited and long-delayed standard passed a major milestone in January 2006, when warring factions submitted a compromise draft standard proposal to the IEEE Task Group N, which quickly accepted it. This ended a long battle between the two main groups, World-Wide Spectrum Efficiency (WWiSE), backed by Texas Instruments, Motorola and Airgo Networks and TGn Sync, backed most notably by Intel.
Somewhere between 802.11g and 11n are products that manufacturers started pumping out in late 2004. These products used chipsets from Airgo Networks and employed MIMO technology to achieve high speeds similar to products using Atheros' Super-G "Turbo" mode, but without the interference with neighboring wireless LANs. See this review of the Linksys Wireless-G Broadband Router with SRX for more details.)
These products established a unique category of products that came to be known as "Pre-N" or more commonly MIMO, since the Wi-Fi Alliance quickly threatened to withdraw certification from any companies trying to market products as "draft 11n". Never wanting to miss a trend (or chance to foist upgrades on an unwitting public) manufacturers began pumping out "MIMO" products a'plenty throughout 2005. Since MIMO can be implemented in a variety of ways, products using chipsets other than Airgo's appeared, with varying levels of performance. (See our MIMO Face-Off for a comparative review of eight "MIMO" products".)
Now that there is an official draft 802.11n standard, the latter half of 2006 will see a number of "draft 11n" products hit the market. It's interesting to note that the upcoming chipsets from Atheros, Broadcom and Marvell all are dual-band designs (Airgo's has been dual-band from the start). But, at least until now, consumer-level "MIMO" products have stuck with operating in the 2.4GHz band only.
One final note is that 802.11n products will use a 40MHz bandwidth, which is double the 20MHz bandwidth used by 802.11b and g products. This 40MHz bandwidth will be needed to deliver more than 100Mbps of application level throughput. Our test of NETGEAR's RangeMax 240, which uses an early form of 40MHz bandwidth technology based on Airgo's third-generation chipset, showed interference problems with 802.11b/g products operating on Channel 6. So 11n could prove to be a not-so-welcome addition to wireless neighborhoods.
None yet since there is no standard.
- Backward-compatible with existing 802.11a/b/g technologies
- Application level throughput of over 100Mbps (under best-case conditions)
- Can operate in both 2.4 and 5 GHz bands
- Can interfere with "legacy" 2.4GHz products
- 2.4GHz products still susceptible to cordless phone, microwave, etc. interference
Recommendation: 11n-based gear is probably in your future. But current "MIMO" products are not upgradeable and don't count on early "draft 11n" products being upgradeable either. Best to wait until late 2006 if 11n upgradeability is important to you. Otherwise go ahead and buy if you really need high wireless speed and range.