Networking

802.11n complications are imminent

As you likely know, the current fair-haired wireless LAN version, 802.11n, is multidimensional, making product comparisons challenging. Those comparisons are likely to soon get even thornier when 1×1, single-stream 802.11n products emerge for netbooks, smartphones and even laptops. At issue: the Wi-Fi Alliance currently lacks certification programs and categories to accommodate this new breed of 802.11n product.

As a result, viable 1×1 11n products could emerge in the near term that aren’t Wi-Fi certifiable. In addition, faulty, uncertified products operating in 1×1 11n mode could make their way into the market.

You’ve often seen vernacular such as 2×3 or 3×3 MIMO (or “multiple input, multiple output”) associated with 802.11n. These numbers indicate how many transmit and receive antennas and radios are in an access point (AP) or client device. They determine how many different spatial streams of traffic can be sent at one time to improve signal reception (a separate radio and antenna pair is required for each data stream sent and received).

One question has long been: What about smaller devices, such as smartphones, without the juice necessary to support multiple antennas and, thus, MIMO, which is considered a primary 802.11n enabler? Are the benefits of 802.11n simply inaccessible to a growing population of handheld users?

Not necessarily. A generation of products is said to be emerging that supports 802.11n in a 1×1 configuration. This sounds oxymoronic: Indeed, you can’t have the most highly revered benefit of 802.11n, MIMO, when you only have one transmitting and one receiving antenna and a single spatial stream.

However, what you might get are other 802.11n benefits. MIMO is just one contributor to the performance boost associated with 802.11n. In theory, you could also get the 40MHz channel-bonding feature and the 802.11n’s packet-aggregation capability. Some Wi-Fi experts say that 100Mbps throughput with a single spatial stream (no MIMO) is achievable using just these 11n elements – and at the same or lower cost than 802.11g.

Supposedly, such products are en route to market.

However, the way the Alliance is set up is by device category, which made sense in the black-and-white worlds of 802.11a/b/g. For example, the Alliance will test and certify smartphones with a single spatial stream for interoperability. However, by the Alliance’s definitions, to qualify as an 802.11n laptop, the device must support at least two spatial streams. So if a 1×1 laptop comes out, the Alliance wouldn’t recognize, test, and certify it under its current setup.

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