The Many Faces Of 802.11n

Wireless local networking has been a massive hit with consumers and businesses, but the promise of 802.11n, the latest version of the Wi-Fi standard, is clouded with confusion. There are literally dozens of different combinations of the core technologies that make up "wireless n", and many offer performance no better than existing 802.11g networks. Sorting these out is difficult for even the most experienced wireless networking engineer, let alone the average consumer.

802.11n is the fifth major revision to the industry-standard 802.11 wireless Ethernet specification. Like its predecessors, 802.11n maintains backward-compatibility while still moving forward with new features and greater performance.

The core components of 802.11n include wider radio channels, MIMO multi-stream architecture, and tuning of the data frames sent over the network. But most of these new components are optional or scalable, so not all 802.11n connections are equal. In fact, many casual users will see no difference when moving from 802.11g to "wireless n"!

These new features of 802.11n are optional, and most consumer implementations are severely limited for compatibility reasons. Typical consumer networks will use the same few 20 MHz channels in the crowded 2.4 GHz band. Even if both ends of the connection are 802.11n-compatible, they may not both support performance-enhancing features and so might have no real-world performance boost. On the other hand, MIMO access points will reduce the effect of distance on throughput for all clients, regardless of whether they support any 802.11n features.

Disappointed ConsumersMost end users will not currently experience the true capabilities of 802.11n networking. Instead, they will be limited to about the same performance as current 802.11g Wi-Fi networks, which is a shame. It is disappointing that performance enhancements like 5 GHz operation and wide 40 MHz channels are usually disabled by default.

But more troubling is the fact that client-side 802.11n adapters do not necessarily support multiple spatial streams or 5 GHz operation. Many consumers will assume that "Wi-Fi n" is better and faster, and vendors will be happy to hype these higher-priced products. But 2.4 GHz devices cannot deliver on these promises.