802.11n supercharges Wi-Fi

The forthcoming 802.11n standard will increase the capabilities of Wi-Fi kit

The Institute of Electrical and Electronics Engineers (IEEE), based in the US and not to be confused with our own Institution of Electrical Engineers (IEE), creates standards for various aspects of electronics. The best-known standards in the IT field are those written by committee 802, which include the standards for Ethernet, other LAN access methods and LAN security. However, 802 is now most famous for the wireless standards 802.11, 802.15 and 802.20.

I've written before about 802.15 and 802.20, which are pretty interesting, but there are also important developments around 802.11, which deals with wireless LANs. We already have the well-known 802.11, 802.11a, 802.11b and 802.11g but there's plenty more going on. The most interesting is probably 802.11n, which will be a standard for faster wireless LANs. The work is well under way but, as usual, there are several factions, each promoting their own proposals. A clear leader has emerged in the shape of the TGN Sync scheme but the second-placed scheme, called WWise, is still in contention.

Nevertheless, we already have some idea of what the final standard will include. The speeds will be much faster: 150Mbit/s to 350 Mbit/s for the first devices followed by more complex ones going above 600Mbit/s. The advances will be possible thanks to contributions from a range of techniques, a lot of which have not been deployed in many current systems.

Much of the improvement will be due to multiple input, multiple output (Mimo) wireless technology. With Mimo, each device can have several antennas, each connected to a separate transceiver. The advantages are considerable, especially in the typical office where radio signals get reflected off walls and furniture. Mimo can make this a benefit rather than a problem because the multiple paths can be made to carry independent data streams, thus increasing the throughput.

Two antennas at each end can make a significant improvement, and more antennas create an even bigger improvement.

Coded modulation, where the structure of the signal allows the receiver to make a better estimate of what was sent, will also be used. This improves radio performance, extending range and throughput. The techniques used should be as good as theoretically possible thanks to recent breakthroughs in coding.

A significant gain has also been made by increasing the efficiency of MAC-layer data protocols. This is not very high-tech but offers worthwhile improvements.

Together such advances will add up to wireless LAN systems that could be 10 times faster than today's, using technology that is only just out of the research labs.

I still find it quite amazing that this highly-advanced kit will soon be available for about the same price as current systems.