The best way to put Wireless N speed in context is by comparing it with the speed of Wireless G. Most presentation (especially from a marketing perspective) of this new wireless standard claims simply that it’s faster than Wireless G. While this is generally true, there are several contributing factors, not all of which are always relevant. The purpose of this site is to inform the reader on the true sources of speed increase of Wireless N over G, and give advice on deployment and configuration for the best possible results.
One key aspect of wireless communication protocols is the band (or frequency) they employ for their signaling. Wireless G could only use the 2.4GHz band – as did the even older Wireless B standard. On the other hand, Wireless G can operate on both 2.4GHz and 5GHz. The main differences between the two are that 5GHz is a wider band, and that the 5GHz is currently (in general) less populated than 2.4GHz (less devices are using it). The combination of these two factors allows for more channel planning options and the availability of channel bonding when using Wireless N on 5GHz mode (more on this later). The end result all of this has is higher Wireless N speed, since there is less interference and thus a higher quality signal. Note that using Wireless N compatible devices on the 2.4GHz band nullifies this advantage (though there are other improvements of Wireless-N over G – read on).
The main technological improvement of the Wireless-N standard, which is band-independent, is the inclusion of multiple-input multiple-output (MIMO) antenna technology. The bottom line of this improvement is a great increase in data transfer rates. More specifically, it leads to a wireless N speed maximum of 72.2Mbps versus Wireless G’s 54Mbps limit. The speed of Wireless N is multiplied when using multiple MIMO streams (Wireless N supports up to 4 MIMO streams). A further speed increase is achieved through channel bonding (see below).
Wireless N offers channel bonding, which the G protocol did not. The usual process for wireless routers is that they take a 20MHz wide section of the operating band and use it for signaling. The point of channel bonding is to join two such sections together, making a channel 40MHz wide – increasing the data transmitted per second and thus the speed of Wireless N. This feature isn’t really useful when using the 2.4GHz band (in most cases anyway). The band is so narrow that a 40MHz slice takes up nearly all of it. This leads to interference if there are any other wireless routers using the 2.4GHz band (this is pretty much guaranteed in any densely populated area – office buildings, apartment buildings, even houses in dense urban neighborhoods). Thus this feature is most useful when using the 5GHz band, which as mentioned is much wider and less populated and can handle this increase in section width.
Wireless N is particularly handy for bridging together separated wired networks, or linking devices in the TV room to the home network wirelessly with a reliable, high-speed wireless bridge device.
For more information on the technical details of Wireless N and older standards, visit the IEEE standards association’s website: standards.ieee.org.