Current-generation Wi-Fi technology lives in the 5GHz band. Almost all of the major innovation in wireless standards takes place in the relatively untroubled frequencies around 5GHz (and well above), where there’s little radio competition and the living is easy.
But wireless LAN users can’t just stay comfortable in the 5GHz realm – the older 2.4GHz frequency bands are a necessary part of most wireless implementations, and they’re rarely a favorite of the people who have to build and operate Wi-Fi networks.
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LIVING WITH 2.4GHZ WLANS
There are several reasons for that, according to author and WLAN expert Keith Parsons. For one thing, older Wi-Fi devices are forced to share a much more limited number of channels in and around the 2.4GHz bands.
Part of the reason that 2.4GHz Wi-Fi spectrum is so crowded is that manufacturers continue to make endpoints that depend on it, instead of switching to 5GHz, Parsons tells Network World.
“Perhaps not in smartphones or tablets, but many Chromebooks are 2.4GHz only, even today,” he says.
Adrian McCaskill, a wireless architect for World Wide Technology, says that the effect of frequency overcrowding is to limit the amount of air time individual devices have to send and receive data.
“The 2.4GHz spectrum is really noisy compared to 5GHz in general,” he says. “So devices have to wait longer times to get access to the medium. And if you have to support even one legacy 2.4GHz (802.11b ) client it slows down the entire 2.4 environment for all devices. It's definitely a balancing act.”
Some users take the direct approach to the 802.11b problem, like University of Michigan principal systems security development engineer Walt Reynolds.
"We offer the coverage for those who still have devices that need it,” he said, “but we do disable the [802.11]b rates to eliminate those rates slowing down users’ connections.”
Another reason for 2.4GHz-related headaches is a simple lack of space – in the 5GHz ranges, there’s 500MHz of usable spectrum, but just 80MHz for 2.4GHz. What’s more, the fact that the frequency is lower means that its signals propagate farther. While effective range is nice, this also means that it’s much easier for 2.4GHz access points to interfere with one another.
2.4GHz devices not only share that limited amount of spectrum with each other, but with a host of other radio technologies that can potentially interfere with signals. Everything from Bluetooth to old-style cordless phones to wireless cameras and all sorts of embedded devices use the frequency bands around 2.4GHz.
That’s not necessarily the exclusive fault of the device makers, according to Farpoint Group principal and Network World contributor Craig Mathias. Embedded wireless devices – particularly in fields like medicine – can be very tough to upgrade or replace.
“The government can also take a very long time approving new devices and new radios in regulated applications, so many users are just stuck,” he says.
According to Mathias, there’s nothing inherently wrong with 2.4GHz – the real issue is that the outdated 802.11g standard that still has to be used in some settings is garbage. Future Wi-Fi standards should change that, however.
“[802.11ax] should work just fine in the 2.4GHz bands and may finally be the nail in the coffin of .11g that we all so richly need and deserve,” he says.
OFFERING WLAN ADVICE
Working successfully with 2.4GHz isn’t simple, but Parsons says that architecting for 5GHz first can help both frequency ranges.
“Backfill with just enough 2.4GHz to make those devices meet their requirements,” he advises. “The only devices that should be on the 2.4GHz network are those that cannot do 5GHz.”
Network WorldMathias adds that minimizing the use of outdated wireless tech is the best idea for a smoothly functioning environment.
“In general, we recommend to clients that they eliminate the use of all Wi-Fi technologies before .11n (including .11g), but such is not always easy,” he says. “11n in the 2.4 bands works just fine … and there's really no reason not to use it.”