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Old-school Wi-Fi is slowing down networks, Cisco says

Cisco engineers are proposing standards changes to pare down unnecessary traffic

By , IDG News Service
January 27, 2014 05:06 PM ET

IDG News Service - The early Wi-Fi standards that opened the world's eyes to wire-free networking are now holding back the newer, faster protocols that followed in their wake, Cisco Systems said.

The IEEE 802.11 standard, now available in numerous versions with speeds up to 6.9Gbps (bits per second) and growing, still requires devices and access points to be compatible with technologies that date to the late 1990s. But those older standards -- the once-popular 802.11b and an even slower spec from 1997 -- aren't nearly as efficient as most Wi-Fi being sold today.

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As a result, Cisco thinks the 802.11 Working Group and the Wi-Fi Alliance should find a way to let some wireless gear leave those versions behind. Two Cisco engineers proposed that idea last week in a presentation at the working group's meeting in Los Angeles. Their plan drew some debate from others who expect a new wave of low-power Wi-Fi gear to emerge for the so-called "Internet of Things."

The plan is aimed at making the best use of the 2.4GHz band, the smaller of two  unlicensed frequency blocks where Wi-Fi operates. It doesn't affect the 5GHz  band, which most modern Wi-Fi gear can use in addition to 2.4GHz. (The latest  standard, 802.11ac, works exclusively in 5GHz.) The 5GHz band has more  available bandwidth and also is less crowded, while the lower frequencies are  sometimes called a "junk band" because so many devices use it for Bluetooth,  baby monitors and other technologies in addition to Wi-Fi.

One of the main reasons 2.4GHz has a bad reputation is traffic sent using old, slow forms of Wi-Fi, according to Brian Hart, a principal engineer at Cisco, who gave the presentation with fellow Cisco engineer Andrew Myles. That happens partly because of outdated code written back when early Wi-Fi versions were more prevalent, and partly because of IEEE and Wi-Fi Alliance requirements for supporting the lower rates, he said.

Wi-Fi emerged in 1997 with a data rate of just 1-2Mbps. It got a speed boost a few years later with 802.11b, which offered as much as 11Mbps and helped make Wi-Fi a hit. But those standards were left in the dust by 802.11g, with 54Mbps, and 802.11n with as much as 600Mbps. The latest Wi-Fi standard, 802.11ac, goes into the gigabit range. (All these are theoretical speeds, so users get something less in real life.)

But as new versions of Wi-Fi came along, they didn't replace the old ones. Instead, new products have to support all the preceding standards, too. Specifically, they have to be configured out of the box to find other Wi-Fi gear that may be using the old technology. That requires sending packets out at slow speeds, all the way down to that old 1-2Mbps rate.

The slower wireless data traffic is, the longer it occupies the channel it's using. So older forms of Wi-Fi hold onto channels a lot longer than the new ones do. This is especially a problem in 2.4GHz, the only band that the early versions can use, because there are only three non-overlapping channels available there. In some cases, modern Wi-Fi traffic can't reach its speed potential partly because it has to wait in line behind slower packets going out to find old gear, Hart and others say.

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