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

Stephen Lawson | Jan. 28, 2014
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 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.

This is one of the culprits in wireless woes at large public venues such as stadiums, according to Hart.

"The reason it doesn't work is actually [that] a very large proportion, half the traffic sometimes, can be these 1Mbps packets," he said.

The problem is, there's not much Wi-Fi gear today that needs lower rates, Hart said. Most of that slow traffic is from devices probing for antiquated networks they'll never find, according to Hart.

Wi-Fi rules require a default setting of probing at 1Mbps, but users can turn it off, Hart said. In fact, Cisco recommends its customers modify their products to probe at no less than 6Mbps or 11Mbps, he said.

Now, Hart and Myles are proposing to make the low data rates optional.

They say they aren't suggesting the removal of 802.11-1997 and 802.11b from the IEEE standard. Instead, they're proposing changes that would allow for two certification tracks at the Wi-Fi Alliance. One track would hold on to the slower speeds, while the other would gradually discourage the use of the older modes. Hart and Myles refer to the new approach as a "green" certification, saying the slow probe traffic acts like pollution in the 2.4GHz band.

To keep the change gradual, the "green" certification would actually start out with slow rates mandatory. Later, they would be optional, and eventually, vendors would have to leave those old protocols out of their products to earn the "green" certification.

Not so fast, say others in the Wi-Fi world.

"I want to make sure that when we deploy an Internet-of-things type device in the future, that it can rely on the fact that the infrastructure can support its transmissions," said VK Jones, vice president of technology at Qualcomm Atheros. His company is a major Wi-Fi silicon vendor and a subsidiary of Qualcomm, which supplies many of the chips in phones and tablets and is looking to other small connected devices for future growth.

Jones thinks the Internet of things, which may include smart electric meters, environmental sensors, health monitors and many other small, low-power devices, represents a growing class of devices that will often make use of very low Wi-Fi data rates. Range will be the key reason for this, he said: Most such connected devices will have faster standards such as 802.11g built in, but they may be so far from the nearest access point that 1Mbps is the only available rate.


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