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The truth about wireless speeds

The one-third trend continues in 802.11ac

Most people will find 802.11n wireless networking sufficiently fast, but it’s actually slower than last century’s wired ethernet. A truly nippy wireless data system, such as that promised by 802.11ac, is long overdue.

Surfing the web, even streaming video or music, there’s little reason why you’d need anything faster than 802.11n. Yet I’ve been eagerly awaiting the arrival of 802.11ac. This is the new ‘gigabit wireless’ that will become standard within two years. See wireless router reviews.

The problem with today’s 802.11n is it’s just too slow for moving around data. I’d be more content if it performed at the speed the industry would have us believe is possible. After all, 802.11n’s advertised ‘450Mbps‘ is nearly five times quicker than the 100Mbps fast ethernet we used in the 90s. And I could work with that. See Broadband Advisor.

Real-world wireless performance

The practical speeds of Wi-Fi have always been inflated, but it’s a problem that got much worse with the launch of 802.11n.

In 1999, 802.11b networks were said to operate at 11Mbps; actual results were closer to 2Mbps, but this was quick enough for the 512kbps ADSL of the day.

Then came 802.11g in 2003. They said: 54Mbps. Real speed: 15Mbps. A theme began to appear, in which the real-world speed was one-third or less than that promised.

When ‘300Mbps-capable’ 802.11n launched, the waters were further muddied. This transmit rate is theoretically possible using 40MHz channels, two spatial streams and two antennae; most laptops, and every phone or tablet, use one aerial to ride a single 150Mbps stream. These devices are lucky to see 50Mbps.

But the real fraud is the discrepancy between the headline sync speed (transmit rate), and the speed at which your data travels. The engineers know it, but marketing departments don’t promote it.

Unlike wired ethernet, which has little overhead and can deliver your data at more than 90 percent of the so-called PHY layer’s rating, wireless communications need a lot more error correction. Most of the data zipping across your wireless link isn’t your data, but background chit-chat propping up the system. In fact, a fraction is your data; the rest is housekeeping.

So the ‘300Mbps’ printed so clearly on your router’s box often translates into 100Mbps, or much less, of real data throughput - still assuming two antennae, in ideal conditions.

It’s an arms race out there, and router brands work hard to sell their products. Little wonder that it could be easy for end users to get confused and believe they are getting their data transmitted at the gross speeds promised.

Broadcom sells its wireless chips to almost every router maker, and in its marketing material it carefully picks its words in order to stay the right side of telling lies.

Consider the following statement: “5G WiFi from Broadcom works three times faster than the current standard for the most common devices, offering you a streaming video- and data-synching experience with transmissions in excess of a gigabit per second.”

Yes, you can stream video and sync data. And 1,300Mbps raw transmissions are in excess of a gigabit per second. But that’s two separate statements, wrapped to give semblance of a related clause.

Powerline tech that sends data over the mains is just as bad – ‘200Mbps’ HomePlug AV delivers around 65Mbps.

We've tested the world’s first 802.11ac routers: Buffalo's AirStation 1750 and Netgear's R6300. Each promises speeds of 1,300Mbps; based on what you’ve just read, see if you can guess what performance they deliver.

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