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Wireless equipment is advertised as carrying data at a particular speed, but the part that's not highlighted is that the conditions must be right.

I use a 10/100Mbps wireless router at home and I share files between my laptop (wireless at 54Mbps) and my desktop (hardwired at 100Mbps). Why is it when I transfer files from my laptop to my desktop or visa versa, I only get about 2MB/s (16Mbps) and not the full 54Mbps? This has been bugging me for the longest time so any info would be appreciated!

Wireless connectivity can be affected by many, many things.

The first thing to realize is that while your equipment may claim 54 megabits per second, that's only its maximum speed. In my opinion, you'd be quite lucky to actually see it.

The wireless signaling protocol actually has "performance degradation" built in. What that means is that if conditions aren't ideal the device can drop down to lower speeds that are less sensitive to things that might interfere.

Remember that wireless networking is, essentially, radio. When listening to the radio you might be able to tolerate some amount of static, but the quality of what you're listening to, the fidelity, suffers. If you really want the highest possible fidelity you need a strong signal with absolutely no outside noise.

"The key to getting maximum speed is that phrase 'ideal conditions'."

The same is true of WiFi, except that the equivalent of audible 'static' on a radio is something that the wireless protocol uses to determine that it needs to slow down its transmissions in order to be clearly understood by sender and receiver.

The key to getting maximum speed is that phrase "ideal conditions".

Ideal conditions result in strong, clear signals. That means things like good antenna placement, no obstructions to interfere with the signal, no devices nearby that might be radiating electrical noise that would interfere with the signal, keeping the laptop as close to access point as possible, and so on. At the very top of the speed range, even the littlest thing like the direction the antenna or laptop is pointing, or the manufacturing quality of your specific wireless equipment might well have an impact.

Now you're probably saying to yourself "but, I don't have to do any of that, and everything seems to work ok", and you'd be quite right. Except that, as you've seen, you're not getting the full speed you might be expecting.

The wireless protocol is actually pretty robust, and manages to punch through a lot of obstacles. Just ask anyone who keeps picking up their neighbors WiFi, or the WiFi signal from the coffee house across the street. But that robustness comes at a price, and the price is typically speed.

So my advice to you is, naturally, do what's practical to give that wireless signal the best chance of getting through strong and clear from the access point to your laptop and back.

Just don't be surprised if you never see that maximum rated speed.

Article C3589 - December 12, 2008 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

December 12, 2008 12:01 PM

I am under the impression that wireless 'N' has a top speed of 300mb. I have a Linksys WRT300N router and a Dell laptop with a draft N card, but no matter how I position the router and laptop I am not able to get the 300mb speed, any suggestions?

December 12, 2008 1:58 PM

All wireless protocols contain a lot of overhead. That is to say, much of the advertised speed is used for things like keeping the link active, sending/receiving acknowledgements, etc. In fact, even when conditions are ideal, only about 50% of the total bandwidth is available for user data. That means the actual throughput you will experiece will be something less than half of the advertised speed, and could be much slower dependion upon such factors as described by Leo in his answer.

Chris Buechler
December 12, 2008 5:24 PM

This article has a very good explanation of this.

The best you can possibly get through your "54" Mbps wireless is actually ~27 Mbps.

Michael Horowitz
December 16, 2008 10:34 AM

This excellent article, oriented to WiFi N, provides some more information on this topic:

5 Ways To Fix Slow 802.11n Speed
Tim Higgins December 10, 2008

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