People often have problems with slow transfer speeds, so I decided to post this.
The first thing you should understand is how speeds are measured and denoted. Speeds will be reported back in kilobits, kilobytes, megabits or megabytes per second. A common source of confusion is the difference between a bit and a byte. There are 8 bits in 1 byte, so if your transfer speeds are 12 megabits per second, you're really getting 1.5 megabytes per second (12 divided by 8). Some programs report back in bytes, some in bits, it's a matter of which program you're using.
The second thing you need to understand, is you will never get the full advertised speed on your wireless router. If the router says it is 54 megabits per second, you will likely only see half of that in real life situations. This is because of overhead and interference, which you can not get rid of. Even on 100 megabit wired connections, you will likely never see it's full capacity. Most people will see around 2-3 megabytes per second (18-24Mbps) on their 54Mbps (802.11g) router/AP's.
The third thing you need to do, is get a program that will tell you what your current transfer speeds are. You have lots of different options. One of the most commonly used programs is NetMeter. Windows XP even has its own built in speed monitor, but I prefer using a third-party program.
After you've done all of that, actually try transferring a file while running NetMeter, or another transfer speed monitoring program. See what speeds you're currently getting, so you know what you're working with. Make sure the file you are testing with is large enough for an accurate speed result.
Now you're ready to start troubleshooting slow wireless speeds.
First, make note of your original transfer speed as a reference. You don't want to go through troubleshooting without remembering if your new speed was better than the old.
Second, go into your router/AP's web-config and make sure it's set to "Auto Negotiate" connection speeds. Some routers are set out-of-the-box to only hand out connections at 1Mbps (I don't know why). Also, some of them randomly will change their auto-negotiation feature without user intervention.
Third, try locating possible devices interfering with your network. There are lots of different types of devices that could be interfering with your network. To list a few, a neighbor's wireless network, microwaves and cordless phones. To determine if any other wireless networks are in your area, download Netstumbler and run it. It will report back any other wireless networks in your range. If there are other networks, make note of what channel they are operating on. If it's operating on channel 6, and you're also on channel 6, you will likely see interference that could result in slow speeds and/or frequent disconnections from your network, so try changing the wireless channel on your network. If you have 2.4 GHz wireless phones in your home, try finding the option to change the wireless channel they operate on. Many 2.4 GHz phones give you this option to lessen interference, but some may still not have that option. The easiest way to tell your (or your neighbor's) wireless phone is interfering with your network is if when the phone rings, you loose connectivity to the wireless network. If yours is the definite cause of your interference, and you can't change the channel, try buying another phone. You can either get one of the newer phones that operate at more than 5 GHz, or go with some older models that operate at 900 MHz. As odd as it may sound, microwaves operate at frequencies very close to 2.4 GHz and can cause interference. Make sure you don't put your AP near a microwave (who puts AP's in their kitchen anyways  ).
If you can't find any interfering devices in your area, try a different wireless card and/or AP. Either go to a friends house, or try buying another from the local store (then returning it after your testing is done). It's possible your original wireless card isn't very good and doesn't keep a very good link with the AP. It's just as likely your AP is the source of the problem because it has poor range. If you test with a different AP and your speeds are fixed, then you know the AP was the source of your problem. If you test with a different wireless card and your speeds have been fixed, then your wireless card was likely the problem child in your situation.
If you've tried a different wireless card and/or AP, and you still don't have acceptable speeds, try wiring your computer directly into the router. See what speeds it gets that way to make sure the computer isn't the problem. Some older computers may not be able to keep up with faster transfer rates because they can't process the data as fast as you're sending it.
If the computer isn't the problem, make sure you're not trying to get unrealistic speeds. You're not going to get perfect speeds all the time. Wireless is completely different from wired connections and it isn't perfect.
Another thing to take into consideration is what kind of encryption you are using. WEP supposedly takes away ~5-10% of speeds due to the encryption method used; WPA isn't as bad.
Also, try running some of the tweak tests here on DSLR (»/tweaks ) along with DrTCP.
Make sure you're actually connecting to your network, not your neighbors. Change your SSID to something unique so you never get confused about which network is yours.
Also, use the search feature! It's the best tool on DSLR!. A simple search came up with these threads that talk about slow wireless speeds:
»Slow speed, what is wrong?
»How Much Speed Loss Due to Wireless Overhead?
»Wireless Speed Vs Wired Speed
»Question on download speed on wireless
»Very slow speed on my network, need help
»B vs G real world speed??
»Wireless G slow connection..
»How fast should it be?
»How much will WEP slow down my network
Hopefully this helps someone.
Many thanks to Bill  for this faq entry.
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by No_Strings
last modified: 2006-02-21 19:47:05 |
