2012年5月16日星期三

How to Fix Wi-Fi Interference


How to Fix Wi-Fi Interference

When it comes to home networking, wireless seems to be the trend. But while one Wi-Fi networking on its own works wonders, you may soon discover that as your neighbors add on their own wireless networks your own Wi-Fi speeds will diminish.  This kind of interference can make it difficult to stream video through YouTube and Netflix, or play video games over the internet. Fortunately, there are a few precautionary meaures you can take to avoid this kind of interference. Read on to find out how!

What You'll Need:

>> AirPort Utility
>> Free iStumblr application

Possible Symptoms

Some of the telltale symptoms of wireless networking interference are:

- Weak or low signal
- Signal dropping, even when close to the base station
- Slower than usual speeds, even without any traffic on the network
- Steaming audio, video, or over-network file transfers halt, and then restart

What causes these symptoms?

Imagine a room filled with conversation. The overall noise in the room is just that: noise. It's hard to decipher between individual conversations, and if you try to talk, someone else in the room will get louder, eventually drowning you out.

Wireless networks are exactly the same. Think of the people in the noisy room as wireless base stations, sending out a wireless signals (sound waves) to others. When communication begins, a louder base station interrupts the conversation by sending out its signal, creating noise in the wireless medium.

Licensed bands, such as those used by cell phone providers, TV, and radio stations, are not allowed to interfere with each other, and are limited by the FCC to specific regions. Wi-Fi is an unlicensed band, however, and can legally interfere with other networks in the same 2.4GHz frequency. This often happens when wireless networks are too closely located to one another.

Let's look at four different ways that we can help curb this problem and help alleviate some of the issues with wireless interference. We'll show you how to make these changes using an AirPort base station, but almost any wireless router will allow you to make similar changes.

1. Change Channels

One of the easiest ways that you can help alleviate some of the issues with Wi-Fi interference is by changing your router's broadcast channel to one not being used by surrounding routers.



Using a tool such as iStumbler, you can check to see what channel surrounding wireless routers are using. You'll want to change your router to a channel that is not currently being occupied by other routers.


You can make this change by launching AirPort Utility (or your router's configuration page), and navigate to Wireless > Wireless Options, and choose a new channel from the drop-down menu. By default, most routers are configured to automatically select the "best" channel to broadcast on, however, you can change it to a specific channel if your are having repeat Wi-Fi interference problems.

2. Move the Base Station

If you continue to have wireless interference, you may wish to try moving your router to the opposite end of your house or apartment, or try moving it closer to the area where you will use your wireless devices the most.

Another option (and probably the least desired), is to offload some of the wireless strain on your network by using wired connections on your main machines. You can do this by plugging directly into your router, or by using LAN over power-line options.

3. Switch to 5GHz Band

2.4GHz is the most widely used band in wireless networking, but Apple has implemented 5GHz networking over 802.11n only. This means that if the interference is really bad, you can switch to another band and avoid all interference that 2.4GHz networks throw at your router.

You should note that the 5GHz network is only available on 802.11n devices and 5GHz-supported base stations.


To change the band of your AirPort router, navigate back to the Wireless Options panel in AirPort Utility and select "802.11n only (5GHz)" from the Radio Mode drop-down menu.

4. Reduce Power Output

Lastly, a way to reduce interference is by playing nicely with surrounding routers. If you have your radio output power set to maximum, other routers may have difficulty transmitting at their lower power, and may cause them to transmit longer, leading to more interference in the wireless medium.

You may find that by reducing your wireless radio output to a lower setting may reduce your wireless interference symptoms.


In order to change the output power, you'll need the older version of AirPort Utility (available here), and can be done by navigating to your base station > Manual Setup > AirPort > Wireless > Wireless Network Options. Once there, choose a transmit power that's lower than 100% (you can choose between 10%, 25%, 50%, and 100%).

Remember to Update your configuration when you're done.

Cory Bohon is a freelance technology writer, indie Mac and iOS developer, and amateur photographer. Follow this article's author, Cory Bohon on Twitter.


Original Page: http://www.maclife.com/article/howtos/how_fix_wifi_interference

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