Ten Tips and Considerations on Upgrading to Wireless N

By Eric Geier (NoWiresSecurity Founder & CEO) - originally published on InformIT.com

Upgrading your home or office Wi-Fi network to 802.11n—or Wireless N, as I'll refer to it—can provide greater coverage, increased speeds, and overall better performance for more demanding applications and devices.

However, just like everything else that appears too good to be true, there is fine print. You wouldn't achieve these promised speeds and performance levels by just plugging in the Wireless N (or now, Draft N 2) gear "out-of-the-box," or without setting changes and careful considerations.

To help you maneuver through the upgrade, I've compiled ten tips, hitting on important issues you need to know.

1. Use the Same Manufacturer for All Gear

Like the older wireless standards, Wireless N is supposed to be standardized and work among devices from other manufacturers. However, especially with the Wireless N Draft products (before the official standard is complete), you might find that gear from various vendors don't work well together.

It's best to evaluate the product offerings from the vendors, choose the best, and stick with that manufacturer.

2. For Full Improvements, Replace Adapters
To get much improvement from upgrading your Wi-Fi router to Wireless N, you must upgrade your computers and devices to the new standard as well.

There are new technologies in the router that might help signals to Wireless G clients; however in most cases you'll see only slight range improvements.

3. Don't Mix Wireless B/G with N

Wireless N is supposed to be interoperable with Wireless A, B, and G, but it doesn't always work that way. Some older clients might not be able to connect at all, even when the wireless router or APs are in mixed wireless mode. Then when the older clients can connect, they'll slow down the network.

Some clients may take a heavy 80 percent cut in their throughput. To prevent this problem, consider forcing the new APs to use only Wireless N, and keep the old router or APs around to support the old clients.

Although connections among users on the Wireless N router or APs with Wireless G users will still be bottlenecked by the old clients, the throughput cuts on a mixed mode Wireless N router or AP can be much worse.

4. By Default, the Higher Speeds Won't Work

With Wireless N you have the option of using either 20- or 40MHz-wide channels, whereas Wireless G supports only 20MHz. The larger channel footprint, in effect, makes it possible to achieve higher throughput or transfer speeds.

To help reduce the possible interference to Wireless G networks caused by using such larger channels, Wireless N products are shipped with the smaller channel-width set by default.

Thus if you want to get the highest speeds for transferring files between your newly equipped computers, you need to change this setting on your router. Check in the basic wireless settings area of the web-based utility.

5. Use 40MHz-wide Channels Only with Strong Signals

This serves as a disclaimer for the above tip, about changing the default channel width to enable the higher data rates—sometimes referred to as channel bonding. Though the effect can be great, it works only with users that have a good connection.

At a certain point, 40MHz-wide channels and a lowering signal will start to negatively affect the throughput. The worse the signal gets, the more negative its impact.

So if not all your computers are in a good range, you may actually consider leaving the channel-width setting alone.

6. Carefully Select 40MHz-wide Channels

When using Wireless N gear with the default 20 MHz-wide channels, there is no impact on the channel availability, selection, and interference. You still use the three non-overlapping channels of 1, 6, and 11.

However, if you are using channel bonding and making use of the 40MHz-wide channels, there is a major impact. Because the channel frequency range used by the equipment doubles, it essentially means you now have only one non-overlapping channel in the popular 2.4 GHz band, and nine indoors for the 5GHz band.

Thus you need to carefully select the channels.

7. For Fastest Wireless-to-Wired Connections, Go Gigabit

As of now, Wireless N can provide more than 100Mbps wireless connections, surpassing the 10/100Mbps speed of most of the Ethernet ports on networking gear today. This also applies to Wireless N routers and APs.

These ports can thus become a bottleneck in the network; slowing the data rates down below 100Mbps.

This is the case, for example, when transferring files or communicating between a wireless and wired computer connected to the same Wi-Fi router, or two wireless computers connected to two different APs on the same network.

Therefore, for best performance and to plan for the future, make sure that all your gear supports gigabit Ethernet.

8. For Best Throughput, Take Advantage of the 5GHz Band

Wireless B and G gear use the (now congested and interference-prone) frequency band of 2.4 GHz, while Wireless A (primarily used in enterprises for high performance applications) uses the 5 GHz band.

To take advantage of the less-congested band, for more channels, and to enable higher throughput levels, Wireless N supports both bands. Whether you can actually use either band depends upon the particular networking equipment you have.

Most consumer and small business gear primarily supports only 2.4 GHz, while some dual-band equipment is available.

If your network requires the best performance possible, such as for voice and video applications, consider using the higher band.

Just remember that the range will be reduced, simply because of the laws of physics. When using Wireless N 5 GHz gear, you'll see about the same ranges as provided by Wireless G.

9. For Best Performance, Don't Use WEP or WPA

Using the WEP or WPA/TKIP encryption methods on your Wireless N network can dramatically reduce throughput.

To take advantage of Wireless N's great speeds, you need to use WPA2/AES wireless security—either the personal (PSK) or enterprise (802.1X) version.

10. Make Use Of Your Old Wireless B or G Gear

As mentioned, don't throw out your old networking gear after you upgrade to Wireless N! To get the best out of your new toys, you'll want the computers and devices equipped with the old clients to still use the old infrastructure.

Once you've upgraded everything, you might even find other purposes for it, such as to extend your network. If you want to tinker around with wireless stuff you could try out a replacement firmware, such as DD-WRT.

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