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Wireless and Antenna Terms

Wireless routers, access points, and adapters send and receive radio wave signals through antennas. The antenna is hidden inside adapters, but on routers and access points there’s a visible antenna. Radio waves can be focussed like a lightbulb. And like a light, some materials reduce or stop radio waves. While light focused from several lights is brighter and makes it easier to see, several antennas in the same area cause interference — the radio signals will be muddy and confused.

Your goals in optimizing power are:

• Avoid obstacles.
• Avoid interference.
• Increase signal strength. Power affects how far an antenna radiates.
• Use the equipment in places it’s most powerful and most sensitive.

Antennas don’t radiate equally in every direction. Just as the base of a lightbulb blocks light, and just as a light can be focussed by a reflector, so an antenna signal may be blocked and focused. Since people cannot see radio waves, you’ll rely on testing and trial-and-error to get an idea of where antennas “shine” most brightly. An adapter’s antenna is important, but the most powerful and sensitive antennas are on routers, access points, and detachable external antennas.

The focus of an antenna is either omni-directional antenna or directional. “Omnis” are used in most home products, they radiate horizontally all around, but are weaker upward or downward. When visible, these antennas are usually a rod a few inches long. A directional antenna radiates strongly in a limited direction. It is a flat panel or a dish. These are used for point-to-point transmissions (where two antennas are focused directly at each another). These need a line of sight between them, and preferably a large open space around the main beam.

When you are near antennas you’ll still get a signal, even if you are out of the direction of its strongest signals. But when further away, you have to be in the direction the beam is the most powerful and unobstructed to receive it.

One final concept before you go to the above links is interference. Interference is a signal — one you don’t want — at the same frequency as the one you’re using. Interference comes from devices such as microwave ovens, cell phones, 2.4 GHz cordless phones, and copy machines. Interference is also caused when your own wireless signals are bounced off reflecting objects. Objects may partly or completely absorb signals, reflect them, bend them, or let them pass right through. Metal and water (including the water in people!) absorb or reflect signals. Air, wood, and glass tend to let signals pass with weakening. And when outdoors, plants and the weather may cause interference.

Improving Wireless Range: Choosing the Best Locations

This describes moving equipment, positioning antennas, and avoiding obstacles. When optimizing your existing equipment, consider:

• Placing antennas in a good location, at a good angle.
• Avoiding physical things that block signals.
• Reducing the interference from other things that transmit radio waves.

Before starting adjustment, make sure that antennas and cables are securely fastened!

If your network has more than a couple wireless devices, before you move things, decide which wireless devices are transmitting the heaviest load. These links are important to optimize. NETGEAR products have automatic data rate fallback, which allows increased distances without losing connectivity. It also means that devices that are further away are inherently slower. Therefore the most critical links in your network are those where the traffic is high, and the distances are great. Optimize those, first. The ones that are least important are links that have little, occasional traffic, and which have a strong signal strength.

Picking Good Locations for Antennas

• Antennas should be in line-of-sight of one another, where possible. Put your face next to one antenna, to find whether the other is visible.
• Place high, and clear of obstructions as practical.
• Keep antennas 2 feet from metal fixtures such as sprinklers, pipes, metal ceiling, reinforced concrete, metal partitions. (However, antennas on roofs do not necessarily give the best results. )
• Keep away from large amounts of water such as fish tanks and water coolers.
• Antennas transmit weakly at the base, where they connect. So don’t expect good reception from the bottom of a router or access point.

• For multi-story buildings, placing antennas at 45 degrees (diagonally) or 0 degrees (straight out parallel to the floor) may be most effective.

Reducing Interference

Avoid windows unless communicating between buildings. (Windows let in interference from the outside world.)

Place antennas away from various electromagnetic noise sources, especially those in the 2400 – 2500 MHz frequency band. Common noise-creating sources are:

• Computers and fax machines (place wireless equipment no closer than 1 foot)
• Copying machines, elevators and cell phones (no closer than 6 feet)
• Microwave ovens (no closer than 10 feet)

Improving Wireless Range: Tuning Equipment

Using the best channels has a big effect on network performance. Your goal is to choose settings that avoid interference from other networking and radio frequency equipment. (If you have 802.11a or 802.11a/g, channel selection is less important, skip to “Reducing Wireless Network Traffic”.)

f you have a simple home network, and aren’t close to neighbors with wireless equipment, you may be lucky enough just to choose between many channels that work well.

Complications arise when:

• You want much better coverage than you’re getting.
• You use multiple access points or wireless routers. (Then you’ll probably be using more than one channel.)
• You aren’t the only person nearby running a wireless network.

Simple Spacing of Channels

As explained in Improving Wireless Range: Overview, improving signal strength is not like adding more lights to get a brighter living room. Devices that transmit powerfully — such as routers, access points, and cell phone base stations — confuse one another. It’s necessary to distance them and to have them use different channels.

For 802.11b and 802.11g, there are 11 channels for wireless equipment (13 channels in Europe). In the simple situation where there’s little interference, you can choose any channel that works for you. When there is interference from wireless networks that overlap with one another, each network should use one of the non-overlapping channels: 1, 6, or 11 (1, 7, 13 in Europe). Then, 3 networks can use the same space with minimum interference. If you can’t do that, choose channels as widely spaces as possible.

What If a Channel I Want to Use Has Too Much Noise (Interference)?

If your neighbor has a wireless network, it wouldn’t be surprising that they are already using channel 1 and channel 11. Unfortunately, you can’t completely avoid interference just by using other channels. Wireless protocols 802.11b and 11g only have 3 non-overlapping channels. Therefore when 4 or more channels are used in the same area, the level of interference can increase notably. If you and your close neighbor both have a router and a wireless access point, for example — which makes a total of four powerful transmitters — both of you will have a certain amount of interference.

If there’s a severe problem, a practical and sociable thing is to talk to your neighbors using wireless networks that can be seen when you scan. Together, you can choose optimal channels for your respective networks. You’ll want your own channels at least 5 apart. So, for example, you could use channels 1 and 8, and your neighbor could use 5 and 11.

You may be able to place routers and access points further away inside your homes. After all, the kinds of physical barriers that reduce your transmission range also reduce the signal that your neighbor doesn’t want to see.

If you can use a directional antenna, or an antenna cable to shift an antenna, that can help you both. See the articles on antenna selection.

Reducing Wireless Network Traffic

When there’s noise, your network performance drops, so one approach is not to stop the noise, but to reduce the amount of network data being transmitted.

In a noisy environment, it may be useful to keep part of your network wired. If Ethernet cabling isn’t an option, consider NETGEAR’s Powerline products — using existing home wiring instead of cables.

When SSID Broadcast is turned on, it’s easiest for equipment to find the strongest signal. However this also causes network overhead. When the SSID is broadcast, your neighbor’s equipment may keep a record of it, and automatically try to connect several times a second; this can cause significant performance reduction. So where there are close networks, turn off SSID Broadcast, and change the default SSID.

Turning off WEP and WPA may increase network throughput, but exposes your network to hackers. This is not recommended, except for testing purposes.

Improving Wireless Range: Choosing the Right Equipment

This article is useful:

• To compare how various wireless devices should be used, or
• If Choosing the Best Locations and Tuning Your Equipment don’t get the performance you want, or
• You want a big improvement immediately at a reasonable cost.

The cheaper solutions are first, followed by more expensive, but very powerful ones. A network with more than a few computers may benefit from a combination of approaches.

I. A New Router
II. A Second Router as a Wireless Access Point
III. Powerline
IV. An Access Point
V. An Antenna
VI. A Site Survey

I. A New Router

Replace your existing router with a better one. This is recommended if your router is a couple years old. A new router will probably double your coverage in a single area.

Advantages

• Making the change is likely to be simple. New NETGEAR routers come with wizards that make basic installation easy, and will probably fit with your existing network with few other changes.
• The newest NETGEAR routers are excellent values.
• New routers such as the WPN824 RangeMax can deal with tricky wireless environments without any tuning at all.

Disadvantages

• May require you to also buy new adapters to get all the router benefits.
• Isn’t best for difficult environments with spotty coverage, or for covering large areas such as entire buildings.

II. A Second Router to use as a Wireless Access Point

With this solution you disable features of a wireless router, leaving the wireless transmitter working. This configuration uses an existing wired or wireless router. Here’s a sample configuration.

Advantages

• Low cost. With an inexpensive router, this is the cheapest solution.

Disadvantages

• NETGEAR provides no free support at all for this.
• NETGEAR routers are not designed for this purpose, so configuration, behavior, features, and performance may not be as expected. Problems may include no DHCP passthrough and stopping access point roaming.
• Only suitable for small, moderately loaded networks. E.g., not good for running a game server or a database server.
• Can be slightly difficult to configure.

III. Powerline

Instead of networking through the air, or through Ethernet cables, Powerline uses the existing electrical wires in your walls. See Powerline FAQ.

Advantages

• Fairly low cost.
• Excellent solution in difficult RFI environments, since Powerline signals don’t go through the air.
• Good security for casual users.
• Powerline can easily be moved in a house. No reconfiguration is needed, units can be plugged in where and when you want.
• Doesn’t require continuous wireless coverage, just an available electrical plug.
• Works nicely with wireless technology to cover “blind spots”.

Disadvantages

• Powerline performance is not limited by RFI, but it is limited by noisy power. As with wireless, it’s difficult to know exactly how well Powerline will work until you try it.
• Powerline is often not suitable for businesses, dorms, and hotels. See Assessing Powerline for Business Environments.

IV. An Access Point

Dedicated access points have better performance and features than routers that are used as access points (see above).

Advantages

• Can cover an area far distant from your wireless router, without having to cover all the area in between.
• Potentially excellent LAN performance, especially with careful configuration and placement.
• Advanced security features.
• Access points are covered by NETGEAR’s free support policy.

Disadvantages

• Business access
• Using access points in repeater mode does not result in the best performance.
• Configuration is more complicated than other solutions.

V. Antennas

Antennas can provide great power. NETGEAR antennas and boosters are available in the United States that transmit for miles. Less powerful antennas may still cover an entire building.

Advantages

• Antennas give excellent throughput over large continuous areas.
• Antennas are available for outdoor, as well as indoor use.
• Antennas are often the most practical solution for networking between buildings.

Disadvantages

• Antennas must be connected to equipment specifically designed for them. This adds to cost.
• A site survey may be needed before installation. (See below.)
• Antennas may require professional installation. This adds to cost.
• In thunderstorms, connections may be slow or temporarily interrupted. Critical networking or networking in areas of frequent storms may require other network connections as a backup.
• Regulations in all countries limit how antennas can be used.

VI. A Site Survey

A site survey is a study of your environment, your network, and your computing needs. Self-help site survey software is available, but a complete evaluation requires a professional. For a network of more than a few computers, plan on using 1-2 hours of help in the range of $100-$150 / hour. For all but small networks using the cheaper approaches described above, the amount spent will be saved by avoiding buying wrong equipment, or equipment that isn’t cost-effective in your situation. These professionals are found online or in the Yellow Pages under “Radio Communication Equipment”.

Improving Wireless Range: Testing

Test as little or as thoroughly as you like. When making changes, you’ll want to test to see how you’ve improved. When you test, use your actual environment. For example, test at home while others use computers, talk on cell phones, and run the microwave.

Start with the cheapest and fastest test:

See If It Works

If the network works, and you’re satisfied with the performance, don’t do anything else. If it seems like it’s working, it is.

To Test Coverage Using the NETGEAR Utility

Each wireless device has a software utility monitoring signal strength and transmission. Most have a meter that reads green, yellow or red. (One adapter has bullets from 8 to 0, instead.) When the meter is green, then that device is getting a strong signal and good throughput. As you move further away from the router or access point, the signal strength drops to yellow. As the signal gets weaker, throughput automatically is adjusted downward, but the connection is maintained. Eventually, you move so far away that the meter turns red: at that point you will have throughput and connection problems.

You can get a idea of where signal is strong by walking around and seeing where it’s green, yellow or red. In fact, this is a technique used by NETGEAR in testing.

To Test Whether Two Transmitters are Too Close

The closer two routers or access points using the same channel are, the more they interfere with each other’s signal. Take an adapter plugged into a laptop, and establish a connection with a router or access point. Then move to within 6 feet (2 meters) of the router or access point’s antenna. Scan the network for available signals. If you can see any other router or access point that is using the same channel, then you should either:

• Move the routers or access point further apart.
• Turn off one of the routers or access points.
• Change the channel of one of the routers or access points.

To Test For Packet Loss

This test is good to run while someone else is setting the position of the antenna for you.

The throughput meter gives an accurate measure of how much traffic is on your network, but does not show how much traffic is being lost and which must therefore be retransmitted. When packets are frequently dropped — for example in a very noisy environment — it puts a burden on your network. A small amount of packet loss on an Ethernet network is acceptable (1% or 2%). However, if there is several percent loss, or there are periods of several seconds of packet loss, then you should optimize your network.

Test packet loss using ping. (For other information, including how to interpret other ping results, see Testing Connections with Ping.)

1. On a Windows computer, type Start > Run > cmd. The cmd.exe window appears.

2. At the command prompt (the flashing cursor), type ping IPAddress -t, where “IPAddress” is replaced by the LAN address of the router, access point, or adapter you transmitting to. So your command would look something like this: ping 192.168.0.2 -t.

3. Press Enter. Now, every second, the device you are on will ask the remote device to respond to it.

4. When a packet is lost, the words “Request Timed Out” are displayed.

5. Press Control and the C key at the same time to end the test. The test concludes with a summary of all the packets lost.

6. Close the cmd.exe window whenever you choose.

6. Use Professional Help

Professionals have specialized equipment and experience that can be used to set up very effective networks. This is especially attractive for setting up wireless networks in large buildings or large outdoor areas. A professional can:

• Draw up a “site survey” map that identifies sources of noise and obstructions.
• Test the effectiveness of an existing wireless network.
• Make recommendations about equipment purchase.
• Make recommendations about equipment location and configuration.
• Make recommendations about how to mitigate noise sources.
• Do the actual equipment installation for you.

These professionals can be found online or in the Yellow Pages under “Radio Communication Equipment”.