Although troubleshooting any piece of network equipment can be frustrating, troubleshooting wireless equipment is a little more so because there’s so much that you just can’t check. After all, radio waves are invisible. That’s the rub with improving the throughput (performance) of your wireless home network, but we’re here to help. And don’t get hung up on the term throughput (the effective speed of your network); when you take into account retransmissions attributable to errors, you find that the amount of data moving across your network is lower than the nominal speed of your network. For example, your PC may tell you that you’re connected at 54 Mbps, but because of retransmissions and other factors, you may be sending and receiving data at about half that speed.
The trick to successfully troubleshooting anything is to be logical and systematic. First, be logical. Think about the most likely issues (no matter how improbable) and work from there. Second, be systematic. Networks are complicated things, which mandate a focus on sequential troubleshooting on your part. Patience is a virtue when it comes to network debugging.
Perhaps hardest of all is making sense of performance issues — the subject of this topic. First, you can’t get great performance reporting from consumer-level access points, or APs. (The much more expensive ones sold to businesses are better at that.) Even so, debugging performance based on performance data in arrears is tough. Fixing performance issues is a trial-and-error, real-time process. At least most wireless client devices have some sort of signal-strength meter, which is one of the best sources of information you can get to help you understand what’s happening.
Signal-strength meters (which are usually part of the software included with your wireless gear) are the best way to get a quick read on your network. These signal-strength meters are used by the pros, says Tim Shaughnessy at NETGEAR: "I would highlight it as a tool." We agree.
It’s a good idea to work with a friend or family member. Your friend can be in a poor reception "hole" with a notebook computer and the wireless utility showing the signal strength. You can try moving or configuring the access point to see what works. Just be patient — the signal meter may take a few seconds to react to changes (count to ten after each change, it’s what we do to make sure we are not rushing the process).
Because not all performance issues can be tracked down (at least not easily), in this topic we introduce you to the most common ways to improve the performance of your wireless home network. We know that these are tried-and-true tips because we have tried them ourselves. We’re pretty good at debugging this stuff by now. We just can’t seem to figure out when it’s not plugged in!
Move the Access Point
A wireless signal degrades with distance. You may find that the place you originally placed your access point, or AP, doesn’t really fit with your subsequent real-world use of your wireless local area network. A move may be in order.
After your AP is up and working, you will probably forget about it — people often do. APs can often be moved around and even shuffled aside by subsequent gear. Because the access connection is still up (that is to say, working), sometimes people don’t notice that the AP’s performance degrades when you hide it more or move it around.
Check the obvious
Sometimes, what’s causing you trouble is something simple — which you can fix simply. For example, one of us was surprised that his access point just stopped working one day. The culprit was his beagle, Opie, who had pulled the plug out of the wall. As obvious as this sounds, it took the unnamed person an hour to figure it out. Now, if someone told you, "Hey, the AP just stopped working," you would probably say "Is it plugged in?" The moral: Think of the obvious and check it first.
Here are a few more "obvious" things to check:
Problem: The power goes out and then comes back on. Different equipment takes different lengths of time to reset and restart, which causes the loss of connectivity and logical configurations on your network.
Solution: Sometimes, you need to turn off all your devices. Leave them all off for a minute or two, and then turn them all back on, working your way from the Internet connection to your computer — from the wide area network (WAN) connection (your broadband modem, for example) back to your machine. This process allows each device to start up with everything upstream properly in place and turned on.
Problem: Your access point is working fine, with great throughput and a strong signal footprint, until one day it all just drops off substantially. No hardware problem. No new interferers installed at home. No new obstructions. No changes of software. Nothing. The cause: Your next-door neighbor got an access point and is using his on the same channel as yours.
Solution: This problem is hard to debug in the first place. How the heck do you find out who is causing invisible interference — by going door to door? "Uh, pardon me; I’m going door to door to try to debug interferers on my access point. Are you suddenly emitting any extraneous radio waves? No, I’m not wearing an aluminum foil hat. Why?" Often, when debugging performance issues, you need to try many of the one-step solutions, such as changing channels, to see whether they have an effect. If you can find the solution, you have a great deal of insight into what the problem was. (If changing channels solved the problem, someone nearby was probably using the same channel, and you can then start tracking down who that is!)
The wireless utility for the adapter may have a tab, called a site surveyor station list, that lists the APs in range. The tab may show your neighbor’s access point and the channel it’s on.
APs that follow the 802.11n draft 2.0 standard dynamically switch channels when there’s too much interference. The 802.11n equipment we have seen does not even give you an option to choose a channel because of this dynamic switching capability. Keep in mind that the higher speed of these APs is achieved by combining channels so they can send and receive data on more than one channel at a time and can use more than one antenna to send and receive data. To take full advantage of the dynamic nature of 802.11n, you need an 802.11n AP or router as well as an 802.11n network adapter in your computer.
Before you chase a performance issue, make sure that you have one. The advertised rates for throughput for the various wireless standards are misleading. What starts out at 54 Mbps for 802.11g is really more like a maximum of 36 Mbps in practice (and less as distance increases). For 802.11n, it’s more like 125 Mbps at best, rather than the 248 Mbps you hear bandied about. You occasionally see high levels (like when you’re within a few yards of the access point), but that’s rare. The moral: If you think that you should be getting 248 Mbps but you’re getting only 100 Mbps, consider yourself lucky — very lucky.
Speed: What to expect
Many of the newest technologies use multiple methods to greatly increase the effective speed and range of wireless connections. Unfortunately, much of that speed boost can be lost if you’re in an area with lots of radio interference. If you have lots of noise in the area or many networks fighting for open channels, the base speed of what you’re using — 54 Mbps for n and 11 Mbps for g — is the best you can hope for.
Make sure that other gear isn’t blocking your AP, that it isn’t flush against a wall (which can cause interference), that its vertical orientation isn’t too close to the ground (more interference), and that it isn’t in the line of sight of radio wave interference (such as from microwaves and cordless phones). Even a few inches can make a difference. The best location is in the center of your desired coverage area (remember to think in three dimensions!) and on top of a desk or bookcase.
Move the Antenna
Remember the days before everyone had cable or satellite TV? There was a reason why people would fiddle with the rabbit ears on a TV set — they were trying to get the antenna into the ideal position to receive signals. Whether the antenna is on the client or on the access point, the same concept applies: Moving the antenna can yield results. Because different antennas have different signal coverage areas, reorienting them in different declinations (or angles relative to the horizon) changes their coverage patterns. A strong signal translates to better throughput and performance.
Look at it this way: The antenna creates a certain footprint of its signal. If you’re networking a multistory home and you’re not getting a great signal upstairs, try shifting your antenna to a 45° angle, to increase a more vertical signal — that is, to send more signal to the upstairs and downstairs and less horizontally.
Change Channels
Each access point broadcasts its signals over portions of the wireless frequencies called channels. The 802.11g standard (the most common system at the time we wrote this topic) defines 11 channels in the United States that overlap considerably, leaving only 3 channels that don’t overlap with each other. The IEEE 802.11a standard specifies 12 (although most current products support only 8) nonoverlapping channels. The 802.11n draft 2.0 proposal uses the same 11 channels as 802.11g at 2.4 GHz and the 12 channels of 802.11a at 5 GHz in the United States, again with overlapping channels.
802.11n is designed to work with all the previous standards. The dynamic switching of channels on either frequency available to it means you have a lot less to configure during setup. Some single-frequency APs still give you the option to choose channels at the beginning, but they don’t necessarily have to stay on that channel as they work.
This situation affects your ability to have multiple access points in the same area, whether they’re your own or your neighbors’. Because channels can overlap, you can have the resulting interference. For 802.11g access points that are within range of each other, set them to different channels, five apart from each other (such as 1, 6, and 11), to avoid inter-access point interference.
Check for Dual-Band Interference
Despite the industry’s mad rush to wirelessly enable every networkable device it makes, a whole lot hasn’t been worked through yet, particularly interoperability. We’re not talking about whether one vendor’s 802.11g PC Card works with another vendor’s 802.11g access point — the Wi-Fi interoperability tests usually make sure that’s not a problem (unless one of your products isn’t Wi-Fi certified). Instead, we’re talking about having Bluetooth,working in the same area as 802.11b, g, and n, or having older 802.11a APs and 802.11b, g, and n APs operating in the same area. In some instances, like the former example, Bluetooth and 802.11b, g, and n operate in the same frequency range, and therefore have some potential for interference. Because 802.11a and 802.11b, g, and n operate in separate frequency bands, they’re less likely to be exposed to interference.
Some issues also exist with how the different standards are implemented in different products. Some APs that support 802.11g and n, for example, really support one or the other — not both simultaneously. If you have all g in your house, that’s great. If you have all n, that’s great. If you have some n and the access point detects that g is in the house, it could downshift to g rates. You may be all set, but then your neighbor upstairs may buy a g network adapter (because you’ve said "Sure, no problem, you can share my Internet connection."). He’s not only freeloading, but he also could be forcing your whole access point to shift down to the lower speeds.
To be fair, many of these very early implementation issues have gone away while vendors refined their solutions. Check out how any multimode access point that you buy handles dealing with more than one variant of 802.11 at the same time. Most newer APs compartmentalize their signals so that they can allow the faster 802.11n signals to connect at full (or nearly full) speed, while still allowing older 802.11g signals on the network, which is very nice and almost necessary.
Check for New Obstacles
Wireless technologies are susceptible to physical obstacles.One person in our neighborhood noticed a gradual degradation of his wireless signal outside his house, where he regularly sits and surfs the Net (by his pool). The culprit turned out to be a growing pile of newspapers for recycling. Wireless signals don’t like such masses of paper.
Move around your house and think about it from the eyes of Superman, using his X-ray vision to see your access point. If you have a bad signal, think about what’s in the way. If the obstacles are permanent, think about using a HomePlug or other powerline networking wireless access point to go around the obstacle by putting an access point on either side of the obstacle.
Another way to get around problems with obstacles is to switch technologies. In some instances, 802.11n products could provide better throughput and reach than your old 802.11g when it comes to obstacles. Many draft 2.0 products use special radio transmission techniques that help focus the signal into the areas containing your wireless client devices. These aimed signals can help you overcome environments that just don’t work with regular Wi-Fi gear. If you’re in a dense environment with lots of clutter and you’re using 802.11g, switching to 802.11n may provide some relief.
Install Another Antenna
In next topic, we point out that a detachable antenna is a great idea because you may want to add an antenna to achieve a different level of coverage in your home. Different antennas yield different signal footprints. If your access point is located at one end of the house, putting an omnidirectional antenna on that access point is a waste because more than half the signal may prove to be unusable. A directional antenna better serves your home.
Antennas are inexpensive relative to their benefits and can more easily help you accommodate signal optimization because you can leave the access point in the same place and just move the antenna around until you get the best signal. In a home, there’s not a huge distance limitation on how far away the antenna can be from the access point.
802.11n systems, with their special MIMO transmission technologies, are typically designed to use only the antenna that came with the system. You can’t just slap any old antenna onto an 802.11n AP or router. For the most part, this isn’t a problem, simply because 802.11n has significantly better range than older systems such as 802.11g.
Use a Signal Booster
Signal boosters used to be offered when 802.11g came out a few years ago. The concept was that if you have a big house (or lots of interference), you can add a signal booster, which essentially turns up the volume on your wireless home network transmitter. Unfortunately, it does nothing for the wireless card in your computer, and that was the great failing in this product. Your base station would be stronger, but your workstation’s signal would be the same. So, you could see your base station better, but couldn’t communicate with it any better because your wireless card was at the same signal strength.
A signal booster was supposed to improve the range of your access point. The 802.11g products now typically have a range of 100 to 150 feet indoors mainly because 802.11g products operate at a relatively low frequency. 802.11a products have an even shorter reach — up to 75 feet indoors — because the higher frequencies that 802.11a use lose strength faster with distance than do the lower frequencies used by 802.11g. The 802.11n products from companies such as Belkin reach at least another 25 to 50 feet, and many products using MIMO also achieve better range.
The signal range of the APs now on the market is steadily increasing because manufacturers are creating more efficient transceiver chipsets. We recommend reading the most recent reviews of products because products truly are improving monthly.
You can still find signal boosters for sale on eBay from companies such as Linksys, which sold the WSB24 Wireless Signal Booster that piggybacked onto a Linksys wireless access point (or wireless access point router).
Signal boosters have pretty much been discontinued, and even though your can still get them, we strongly recommend staying away from them because you have many other options that are more versatile and compatible with what you already have and that keep you up-to-date with the newest technologies.
If you happen to come across one of these — or someone gives you one — you should know that signal boosters are mated devices, which means they’re engineered for specific products. Vendors have to walk a fine line when boosting signals in light of federal limits on the aggregate signal that can be used in the unlicensed frequencies. For example, the Linksys Wireless Signal Booster was certified by the Federal Communications Commission (FCC) for use with the WAP11 Wireless Access Point and BEFW11S4 Wireless Access Point Router only. Linksys says that using the WSB24 with any other product from either Linksys or another vendor voids the user’s authority to operate the device.
The main reason that companies such as Linksys sold their signal boosters for use with only their own products is certification issues. The FCC has to approve any radio transmission equipment sold on the market. A great deal of testing must be done for a piece of gear to get certified, and the certification testing must be done for the complete system — and vendors usually do this expensive testing only with their own gear.
As some reviews have pointed out, however, you could use the WSB24 with any wireless LAN product that operates in the 2.4 GHz band — notably, 802.11g products. You couldn’t use it with 802.11a or any dual-band 2.4/5 GHz products; its design couldn’t deal with the higher frequency.
Add an Access Point
Adding another access point (or two) can greatly increase your signal coverage, as shown in Figure 18-1. The great thing about wireless is that it’s fairly portable — you can literally plug it in anywhere. The main issues are getting power to it and getting an Ethernet connection (which carries the data) to it.
The first item is usually not a problem because many electrical codes require, in a residence, that power outlets be placed every eight feet. The second issue (getting the Ethernet connection to your AP) used to be a matter of running all sorts of wiring around the house.
After you get the connectivity and power to the place you want, what do you need to consider when you’re installing a second AP? Choose the right channel: If you have auto channel selection in your AP, you don’t need to worry because your AP’s smarts handle it for you. If you’re setting the channel manually, don’t choose the same one that your other AP is set to.
Figure 18-1:
Three APs provide a much stronger signal than a single AP.
Carefully choose which channels you use for each of your access points. Make sure that you have proper spacing of your channels if you have 802.11g access points (which have overlapping bands). Read the section "Change Channels," earlier in this topic, for more information on channels.
Add a Repeater or Bridge
Wireless repeaters are an alternative way to extend the range of an existing wireless network instead of adding more APs. We talk earlier in this topic about the role of bridges and repeaters in a wireless network.
Not many stand-alone repeaters are on the consumer market. However, what’s important for our discussion is that repeater capability is finding its way into the AP firmware from many AP vendors. A wireless AP repeater basically does double duty — it’s an AP as well as a wireless connection back to the main AP that’s connected to the Internet connection.
Meraki Networks (meraki.com) has created the Meraki Mini ($50), the ultimate smart AP. If you use one connected to an Ethernet connection from your wireless network, you get a simple wireless AP running 802.11b/g. You add another unit by plugging it into an electrical connection within range of the first unit. The second unit will find the first and, using a sophisticated mesh routing technology, will increase the range of the first AP and increase the capacity as well. Meraki is selling these supersmall APs (about the size of a deck of cards) for communities. While you can buy a couple for yourself, they want to sell these to whole neighborhoods so you and your friends can build your own wireless mesh network. At its most basic level, a repeater simply regenerates a wireless network signal to extend the range of the existing wireless LAN. You set the two devices to the same channel with the same service set identifier (SSID), thus effectively broadening the collective footprint of the signal.
If you have throughput performance issues because of interference or reach, putting an AP into repeating mode may help extend the reach of your network.
However, it’s not clear that adding a repeater helps actual throughput in all situations, unfortunately. Some testing labs have cited issues with throughput at the main AP because of interference from the new repeating AP (which is broadcasting on the same channel). Others note that the repeater must receive and retransmit each frame (or burst of data) on the same RF channel, which effectively doubles the number of frames that are sent. This effectively cuts throughput in half. Some vendors have dealt with this through software and claim that it’s not an issue.
It’s hard at this juncture to make a blanket statement about the basic effectiveness of installing an AP in repeater mode, particularly versus the option of running a high-quality Ethernet cable to a second AP set on a different channel. If you can do the latter, that’s preferable.
When you’re using the bridging and repeating functions of APs and bridges, we recommend that you use products from the same manufacturer at both ends of the bridge, to minimize any issues between vendors. Most companies support this functionality only between their own products and not across multiple vendors’ products.
Check Your Cordless Phone Frequencies
The wireless frequencies at 2.4 GHz and 5.2 GHz are unlicensed (as we define in Part I of this topic), which means that you, as the buyer of an AP and operator of a wireless broadcasting capability, don’t need to get permission from the FCC to use these frequencies as long as you stay within certain power and usage limitations as set by federal guidelines. It also means that you don’t have to pay any money to use the airwaves — because no license is required, it doesn’t cost anything.
Many consumer manufacturers have taken advantage of free radio spectrums and created various products for these unlicensed frequencies, such as cordless phones, wireless A/V connection systems, RF remote controls, and wireless cameras.
A home outfitted with a variety of Radio Shack and X10.com gadgets may have a fair amount of radio clutter on these frequencies, which can cut into your network’s performance. These sources of RF energy occasionally block users and access points from accessing their shared air medium.
As home wireless LAN use grows, people report more interference with home X10 networks, which use various wireless transmitters and signaling over electrical lines to communicate among their connected devices. If you have an X10 network for your home automation and it starts acting weird (such as the lights go on and off and you think your house is haunted), your LAN might be the source of the problem. A strong wireless LAN in your house can be fatal to an X10 network.
At some point, you have to get better control over these interferers, and you don’t have many options. First, you can change channels, like we mention earlier in this topic. Cordless phones, for example, use channels just like your local area network does; you can change them so that they don’t cross paths (wirelessly speaking) with your data heading toward the Internet.
Second, you can change phones. If you have an 802.11n or g network operating at home on the 2.4 GHz band, consider one of the newer 5 GHz cordless phones for your house. Note: An old-fashioned 900 MHz phone doesn’t interfere with either one, but finding one these days is a miracle.
You may find that your scratchy cordless phone improves substantially in quality and your LAN performance improves too. Look for other devices that can move to other frequencies or move to your 802.11 network.
At the end of the day, interference from sources outside your house is probably your own fault. If your neighbor asks you how your wireless connection works, lie and tell her that it works horribly. You don’t want your neighbor getting one and sending any stray radio waves toward your network. Do the same with cable modems. You don’t want your neighbor’s traffic slowing you down because it’s a shared connection at the neighborhood level. Interference is a sign of popularity — it means that lots of other people have caught on. Keep it your little secret.
