Wireless Networking - Hype, Reality and How-To

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Like it says – Mike

INTRODUCTION

Wireless networking can add flexibility and ease of deployment for your network if you understand its limitations. My belief is that it can be a valuable addition to a wired network, but with current technology is unable to be a replacement for wired networks where performance and reliability are important.

I am coming from the perspective of having been part owner of a WISP (Wireless ISP). I have also set up wireless LANs for many clients and have had a wireless LAN in my home for a number of years. I have my opinions and recommendations – whether they match anyone else’s or whether they’re the best for your particular layout, who knows… but I have known for years that wireless promises much that it can’t deliver. I will expose the truths that marketing doesn’t want you to know, and give you tips on how to plan and improve your wireless network.

BACKGROUND

Wireless networking. What is that? Well, basically it is networking your computer to other computers using radio waves instead of a physical wire. We use wireless remote controls on our televisions, cordless telephones and in recent years the usage of cellular phones have increased dramatically. With seemingly every electronic device shedding their copper umbilical cords, why should computers be left out of this mass evolution? Wireless networking was developed to enable computers to shed the network cable.

As with any other communications device, wireless networking relies upon standards to allow devices of varying brands to communicate with one another. You may have heard of WiFi or 802.11. WiFi commonly refers to the standard of 802.11b which is probably the most widespread at this time. If your device supports it, that means you have a fighting chance to be able to connect to any commercial WiFi hotspot, which is basically a free or fee based public wireless internet connection. WiFi is not the best nor the fastest, but is the most common because it is the lowest common denominator of wireless standards, but is far from being the only one.

802.11a is a rare one, found mostly in more expensive devices and unless the device explicitly supports the other standards, is inoperable with the more common standards. This standard uses 5.8 GHz frequencies while all other standards use 2.4 GHz frequencies and is so rare that it is unlikely to find such devices even for sale at the more common retailers.

802.11b is advertised as 11 Mbps and because it is the most widespread, is the standard for WiFi. That’s important knowledge for anybody with a notebook looking for a wireless internet connection. Since it is so common, all notebooks sold today will support it if it has wireless connectivity at all.

802.11g is the current reigning standard. It operates on the same frequencies as 802.11b and indeed is backwards compatible with the older standard while allowing for higher speeds of 54 Mbps, thus often referred to with the catchier moniker of 54g.

802.11n is the next standard. Currently there are no official 802.11n devices; however some manufacturers are trying to jump the gun by offering “pre-N” devices for sale. Though manufacturers are quick to promise guaranteed compatibility with the eventual standard, I hesitate to recommend such devices due to the track record of tech companies promising more than they eventually deliver. 802.11n uses the same frequencies as the other common standards, but combines multiple channels and antennas to increase speed, range and reliability. For these reasons 802.11n has much to recommend, but that’s the eventual standardized product and not the “pre” offerings.

MIMO is a “pre-pre-N” offering. While it has been popular with manufacturers in giving them a new product to market, it’s even less likely to be inter-operable with the eventual standard.

WHAT TO EXPECT

Expect wireless to be slower than wired.

Wireless “speeds” are a marketing gimmick. With a wired LAN your 100 Mbps full duplex speed is 100 Mbps both ways. With a wireless LAN, that 11 Mbps is both ways added up, meaning your throughput is only 5.5 Mbps. With a 54 Mbps wireless connection, your throughput is only 27 Mbps.

The “turbo” speeds are even worse.

A wireless product advertised at 108 Mbps does not give twice the throughput of a 54 Mbps wireless connection, plus these “nonstandard” protocols may not be compatible between brands, meaning that the network will fall back to “standardized” speeds. Also, all this throughput is in perfect conditions. In real life you may not get a perfect signal strength or signal quality, so throughput goes down.

Expect wireless to be less reliable than wired.

How many of you cell phone users have gotten dropped calls even when you were standing still? Cingular has recently started advertising that they are rated #1 for fewest dropped calls. Note that they don’t claim NO dropped calls, just fewer than other wireless providers.

A dropped wireless connection means no web pages. It means your downloads stall. It means you get disconnected from the server you were gaming on. It isn’t a matter of IF a connection will be dropped, but WHEN. This doesn’t mean to say that wireless connections are so unreliable as to be unusable, but it just means that it is not as reliable as a wired connection. After all, when was the last time your land-line phone connection got dropped?

Expect hardware to cost more than wired.

Pretty much all motherboards and even notebook computers have had a 10/100 network interface built in to them for a number of years. Since Intel started the Centrino program, notebooks with wireless have become commonplace, but desktop computers and motherboards with few exceptions do not come with wireless networking. This means added cost to add wireless to a desktop computer.
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PLANNING YOUR WIRELESS NETWORK

“An ounce of prevention is worth a pound of cure.”

This saying can be applied to wireless networks by changing prevention to planning and cure to troubleshooting, so “An ounce of planning is worth a pound of troubleshooting.” With the convenience offered by not being tied down to a network outlet, people overlook the fact that wireless networks do need some planning for it to have the greatest range and reliability.

You will need to figure out what equipment you need and where that equipment will be installed. The basics are that you will want all equipment to be of the same type/standard. For instance, the most popular is 802.11g so you may want to plan your network around using that type of equipment and shop accordingly.

If you are just sticking to that standard then just about anything will work. If you were hoping for faster speeds, then you need to start thinking in terms of one manufacturer. The reason is that with non-standard speeds, a card from one manufacturer may not be able to talk at that speed to a card from a different manufacturer. To increase chances of success, buy all cards from the same manufacturer and of the same model line.

Besides choosing type and brands, you will need to choose the type of components. Notebooks may have mini-PCI cards built in or wireless PC cards (formerly known as PCMCIA). Desktop computers use PCI cards. Both notebooks and desktops can use USB adaptors, though I feel that those adaptors are more for convenience and ease of installation and may not be the best choice for a permanent setup.

There are a few reasons I say this. One is that though it may seem convenient at first, it is another item sticking out of your computer and usually on a cable because they often am not slim enough to coexist peacefully with other devices plugged in around it. Another is that most USB devices (but not all) do not have higher gain antennas or the capability to use external antennas. Some companies now make USB adaptors with higher gain directional antennas which would solve one of those issues. For the access point that the clients connect to, wireless routers (a router with a wireless access point built in) are near universal now as stand alone access points and routers are getting rare. It is possible to disable the router portion of many of these devices and thus use them as standard access points.

As for where the devices should be set up, live by these rules of thumb:

Put the access point as close as possible to the center of the whole area that you plan to have wireless coverage. Know that metal (refrigerators, filing cabinets, the computer’s tower case itself) will block/bounce the signal and walls will attenuate (diminish) the signal. If the incoming internet connection is at a location which isn’t optimal for wireless, consider have a router at the internet connection and run a network cable between the two points.

BASIC SETUP

Get decent equipment that have removable antennas!!! This usually rules out USB devices.

Already touched upon above, purchase equipment with removable antennas. This is especially important for the access point/wireless router because replacing an antenna at a client will only improve that client while replacing an antenna at the base station (access point) will improve all clients.

Plan placement of your antennas (they can be separate from devices) so as to minimize traveling through walls or anything metal – or anything at all for that matter.

Access point antenna needs to be as close as possible to the center of the area you want wireless coverage. Don’t place your PC behind a filing cabinet.

Find a channel that isn’t taken by a neighbor (or overlapped).

This one may be tricky. You will need a computer that already has a wireless card installed and use it to scan for signals. The utilities that comes with wireless cards often have a “site survey” section where it will scan for any wireless signals and give you some basic information about them. Hopefully the utility will also report on hidden wireless signals (those that don’t broadcast SSID).

What you want to do is to write down the channels of all wireless signals you pick up with perhaps a note on signal strength. There are 11 channels available for use. The problem is that the wireless signal is not locked within the confines of a single channel, but instead actually covers a band of channels centered on the selected channel.

This means if you have two wireless networks near each other and one is using channel 4 and the other is using channel 5, they will actually interfere with each other. Some wireless purists will claim that there are only three usable wireless channels, 1-6-11. I’ve actually seen success with squeezing four, 1-4-8-11. This also depends on the signal strength of nearby connections. Obviously a strong wireless signal will have a greater chance of interfering with a near-overlapping channel than a weaker signal. If you find that there are a lot of wireless connections in your vicinity, you may have to decide on which one you will overlap by looking at signal strength. For instance:

channel/strength
1/**
4/*
6/*****
9/***
11/*****

Confronted with such a site survey, I would place my access point on channel 3 because the ones likely to interfere are weaker signals.

Set up some kind of security for your wireless network, if only to keep your neighbor’s son from sucking up your bandwidth downloading torrents or something.

If you really want to share your internet connection and don’t care who uses it or who can browse your network, then feel free to leave your connection wide open. Some people do this intentionally to provide such a service and that’s fine, but if you don’t want anyone to be able to connect to your network and use it or browse your shared files, then secure your wireless network.

There are many levels of security and many ways to achieve security.

For the absolute paranoid, there is to my knowledge no 100% security for wireless networking, so if you are the type to wear aluminum hats, then hard-wire all your computers. The highest security does, however, make it darn near impossible to break in and involves using strong encryption, using RADIUS authentication servers, using VPN to a proxy server, and using non-standard setups (such as 802.11a).

All except the first item are expensive to implement. Don’t worry though, you aren’t trying to keep out a world class hacker/cracker, but just the nosey kid next door. No matter how high an opinion you have of yourself, those world class hackers/crackers are not interested in what your network has to offer and won’t even waste their time with you.

People who want to use a particular wireless connection will need to have a reason to do the work and risk getting caught, such as targeting a bank or a company. People who just want a wireless connection to send some email and download some pr0n will just try to find an unsecured network, and there are so many of those around that nobody will waste their time with your network if your neighbor is giving it away for free.

For your own network, just use whatever level of encryption that is supported by all your devices. I know that what I say may sound counter to what all the security experts recommend, but know that they are in the business to make you paranoid and thus make them money. Any encryption will keep out the casual users and for the professionals that know how to break in, don’t worry because they don’t even know you exist.

By the way, my security advice is primarily for home users. I do not recommend any financial institutions or large businesses to use such low levels of security because they are the ones that do have something to protect. Joe Sixpack home user does not have anything to protect besides his pr0n and illegal MP3 collection.
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IMPROVING RANGE

What blocks wireless signals? Well, anything that blocks light will attenuate wireless signals to some degree, but metal is what will block more than any other material. This means you either have to remove environmental factors or you have to boost your signal. Removing environmental factors can be as easy as rearranging so that the wireless access point or wireless router is not behind a metal filing cabinet. Sometimes moving things around a few inches to a few feet will work wonders.

If you’ve rearranged things as much as you can, the next step is to boost the wireless signal and there are two ways to do that, a higher gain antenna or higher power output. The easiest thing to do is to replace the stock removable antenna on the access point/router with a higher gain unit. Those attach just like the stock antenna but are usually larger.

For antennas, “gain” is measured in dBi. The typical stick antennas with most consumer wireless equipment is 2 dBi. You can easily purchase up to 24 dBi gain directional antennas and up to 15 dBi gain omni antennas. Note that higher gain usually means physically larger antenna. Often just going from the 2 dBi stick antenna to 6-10 dBi will result in greatly improved signal.

If you have to go greater than that in a house, well then there’s probably something else causing interference. Oh yeah – anytime you start swapping antennas or amplifiers, know your connector. There are a number of different connectors in wide use. Most of the consumer devices use a type called RP-SMA.

If you’ve tried everything including high gain antennas, changing channels, moving antennas around, making sure hardware is working, and just can’t get a strong signal, then it’s time to AMPLIFY.

There are some FCC laws regarding how much power you can put out in these unlicensed frequencies that go something like this… 100 mW. Now, I’m not 100% sure on these things, so if you get fined and your equipment confiscated, don’t come crying to me.

How it works is the radio puts out a certain amount of power. You multiply it by the gain of the antenna but subtract out any losses in connectors and cabling (some cabling loses more than others). Most consumer equipment puts out between 30-50 mW power (depending on channel and design). The 2 dBi antenna doubles it, minus a bit for the antenna’s connector. The typical higher gain antenna is actually on a cable which is good for placement, but you lose some of the gain in the connector and the cabling.

Overall that 6 dBi antenna you purchased may be good for a real-life 1-2 dBi gain over the stick antenna. If this isn’t enough to get you the signal strength you want, then get an amplifier. An amplifier does just what it sounds like, amplifies the signal. Now, it isn’t perfect since it also amplifies any noise in the signal, but often it is “good enough” to make a wireless connection reliable when it was on the edge of reliability.

As for going over what FCC will let you, well – who’s checking? Again, don’t point your finger at me if you get busted, but boosting the signal above allowed levels is like driving 5 MPH over the speed limit on the interstate highway. EVERYBODY does it. Well, not typical home users, but I’m willing to bet that the majority of WISPs does it. AFAIK the FCC doesn’t have officers patrolling around the USA looking for too-strong signals. They only do something about it if someone complains. Still, leave amplification as a last resort because higher gain antennas are always better than amplification and always less expensive.

TROUBLESHOOTING

Sometimes everything is set up properly but wireless isn’t working as well as you think it should. The first thing is that if everything is working but transfer rates are slower than you expect, perhaps you expected too much? Remember that the TRUE throughput of even 54 Mbit wireless is really ¼ that of a 100 Mbit wired Ethernet. Copying files over a wireless network will not be as fast as over a wired network and there is very little you can do about it at this time (until 802.11n is finalized).

Also, the theoretical throughput is only if you have a perfect signal. Once the signal travels through 6 walls to get to the other end of the house, you may be lucky that you have a reliable connection at all, let alone what kind of performance you get from it.

Choose one brand and stick with it. Why? Because all the non-standards (such as any “turbo” speed) may not talk to one another, and I’ve even seen standardized devices not want to network with one another. We’re not talking about from one end of the house to another, we’re talking about setting the two devices right next to each other and they won’t get along. The situation is much improved these days but this was a particular problem when 802.11g first came out. Also, if you want to take advantage of any “turbo” speeds, then you pretty much have to stick with one manufacturer.

See if all clients are having problems (indicating a problem with the access point or channel selection) or if only one client is having a problem (indicating a placement issue or bad hardware). Perhaps consider higher gain antennas if it is just a general weak signal. Also, know that wireless “range” that the manufacturers advertise is usually a lie – okay, that may be too strong a word so let’s use “overly optimistic.”

If you are in the middle of nowhere and out in a field, then wireless may almost work as advertised. Otherwise expect the range to be shorter than the manufacturer claims. This is like your 200 GB hard drive formatting to 186 GB, or you not getting anywhere close to the EPA gas mileage rating in your car. Anyone have a cordless phone from before the 900 MHz era? I recall cordless phone manuals stating that the phones have a 1000′ range. Most people couldn’t make it into their neighbor’s yard before the phones became unusable, and that’s far short of 1000′.

Another thing to try is to change wireless channels. Do a site survey to see what channels your neighbors are on. Perhaps wireless performance degraded over time because more neighbors got wireless routers? If your computer doesn’t report any wireless connections or if there’s only a handful, then you’re okay.

Note that some people (thinking it protects them) turn off SSID broadcast which means Windows won’t report that base station as existing if you use the built-in utilities and not the utility that came with your wireless card (which may or may not report hidden connections). You can use software such as Netstumbler to find even these hidden wireless stations. Once you’ve found them, plot out the channels they use and the signal strength. Chances are that if the signal is too weak for you to use, then it may not interfere too much with your own setup.

Other sources of possible interference are older microwave ovens, older 2.4 GHz phones and wireless A/V senders. Honestly I haven’t seen 2.4 GHz phones interfere, but I HAVE seen wireless A/V senders and older microwave ovens totally kill the wireless signal.

Besides interference, wireless signals can be blocked. What is a wireless signal? Well, basically it is radio waves which is like the second cousin once removed from light waves. Anything that can block light can block wireless signals to a varying degree. Our WISP had connections as far as 7-9 miles. That’s with a clear line of sight, as in you can get really powerful binoculars or telescope and see the other antenna with nothing in between (usually we couldn’t and had to use a GPS to aim).

There are other WISPs that have gotten greater distances than we’ve done. Once you put your equipment inside your house, forcing the signal to go through walls and furniture, the signal can diminish pretty quickly after a couple of walls. Note that some materials tend to block signals more than others. If you put your access point behind a metal filing cabinet, that’s a good way to attenuate the signal. Metal = bad for wireless to travel through. This can affect where you put your devices.
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RANDOM INFORMATION AND SUGGESTIONS

Wireless bridging... doesn’t always work between brands and is yet another thing to figure out how to setup. If you are connecting two LANs and are unable to inexpensively run cabling between the two (let’s say buildings a block away) then wireless bridging may be a feasible solution. If you are just wanting to connect a cluster of hard-wired networked devices into an existing wireless LAN, I have an easy solution for you… a wireless Ethernet converter.

If you need to run a wireless connection over great distances, something to consider is what’s called the Fresnel Zone.

Radio waves travel in a straight line, but takes up space around it. What I mean is this – imagine a laser beam. That’s a fairly coherent line. You can put a laser pointer on the floor and if you don’t have long carpet you can shoot a beam to the opposite wall’s base. Well, radio waves will lose signal strength if you try to do that. Think of the radio waves as a jump rope and the antennas on either end as people swinging the jump rope. It’s actually not that much, but suffice to say that (on a single floor) if you put two wireless devices on a cement floor, you’ll find that signal strength goes up if you raise them just a foot off the floor. This can be pretty important if your distance between antennas is measured in miles.

Antenna polarity and signal shape:

Most equipment assumes vertical polarity. It’s a simple matter with most antennas – basically if it is an omni directional whip antenna, then if it is pointed at the sky it is vertical. Directional antennas will usually have something printed on them directing you to rotate it 90º to change polarity if the antenna supports it. Some directional antennas are made with only one polarity.

As for signal shape, the higher the gain, the more directional the signal. For instance, think of the signal as one of those focusing Mag flashlights. If you focus the beam, it gets smaller but brighter. Same thing with wireless signals: if the beam is focused using a higher gain antenna, then you have to aim it better.

Here’s one part that may be important to wireless networks in multi-story buildings: Omni directional antennas does not mean the beam spreads out in a sphere from the antenna. The antenna has polarity and the beam will spread out in sort of a doughnut shape from the antenna. The lower the gain, the closer to a sphere (but with less strength). The higher gain, the flatter the doughnut gets, but it spreads out farther (more strength on axis).

What does this mean in a multi-story building? Well, planning becomes more essential because you have to make up for weaker signals above/below antennas. Something that can help alleviate dead spots is perhaps locating your antenna close to the first floor ceiling of a two story building, or the floor of the second floor. Also, consider plotting out where all the other wireless devices will be.

For instance if your living room is right over the basement room and the upstairs is right above that, in a straight line, then you can just rotate all the antennas so that they are “horizontal” polarity and pretend that you just have three rooms separated by two walls, turned on its side. If your antenna in the basement is located at one end of the building, another option can be to use a high gain “sector” antenna. These are expensive, but basically you get gain while still having a wide beam. Then, you can just point it towards the opposite corner of the house (attic) and the wide beam will cover the rest of the house.

More wireless clients = less reliable network. This won’t affect most home users but can affect businesses. This is also true of consumer routers, but that’s another story.

If the area you want wireless to reach is really close or really easy to hard-wire, then run a network cable to that location. You’ll thank yourself in the long run.

ACCESS POINT:
Buffalo AirStation Turbo G High Power Wireless Smart Router

This device has a few things going for it:

  1. “High Power” actually means it puts out higher mW than competing devices
  2. Brand tested more reliable than others at Tom’s Networking
  3. I personally use it and have found it reasonably more reliable than a few other brands (note that I’m using “brand” generically because a particular manufacturer can make one good product and another crappy product)
  4. Removable antenna means you can go high gain
  5. Has button on top to easily disable router part so it can be use as an access point with a separate router (in my case, a computer)
  6. Of less utility, has a 125 Mbps mode which only works with other Buffalo products
  7. AOSS for easy setup if using other Buffalo brand equipment

ETHERNET CONVERTER:
Buffalo AirStation Turbo G High Power Wireless Ethernet Converter

Instead of creating two wireless bridges, why not just use two of these and simplify your network? These are wireless clients that are stand-alone boxes with four network ports. Basically you connect these as standard wireless clients and then just plug your devices into them like you would a wired network.

  1. “High Power” actually means it puts out higher mW than competing devices
  2. Brand tested more reliable than others at Tom’s Networking
  3. I personally use it and have found it reasonably more reliable than a few other brands (note that I’m using “brand” generically because a particular manufacturer can make one good product and another crappy product)
  4. Removable antenna means you can go high gain
  5. Of less utility, has a 125 Mbps mode which only works with other Buffalo products
  6. AOSS for easy setup if using other Buffalo brand equipment

AMPLIFIER:
Hawking HSB2 Hi-Gain WiFi Signal Booster

Most – actually all other WiFi amplifiers I’ve seen are for commercial use with N-type connectors. I think this Hawking is one of the few, if not the only unit made with RP-SMA connectors that work with most consumer devices. Another thing is that it has adjustable boost, so you only amplify it however much needed to make your network operational without adding extra noise to the signal. Another benefit of this to other amplifiers is price – it is available under $100 while most other amplifiers are 2-3 times the cost. Note that I have not used this device but have used other amplifiers and they usually do what they claim.

ANTENNAS:
Whatever works with your device for your application (FAB-corp.com)

I’ve purchased from that place and they have reasonable prices. They are geared more for wireless bridging between buildings and WISPs but will sell to end users. I currently use some AirLink+ antennas (Fry’s Electronics house brand) and while they work, they aren’t worth buying at regular pricing of $30. Fry’s often has them on sale for under $10 which makes them worth the (lower) price.

I use an omni on my access point and a directional on my client. Thing is that they used to sell the same thing at either 6 or 7 dBi gain, but now the same items magically are at 8 dBi gain – I wonder about that. They do work though, so as I said for under $10… otherwise go to FAB (linked above) to see what they have.

Remember your connector type. For omni on the access point, the easy thing to do is to replace the “rubber duck” antenna with a higher gain unit and FAB has 5.5 dBi for $10 and 9 dBi for $20. If you need to be able to place/aim the antenna, then find one that’s on a cable. For directional antenna, typically indoors you’d use a small panel antenna and FAB has them starting at $25 which will positively spank those cheap AirLink+ antennas. Note that most of the antennas at FAB use N-type female connectors so you’d need a “pigtail” that’s RP-SMA (probably female) to N-type male. Pigtails can get pricey but are required with these better antennas. When in doubt, call them and they’ll answer your questions.

Mike (AKA Zap)

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