Bluetooth and Other Wireless Networks

Getting the most from computer technology is all about selecting the best and most dominant technology standards. The most dominant technology for wireless home networks is clearly the 802.11 (Wi-Fi) family of technologies defined by the 802.11a, 802.11b, 802.11g, and 802.11n standards.Wi-Fi is, simply, the reason why you’re reading this topic. It’s the technology that has made wireless networks such a huge hit.

But, Wi-Fi isn’t the only game in town. You run into other home networking standards when you buy and install your Wi-Fi gear — standards that make it easier to get Wi-Fi where you want it.

Another popular wireless technology is Bluetooth (a short-range wireless networking system that’s built into many cellular phones). Even if you intend to purchase and use only Wi-Fi wireless networking equipment, you should still be aware of Bluetooth. Who knows? It may come in handy.

We also talk about a few other key wired home networking standards (oops, did we say a dreaded word: wired?) such as HomePlug, the standard for networking over your electrical power cables in your home. As surprising as it may seem, you can actually connect your computers, access points, and other devices over these in-wall cables. What’s more, many APs come with these interfaces onboard to make it easier for you to install that AP wherever you want it. Isn’t that nice? You betcha.

Finally, we talk about a few wireless networking standards that are designed not for data networking in the home, but rather for control networks. These standards, lead by ZigBee and Z-Wave, send signals around your home that let you automate and remotely control devices in the home. For example, you could use a ZigBee or Z-Wave system to turn on lights in remote locations, raise or lower drapes, or adjust your central heat or air conditioning. These are things that adventurous homeowners have been able to do for a long time by using wired solutions or unreliable powerline solutions such as X10; with these new wireless systems, anyone can get into home control and automation without a big wiring job and without the headaches of dealing with the AC powerlines.

Who or What Is Bluetooth ?

One of the most often talked about wireless standards, besides Wi-Fi, is Bluetooth. The Bluetooth wireless technology, named for the tenth-century Danish King Harald Blatand "Bluetooth," was invented by the L. M. Ericsson company of Sweden in 1994. King Harald helped unite his part of the world during a conflict around A.D. 960. Ericsson intended for Bluetooth technology to unite the mobile world. In 1998, Ericsson, IBM, Intel, Nokia, and Toshiba founded Bluetooth Special Interest Group (SIG), Inc., to develop an open specification for always-on, short-range wireless connectivity based on the Ericsson Bluetooth technology. Its specification was publicly released on July 26, 1999. The Bluetooth SIG now includes 3Com, Agere, Ericsson, IBM, Intel, Microsoft, Motorola, Nokia, Toshiba, and nearly 2,000 other companies. Thousands of Bluetooth-enabled products are already on the market, with many more on the way, and over 800 million Bluetooth-enabled devices have been shipped worldwide (that’s a not-so-insignificant number!).

Sometimes a network of devices communicating via Bluetooth is described as a personal area network (PAN) to distinguish it from a network of computers often called a local area network (LAN).

The most common use of Bluetooth these days is in the world of mobile phones (and the geeky or cool — we’ll leave the distinction up to you — Bluetooth hands-free headsets hanging off millions of ears out there). But there’s more to Bluetooth than just phones. The following is a small sampling of existing Bluetooth products:

Microsoft Wireless IntelliMouse Explorer for Bluetooth (a wireless mouse) Apple wireless keyboard and mouse ‘ IOGEAR Bluetooth wireless stereo headphone kit HP Deskjet 460 printer ‘ Motorola V3 RAZR mobile phone

Motorola Bluetooth hands-free car kit

Jabra BT800 Bluetooth headset

Belkin Bluetooth Universal Serial Bus (USB) adapter

Although intended as a wireless replacement for cables, Bluetooth is being applied to make it possible for a wide range of devices to communicate with each other wirelessly with minimal user intervention. The technology is designed to be low-cost and low-power to appeal to a broad audience and to conserve a device’s battery life.

Wi-Fi Versus Bluetooth

Wi-Fi and Bluetooth are designed to coexist in the network, and although they certainly have overlapping applications, each has its distinct zones of advantage.

The biggest differences between Wi-Fi and Bluetooth are

Distance: Bluetooth is lower powered, which means that its signal can go only short distances (up to 10 meters, or a bit more than 30 feet). 802.11 technologies can cover your home, and in some cases more, depending on the antenna you use. Some Bluetooth devices operate under a high-powered scheme (called Class 1 Bluetooth devices), which can reach up to 100 meters. Most home Bluetooth devices don’t have this kind of range, mainly because they’re designed to be battery powered, and the shorter Class 2 range of 10 meters provides a better tradeoff between battery life and range.

Speed: The latest versions of Wi-Fi can carry data at rates in the hundreds of megabits per second; the fastest existing Bluetooth implementations have a maximum data rate of 3 Mbps. So think of Wi-Fi as a networking technology that can handle high-speed transfers of the biggest files, and Bluetooth as something designed for lower speed connections (such as carrying voice or audio signals) or for the transfer or synchronization of smaller chunks of data (such as transferring pictures from a camera phone to a PC).

Application: Bluetooth is designed as a replacement for cables: that is, to get rid of that huge tangle of cables that link your mouse, printer, monitor, scanner, and other devices on your desk and around your home. In fact, the first Bluetooth device was a Bluetooth headset, which eliminated that annoying cable to the telephone that got in the way of typing. Many new cars are also outfitted with Bluetooth so that you can use your cell phone in your car, with your car’s stereo speakers and an onboard microphone serving as your hands-free capability. Pretty neat, huh?

Wi-Fi (802.11a/b/g/n) and Bluetooth are similar in certain respects: They both enable wireless communication between electronic devices, but they are more complementary than direct competitors. Wi-Fi technology is most often used to create a wireless network of personal computers that can be located anywhere in a home or business. Bluetooth devices usually communicate with other Bluetooth devices in relatively close proximity.

The easiest way to distinguish Wi-Fi from Bluetooth is to focus on what each one replaces:

Wi-Fi is wireless Ethernet: Wi-Fi is a wireless version of the Ethernet communication protocol and is intended to replace networking cable that would otherwise be run through walls and ceilings to connect computers in multiple rooms or even on multiple floors of a building.

Bluetooth replaces peripheral cables: Bluetooth wireless technology operates at short distances — usually about 10 meters — and most often replaces cables that connect peripheral devices such as a printer, keyboard, mouse, or personal digital assistant (PDA) to your computer.

Bluetooth replaces IrDA: Bluetooth can also be used to replace another wireless technology — Infrared Data Association (IrDA) wireless technology — that’s already found in most laptop computers, PDAs, and even many printers. Although IR signals are secure and aren’t bothered with radio frequency (RF) interference, IrDA’s usefulness is hindered by infrared’s requirement for line-of-sight proximity of devices. Just like the way your TV’s remote control must be pointed directly at your TV to work, the infrared ports on two PDAs must be lined up to trade data, and your laptop has to be "pointing" at the printer to print over the infrared connection. Because Bluetooth uses radio waves rather than light waves, line-of-sight proximity isn’t required.

Like Wi-Fi, Bluetooth can offer wireless access to LANs, including Internet access. Bluetooth devices can potentially access the Public Switched Telephone Network (PSTN: you know, the phone system) and mobile telephone networks. Bluetooth is able to thrive alongside Wi-Fi by making possible such innovative solutions as a hands-free mobile phone headset, print-to-fax, and automatic PDA, laptop, and cell phone/address book synchronization.

Piconets, Masters, and Staves

Communication between Bluetooth devices is similar in concept to the ad hoc mode of Wi-Fi wireless networks.A Bluetooth device automatically and spontaneously forms informal WPANs, called piconets, with one to seven other Bluetooth devices that have the same Bluetooth profile. (A Bluetooth profile is simply a specific Bluetooth application — like a headset profile for attaching a wireless headset to a phone, or an audio profile for playing music over a wireless Bluetooth connection.) Piconets get their name from merging the prefix pico (probably from the Italian word piccolo [small]) and network. A capability called unconscious connectivity enables these devices to connect and disconnect almost without any user intervention.

A particular Bluetooth device can be a member of any number of piconets at any moment in time (see Figure 3-1). Each piconet has one master, the device that first initiates the connection. Other participants in a piconet are slaves.

The three types of Bluetooth connections are

Data only: When communicating data, a master can manage connections with as many as seven slaves.

Voice only: When the Bluetooth piconet is used for voice communication (for example, a wireless phone connection), the master can handle no more than three slaves.

Data and voice: A piconet transmitting both data and voice can exist between only two Bluetooth devices at a time.

Each Bluetooth device can join more than one piconet at a time. A group of more than one piconet with one or more devices in common is a scatternet. Figure 3-2 depicts a scatternet made up of several piconets.

The amount of information sent in each packet over a Bluetooth connection, and the type of error correction that is used, determine the data rate a connection can deliver. Bluetooth devices can send data over a piconet by using 16 types of packets. Sending more information in each packet (that is, sending longer packets) causes a faster data rate. Conversely, more robust error correction causes a slower data rate. Any application that uses a Bluetooth connection determines the type of packet used and, therefore, the data rate.

Piconets have one master and at least one slave.

Figure 3-1:

Piconets have one master and at least one slave.

A Bluetooth scatternet is composed of several piconets.

Figure 3-2:

A Bluetooth scatternet is composed of several piconets.

As mentioned, Bluetooth isn’t nearly as fast as Wi-Fi — many Bluetooth devices reach a maximum data rate of 723 Kbps (compare that to 248 Mbps for 802.11n), but that’s not usually important because Bluetooth is typically not used for transferring huge files and the like. The newest version of Bluetooth (Bluetooth 2.1) includes something called EDR (Enhanced Data Rate) that allows data transfers at speeds of up to 2.1 Mbps. (The raw speed is 3 Mbps; 2.1 is the actual data throughput rate.)

To maintain the security of the data you send over a Bluetooth link, the Bluetooth standard includes several layers of security. First, the two Bluetooth devices that are connecting use authentication to identify each other. After the authentication process (sometimes called pairing in the Bluetooth world), the devices can begin sharing information. The data being sent across the radio link is encrypted (scrambled) so that only other authenticated devices have the key that can decrypt (unscramble) the data.

Both Wi-Fi (the 802.11b, g, and n versions) and Bluetooth use the 2.4 GHz frequency radio band, but note the significant differences in how these technologies use the band. Bluetooth radios transmit a signal strength that complies with transmission regulations in most countries and is designed to connect at distances from 10 centimeters to 10 meters through walls and other obstacles — although like any radio wave, Bluetooth transmissions c an be weakened by certain kinds of construction material, such as steel or heavy concrete. Although Bluetooth devices can employ a transmission power that produces a range in excess of 100 meters, you can assume that most Bluetooth devices are designed for use within 10 meters of other compatible devices, which is fine for the applications for which Bluetooth is intended, such as replacing short-run cables.

To make full use of the 2.4 GHz frequency radio band and to reduce the likelihood of interference, Bluetooth uses a transmission protocol that hops 1,600 times per second between 79 discrete 1 MHz-wide channels from 2.402 GHz to 2.484 GHz. Each piconet establishes its own random hopping pattern so that you can have many piconets in the same vicinity without mutual interference. If interference does occur, each piconet switches to a different channel and tries again. Even though Wi-Fi (802.11b, g, and n) and Bluetooth both use the 2.4 GHz band, both protocols use hopping schemes that should result in little, if any, mutual interference.

Understanding Bluetooth versions

Bluetooth has been around for a few years now and, like most technologies, has undergone some growing pains and revisions. In fact, multiple versions of Bluetooth-certified equipment are available, as newer and more capable variants of Bluetooth arrive on the market.

The most common variant of Bluetooth is known as Bluetooth 1.2. This is basically a version of Bluetooth with all the bugs removed. Bluetooth 1.2 devices (most currently available devices, in other words) are backward compatible with earlier Bluetooth 1.0 and 1.1 devices. So, they work the same way, at the same speeds — just better. (Some technical advances in 1.2 allow most devices to have better real-world speeds.)

A growing number of Bluetooth devices support the Bluetooth 2.0 + EDR (extended data rate) standard. You can think of Bluetooth 2.0 + EDR versus the 1.x variants as being similar to 802.11g versus 802.11b. It is faster (with a maximum speed three times as high — 2.1 Mbps versus around 700 Kbps for the EDR, or enhanced data rate), is better at resisting interference, and just basically works better all around. If you’re shopping for something that may be sending larger files or requiring faster data transfers, such as a Bluetooth-equipped laptop (or a Bluetooth-enabled smartphone that can be used as a modem for your laptop), consider insisting on Bluetooth 2.0 and EDR.

In mid-2007, Bluetooth 2.1 was released. This version of Bluetooth isn’t any faster than 2.0 + EDR, but it includes some performance and battery life improvements. The biggest change in Bluetooth 2.1 (there are only a handful of 2.1 devices on the market as we write) is the support for something called NFC (Near Field Communications). With NFC, a special low-power radio system lets two devices in very close proximity (a few centimeters) "talk" to each other — two Bluetooth systems with NFC could be paired by simply holding them very close to each other. This NFC pairing (when it hits the market) will make using Bluetooth even easier by significantly reducing the steps needed to get two devices connected.

Coming down the pike is the Bluetooth 3.0 standard — and the Bluetooth folks have adopted a new technology called UWB (see the sidebar "Ultracool ultra wideband (UWB) is coming" for more on this technology) to make Bluetooth even faster in the future. Additionally, Bluetooth will also incorporate a technology from Nokia called Wibree, which allows ultra-low-power implementations of Bluetooth for devices with limited battery or power supplies.

Integrating Bluetooth into Your Wireless NetWork

Products that are the first to take advantage of Bluetooth technology include the following:

  • Mobile phones Cordless phones PDAs
  • Bluetooth adapters for PCs Bluetooth hands-free car kits Videocameras
  • Videogaming consoles and controllers (the Nintendo Wii, for example)
  • Digital still cameras
  • Data projectors
  • Scanners
  • Printers

You can get a great idea of all the various ways that Bluetooth can be used in your network by going to the official Bluetooth products Web site at www., which lists over 2,700 products.

One of the more interesting and most widely used applications of Bluetooth technology is for cell phones. Bring your Bluetooth-enabled phone home, dock it in a power station near your PC, and it instantly logs on to your wireless home network via a Bluetooth connection to a nearby PC or Bluetooth access point. Phones that function as PDAs can update their address books and sync data from the PC. All your events, to-do lists, grocery lists, and birthday reminders can be kept current just by bringing your Bluetooth-enabled product in range. You can even get Bluetooth headsets for your Bluetooth phones — getting rid of that wireless headset hassle.

Bluetooth technology is advancing into the arena of autos, too. In response to interest by the automotive industry, the Bluetooth SIG formed the Car Profile Working Group in December 1999. This working group has defined how Bluetooth wireless technology will enable hands-free use of mobile phones in automobiles. Car manufacturers have begun to embrace Bluetooth in a big way over the past few years. Acura was perhaps the first car maker to offer Bluetooth (at least in the U.S. market) with the Acura TL. Using the Bluetooth

in this car, you can "pair" your mobile phone and then use the steering wheel controls, navigation system screen and controller, and the car’s audio system to control and make phone calls. Very cool. Other manufacturers such as BMW, MINI, Ford, Mercedes Benz, Toyota, and Lexus have followed suit — those that haven’t will soon, you can be sure.

The current versions of Microsoft Windows Mobile, Windows XP (Service Pack 2), and Windows Vista offer built-in support for Bluetooth devices. All versions of Mac OS (from 10.2 Jaguar on) also have integrated support for Bluetooth.

Bluetoothing your phones

As we write in late 2007, 75 percent of all new mobile phones ship with built-in Bluetooth capabilities. That’s a lot of phones — and a lot of Bluetooth chips. The most common use of Bluetooth in phones is providing hands-free operation, either using a Bluetooth headset or a hands-free Bluetooth system inside a car. Hands-free operation of mobile phones can be handy (pun intended) whenever you’re talking on your phone, but when you’re in a car it can be not only convenient but legally mandated. A number of cities and states in the U.S. (and beyond) ban cell phone use in a car unless a hands-free system is in place.

If your car doesn’t have built-in Bluetooth capabilities and you just can’t imagine seeing yourself in the rear-view mirror with a Bluetooth headset jutting off your ear, you can install a hands-free kit in most cars without too much work. An even easier option is to consider a GPS navigation system; many aftermarket GPS systems now include Bluetooth and can use the speaker built into the GPS or connect to your car’s stereo system for hands-free calling.

There’s more to Bluetooth and your phone than just hands-free operation. Bluetooth can also be used to synchronize your phone with your PC or Mac. Most smartphones and many regular mobile phones (those in the industry call these feature phones) can use their Bluetooth connections to synchronize your phone book, calendar, photos, music, and more with a Bluetooth PC — no cables required. All you need is a Bluetooth adapter, like the one shown in Figure 3-3, for your PC (if it doesn’t have Bluetooth built in already), some software from your phone manufacturer, and a few minutes of configuration.

A final use of Bluetooth and mobile phones comes into play when your mobile phone includes a fast data plan (usually called 3G networking, such as EV-DO, EDGE, or HSDPA, discussed in next topic). Most of these services can be used on your laptop computer when it is tethered to your mobile phone using Bluetooth. The specifics on how this works vary from phone to phone and from mobile phone carrier to carrier, so we can’t tell you exactly how to set this up for your particular situation, but your mobile phone carrier will provide instructions.

Many mobile phone providers charge an extra monthly fee (on top of your probably already high mobile data service fee) for this use. Check your carrier’s Web page for details before you do this.

Use a USB adapter to add Bluetooth capability to a desktop or laptop PC.

Figure 3-3:

Use a USB adapter to add Bluetooth capability to a desktop or laptop PC.

Wireless printing and data transfer

Hewlett-Packard and other companies manufacture printers that have built-in Bluetooth wireless capability, which enables a computer that also has Bluetooth wireless capability to print sans printer cables. Bluetooth is used in other PC applications, such as wireless keyboards and wireless computer mice.

Another great use of Bluetooth wireless technology is to wirelessly transfer your digital photographs from your Bluetooth-enabled digital camera to your Bluetooth-enabled PC or Bluetooth-enabled printer — or even directly to your Bluetooth-enabled PDA. The newest wave of smartphones from several manufacturers includes wireless-enhanced models that include both Bluetooth and Wi-Fi built in. Wouldn’t it be cool to carry your family photo album around on your Treo or iPhone to show off at the office?

Extending Your Wireless Home NetWork With "No New Wires" Solutions

Wireless networking is great — so great that we wrote a book about it. But in many instances, wireless is just one way to do what you want; and often,Ultracool ultra wideband (UWB) is coming With all the innovation happening in the Wi-Fi and Bluetooth areas, more neat stuff is on its way. Ultra wideband (UWB) is a revolutionary wireless technology for transmitting digital data over a wide spectrum of frequency bands with very low power. It can transmit data at very high rates (for wireless LAN applications in the home). Within the power limit allowed under current FCC regulations, ultra wideband also has the ability to carry signals through doors and other obstacles that tend to reflect signals at more limited bandwidths and higher power. At higher power levels, UWB signals can travel to significantly greater ranges.

Ultra wideband radio broadcasts digital pulses (rather than traditional sine waves) that simultaneously transmit a signal across a very wide spectrum. The transmitter and receiver are coordinated to send and receive pulses with an accuracy of trillionths of a second! Not only does UWB enable high data rates, but it also does so without suffering the effects of multi-path interference.Because UWB has the ability to time-gate (that is, prescribe the precise time when it’s supposed to receive the data), the receiver allows it to ignore signals arriving outside a prescribed time interval, such as signals caused by multipath reflections.

UWB is still in the early stages, but it’s coming on strong. UWB is simpler, cheaper, less power-hungry, and 100 times faster than Bluetooth. What more could you want? UWB communication devices could be used to wirelessly distribute services such as phone, cable, and computer networking throughout a building or home.

Many companies and groups of companies have been promoting UWB for a variety of uses. One of them, the WiMedia Alliance, made (another!) alliance with the Bluetooth SIG to develop a new 3.0 version of Bluetooth that will eventually allow speeds of up to 480 Mbps for Bluetooth devices.

You may be thinking, well won’t that make Wi-Fi obsolete? Well it will be as fast as or faster than Wi-Fi, but it will still be a relatively short-range technology — this high-speed version of Bluetooth won’t cover your entire home like Wi-Fi will, so it will still be best suited for cable replacement rather than whole-home networking.

A common application of wireline and wireless networking is a remote access point that you want to link back into your home network. Suppose that your cable modem is in your office in the basement, and that’s where you have your main wireless router or access point. Now suppose that you want wireless access to your PC for your TV, stereo, and laptop surfing in the master bedroom on the third floor. Chances are that your AP’s signal isn’t strong enough for that application up there. How do you link one AP to the other?

You could install a wired Ethernet solution, which would entail running new CAT-5e/6 cables through your walls up to your bedroom. It’s pretty messy if you ask us, but this approach certainly provides as much as 1,000 Mbps if you need it.

If you can run CAT-5e/6 cable and create an Ethernet network in your walls, you should, so by all means do so! But most folks can’t do this, so these other solutions are the way to go.

A more practical way to get your cable modem up to the third floor is to run a powerline link between the two points. Think of this as one long extension cord between your router or AP in the basement and your AP in your bedroom. Although not all of these powerline technology links can carry data as fast as an 802.11n Wi-Fi connection, they will likely exceed the speed of your Internet connection. If that’s your primary goal, these are great, clean, and easy options for you.

The powerline networking concept takes a little getting used to. Most of us are used to plugging an AC adapter or electrical cable into the wall and then another Ethernet cable into some other networking outlet for the power and data connections. With powerline networking, those two cables are reduced to one — the power cable! That electrical cord is your LAN connection — along with all the rest of the electrical cabling in your house. Cool, huh? To connect to your computer, you run an Ethernet cable from the powerline networking device (router, AP, and so on) to your computer, hub, or switch.

Networking on powerlines is no easy task. Powerlines are noisy, electrically speaking, with surges in voltage level and electrical interferences introduced by all sorts of devices both inside and outside the home. The state of the electrical network in a home is constantly changing, as well, when devices are plugged in and turned on. Because of this, powerline networking systems adopt a sophisticated and adaptive signal processing algorithm, which is a technique used to convert data into electrical signals on the power wiring.

When it comes to powerline networking, you have the following options:

HomePlug Networking: This is the granddaddy of powerline networks, having been on the market for about ten years. Most equipment available today, such as NETGEAR’s WGX102 Wireless Range Extender (, uses the original HomePlug standard (HomePlug 1.0), which offers speeds of 14 Mbps. (The WGX102 actually uses a proprietary version of HomePlug that is faster.) The HomePlug folks have developed a newer version, called HomePlug A/V, which will, when it hits the market, support speeds of over 200 Mbps.

DS2 Powerline Networking: A Spanish company called DS2 ( has created their own powerline networking system that supports speeds of up to 200 Mbps over home powerlines. This system is mainly used in equipment provided to customers by phone companies in Europe, but in North America, D-Link ( offers a set of powerline Ethernet adapters that are built around DS2′s chips. Unlike the NET-GEAR system, mentioned in the preceding paragraph, which has an 802.11g AP built into the adapter, the D-Link system simply extends your Ethernet network to the remote location. You’ll need to add an additional access point to make this a wireless solution.

The most common application for powerline networking is as an Ethernet bridge.You need two of them: one to connect to an Ethernet port on your router (or any LAN jack in your home) and another to plug into the wall outlet wherever you need LAN access.

The bridge typically has a power cord on one side of the box and an Ethernet or USB connector on the other. Plug the power cord into any wall outlet and plug the Ethernet or USB into the computer or other networked devices, and you have a connection. Figure 3-4 shows a typical use of HomePlug bridges.

Some manufacturers, such as NETGEAR, offer powerline networking adapters with a built-in Wi-Fi access point. Plug one of these into your wall, along with a stand-alone powerline Ethernet bridge back at your main router location, and you have an instant remote AP!

Using your TV cables to extend your Wi-Fi network

An interesting approach to expanding your 802.11b or g wireless network’s reach has recently been launched by AuraOne Systems. The AuraGrid Wireless Extension system (which costs $89 for a four-room kit) uses your home’s coaxial cable wiring — the wires used to connect your TVs to the cable TV network — as an antenna extension system that brings your wireless network signal to all the nooks and crannies in your home.

To use the system, you simply need to install the AuraGrid duplexer in your garage (or wherever your cable TV lines enter the house), and then simply connect antenna devices to each outlet where you want to improve your wireless signal. Finally, connect the antenna port on your access point to an AuraGrid splitter. That’s it! If you can hook up your DVD and TV, you can handle this process. The AuraGrid works only with cable TV systems and interferes with a satellite TV signal, so if you have DirecTV or DISH Network, you can’t use those wires for this purpose.

It’s important to note that the AuraGrid system won’t work with 802.11n systems, but for most folks that’s not an issue, simply because 802.11 n’s greater range makes the system unnecessary.

Plug your computer into the wall — and that's all.

Figure 3-4:

Plug your computer into the wall — and that’s all.

Controlling Your Home without Wires

Throughout this topic, we talk about using wireless networks to send data around your home. This data could be what you traditionally think of as data (Web pages, e-mail, Word documents, and so on), or it could be different kinds of data (such as music MP3 files, digital photos, or video), but in the end it’s all about getting one hunk of bits and bytes from one place in your home to another. The bits and the bytes — the payload of your networked communications — are the key here.

A completely different kind of wireless networking is control networking. In a control network, you aren’t setting out to move data around the house; instead you are using a wireless network to send commands to devices in your home. In this instance you aren’t sharing a data file with someone (or some device in your home) so much as telling it what to do (you bossy person you!).

Home control has been around a long time (we’ve been writing about it for over a decade, and it existed for decades before that), but traditional home control systems used complicated (and expensive) proprietary wiring systems or an old powerline networking system called X10.

Using other existing wires

Besides powerlines, your home will probably also have a number of phone lines and coaxial (cable TV) cables running through your walls. These wires can also potentially be used to extend the reach of your wireless network without installing new Ethernet cables in your home. We say potentially because although these wires definitely can do this job, no companies are currently shipping products to consumers that would let you use the wires this way.

In the past, a system called HomePNA (for Home Phoneline Networking Alliance) was widely available and did much the same thing that HomePlug and other powerline networking systems did, only leveraging the phone lines in your walls. Since the last edition of this topic, HomePNA networking solutions have become unavailable in the consumer marketplace. That’s too bad, because the technology has been greatly improved and works well. The companies behind the technology have, however, focused on the phone company market, rather than the consumer home networking market. HomePNA gear is found in many of the TV set-top boxes provided where phone companies offer television services — the technology is used to carry TV programming from a master set-top box to satellite set-top boxes throughout the home.

A similar technology, called MoCA (Multimedia over Coax) is used to carry TV programming and other data over the coaxial cables used for cable and satellite TV distribution. Again, like the current version of HomePNA, MoCA is a telephone (or cable) company technology — it’s installed inside set-top boxes and not sold in the form of consumer equipment that can be purchased at the local Best Buy.

We think that this will change over time, and we hope that it does because phone lines and coaxial cables are better suited for carrying data than are powerlines. Keep your eyes peeled on these group’s Web sites ( and to see when consumer products become available.

The big news in home control, however, is the introduction of wireless networking into the mix. Wireless home control networks are designed around extremely low-power and low-cost chips that can (eventually) be built right into all sorts of appliances and electrical devices in the home.

Home control networks are low-speed networks. Because home control networks don’t need to be concerned with carrying a big fat stream of high-definition data or the 80 megabyte Windows update du jour, they can get away with relatively puny data rates in the name of cost savings (it doesn’t take a lot of bandwidth to say "dim the lights in the hall").

In another effort to trim expenses, home control networks are short range (the chips can be smaller and cheaper if they don’t transmit as much power as, for example, an 802.11n chip). This may seem a bit counterintuitive — after all, home control systems won’t work well if you can’t reach the devices in your home that you want to control — but these networks overcome the issue of short range by using a mesh topology. Mesh means that each radio in the system can talk to every other radio, and in doing so they can retransmit the commands you send throughout the home. The most common metaphor here is the frog in the lily pond — the frog can’t jump all the way across the pond in one fell swoop, but he can bounce from pad to pad until he finds his way across. A wireless home control network does the same thing, "organizing" itself and providing a route throughout the home for your control signals.

The network effect is in full effect in mesh networks like this. In case you’re not familiar with it, the network effect states that the value of networked devices is exponentially related to the number of those devices. (For example, if only one fax machine existed in the world, it would be useless; if millions exist, they can be very useful.) A similar thing is true for mesh networked home control devices (called modules). One or two would work okay, if they were near each other, but when a home has dozens (or even hundreds), all sorts of devices can communicate with each other and the whole network will perform significantly better.

The two main technology competitors for this (still new) marketplace are

ZigBee: ZigBee is a wireless automation networking standard based on an international standard (called IEEE 802.15.4 — similar to the 802.11 standards used for Wi-Fi networks). As we mention earlier, ZigBee systems use a peer-to-peer networking infrastructure, called mesh networking, to reach throughout the home. ZigBee provides a data rate of 250 Kbps, while using chips that are inexpensive to manufacture. A group called the ZigBee Alliance ( — similar to the Wi-Fi Alliance — is helping manufacturers bring ZigBee products to market and helping ensure that the products work well together. As we write, only a few dozen ZigBee products are on the market, but dozens of manufacturers have joined the alliance.

Z-Wave: A Danish semiconductor company called Zensys ( has developed a competitor to ZigBee called Z-Wave. Z-Wave is a wireless, mesh, peer-to-peer automation networking protocol that’s similar to ZigBee. Z-Wave systems operate at speeds of up to 9.6 Kbps (slower than ZigBee but still more than fast enough for home automation and control). Z-Wave products are still new to the market, but several major manufacturers, such as Leviton ( and Wayne Dalton (, are shipping products using Z-Wave.

ZigBee and Z-Wave are similar systems that do not work together. That is to say, a ZigBee chip and a Z-Wave chip can’t talk to each other and work together in a home control network. But they can both be installed in the same home without causing interference nightmares. So while your ZigBee and Z-Wave networks can’t directly interoperate, there’s no problem with having both in your home (if you choose to do so) — for example, you could have a Z-Wave lighting control system and use ZigBee to control your heating and air-conditioning systems.

ZigBee and Z-Wave chips can be integrated directly into an appliance or electrical device (this will be more common in the future), or they can be integrated into a control module (a device that sits between your control network and the thing you want to control, and translates network commands into commands that the end device understands, such as on or off).

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