Bluetooth is a short-range, frequency-hopping spread spectrum (FHSS) radio service that operates in the same unlicensed 2.4 GHz frequency range as WiFi networks and many cordless telephones, microwave ovens, baby monitors, garage door openers, and other wireless products. Frequency-hopping spread spectrum means that a Bluetooth transmitter splits the radio signal into very small segments and hops among 79 different frequencies 1,600 times per second to reduce interference and fading.

Because a Bluetooth radio is both a transmitter and a receiver, it’s sometimes known as a transceiver. In order to further reduce the likelihood of interference, Bluetooth transmitters use very weak signals. The output power of the most common Class 2 Bluetooth radios is just 2.5 milliwatts (0.0025 watts) or less, which gives the signal a range of about ten meters (30 feet) in free space. By comparison, a cellular mobile telephone typically transmits at .6 watts or 3 watts. More powerful Class 1 Bluetooth radios with a maximum range of about 100 meters (320 feet) are also available.

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In spite of the name, Bluetooth is not a second-string pirate captain or a particularly bizarre dental malady. It is, in fact, a short-range wireless communications technology. The original Harald Bluetooth was a tenth-century Danish king who united parts of Norway and Denmark into a single Viking kingdom. Modern Bluetooth technology was named in his honor because it was intended to unite the worlds of portable computers and mobile telephones. Today, Bluetooth has become an industry standard for wireless connections among computers, printers, and other peripheral devices, along with mobile phones, headsets, and even wearable items with built-in wireless data exchange.

In general, Bluetooth is intended to replace wired connections between electronic equipment. Ultimately, the designers of Bluetooth hoped to completely replace the confusing tangle of wires and cables behind many computers with a single wireless interface module. More important, Bluetooth makes it possible to use external peripherals (including keyboards, mice, and printers) or transfer data to a computer without the need to find and attach a cable first.

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Bluetooth was designed to replace the short cables that connect a desktop or laptop computer to peripheral devices such as the keyboard and mouse. If both your computer and your mobile telephone have Bluetooth adapters, it’s possible to establish a Bluetooth link between them and place calls to an Internet service provider (ISP). The maximum range of a Bluetooth connection is about 300 feet (100 meters), at a maximum data transfer rate of about 720 Kbps. In most cases, this kind of Internet connection is not worth the trouble to set it up; it’s mostly useful for uploading ringtones and other data to your phone or downloading text files or voice messages to your computer, rather than connecting the laptop to the Internet.

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Some wireless connections to the Internet can be slower than connections through a high-speed wired Internet connection (such as a LAN or a DSL or cable modem service), but they’re much more convenient when you’re away from home base. However, there are several types of wireless network access, each of which has its own set of benefits and drawbacks.

The most common wireless services include Bluetooth, Wi-Fi, WiMAX and several digital cellular data technologies. EDGE (Enhanced Data rates for GSM Evolution), 1xEV-DO (Evolution-Data Only), UMTS (Universal Mobile Telephone Service, also called WCDMA, or Wideband Code-Division Multiple Access) and 1xRTT (Radio Transmission Technology), are all methods for sending data through a cellular mobile telephone network.

With a few exceptions, the data transfer rate decreases as the coverage area increases; in other words, you can exchange files and Internet services faster through a nearby Wi-Fi hotspot than through a cellular data service that covers an entire metropolitan area. The exceptions are a mobile modem, which uses the mobile voice network, and WiMAX, which is not yet available in most locations.

Eventually, the radios and network interfaces that support wireless access to the Internet will automatically find the type of signal that can handle the fastest data transfer to and from your current location, and set up a link to your computer. In the future, when you’re in an airport waiting area or a coffee shop, the computer will find and use a fast Wi-Fi service; but when you’re visiting your elderly aunt, it will use one of the slower cellular data services instead. Today, that kind of seamless handover is not yet possible so you must set up each type of link separately

When you first try to connect to your network, your wireless adapter’s software will scan the area for available networks and then display a list of networks. If you don’t see your own list in this network, you may have disabled the router’s SSID feature, which broadcasts the SSID to local wireless adapters. Disabling the SSID broadcast is a common security method, as it effectively stealths your network, making it that much harder for would-be hackers to spot.

The good news is that your adapter doesn’t need to see the SSID to connect to your router. Your adapter’s software includes a manual connection feature that lets you enter your network’s information, including the SSID. Once you enter the appropriate SSID and encryption information, you’ll be able to connect to your router without any trouble.

Determine whether physical obstacles are weakening the signal. Not surprisingly, wireless networks offer the strongest signals in open spaces, but unless your home resembles a big hall, your wireless network must negotiate walls and floors, both of which can reduce the strength and range of the signal. Today’s home networking equipment can reach as far as 300 feet in the very best circumstances, but your home’s metal and concrete will savage your router’s signal strength. If the computers closest to your wireless AP or router aren’t dropping the wireless connection and the computer that is dropping the connection is at the far end of the house, you can probably blame your network troubles on distance and physical barriers.

There are two popular types of signal-strengthening devices on the market for home users: range boosting antennae and repeaters. Several manufacturers offer APs and wireless routers that have removable antenna. If you can detach your router’s antenna, you can replace it with an antenna that offers more dBi. Chances are, your router’s manufacturer also offers an optional range-boosting antenna.

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Make sure your AP or router supports the same wireless networking standard that your adapter uses. For example, you can use 802.11b and G devices without any compatibility problems, but you can’t use an 802.11a adapter to connect to an 802.11g network. This may seem like a no kidding sort of solution, but if you’ve ever fretted over a seemingly dead PC, only to discover that the power cord was unplugged, you’ll agree that sometimes the obvious answer is the one.

Renew the router’s DHCP settings. Your router most likely uses the DHCP networking protocol to automatically assign IP addresses to all of the PCs on the network. You can often fix a dropped connection by entering your router’s firmware menu and using the firmware’s DHCP Release/Renew feature. Read Basic Troubleshooting Routers and Hubs
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Switch your wireless connection software. Chances are, you’re using the adapter manufacturer’s software. Windows XP includes the Wireless Zero Configuration Utility, but your adapter’s software overrides it by default. You can switch to the Zero Configuration Utility only if your adapter’s software permits it. Find the adapter’s icon in the System Tray and then right-click it. You may see Use Windows XP Wireless Configuration. Click the link, open the Control Panel and then open Network Connections. Next, double-click the Wireless Network Connection icon to view available networks.