Wireless Networking: Making the Connection

Making the Connection

In the April 25, 2002, edition of Mobile & Wireless UPDATE, I looked at the features and functionality of WiFi wireless LANs (WLANs) and Bluetooth personal area networks. This time, I want to continue my discussion of this topic by looking at connection options.

WiFi—the 802.11b wireless standard—offers two popular connection modes: Infrastructure mode lets you connect a client to a wireless Access Point (AP), and Ad-Hoc mode lets you directly connect one client to another client. Infrastructure mode is suitable for most connections, letting you connect to a network to access the Internet and network resources. To use a WiFi network in Infrastructure mode, your WLAN environment must have one or more wireless APs. These wireless APs must have a direct Ethernet connection to the network and must be configured with an IP address and subnet mask. Ad-Hoc mode is useful for establishing a wireless connection between a laptop and a Pocket PC—for example, I can use the Remote Display Control for Pocket PC PowerToy to view a live Pocket PC screen displayed on the laptop. For more information about this feature, go to http://www.microsoft.com/mobile/pocketpc/downloads/powertoys.asp

Enabling WiFi connectivity is quick and simple. After you install your WiFi card and the appropriate drivers, you can connect to a wireless AP. Typically, you need to know the WiFi network's Service Set Identifier (SSID), and you need to be operating the WiFi card in Infrastructure mode. After you establish the WiFi connection with the appropriate security (if applicable), you can obtain the IP settings (usually through DHCP) and connect to your network. You can now access any Internet and intranet resources that you typically use over an Ethernet connection. If you need to access a secured AP, the AP must have either a Wired Equivalent Privacy (WEP) key or—if the AP uses 802.1x—an appropriate certificate.

If you have Windows XP Professional Edition or XP Home Edition, you can access some cool WiFi features, including automatic network discovery (which finds SSIDs in your local area), automatic connections, and IP configuration. You also get Plug and Play (PnP) functionality, so you can plug in most major WiFi cards and XP will automatically configure the cards for use.

Bluetooth connections work somewhat differently from WiFi connections. The Bluetooth specification lets you connect, in your personal area network, as many as eight devices in a piconet. A piconet is a group of devices within a 30' radius interacting with each other. One device in the piconet acts as a master, and the others are slaves. This configuration facilitates efficient use of the wireless Bluetooth network. Users can connect in an anonymous mode to access printers, soda machines, exchange business cards, and other consumer functionality. In this scenario, the user's Bluetooth device would detect other nearby Bluetooth devices, then connect directly.

Several Bluetooth AP vendors have created standalone Bluetooth devices that permit network connectivity similar to the WiFi wireless APs discussed above. However, Bluetooth connections more often involve a pairing of devices. Typically, a Bluetooth device performs an initial discovery process to find nearby devices. Then, participating users must enter a random key in each device to pair the devices. After the Bluetooth devices are paired, they can connect quickly and securely when they're within range of each other. Such a scenario applies to the use of a Bluetooth headset with a Bluetooth phone, a Bluetooth PDA with a Bluetooth phone, or similar connections in which anonymous use isn't appropriate.

Configuring Bluetooth is simpler than configuring WiFi. Bluetooth devices typically offer a configuration utility, with which you can find nearby devices, pair them, and connect.

In the next Mobile & Wireless UPDATE, regular edition, I'll take a final look at WLAN configuration and functionality. See you then.

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