Wireless is all the rage, whether it’s wireless telephones, wireless networking, or wireless hardware devices. Modern operating systems must be able to support wireless technologies like infrared (IR) and radio frequency (RF). Microsoft included built-in support for wireless connectivity in Windows 2000, making it easy for users to take advantage of this brave new “look, ma, no cables” world.
In this Daily Drill Down, I’ll explain how Windows 2000 provides support for infrared-based wireless technology, how you can configure infrared devices, and how you can establish infrared networking connections using a Windows 2000 Professional computer.
Understanding infrared wireless technology
Infrared is a communications medium that allows two computers, or a computer and a hardware device, to establish a point-to-point connection without requiring certain cables or connectors. Many notebook computers come with infrared transceivers built in, and IR can be added to desktop or notebook computers via add-on cards or external serial devices.
Infrared technologies come in two flavors: line-of-sight and diffuse. Line-of-sight is most common because it offers a longer range, higher speed, and requires less power. Diffuse technologies are appropriate when the environment includes obstructions that interfere with line-of-sight alignment.
IrDA standards and Windows 2000
Windows 2000 infrared support complies with the Infrared Data Association (IrDA) standards, which include the following Physical layer protocols:
- IrDA SIR: This implementation of infrared uses existing serial hardware for synchronous communication. It can run at up to 115 Kbps.
- IrDA FIR: This implementation is faster, at up to 4 Mbps. It requires an IrDA FIR transceiver, which is attached via a card or USB.
Categorizing infrared protocols
Differences exist between the IrDA protocols used for attaching low-speed peripheral devices (IR keyboards and mice, for example) and the higher-speed protocols used for IR networking.
- IrDA-C protocols, previously called IrBus, are used for PC peripheral devices. They operate at 75 Kbps with low latency and can be shared among multiple devices at a distance of around 20 feet.
- IrDA-D protocols, also called IrDA 1.1, are used for infrared networking connections in Windows 2000. They can communicate at 4 Mbps.
How infrared works
With IR, the two computers, or the computer and the IR device, must have IrDA transceivers. You can recognize the transceiver by locating the small red translucent window. (Think of the red window on a TV remote control.) In IR communications, the sending device is the primary or commanding device. When the connection is made, the protocols determine which device is primary and which is secondary (the receiving device). The devices will continue in these roles for the duration of the connection.
A computer with an IR port is generally able to act as either a primary or secondary device. Some peripherals can only act as secondary devices.
The link can be established in two ways:
- A device may automatically detect another IR device and establish the connection.
- A user may send a connection request from the primary device.
Infrared devices and Windows 2000
As wireless connectivity in general and infrared in particular become more popular, you can expect to see a wider variety of IR devices. A number of IR devices are available, including IR printers, keyboards, and pointing devices. Also, some digital cameras can connect to a computer via IR to transfer images. Windows 2000 supports the IrTran-P protocol for image exchange with compatible cameras.
Before attempting to install an infrared device, you should check the Windows 2000 Hardware Compatibility List to confirm that the hardware has been tested with Windows 2000.
Installing and configuring an infrared device
|Use the Add New Hardware Wizard to install an infrared device.|
You can use the Windows 2000 Add New Hardware Wizard to add an infrared device (see Figure A). If you have the manufacturer’s driver disk, select Have Disk when given the option.
If you install a Plug and Play infrared device, it may be found and installed automatically when you restart the computer. Serial IrDA transceivers must be installed manually via the Add New Hardware Wizard.
Configuring infrared ports
Depending on your computer, you may be able to configure one of your serial ports to act as an IR port for an internal device. This will allow Plug and Play to detect the IR device. Note, however, that this disables the serial port. This procedure is not to be used if you’re going to connect an external IR device to the serial port.
The reconfiguration of the serial port is done through your system BIOS, so this feature must be supported by the BIOS. Enter Setup when you boot the computer, find the Peripherals configuration screen (you may need to consult your motherboard manual), and, under Com Port Configuration, change the mode for the selected serial port to IrDA (or Infrared).
Troubleshooting infrared devices in Windows 2000
Problems with infrared connectivity may be related to the device’s property settings. To access the settings, right-click My Computer, select Manage, and then select Device Manager in the left console pane. Choose Infrared Devices in the right details pane, then right-click and select Properties. Click the IrDA Settings tab (see Figure B).
|Lowering the maximum connection rate may correct IR communications problems.|
A common cause of IR connectivity problems is having the maximum connection rate set too high. Try lowering this setting to correct communications problems. Although IrDA-SIR supports up to 115-Kbps speeds, some devices don’t.
Infrared networking with Windows 2000
Infrared networking is based on the familiar OSI networking model. At the Physical layer, an IR transceiver is connected to the computer via a SIR or FIR implementation.
At the Data-Link layer, the IrLAP protocols perform two functions:
- Discovery: The discovery protocol is used by applications to discover other IrDA devices, their names, and their MAC addresses.
- Establishment of a high-level data-link control (HDLC) connection: This provides a reliable link between two devices.
At the Network and Transport layers, the IrLMP and TinyTP protocols provide support for multiple sessions so that more than one application can listen for incoming connections simultaneously. The Winsock API provides an interface with applications and allows communication with non-Windows devices.
Establishing an infrared network connection
|To configure infrared networking, use the Network Connection Wizard.|
An infrared network connection is configured via the Network And Dial-up Connections settings. Click Start | Settings | Network And Dial-up Connections. To create the connection, choose Make New Connection, click Next, and choose View Advanced Options. You’ll need to select Connect Directly To Another Computer, as shown in Figure C.
|Select whether this computer will act as Host or Guest.|
You must select Host or Guest, depending on whether the computer will receive the connection or dial the connection, respectively, as shown in Figure D.
|Select the infrared device to be used to make the connection.|
The next step is to select Infrared Port in the drop-down box on the next screen, as shown in Figure E.
|Select which users will be allowed to connect to a host computer.|
You’ll need to specify which users are authorized to use the connection, if the computer will be acting as a host (see Figure F).
If you’ve selected Guest, you’ll be asked to decide whether to make the connection accessible to all users or just the current user. You’ll also be asked to name the connection.
Sending and receiving files over an infrared link
To connect using the infrared link, in Network And Dial-up Connections, double-click the infrared connection you created previously, click OK, and select Connect from the File menu.
Remember that IrDA is line-of-sight technology. The IR transceivers (red “eyes”) must be positioned correctly so that they “see” each other. When this occurs, an icon will appear in the taskbar to indicate that the link is established.
Files can be transferred over the link in several ways, once it’s established:
- Click the taskbar icon representing the link and specify the files you want to send in the Wireless Link dialog box.
- Drag the files to the desktop icon that represents the connection.
- Right-click the files in Windows Explorer and select Send To and Infrared Recipient.
- Use the irftp command at the command line.
IR has security advantages over cabled and RF communications. Cables can be “tapped into” and the data stolen, and radio frequencies can sometimes be intercepted from a distance. Infrared’s distance limitation as a short-range technology is an asset when it comes to security.
Wireless technologies are becoming more important as our society becomes more mobile and computer users seek to simplify their lives by “cutting the cords” that entangle them. With Windows 2000’s infrared support, you can install and use handy IR peripherals such as keyboards and mice, print to IR-enabled printers, and transfer files over a wireless IR network connection—all without cables.
Debra Littlejohn Shinder, MCSE, MVP is a technology consultant, trainer, and writer who has authored a number of books on computer operating systems, networking, and security. Deb is a tech editor, developmental editor, and contributor to over 20 additional books on subjects such as the Windows 2000 and Windows 2003 MCSE exams, CompTIA Security+ exam, and TruSecure's ICSA certification.