Wireless Communications for Windows 95
Mark Williams
November 1, 1995
The PC connectivity world today is mostly wired, with the cable type dictating the application. A link over a parallel cable means printing, while a link over a serial cable serves a modem. Right now, a user consciously needs to start a connection over the cable that matches the application. Starting a connection is a hassle that many potential computer users just won't put up with.
As time goes on, wireless communications are going to play an increasingly important role in computers, particularly for mobile users. As more wireless PC connectivity hardware and software become available, applications will provide new connectivity features. Applications will initiate connectivity on an as-needed basis, and a user will not even need to know the connection type in order to use it.
Because of its low cost and simple implementation, the first widely available wireless connectivity medium for PCs is infrared (IR). The engineering requirements are straightforward, and the component cost is less than $5 per device. Computer system and peripheral makers are already integrating infrared devices with computers and printers.
Microsoft releases IR-related products
A Microsoft development team that focuses on mobile computing issues has just released its first products: the Infrared (IR) Communications for Windows 95 device driver, and the IR Communications for Windows 95 Device Driver Kit (DDK), which was developed with Hewlett-Packard. The driver is also part of the DDK.
Software developers can get the IR Communications device driver from the Windows Driver Library (WDL) and can install the driver on computers with IR ports to add IR capability to Windows 95. Communicating applications that use serial and parallel cable links can then be tested over the new IR link, which can operate at speeds up to 115.2 kilobits per second (kbps).
Independent hardware vendors (IHVs) and original equipment manufacturers (OEMs) can get the IR Communications for Windows 95 DDK by contacting their Microsoft OEM sales representative. IHVs and OEMs can use the sample IR driver source code as a starting point to build IR drivers that operate with their IR-capable devices. Examples of such IR-capable devices are IR ports built into computer platforms, IR adapters that plug into serial and/or parallel ports built into computer platforms, LAN-access points, remote keyboards, printers, cellular and land-line phones, digital cameras, pagers, home entertainment center equipment, and kitchen appliances.
Based on feedback from computer manufacturers, Microsoft predicts that the majority of new portable PC systems will ship with built-in IR ports that are compatible with Windows 95. For systems without IR built in, Microsoft is working with IHVs that make IR adapters that plug into Windows 95-based computer serial ports and provide IR capability.
Companies that have not thought of themselves as makers of computer peripherals, such as manufacturers of kitchen appliances, home entertainment centers, and cameras, will likely build IR into their devices and become potential Windows 95 IHVs.
The Infrared Data Association (IrDA) has already developed infrared communications standards that are accepted by the computer, communications, home entertainment, and semiconductor industries. (See "The IrDA and Its Standards," below, for a description of the standards.) As long as the makers of these devices strive to comply with the IrDA standards, all these different types of IR devices will be able to communicate with each other and with computers running the IR Communications for Windows 95 device driver. In the rest of this article, the term IrDA-compliant will be used to refer to all these types of IR devices.
Microsoft and IrDA
Microsoft has been an executive member of IrDA since its founding and promotes the IrDA effort to standardize infrared communications protocols across the industry. Microsoft's infrared products are designed to comply with the IrDA specifications. This ensures interoperability between IR-capable computers running Windows 95 and all other devices that support the IrDA specifications.
If you are an independent software vendor (ISV) writing applications for IR-capable computers running Windows 95, IR drivers built with the IR Communications for Windows 95 DDK enable you to use standard Win32 communications APIs to transfer data between IrDA-compliant devices. Many existing applications that communicate over serial and/or parallel cables using these APIs will communicate over IrDA-compliant IR links without any reprogramming.
Microsoft's future IR products will also be designed to comply with the evolving IrDA standards, which will take advantage of the dynamic, ad-hoc nature of the media and hardware advances (such as fast IR data exchange at speeds up to 4.0 mbps).
Scenarios with IrDA-capable devices
People will be able to use their computers in new ways when IR communications are added to Windows 95 and IrDA-compliant devices abound. Here is a tale that illustrates some of these.
In the workplace and on business trips. Most workers will have an IR-capable desktop computer and an IR-capable portable computer. The portable is either "docked" to the desktop or carried with the worker as she roams between office buildings and labs.
To prepare for a meeting, the portable owner downloads the departmental project schedule information from a LAN database to the desktop, adds some late-breaking information that is only on her desktop PC, and then squirts a filtered set of schedule information to the portable using the IR link.
When she arrives at the meeting in a nearby building, all the attendees have IR-capable laptops loaded with their department's part of the schedule. During the beginning of the meeting, each worker uses the laptop to check schedule facts, take notes, revise the dependencies in their schedules, and squirt schedule facts to each other as needed.
During the break, workers with access to an IR-capable LAN access point, which will be available in most meeting rooms, can use laptops to send and receive e-mail messages relevant to the meeting.
After the break, the attendees collaborate on a new schedule by using IR-capable conferencing software on their portables. When a realistic schedule is hammered out, one worker with the agreed-upon schedule on her portable leaves immediately for the airport to fly to a board meeting to present the schedule.
She uses the laptop to continue exchanging e-mail messages in the airport and hotel by using an IR-capable public phone. While in transit, she receives detailed messages about the upcoming board meeting on her IR-capable pager and organizes the messages by squirting them into the IR-capable personal information manager (PIM) application on her laptop.
In a hotel room, she uses the notebook to add the latest schedule information to an electronic slide presentation. In the hotel business service center, she uses the IR-capable presentation graphics software to squirt the slide images to an IR-capable laser printer, producing handouts for the meeting.
At the board meeting, she displays the electronic slides to an audience by squirting them one at a time from the notebook computer to a high-speed IR-capable large screen video projector (some slides have digital video and audio clips that demonstrate the physical processes underlying the schedule dependencies she is presenting).
At home or as tourists. After the board meeting, she takes her family's IR-capable digital camera and one of the family's IR-capable handheld PCs out of her luggage and heads for the sprawling combination super mall/amusement park.
She doesn't have much time, so she immediately goes to an IR-capable information kiosk and downloads a user interface onto her handheld PC through the IR port. She uses the interface to navigate symbolically through the acres of attractions and to query the information kiosk for squirts of detailed information about some of the attractions.
When she locates an attraction her kids are interested in, she walks there and takes some snapshots. When she gets back to the hotel, she squirts the best of the snapshots from her IR-capable digital camera to the IR-capable laptop. She uses the hotel business center to send an e-mail message home that asks her son to pick her up at the airport, with the digital snapshots as attachments.
Meanwhile, her son and a friend are attending a lecture at the local college campus. They use their handhelds to download the class handouts and the next homework assignment from the professor's IR-capable portable computer. They collaborate on the assignment during the lecture, and on the way out they squirt the completed assignment back onto the professor's computer.
In the off-campus CyberCafe, they start going over the lecture notes they downloaded and then surf the Internet, using the cafe's IR access point, looking for information that will invalidate what they have just been told by their professor.
Getting into IR
OK, so maybe the average person wouldn't have such a computer-filled day. However, all the uses described here will become possible. And Microsoft has plans to develop extensions to Windows for other wireless media in addition to IR. Can you imagine other scenarios, especially when other forms of wireless communication, such as radio frequency (RF) or cellular data, are integrated with computers?
Here are some basic suggestions for getting started with the low-cost IR media that is available today:
• Purchase a couple of IR-capable devices designed to be IrDA-compliant.
• Start experimenting with the Microsoft IrDA-compliant IR Communications for Windows 95 DDK.
Purchasing IR-capable devices
Current infrared devices designed to be IrDA-compliant operate over a minimum range of one meter between transmitter and receiver, and within a 30-degree angled cone. The current IrDA specification is optimized for point-to-point links between two or more devices. Keeping the cone angle narrow minimizes problems associated with interference and "hidden transmitters." The first revision of the IrDA specification provides for up to 115.2 kbps serial infrared links. Several notebook computers already include built-in IR ports with these characteristics. These computers include DEC HiNote Ultra, Gateway 2000 Liberty, HP Omnibook, IBM ThinkPad, Midwest Micro Elite, and Texas Instruments 5000.
IR adapters that add IR capability to Windows-based computers by plugging into a serial port are available for as little as US$35 from numerous peripheral manufacturers. See below ("IR Adapter Manufacturers") for the names and addresses of the manufacturers of adapters that have been tested using the Microsoft IR driver.
Printer manufacturers are also supporting IR communications. New printer models, such as the Hewlett-Packard LaserJet 5MP, feature an IR port in addition to the usual serial and parallel interfaces. These printers can communicate wirelessly with portable PCs and other infrared devices.
Experimenting with the IR communications products
Once you have a couple of IR devices that are designed to meet the IrDA specifications, you can use the IR Communications for Windows 95 device driver to start exchanging data between applications using the IR devices. To work with the IR Communications driver, applications must use the Win32 communications APIs.
IHVs and OEMs can use the sample C-language source code in the IR Communications for Windows 95 DDK to develop an IR device driver for new IR-capable devices. The DDK documentation pinpoints the few lines of code you will have to change in the sample IR driver source code to implement your own low-level driver. The IR Communications DDK is available from your Microsoft OEM sales representative.
The IR Communications for Windows 95 SDK will provide a set of APIs and protocols for IR links that go beyond the Win32 communications APIs. These include:
• IR Sockets APIs, which enable application developers to quickly port existing Windows Sockets applications to use IR links.
• File Transfer APIs, which enable application developers to use files as units of transfer over IR links.
• Object Exchange protocol, which enables developers to transfer small units of information (objects) such as business cards, address book entries, or sales transaction records over IR links and keep the objects on different computers in synchronization with each other.
• IrLAN protocol, which enables applications to access information on networks of many different protocols and addressing schemes through an IR port.
Looking ahead, the SDK Beta is scheduled to be available on an upcoming release of the Microsoft Development Platform. The final version of the SDK is slated for release in the second quarter of 1996.
Mark Williams is a senior technical writer in the Microsoft Personal Systems Division. He writes about device drivers and other hardware-related issues.
The IrDA and Its Standards
The Infrared Data Association (IrDA) is a group of computer, telecommunications, and semiconductor manufacturers and consumer products companies that have worked together to define the IrDA specification as an industry standard. By implementing the IrDA standard, member and nonmember companies can create devices that cooperate with each other to share the IR spectrum in a cooperative fashion. For more information about IrDA, contact:
Infrared Data Association
PO Box 3883
Walnut Creek, CA 94598
Tel: (510) 943-6546
Fax: (510) 943-5600
E-mail: irda@netcom.comCurrent IrDA standards
• Serial Infrared (SIR) physical layer specification, which provides for serial infrared links running up to 115.2 kbps. Higher-speed physical layer specifications have been approved by IrDA that will support link speeds of 1.152 mbps and 4.0 mbps.
• IR Link Access Protocol (IrLAP) provides a reliable point-to-point link, which effectively replaces a three-wire serial cable connection.
• IR Link Management Protocol (IrLMP) provides for multiple sessions over the single point-to-point link. An Information Access Service (IAS) is also specified through which a device can learn about the services offered by another device.
IrDA standards currently under development
• IR COMM, which provides full emulation of three-wire, nine-wire, null modem, and parallel connections. The emulation sends the state information that is normally maintained by signals on the carrier detect (CD), data terminal ready (DTR), clear to send (CTS), and other communication control lines.
• Tiny TP, which provides a tiny transport protocol to provide session level flow control on a link.
• Object Exchange, which provides a protocol that transfers generic data objects (such as a business card or an address book entry) between applications running on different computers.
IR Adapter Manufacturers
The names and addresses of manufacturers of IR adapters that have been successfully tested with the IR driver executable in the IR Communications for Windows 95 DDK:
ActiSys, Inc.
1507 Fulton Place
Fremont, CA 94539
Tel: (510) 490-8024
Fax: (510) 623-7268
E-mail: corp@actisys.comAdaptec, Inc.
691 South Milpitas Blvd.
Milpitas, CA 95035
Tel: (800) 959-7274
Fax: (408) 957-7223Extended Systems, Inc.
5777 North Meeker Ave.
Boise, ID 83713-1520
Tel: (208) 322-7575
Fax: (208) 377-1906