Networking

Our Wireless Future
Wireless Networking at NYU

Gary Chapman

Imagine you are using your laptop computer in Bobst Library to access information resources on the Internet. Occasionally you send an electronic mail message, or receive one from a friend or colleague. Without turning off your machine, without plugging or unplugging any wires, you move from one location to another within the library, continuing your work. For a breath of fresh air, you carry your machine out to a bench in the park, and continue to browse the Web and receive e-mail. Time for class? Off you go to a classroom in Main Building; upon arrival, you find your machine has received another e-mail message while you walked.

While such a continuous connection to the Internet is not yet a practical reality on NYU's campus, the technology now exists to make it entirely possible, thanks to recent developments in wireless communications. ACF has been experimenting with, and has actually begun to deploy, wireless networking gear at the Washington Square campus. This is providing us with our first glimpse of what we believe to be a major evolutionary step in data networking: the combination of wireless with wired networks to provide a more flexible, versatile and even economical network infrastructure than has previously been possible.

The first application of wireless networking on NYU-NET was installed in early August to hook up a set of new offices at 411 Lafayette Street. While leasing a high-speed data line from Bell Atlantic would have been the traditional approach, we judged that wireless equipment was now sufficiently mature to put into production use here at NYU. From the front windows at 411 Lafayette, looking northwest across the street, you see the back of 726 Broadway, a building that is equipped with fiber-optical cabling and networking gear linking it directly into the NYU-NET infrastructure. To make the link, we needed two small antennas and two wireless devices. At 411 Lafayette we positioned a wireless bridge, and at 726 Broadway we installed an access point device that makes the transition from wireless to the wired local network. Within each building the wireless bridges are physically wired into their respective local area networks. Providing 2.5 to 3 megabits per second of communications bandwidth, the wireless link across Lafayette Street doubles the capacity of a leased T1 line, and has no additional monthly charge. Very high frequency radio waves are used; in fact, we use continuously changing frequencies, an approach that makes the communications link highly secure and highly resistant to interference from other radio sources in the vicinity.

This example of wireless networking is just one possible application. In this case, the purpose is to make a link between two different wired segments of the network. A potentially far more exciting application involves using similar wireless equipment to provide network connectivity to laptops or desktops, either on an individual basis or for a group of machines in a given location.

What would be needed to create the scenario described at the beginning of this article is a handful of combination antenna/transmitter/receivers on NYU buildings and a laptop equipped with a wireless communications card (a PCMCIA or PCcard) to send and receive signals.

A third, intriguing application is to use wireless links in place of the standard jacks and wiring that run in any office from wall-mounted data jacks back to equipment located in a nearby telecommunications closet. The approach would be to install one or more wireless access points attached to the wired NYU-NET infrastructure in the closet. Then, for each computer, purchase what might be called a "wireless ethernet jack" -- a wireless transmitter/receiver which communicates over NYU-NET via the access points. Each computer then plugs into the wireless ethernet jack via a standard twisted-pair cable from its ethernet port. From the computer's point of view, it is attached to this network just like any other network.

This solution would be of particular interest for an office floor or similar location where the cost of wiring to each computer is unusually expensive or difficult, or for an office in a temporary location where the cost of installing permanent wiring is not justified. We could even take this approach for a situation where installed wiring is at capacity, and there is a need to connect a few additional computers to the network. It could also be used in a laboratory where a computer on a cart is moved frequently from location to location.

Each of these applications are entirely practical at this time, although in many situations traditional wired approaches may involve less equipment, lower installation costs or greater communications bandwidth. We can anticipate, however, that wireless equipment costs will continue to decline as its capabilities and speed increase. For right now, wireless networking offers solutions for special cases, and thus represents a new set of tools in our networking tool chest. Within a few years, wireless networking may conceivably achieve full parity with wired solutions and become commonplace on NYU-NET.

Posted October 5,1998