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Hello everybody,

The company I am working for is looking at installing a wireless LAN for their new office. There will be approximately 50 - 100 people spaced fairly close together. Is Wireless LAN a practical option for this sort of environment? Is there any way of guaranteeing a minimum bandwidth, and what sort of bandwidth would be possible?

Any help would be much appreciated.

A WLAN is probably doable, if properly designed. The most important question is what the bandwidth requirements of each individual user are. If the users are doing typical web browsing type stuff, then a data rate of just 250 kbps or 500 kbps may provide excellent service. If higher data rates are needed, fewer users can be served.

A typical 802.11g or 802.11a AP can offer a best-case usable throughput of about 18 Mbps to 22 Mbps, in my experience. That's best-case, which means the users are in line of sight of the AP--no walls between them, etc... It sounds like that might be the case in your WLAN, though. As you add walls and distance, throughput drops.

With 802.11g, you could have up to three APs covering the same small area, for a total usable throughput of about 54 to 66 Mbps. At 500 Kbps per user, that would amount to about 108 to 112 users. With 802.11a, you can have up to eight APs in the same indoor area, for a total of about 288 to 352 users (again, assuming 500 Kbps per user), but the expense of buying eight 802.11a APs would be prohibitive to some people.

There are various ways of performing QoS in a WLAN. As far as "guaranteed bandwidth" goes, well, it depends on the quality and reliability of your wireless design. If the wireless network itself can't provide reliable connectivity and throughput, then no amount of Qos can compensate. But with a reliable wireless network, many QoS solutions exist and one of them would probably meet your needs.

One more thing: you say 50 to 100 users in the same area, but in most network designs, it's assumed that only a certain percentage of the users will actually be active at a time. If you can figure out what degree of oversubscription your network can tolerate, you can design for fewer users than you'll actually have, making things cheaper and simpler.