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How many devices can a point to multipoint wireless bridge connect?

I am the engineer responsible for implementing a wireless campus network. I have to install some point to multipoint bridges in the high buildings of the city to cover all the area needed.

Besides the antenna problem (omni, yagi, whatever) I have not found yet an answer to: What is the maximum number of devices that a point to multipoint wireless bridge 801.11b can connect? Is it worthy to implement the 801.11b+ (22Mbps)?
Some products specify a hard limit on the number of stations that can be associated at any point in time. This number reflects constraints coded into the product, often something like 32 or 1024. However, that doesn't tell you how many stations can practically share the channel at any point in time. For example, an 802.11b AP using one 11 Mbps channel has a maximum effective throughput of about 5.5-6 Mbps. If each station uses about 400 Kbps, that's 15 stations. You need to look at your own actual application requirements to figure out the answer for your network.

Some vendors sell products that boost the maximum linkspeed from 11 Mbps to 22 Mbps. Use these only if you plan to buy all cards, APs and bridges from the same vendor, because extensions won't work with other-vendor stations. If you need more bandwidth, you would be better off purchasing products that comply with (pre)802.11g and promise free upgrades to comply with final 802.11g when ratified. These products will also have multi-vendor problems in the near-term, but have a clearly stated migration path to achieve multi-vendor interoperability without buying new hardware.

This was last published in May 2003

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