Distributed Wireless Networking

By Joshua Erdman
Digital Foundation, inc.

A distrubuted network provides wireless network access to end users. This is almost similar to a Point-to-MultiPoint network (article coming soon).

Terminology

Usually the local transmitter that provides wireless access to all user is called the access point. The device or transmitter used at each client is usually a wireless card (but sometimes called a workgroup bridge).

Transmit Power and Coverage

Communication with wireless is 2 way. Just because you have an access point with a 500mW amplifier does not mean that you will provide your client a much more significant amount of distance. Yes they will 'hear' the signal from the access point but will your access poitn 'hear' their weak signal? Wireless cards for laptops transmit as little power as possible to prolong battery life. The only good way to provide alot of coverage is by adding multiple transmitters. Then this introduces new complexities (such as the ability to roam from one transmitter to the other) and ensuring that the transmitters do not interefere with eachother ont eh same frequesncy.

Purchasing Considerations

The things to focus on with distributed wireless is:

Building Penetration
Minimum Speed Requirements
Security of data transmitted

Knowing these requirements will ensure that you choose a transmitter with the right security and power requirements and the correct antenna.

Cost

Expect to pay at least $80 per transmitter (they usually come with an antenna). The cost of transmitters can easily increase by $300 for models that are designed to handle roaming users.

Manufacturer	Average Price	Features/ Transmit Power	Comments
Cisco Aeronet 1100	~$600	802.11b/g 100 mW	One of the best
Cisco Aeronet 1200	~$800	802.11a/b/g 100 mW	By far the best!
Raylink Access Point	~$600	802.11b 100 mW	Slow, only 2 mbps, but provides better reception in buildings
Linksys Wireless-G Access Point	~$100	802.11b/g 11 mbps	Quick and Cheap solution. Great for a small office with limited distance needs.

Article last reviewed: 01/05/2004

Created by: Digital Foundation, inc.

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