WLAN Design
Applications and data collection

Be aware of the applications that users may be utilizing . A user who performs the occasional file transfer and checks e-mail has very different needs from someone using a computer-aided design (CAD) application across the network. Most offices today use a client/server model with frequently used applications loaded on each terminal. Some companies are moving to thin clients and may have much greater bandwidth requirements. This type of setup requires a reliable connection to the network, since an interruption of network service renders the user helpless.

If the customer intends to use data collection devices exclusively, this will change the way the site survey is performed . Most data collection devices today operate at 2 Mbps and do not require 11 Mbps. If the customer is using a 2-Mbps data collection device with no intention of adding other wireless clients that may operate at 11 Mbps, then perform the site survey at 2 Mbps.

Make sure that all areas where the data collection devices will be used have a 2-Mbps link. Some data collection devices have the ability to rate shift. Discuss the devices that the customer will be using, what abilities these devices have, and how the customer intends to use them.

As discussed earlier, retail or warehousing sites may have areas where large numbers of users will be located. A receiving area may be this type of an area. As equipment is unloaded off trailers, it is unboxed and bar codes are scanned in rapid succession. The bandwidth needs are going to be determined by the application. For example, a screen-scraping emulation sends large packets containing a lot of data. If there are 20 to 30 users scanning barcodes and entering keystrokes in rapid succession, a single AP may not be enough.

For example, if all of the data collection devices are operating at 2 Mbps, the AP is only operating at 2 Mbps. This does not mean that the AP is limited to 2 Mbps, but all clients are communicating with the AP at 2 Mbps. While a 55-Mbps or 11-Mbps connection might be sufficient to handle the 20 to 30 users, the 2-Mbps connection may not be. The packet size of the application and the number of users must be considered to determine if extra APs are needed in this area.

Copper versus WLAN
Copper installations can still provide higher data rates, but price is no longer a factor. A WLAN can be installed for roughly the same price as a copper-based network, and it provides many benefits over a wired network. As prices continue to decrease on wireless products and throughput speeds continue to increase, wireless will continue to increase in popularity. This may also be a factor in the design. If the customer wants to start by using a few wireless clients and then increase the number after ensuring the reliability, the WLAN must be designed to accommodate future expansion.