Wireless LAN Requirements
Jim Geier is the author of Wireless LANs: Implementing Interoperable Networks (1999, Macmillan Technical Publishing).
As part of a wireless LAN implementation, a company first needs to determine requirements. This step is extremely important because it provides a basis for the selection of technology/standard and design of the wireless LAN.
The wireless LAN requirements should address the following elements:
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Coverage and mobility—Specifying the coverage, or area where the end users will operate the wireless devices, helps the designer determine the number and location of wireless LAN access points. Mobility requirements derive from the movement of users through the coverage areas. It's generally best to illustrate the coverage areas on drawings of the facility or building.
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Application requirements—These specify the transmission needs of the software that will operate over the wireless LAN. For example, warehouse-management system software requires the transmission of relatively low-bandwidth bar-code information between wireless handheld bar-code scanners and a host computer. A desktop video application, however, requires the transmission of real-time video signals. How frequently you expect to use these different information types helps determine the design specifications for your data transmission rate and throughput.
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Number of users—Simply put, this is the number of devices that require access to the wireless LAN. Be sure to allow for future expansion.
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End-user device types—Included in this category are laptop computers, bar-code data collectors, and mobile patient monitors. You should identify the available physical interfaces—such as PC card, PCI, ISA, or USB—for each device.
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Battery longevity—For mobile and portable applications, specify the length of time that the end-user devices need to operate on a set of batteries. This information indicates whether wireless LAN components need to support power-management functions.
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System interfaces—Most likely, the wireless LAN will have to interface with existing systems such as Ethernet networks, applications, and databases. The system interface requirements describe the architectures and communications protocols of these systems.
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Information security requirements, or the level of protection that your data needs from particular threats—The degree of needed security depends on the severity of the consequences that the organization faces if data is lost. These requirements determine whether you should include mechanisms such as encryption.
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Environment—Conditions such as room temperature and humidity, construction materials, floor space, and presence and intensity of electromagnetic waves could affect the operation of the system. In most cases, you should perform a site survey to inspect the facility and evaluate the presence of potential radio-frequency interference.
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Schedule—Identify any circumstances that will affect the schedule, such as the availability of funds, an urgency to see a return on investment, the availability of project team members, and the interdependency between this project and others. Spell out the schedule requirements so that the team knows the time frames it must work within.
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Budget—An organization may have a limited amount of money to spend on the wireless LAN. If you know the budget constraints, it's best to identify them in the requirements.
As part of a requirements analysis, formulate questions related to these requirements elements, and interview applicable company staff for answers.
About the Author
Jim Geier provides consulting services related to wireless networking to companies worldwide. He is the author of the book Wireless LANs: Implementing Interoperable Networks (Macmillan Technical Publishing, 1999). His "Online Guide to Wireless Networking" is located at http://www.wireless-nets.com/guide.htm.