Assess Requirements Before Designing WLAN
By Jim Geier 

 

When deploying wireless LANs, most people begin the project by jumping into technical matters, such as deciding upon which version of 802.11 to use, which vendor to select, and how to overcome the limitations of 802.11 security. These are important elements of implementing a wireless LAN; however prior to getting too far with the project, you must give careful attention to requirements analysis and design in order to end up with an effective solution. 

Think about requirements first
At the beginning of the project, be sure to define requirements by performing some analysis. The main idea is to determine what the wireless LAN is supposed to do before moving forward. Avoid purchasing and installing the wireless LAN without this upfront planning. If you don't fully define requirements, the network probably won't fully meet needs of the users. You certainly wouldn't want to install the network and then have angry users identify missing requirements. 

Requirements include immediate and future needs of the users, company, and the existing information system. Requirements are what the wireless LAN must comply with, such as range, throughput, security, battery longevity, application software, operating systems, end-user hardware, etc. Some of these requirements are obviously different and more complex than what you need to consider for wired networks, so pay closer attention when deploying wireless solutions. 

Keep in mind that the intent of defining the requirements is to determine what the wireless LAN must do, not how it will do it. Avoid making technical decisions when defining requirements unless there are company mandates in place that tell you otherwise. For example, the selection of 802.11b over 802.11a is likely not a requirement. Your choice of 802.11b in the requirements stage could limit the ability to support other requirements not yet known. Before making that selection, you first need to fully understand other requirements, such as throughput requirements of applications, number of end-users, ranges, etc. It's best to leave the technical decisions to the design stage after all requirements are well defined and agreed upon. 

The amount of time needed for defining requirements will vary depending on the size and complexity of the application. For example, a wireless LAN that connects 20 office workers may only require a few hours to outline the requirements. A larger project satisfying the needs of 3,000 people within a company that plans to use wireless LANs in warehouses, manufacturing plants, and corporate offices may require several weeks or months to define requirements. 

Regardless of the size of the network, focus long enough on requirements to ensure consensus before moving forward. The outcome of the requirements stage should provide enough information so that you can easily convey the requirements to the company decision makers and potential bidders. 

Now you can get technical
After you have a firm set of requirements, focus on design. This determines how you're going to satisfy requirements with least cost. Consider technical alternatives for satisfying the requirements by choosing 802.11b or 802.11a, selecting a vendor, identifying access point locations, assigning channels to access points, choosing security mechanisms, etc. The design should fully describe what components and configurations are necessary to satisfy the requirements. 

Through the design process, produce a design specification that highlights the chosen design elements and provides a diagram indicating the placement of access points within the facility. For smaller networks, you may only spend a day or so designing the solution. In larger implementations, it may take weeks or months to fully define enough technical detail before moving forward with the acquisition of hardware and installation services. These larger projects will likely benefit from simulation, prototyping, or pilot testing as part of the design to ensure you've made the right choices and the requirements are fully realizable. 

Want to learn more about wireless LAN requirements and design? Stay tuned! Future tutorials will go into more details.