WIRELESS INFRASTRUCTURE

  • 02/20/2018
    6:00 AM
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WiFi Design: Practical Shortcuts

If you are faced with a tight budget or other constraints, you can still deploy a WLAN that meets most business requirements.

There are several industry resources to assist WiFi engineers and other IT professionals deploy WiFi the “right way.” These include vendor neutral certifications offered by organizations like CWNP, as well as vendor-specific certifications and best practices documentation. However, wireless engineers are often forced to take shortcuts or do things the wrong way because they are over-constrained.

In systems engineering, requirements are the objectives that to be achieved, and constraints are the obstacles to be worked around. Requirements are independent of each other and solution neutral, such as “allow up to 1,000 wireless devices to simultaneously connect” and “provide a minimum of 5 Mbps downstream and 5 Mbps upstream to each client device.” Constraints, by comparison, are often highly cross-coupled to each other and to requirements.

The most common WiFi deployment constraints encountered on projects are as follows. Typically, a particular project will be subject to more than one of these, but not all of these will apply.

  • Limited budget
  • Limited time to deploy
  • Aesthetics
  • Cannot get Ethernet cabling to deploy APs in desired locations, e.g., cannot get wiring into rooms
  • Rules to use a particular AP vendor e.g. your employer is a partner and gets special distribution pricing
  • Rules to use a particular AP model e.g. your employer is sitting on a large inventory of product Extremely noisy RF environment from surrounding WiFi networks or other systems
  • Lack of access to facility, e.g., cannot visit site for pre-deployment measurements
  • Lack of information, such as floor plans to scale, knowledge of building materials

In many cases, these constraints actually drive the WiFi design instead of the requirements. Especially in small-to-medium business deployments, both lack of information and lack of access because of project budget constraints are so common that NOT having these on a project is a rare pleasure.

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wireless networking
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(Image: Pavel Ignatov/Shutterstock)

Nonetheless, it is still usually possible to generate a WiFi design that reasonably, if not optimally, satisfies the project requirements. This necessitates some out-of-the-box creativity, but it can be done. As WiFi designers, there are four degrees of freedom that we have control over:

  • AP make/model (and antenna when using an AP with external antenna ports)
  • Location of APs
  • Channel selection (per band)
  • Transmit power (per band)  

Next Page: Working around constraints

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