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What is a Site Survey?

A site survey is an in-depth examination and analysis of a proposed wireless LAN site. The purpose of a site survey is to determine the number of access points needed, the types of antennas needed, and the best placement for those access points and antennas.

Although the goal of a site survey is simple, the means of arriving at that goal are not. Some of the steps involve taking measurements, but most  involve experience, trial and error, and a little guesswork rather than numbers and figures.

When to Perform a Site Survey

Intel® recommends that you perform a site survey prior to installing a wireless LAN. Site surveys are especially important when:

  • You are installing a new site — Evaluate the placement of the access points and antennas throughout the proposed site.
  • You are changing an existing site — When modifying or extending an existing network structure, re-evaluate the placement of the access points and antennas. If you need a different level of coverage in some areas, you may need to move, replace, or supplement access points and antennas.
  • You are physically changing the site — Remodeling may introduce new sources of interference, such as motors and metal structures within the coverage area of the access point, even if it does not directly effect the sites where the access points are located.

Elements of an Effective Site Survey

An effective site survey requires four elements. Failure to commit the appropriate time, money, and energy to accomplish a proper site survey in advance may result in greater expenditures of money and time later, when problems arise that require repeated adjustments to the wireless configuration. The four elements of an effective site survey are:

  1. Examine the network usage problems solved by the wireless LAN.
    How many clients need a wireless LAN connection? What areas of the site require wireless LAN connectivity? How many hours each day is wireless LAN connectivity required? Which locations are likely to generate the largest amount of data traffic? Where is future network expansion most likely?
  2. Study blueprints of the proposed wireless LAN site.
    A site blueprint provides a map of the site as well as the location of objects, such as walls, partitions, and anything else that could affect the performance of a wireless LAN. Examining the site blueprint prior to conducting the physical walk-through helps you identify areas in which wireless equipment is likely to perform well and areas where it is not. Many obstructions are not readily visible and, in some cases, a room originally built for a specific purpose, such as a radiology lab, might have been converted into something completely different, such as a conference room. The blueprint may also show areas proposed for future building expansion. To prepare for the next step of the site survey, mark possible wireless device locations on the blueprint and refer to the marked blueprint during the physical walk-through and inventory.
  3. Conduct a physical walk-through and inventory.
    The primary purpose of the physical walk-through is to document any items or materials near a proposed device location that may interfere with reception or transmission and affect network performance. Document stock and inventory levels, current environmental conditions and any materials that may interfere with the wireless LAN.
  4. Measure the radio frequency transmissions.
    The Intel® PRO/Wireless LAN Site Survey Utility allows you to measure the signal strength, transmission rate and the number of successfully transmitted packets. This step in the site survey involves mounting access points and antennas in the proposed locations and measuring the RF signal strength, transmission rate and packet throughput.

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