Site Surveys; Avoiding Damage To Radios In A Testing Environment - Cisco Aironet 1550 Series Getting Started Manual

Site Surveys

Cisco recommends that you perform a site survey before installing the equipment. A site survey reveals
problems that can be resolved before the network is operational. Because 802.11a/b/g/n operates in an
unlicensed spectrum, there may be sources of interference from other 802.11a wireless devices
(especially in multi-tenant buildings) that could degrade your 802.11 signals. A site survey can
determine if such interference exists at the time of deployment.
A proper site survey involves temporarily setting up mesh links and taking measurements to determine
whether your antenna calculations are accurate. Determine the correct locations and antenna types
before you drill holes and route cables and mounting equipment.
When power is not readily available during a site survey, use an unrestricted power supply
Tip
(UPS) to temporarily power the mesh link.
Consider the following operating and environmental conditions when performing a site survey:
• How far is your wireless link?
• Has a previous site survey been conducted?
• Do you have a clear Fresnel zone between the access points or radio line of sight?
• What is the minimum acceptable data rate within the link?
• Do you have the correct antenna (if more than one antenna is being offered)?
• Do you have access to both of the mesh site locations?
• Do you have the proper permits, if required?
• Are you following the proper safety procedures and practices?
• Have you configured the access points before you go onsite? It is always easier to resolve
configurations or device problems first.
• Do you have the proper tools and equipment to complete your survey?

Avoiding Damage to Radios in a Testing Environment

The radios on outdoor units (bridges) have higher transmit power levels than radios on indoor units
(access points). When you test radios in a link, you must avoid exceeding the maximum receive input
level of the receiver. At levels higher than the normal the operating range and packet error rate (PER)
performance of the receiver is degraded. At even higher levels, the receiver can be permanently
damaged.
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