General Considerations

•Fresnel Loss - The Fresnel Zone is a theoretical area around the line of sight of an antenna transmission that can affect the signal strength. Objects that penetrate the Fresnel Zone can cause fading of the transmitted signal. This fading is caused by the cancellation of the signal due to out-of-phase reflections. An unobstructed line of sight is important, but it is not the only determination of an adequate placement. Even though the path has a clear line of sight, if obstructions (such as terrain, vegetation, metal roofs, cars, etc.) penetrate the Fresnel zone, there will be signal loss. The following illustrates a Fresnel zone.

Fresnel Zone

D1D2

Transmitter

Receiver

•Free Space Path Loss – As an RF signal travels through space, it is attenuated by the distance from the initial transmission point. The farther away from the transmission point, the weaker the RF signal.

•Foliage Loss – Tree and plant foliage will cause additional signal loss. Seasonal density, moisture content of the foliage, and other factors such as wind may change the amount of loss. Caution should be used when a link may transmit though this type of environment.

•Carrier to Interference – describes how much signal advantage must be engineered into the radio link to tolerate an interfering transmission.

•How many point-to-point links are being planned for deployment? Each backhaul timing master will need to utilize a cluster management module for seamless operation within the entire Canopy System.

•How will the access point clusters be deployed relative to planned point-to-point links?

Backhaul User Manual Issue 3

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