Installation Manual

Tsunami Multipoint Version 1.3 Installation Guide
Path Planning
To get the most value from a wireless system, path planning is essential. In addition to the fact that
radio signals dissipate as they travel, many other factors operate on a microwave signal as it moves
through space. All of these must be taken into account, because any obstructions in the path can
attenuate the signal.
Calculating a Link Budget
A link budget is a rough calculation of all known elements of the link to determine whether the signal
will have the proper strength when it reaches the other end of the link. To make this calculation, consider
the following information.
▪ A signal degrades as it moves through space. The longer the path, the more loss it experiences. This
free-space path loss is a factor in calculating the link viability. Free-space path loss is easily
calculated for miles or kilometers.
▪ Availability represents the quality of a link. It is the ratio of the time that the link is available to the
total time. This serves as a guide to the service you can expect, on the average, over a period of one
year.
You can lower the bit error rate (BER), resulting in greater reliability, by reducing the data throughput or
reducing the distance between the BSU and the SU.
Note: In terrestrial communication, path loss does not necessarily follow 20dB per decade degradation as used in
free-space loss. Instead, 25-35 dB per decade is more common in a metropolitan near-line-of-sight
environment.
Unlicensed Frequencies (U-NII)
The FCC has identified the frequencies from 5.725 to 5.825 GHz as Unlicensed National Information
Infrastructure (U-NII). This band can be used by anyone without having to obtain a license. However, you
must use radio equipment that is “type approved” by the FCC or local government for use within the
specific band.
PMP Radio Information
The following sections provide information about the Tsunami Multipoint radio components. See
“Appendix C. Technical Specifications” on page 57 for product technical specifications.
Chapter 1. Site Planning 14
CPN 63179 Issue Date: 01/24/03