AireLink
60 Installation and User Manual Rev. D
Surveying the Installation Site
Page 33
Rain attenuation of millimeter wave signals has been studied extensively over several decades and
models are available to reliably predict the availability of a millimeter wave transmission system in
various rain zones around the world. Based on the actual rain rates collected in specific regions, the
International Telecommunications Union (ITU) has published charts dividing the globe into separate
rainfall regions. Similar charts with slightly different geographical breakdowns exist, based on the work
of the researcher Crane. Both charts can be used to predict availability performance of millimeter wave
transmission systems. Figure 2-3 shows the ITU chart of different rain rate regions of the world. The
regions are divided by using an alphanumerical notation with region
A
having the least and region
Q
having the highest rain fall rates. Naturally the highest rain rates occur around the equator (rain zones
N, P, Q) and in these regions rain rates up to 250 mm/h can be observed for very short periods of
time. Very low rain rates (rain zone A) can be observed in the African, Middle Eastern and Asian dessert
regions as well as in the Northern Polar regions.
Figure 2-3: ITU rain zone chart of the earth
Using the ITU or Crane rain zone charts one can calculate the availability of a millimeter wave
transmission system in a specific rain zone. When it comes to rain attenuation it is important to keep
in mind that the rain fall rate and not the total amount of yearly rainfall determines the availability of
a millimeter wave radio system. For example, it is well known that the number of rainy days in the
North Western region of the United States and in cities like Seattle greatly exceeds the number of rainy
days in the South Eastern areas like Florida. However, when looking at Table 2-2, representing the
actual duration of peak rain fall rates in mm/hour in different rain zones, one finds that the rain fall
rate (or rain intensity) in the North Western region of the United States is far less when compared to
Summary of Contents for AireLink 60
Page 1: ...LightPointe AireLink 60 Installation and User Manual...
Page 28: ...AireLink 60 Installation and User Manual Rev D Introduction Page 28...
Page 40: ...AireLink 60 Installation and User Manual Rev D Surveying the Installation Site Page 40...
Page 56: ...AireLink 60 Installation and User Manual Rev D Recommended Software Pre Configurations Page 56...
Page 81: ...AireLink 60 Installation and User Manual Rev D System Installation Page 81...
Page 112: ...AireLink 60 Installation and User Manual Rev D CLI Command Line Interface Page 112...
Page 116: ...AireLink 60 Installation and User Manual Rev D Bluetooth AireLink Viewer Page 116...
Page 121: ...AireLink 60 Installation and User Manual Rev D SNMP Page 121...
Page 125: ...AireLink 60 Installation and User Manual Rev D Troubleshooting and Diagnostics Page 125...
Page 129: ...AireLink 60 Installation and User Manual Rev D Advanced Troubleshooting Methods Page 129...
Page 133: ...AireLink 60 Installation and User Manual Rev D Technical Support Page 133...