User's Manual

Estimating RF Coverage
InterReach Fusion Wideband Installation, Operation, and Reference Manual Page 89
D-620616-0-20 Rev K • TECP-77-044 Issue 9 • March 2015 © 2015 TE Connectivity
5 Path Loss Slope: For a rough estimate, Table 73 on page 85 shows that a building with 80%
hard wall offices and 20% cubicles, a
t 1920 MHz, has an approximate path loss slope (PLS) of
38.1. Given the RF link budget of 97.0 dB, the distance of coverage from each RAU will be 30.2
meters (99 ft). This corresponds to a coverage area of 2,868 sq. meters (30,854 sq. ft.) per
RAU (refer to “Equation 2—Path Loss Equation” on page 84 for details on path loss
estimation). For this case we assumed a circular radiation pattern, though the
actual area
covered depends upon the pattern of the antenna and the obstructions in the facility.
6 Equipment Requ
ired: Since you know the building size, you can now estimate the Fusion
Wideband equipment quantities needed. Before you test any RF levels in the building, you can
estimate that four antennas per level will be needed. This assumes no propagation between
floors. If there is propagation, you may not need antennas on every floor.
• 4 antennas per floor × 16 floors = 64 RAUs
• 64 RAUs ÷ 8 = 8 Expansion Hubs, as there is a maximum of 8 RAUs pe
r Expansion Hub
• 8 Expansion Hubs ÷ 4 = 2 Main Hubs, as there is a maximum of 4 E
xpansion Hubs per Main
Hub
Check that the fiber and CATV cable distances are as recommended
.
If the distances differ, use
the tables in “System Gain” on page 82 to determine system gains or losses. The path loss may
need to be recalculated to a
ssure adequate signal levels in the required coverage distance.
The above estimates assume that all cable le
ngth requirements are met. If Expansion Hubs
cannot be placed so that the RAUs are within the distance requirement, additional Expansion
Hubs may need to be placed closer to the required RAUs locations.
An RF Site Survey and Building Evaluation is required to accurately estab
lish the
Fusion
Wideband equipment quantities required for the building. The site survey measures the RF
losses within the building to determine the actual PLS, used in the final path loss formula to
determine the actual requirements of the Fusion Wideband system.