User's Manual

Designing a Fusion Wideband Solution
Page 62 InterReach Fusion Wideband Installation, Operation, and Reference Manual
© 2015 TE Connectivity D-620616-0-20 Rev K • TECP-77-044 Issue 9 • March 2015
DESIGN OVERVIEW
Designing a Fusion Wideband solution is a matter of determining coverage and capacity needs.
This requires the following steps:
1 Determine the wireless service provider’s requirements;
refer to “Do
wnlink RSSI
Design Goal” on page 64.
The following information is typical
ly provided by the service provider:
• Frequency (for example, 1900 MHz)
• Band (for example, “A-F” band in
the PCS spectrum)
• Protocol (for example, CDMA, GSM, 1xRTT, GPRS, and so on)
• Number of
sectors and peak capacity per sector (translates to the number of RF carriers
that the system will have to transmit)
• Downlink RSSI design goal (RSSI, received si
gnal strength at the wireless handset, for
example, –85 dBm)
The design goal is always a stronger signa
l than the mobile phone needs. It includes
inherent factors which affect performance.
• RF source (Base Station or bidirectional amp
lifier
or repeater), type of equipment if
possible.
2 Determin
e the downlink Power Per Carrier from the RF source through the DAS; refer
to “Maximum Output Power Per Carrier” on page 65.
The maximum Power Per Carrier is a
function
of modulation type, the number of RF carriers,
signal quality issues, regulatory emissions requirements, and Fusion Wideband’s RF
performance. Power Per Carrier decreases as the number of carriers increases.
3 Develop an RF link budget; refer to “Est
imating RF Coverage” on page 83.
Knowing both the Power Per Carrier and RSSI design goal, you can develop an RF downlink
link
budget which estimates the allowable path loss from a RAU’s antenna to the wireless
handset.
allowable path loss = Power Per Carrier
+ antenna gain – design goal
Satisfactory performance can be expe
cted as long as path loss is below this level.