Installation Guide

Hardware Installation Guide Radio Site Planning
02030311-08 Airspan Networks Inc. 5-5
5.5. Adjacent Base Station Radios
For installations involving co-location of BSRs, it is important to assign frequencies
of maximum spacing. This is to reduce possible radio interference between
adjacently installed BSRs. In addition, a 1-meter separation must exist between
adjacent BSRs.
5.6. Calculating Link Budget
Link budget is the computation of the maximal achievable reception level for the
communication link between the Base Station and the subscriber site. This level is
the minimum required received signal level (RSS) at the antenna port for the radio to
close the communication link at a given data rate and under the worst-case fading
channel. This level must be greater or equal to the radio's receiver sensitivity, which
is the minimum RF signal power level required at the input of a receiver for certain
performance (e.g. > BER).
This takes into account the following aparameters:
 Transmit (dBm) EIRP:
Tx transmitter power (dBm) - cable loss (dB) + Tx antenna gain (dBi)
 Propagation (dB):
Free space loss (dB) = 32.44 + 20logd(km) + 20logf(MHz), where f is the
frequency in MHz, and d is the distance between transmitting and receiving
radios in km.
Note: Free space propagation loss is valid when the first Fresnel Zone is clear.
 Receive (dBm):
Rx antenna gain (dBi) - cable loss (dB)
The formual to calculate receive signal power:
Rx = Tx EIRP – (path loss) + receive (i.e. Tx gain – Tx cable loss)