User Manual

Link planning Planning considerations
2-14
pmp-0047 (December 2012)
Link planning
This section describes factors to be taken into account when planning links, such as range, obstacles, path loss and
throughput.
Range and obstacles
Calculate the range of the link and identify any obstacles that may affect radio performance.
Perform a survey to identify all the obstructions (such as trees or buildings) in the path and to assess the risk of
interference. This information is necessary in order to achieve an accurate link feasibility assessment.
The PMP 450 Series is designed to operate in Near-Line-of-Sight (nLOS), Non-Line-of-Sight (NLOS) and Line-of-
Sight (LOS) environments. An NLOS environment is one in which there is no optical line-of-sight, that is, there are
obstructions between the antennas. See Figure 1 Line Of Sight Diagram.
OFDM technology can often use multi-pathing to an advantage to overcome nLOS, especially in cases where the
Fresnel zone is only partially blocked by buildings, “urban canyons”, or foliage. OFDM tends to help especially
when obstacles are near the middle of the link, and less so when the obstacles are very near the SM or AP.
However, attenuation through walls and trees is substantial for any use of the 5.8 GHz frequency band. Even with
OFDM, these products should not be expected to penetrate walls or extensive trees and foliage.
Table 15 Link budget details – PMP 450 link, 20 MHz Channel Bandwidth
Product Parameter
Range Details
2x 4x 6x
PMP 450
Modulation QPSK-MIMO-B
16QAM-
MIMO-B
64QAM-
MIMO-B
5.4/5.8-GHz
Max. LOS
Link Budget
(no fade
margin)
with Integrated SM antenna 6.7 mi / 10.9 km 2.7 mi / 4.3 km 1 mi / 1.7 km
with LENS that adds 5.5 dB
to SM Range
12.7 mi / 20.5
km 5 mi / 8.1 km 2 mi / 3.2 km
with Reflector Dish that
adds 14 dB to SM Range 34 mi / 54.7 km
13.5 mi / 21.7
km 5.3 mi / 8.6 km
5.4/5.8-GHz
Max. nLOS
Link Budget
(additional 5
dB link loss)
with Integrated SM antenna 3.8 mi / 6.1 km 1.5 mi / 2.4 km 0.6 mi / 0.9 km
with LENS that adds 5.5 dB
to SM Range 7.1 mi / 11.5 km 2.8 mi / 4.6 km 1.1 mi / 1.8 km
with Reflector Dish that
adds 14 dB to SM Range
19.1 mi / 30.7
km
7.6 mi / 12.2
km 3 mi / 4.8 km
5.4/5.8-GHz
Max. NLOS1
with Integrated SM antenna 1.2 mi / 1.9 km 0.4 mi / 0.7 km 0.1 mi / 0.3 km
with LENS that adds 5.5 dB
2.2 mi / 3.6 km 0.9 mi / 1.4 km 0.3 mi / 0.5 km