Chapter 3: System planning
Planning for connectorized units
Page 3-29
Planning for connectorized units
This section describes factors to be taken into account when planning to use connectorized
ODUs with external antennas in PTP 670 links.
When to install connectorized units
PTP topology
The majority of radio links can be successfully deployed using the Integrated ODU. However
the Integrated ODU may not have sufficient antenna gain in some areas, for example:
•
Where the path is heavily obscured by dense woodland on an NLOS link.
•
Where long LOS links (>23 km or >14 miles) are required.
•
Where there are known to be high levels of interference.
LINKPlanner can be used to identify these areas of marginal performance.
In these areas, use the Connectorized ODU with external antennas.
HCMP topology
The Master ODU in an HCMP sector will normally be installed with a connectorized antenna
with sector or omni-directional coverage.
Slave ODUs in an HCMP sector will normally be installed using the Integrated ODU, but might
be installed using the Connectorized ODU with external antennas, for example:
•
Where the path is heavily obscured by dense woodland on an NLOS link.
•
Where there are known to be high levels of interference.
Choosing external antennas
When selecting external antennas, consider the following factors:
•
The required antenna gain.
•
Ease of mounting and alignment.
•
Antenna polarization:
o
For a simple installation process, select one dual-polarization antenna (as the integrated
antenna) at each end.
o
To achieve spatial diversity, select two single-polarization antennas at each end. Spatial
diversity provides additional fade margin on very long LOS links where there is
evidence of correlation of the fading characteristics on Vertical and Horizontal
polarizations.
