User's Manual

Planning a MetroE Deployment
Wireless link planning is essential to the success of any microwave installation and is highly
recommended before attempting to install the equipment. In this section we will describe the
elements of the MetroE that are relevant to link planning. If the reader is unfamiliar with
microwave link planning he/she strongly advised to seek qualified assistance or take a suitable
microwave link planning training class.
Personnel installing the equipment must be familiar with fiber splicing, microwave and Ethernet
equipment solution installation and troubleshooting techniques.
Frequency Planning
The MetroE operates over the 5.725 to 5.850 GHz (defined as the ISM band) utilizing one20 MHz
wide channel. The band supports (5) non-overlapping channels and setting of the channel is done
manually. The MetroE link can be configured to use those channels that have been determined to
be free of interference from other users during the link planning process.
You are looking to find and use channels with signal strengths of -90 dBm or lower. If it is not
possible to find a completely clear channel, you can set the RSSI Threshold setting on the
Advanced Screen under Mesh Configuration, ADVANCED, screen) to just above the interfering
signal strength. The Hsyteresis Window, which determines the amount signal must come up past
above the RSSI Threshold, should be set to 3 dBm.
Distance
The MetroE FX5010-ODU can deliver full throughput at a range of 3 miles with 99.999% link
availability in a typical urban strand mount deployment. Link availability is calculated using the ITU
P-530 model which accounts for slow fading do to terrain and climate conditions and assuming a
near-line-of-site path with a multipath loss of 10 db. The Link Availability calculation does not
include potential downtime from transient interference or equipment failure.
Path Profile
Optimal performance is ensured with a line of sight path between the two FX5010-ODUs. This is
defined as a path that is free of obstructions in the Fresnel zone. Obstructions can be trees,
buildings, street signs, etc. An accepted rule of thumb is that LOS conditions exist when there are
no physical obstructions within 60% of the 1
st
Fresnel zone (obstruction free zone). The Fresnel
Zone clearance is determined by the distance between the two ODUs as shown in the following
illustration and table.