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Chapter 3: Bridge Link Planning
The Dual-band Outdoor Access Point / Bridge supports fixed point-to-point or
point-to-multipoint wireless links. A single link between two points can be used to
connect a remote site to larger core network. Multiple bridge links can provide a way
to connect widespread Ethernet LANs.
For each link in a wireless bridge network to be reliable and provide optimum
performance, some careful site planning is required. This chapter provides guidance
and information for planning your wireless bridge links.
Note: The planning and installation of the wireless bridge requires professional
personnel that are trained in the installation of radio transmitting equipment. The
user is responsible for compliance with local regulations concerning items such as
antenna power, use of lightning arrestors, grounding, and radio mast or tower
construction. Therefore, it is recommended to consult a professional contractor
knowledgeable in local radio regulations prior to equipment installation.
Data Rates
Using its 5 GHz integrated antenna, the SMC2891W-AG bridge can operate over a
range of up to 15.4 km (9.6 miles) or provide a high-speed connection of 54 Mbps
(108 Mbps in turbo mode). However, the maximum data rate for a link decreases as
the operating range increases.
When you are planning each wireless bridge link, take into account the maximum
distance and data rates for the various antenna options. See "Transmit Power" on
page C-5.
Radio Path Planning
Although the wireless bridge uses IEEE 802.11a radio technology, which is capable
of reducing the effect of multipath signals due to obstructions, the wireless bridge
link requires a "radio line-of-sight" between the two antennas for optimum
performance.
The concept of radio line-of-sight involves the area along a radio link path through
which the bulk of the radio signal power travels. This area is known as the first
Fresnel Zone of the radio link. For a radio link not to be affected by obstacles along
its path, no object, including the ground, must intrude within 60% of the first Fresnel
Zone.
The following figure illustrates the concept of a good radio line-of-sight.
3-1
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