manual

Network Connectivity
Wireless LAN
Management
Services
19
Setting up point-to-point connections
LANCOM access points serve not only as central stations in a wireless network, they can also operate in point-
to-point mode (P2P) to bridge long distances. For example, they can provide a secure connection between two
networks that are several kilometers apart – without direct cabling or expensive leased lines.
Outdoor wireless LAN solutions
Proper surge protection: an important subject for outdoor WLAN
Outdoor wireless LAN installations should always allow for lightning protection: Even when there are no
visible phenomena such as thunderstorms or a direct lightning strike, invisible electrical discharges from
the atmosphere can still occur, leading to damage or destruction of sensitive wireless LAN modules or other
electronic devices.
Further information can be found in the LANCOM Outdoor Wireless Solution Guide under www.lancom.eu/
outdoor.
When is an external antenna advisable?
In some scenarios the antennas integrated into an access point, or the rod antenna shipped with it, simply
do not provide enough performance. One reason can be the distance that must be bridged. Distances of
several kilometers require a concentrated signal offered by sector antennas, and for extreme cases a highly
concentrated directional antenna with a minimal beam angle may be necessary to amplify the signals from
the radio module. Structural conditions could also favor the use of a sector antenna, for example: If an access
point cannot be installed in a location with a clear line of sight to its peer, it can be connected to a suitably
positioned antenna by means of an extension cable. Find out about the antennas offered by LANCOM under
www.lancom.eu.
You can also use our LANCOM Antenna Distance Calculator to calculate range and throughput of your
installation under www.lancom.eu/antenna-distance-calculator.
Radar systems to be considered close to your wireless link
Outdoor point-to-point links are subject to certain legal constraints. It is vital to avoid interference with radar
systems that are active in the 5-GHz spectrum (e.g. meteorological, military). For this reason the European
regulatory authority ETSI requires WLAN devices operating at 5 GHz to employ the dynamic frequency selection
(DFS) mechanism. This ensures that radar and WLAN systems can co-exist without interfering with one another
and that capacity utilization is spread evenly across available frequencies. The DFS mechanism that ensures a
lawful operation is of course supported by all LANCOM wireless LAN devices.
18
Main ofce
WLAN point-to-point link
Rule of thumb: 2.4 GHz for short ranges and low interference
5 GHz for links over several kilometers
Branch ofce
SA-5L
Surge arrestor between
access point and external
antenna to protect the OAP's
sensitive radio module
OAP-321
An access point with
a powerful integrated
5-GHz directional
antenna often makes
an external antenna
unnecessary.
SA-LAN
Surge arrestor protects
your devices in the LAN
LANCOM OAP
LANCOM router LANCOM switch
Antenna alignment for P2P operations
The precise alignment of the antennas is of critical importance for establishing P2P connections. The more
aligned the receiving antenna is located in the "ideal line" of the transmitting antenna, the better is the actual
power and the effective bandwidth. If the receiving antenna is outside of this ideal area, significant losses in
performance will occur.
360° omni-directional antenna
Omni-directional antenna attached to
the access point via an extension cable.
Sufficient for shorter ranges.
Sector antenna
The antenna's beam pattern is focused for
transmissions in one direction only. Suitable
for longer ranges.
Directional antenna
For strongly focused antenna transmissions.
With opening angles <10°, these antennas
can bridge ranges of several kilometers.