GE MDS iNET 900, Reference Manual

Page: 23 / 188

05-2806A01, Rev. J iNET Series Reference Manual 13
by the repeater station antennas. A detailed discussion on the effects of
terrain is given in Section 4.1.2,
Site Selection (beginning on Page 131).
The following paragraphs contain specific requirements for repeater
systems.
Antennas
Two antennas are required at this type of repeater station—one for each
radio. Measures must be taken to minimize the chance of interference
between these antennas. One effective technique for limiting interfer-
ence is to employ
vertical separation . In this arrangement, assuming
both are vertically polarized, one antenna is mounted directly over the
other, separated by at least 10 feet (3 Meters). This takes advantage of
the minimal radiation exhibited by most antennas directly above and
below their driven elements.
Another interference reduction technique is to cross-polarize the
repeater antennas. If one antenna is mounted for polarization in the ver-
tical plane, and the other in the horizontal plane, an additional 20 dB of
attenuation can be achieved. (Remember that the corresponding stations
should use the same antenna orientation when cross-polarization is
used.)
Network Name
The two radios that are wired together at the repeater site must have dif-
ferent network names.
Option 2—Using the AP as a Store-and-Forward Packet
Repeater
A wireless network can be extended through the use of an alternate
arrangement using the Access Point as a repeater to re-transmit the sig-
nals of all stations in the network. The repeater is a standard transceiver
configured as an Access Point, and operating in Store and Forward
mode. (See Figure 1-9.)
Invisible place holder
Figure 1-9. Typical network with store-and-forward repeater
As with the conventional repeater described in Option 1 above, the loca-
tion of a store and forward repeater is also important. A site must be
chosen that allows good communication with
both the Access Point and
the outlying Remote site. This can be on the top of a hill, building, or
other elevated terrain from which all sites can be “seen” by the repeater
Remote
Remote
Remote
Remote
Access Point
LAN/WAN
REPEATER
LAN
LAN
LAN