GE MDS iNET Series, Справочное руководство

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10 MDS iNET Series Reference Manual 05-2806A01, Rev. L
In a point-to-multipoint scenario, the Access Point services multiple remotes. A problem in the Access Point
will have an effect on all remotes, since none will have access to the network. When operation of the net-
work does not tolerate any down time, it is possible to set up a protected configuration for the Access Point
to greatly reduce the possibility of this occurrence. An MDS P21 Protected Network Station may be used to
achieve redundant operation. It employs two APs in a single enclosure, with appropriate switching circuits.
In this application, two or more Access Points are configured with the same Network Name and kept active
simultaneously, each with its own independent antenna. In this scenario, Remotes will associate with either
one of the available Access Points. In case of a failure of one of the AP’s the Remotes will quickly associate
with another of the remaining Access Points re-establishing connectivity to the end devices.
The Access Points are unaware of the existence of the other AP’s. Because the hopping algorithm uses both
the Network Name and the Wireless MAC address of the AP to generate the hopping pattern, multiple AP’s
can coexist—even if they use the same network name. The collocated AP’s will be using different hopping
patterns and frequencies the great majority of the time. Although some data collisions will occur, the wire-
less-MAC is built to tolerate and recover from such occurrences with minimal degradation.
1.4.3 Collocating Multiple Radio Networks
Many networks can operate in relatively close physical proximity to one another provided reasonable mea-
sures are taken to assure the radio signal of one Access Point is not directed at the antenna of the second
Access Point
.
The Network Name and the association process
The Network Name is the foundation for building individual radio networks. It is part of a beacon signal
broadcast by the Access Point (AP) to any Remote units with the same Network Name. Remotes that join
the network are referred to as being “associated” with the Access Point unit.
Multiple APs with the same Network Name should be used with care. Using the same Network Name in
multiple APs may result in Remotes associating with undesired APs and preventing data exchange from
occurring as planned.
The use of a different Network Name does not guarantee an interference-free system. It does however,
assure that only data destined for a unique network is passed through to that network.
Co-Location for Multiple Networks
It may be desirable to co-locate Access Points at one location to take advantage of an excellent or premium
location that can serve two independent networks. Each network should have a unique Network Name, and
each AP unit’s antenna should be provided as much vertical separation as is practical to minimize RFI.
NOTE:
All transceivers are shipped with the Network Name set to “Not Programmed.” The Network
Name must be programmed in order to pass data and begin normal operations.
Can radio frequency interference (RFI) disrupt my wireless network?
When multiple radio networks operate in close physical proximity to other wireless networks, individual
units may not operate reliably under weak signal conditions and may be influenced by strong radio signals
in adjacent bands. This radio frequency interference cannot be predicted with certainty, and can only be
determined by experimentation. If you need to co-locate two units, start by using the largest possible vertical
antenna separation between the two
AP antennas on the same support structure. If that does not work, con-
sult with your factory representative about other techniques for controlling radio frequency interference
between the radios. (See “A Word About Radio Interference” on Page 112 for more details.)