GE MDS iNET 900, Reference Manual

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60 iNET Series Reference Manual 05-2806A01, Rev. J
• Set the Remote radios to the lower speed (512 kbps for iNET-II, 256
kbps for iNET) to optimize coverage.
• Set the RSSI Threshold to -85 dBm—This level is typically used for
mobile systems with good performance. Make sure there is overlap-
ping coverage of more than one AP to provide a good user experi-
ence and continuous coverage.
At Every Mobile (Remote) Radio
•
Fragmentation Threshold
[
256
]—Set to a small value. This param-
eter defines the size of the message packets transmitted over the
wireless media. These fragments are reconstructed into the orig-
inal packet before delivery to the external device at the remote
end of the link. In a mobile environment with rapidly changing
conditions, setting this value to a minimum value improves the
probability of packets being sent complete on the first try.
At Every AP Radio
Parameter settings that should be reviewed for AP radios providing ser-
vice to mobile remotes:
•
Compression
[
disabled
]—Disable radio compression. Data com-
pression is best performed by the middleware running on the
mobile laptop PC. Gains in efficiency are made because middle-
ware compresses data at a higher stack level, and it aggregates
multiple data frames and streams into a single packet. Compres-
sion at the radio level, although highly efficient, works at the
individual packet level.
•
Dwell Time
[
Set to the minimum value
]—This setting controls the
amount of time that the unit spends on each frequency between
hops. Although overall throughput appears to decrease by this
setting the effects of multipath fading are minimized through
frequency diversity.
•
Beacon Period
[
Set to the fastest value
]—This parameter defines
the interval at which the Access Point transmits a synchroniza-
tion beacon to all remotes. A faster setting minimizes resyn-
chronization times when remote radios roam between access
points or in highly interrupted coverage areas (dense buildings,
for example).
•
RTS Threshold
[
0 -1600 bytes
]—Enable RTS flow at a small value.
This setting is a wireless equivalent to RTS/CTS flow control in
a wired communications circuit. This mechanism prevents
packet collisions caused by the “Hidden Node” scenario, in
which remotes can’t hear each other before transmitting. When
this value is set below 100 or above 1500, it is effectively dis-
abled.