User`s guide

54 MDS iNET 900 Series User’s Guide MDS 05-2806A01, Rev. E.1
Figure 3-22 shows the default values for RSSI and SNR parameters but
these may be changed to optimize performance in your environment. In
properly designed systems, experience has shown that RSSI levels
between -50 dBm and -90 dBm provide reliable operation, provided the
signal-to-noise ratio is 17 dB or above. Tailoring the thresholds with
these baseline values in mind, can provide improved performance in
your system.
The selections on the Auto Data Rate menu are as follows:
•
ADR RSSI Threshold—A specified received signal strength value,
which, if exceeded by the range of the
RSSI Delta setting, causes
a data rate change in the transceiver. [
-50 to -100; -87 dBm]
• ADR RSSI Delta—A user-specified difference from the RSSI
Threshold
figure which, if exceeded, causes a data rate change in
the transceiver. [
0-10; 5]
• ADR SNR Threshold—A user-specified signal-to-noise ratio,
which, if exceeded by the range of the
SNR Delta setting, causes
a data rate change in the transceiver. [
10-30; 26]
• ADR SNR Delta—A user-specified difference from the SNR Thresh-
old
figure which, if exceeded, causes a data rate change in the
transceiver. [
0-10; 2]
3.5.2 Mobile Data Configuration
Because a mobile environment is more demanding than fixed-site oper-
ation, additional considerations must be made at the time of configura-
tion. These key points should be considered for all mobile installations:
• The use of middleware in the mobile laptops is important for the
correct operation of a mobile data system. This software is not pro-
vided by MDS but is available from a number of vendors. Contact
your MDS representative for suggested software.
• Configure the radios for mobile operation at the Remotes
• Set the Remote radios to standard speed (256 kbps for iNET, 512
kbps for iNET II) to optimize coverage
• Deploy Access Points so that they provide overlapping coverage
• Access Points must use the same network name to allow roaming
Enable and disable the mobility function using the Remote radio’s Net-
work Configuration Menu (see Figure 3-23). Although a menu selection
appears in the Access Point’s Network Configuration menu, this setting
may not be changed there. When you enable the Remote radio’s
Mobility Mode option, the radio scans for an alternate AP if the RSSI is
at or below the RSSI threshold defined in the Radio Configuration
screen (see Figure 3-24).
After association is lost with an AP, and scanning for an alternate AP is
started, the former AP is removed from the scan list for one minute, to