RDL-3000 User Manual
70-00158-01-DRAFT Proprietary Redline Communications © 2010 Page 77 of 142 November 25, 2010
transient interference, power variations (fade), and reflections. Adaptive modulation can
be enabled or disabled individually for each Subscriber Link.
When Adaptive modulation is disabled, the modulation and coding are adjusted
automatically to achieve the highest throughput where packet error rates (PER) are
lower than factory-set values. When packet error rates exceed this threshold, the
modulation/code combination is adjusted to maintain the connection at a lower
throughput rate (graceful degradation). The operator must select the maximum and
minimum burst rates for the uplink and downlink.
When Adaptive modulation is disabled, the operator must select only the maximum
uncoded burst rate (UBR) for the uplink and downlink.
Max. DL Burst Rate: Maximum downlink UBR for unicast traffic to this subscriber.
Max. UL Burst Rate: Maximum uplink UBR for unicast traffic from this subscriber.
When Adaptive modulation is enabled, the operator must also select the maximum
uncoded burst rate (UBR) for the uplink and downlink.
Min. DL Burst Rate: (Displayed only when adaptive modulation is enabled) Minimum
downlink UBR for unicast traffic. When the downlink rate falls below this threshold, the
affected rate statistics are displayed in red (Subscriber Links Summary screen) and the
downlink PIR for all Services/Service Groups are reduced proportionally until the
condition clears.
Min UL Burst Rate: (Displayed only when adaptive modulation is enabled) Minimum
uplink UBR for unicast traffic. When the uplink rate falls below this threshold, the
affected rate statistics are displayed in red (Subscriber Links Summary screen) and the
downlink PIR for all Services/Service Groups are reduced proportionally until the
condition clears.
Note: Adjustments to modulation and coding cause temporary changes to the PIR of all
connections on that wireless link. This ensures degradation of the RF signal on any
wireless link does not affect the throughput of other links in the sector.
When adaptive modulation adjusts the uplink or downlink modulation/coding settings of a
wireless link to below the desired minimum burst rate setting, the burst rates are
displayed in red and the
Example: In a link operating at 16 QAM 3/4, transient interference may result in a
temporary change from to 16 QAM 1/2 to maintain the required PER. The RDL-3000
periodically tests transmission at a higher rate and resumes operation at the normal rate
after the interference has cleared.
Downlink PIR: Enter the peak downlink information rate (aggregate downlink traffic for
all Services and Service Groups).
Uplink PIR: Enter the peak uplink information rate (aggregate uplink traffic for all
Services and Service Groups).
Note: Uplink and downlink traffic transmitted over the wireless interface is monitored to
enforce PIR settings (50 - 50000 Kbps). Traffic statistics are reset at the beginning of
each common one-second clock tick. If the maximum throughput is reached on any Link
before the end of the current interval, that Link is excluded from sending additional traffic
until after the next clock tick.
For example, if a Link transmits its full data allocation in the first 650 ms of the current
metering interval, the Link will not receive any additional bandwidth allocation until the
beginning of the next interval (enforced pause of 350 ms).
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