User's Manual

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BreezeMAX Modular Base Station System Manual 167
Associated Radio Cluster: As configured in the Associated ODU.
Uplink (Rx) Frequency: Computed from the configured Downlink (Tx)
Frequency according to the Duplex Separation of the applicable Frequency
Band. In TDD systems the Uplink (Tx) Frequency is the same as the Downlink
(Tx) Frequency.
ODU Frequency Band: The ODU Frequency Band. If there is a mismatch
between the Configured ODU Frequency Band and its actual band, both
values will be displayed.
Operational Status
4.9.5.3.4 Multirate Parameters
BreezeMAX employs a multirate algorithm to dynamically adapt the modulation
scheme and Forward Error Correction (FEC) coding to actual link conditions. The
algorithm is managed by the AU taking into account also information received
from the served SUs. Optimal values are calculated separately for the uplink and
downlink for each SU. MAP messages transmitted to the SUs include information
on the uplink rate that should be used by each SU for its next transmission.
The multirate algorithm optimizes the trade-off between capacity and error rate:
In most deployments, most of the links use high order modulation most of the
time, maximizing capacity. “Bad” links use lower order modulation, maximizing
availability. The algorithm provides independent adaptation per SU, and it is
performed independently for UL and DL, based on link quality information (Burst
Error Rate, SNR). The algorithm provides dynamic adaptation - modulation can be
changed on a per burst basis. UL transmission rate is determined by the AU, and
DL transmission rate is determined by the SU.
The multirate algorithm in the uplink adapts dynamically both the modulation
and the number of sub-channels to be allocated to each SU.
When the Multirate algorithm is disabled, communication with connected SUs will
continue using the last uplink and downlink rates selected by the Multirate
algorithm. The Set Rates option in the SU (see Section 4.10.7.3.4.2), which
becomes available only when the Multirate algorithm is disabled in the AU,
enables setting the Uplink Current Rate and the Downlink Current Rate to any of
the values listed in Table 4-6.
The multirate algorithm chooses dynamically between several rates. These are
also the rates that can be configured for the Basic Rate parameters.