User Manual

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The ACM function operates continuously, i.e. – if RF link conditions change, then the
modulation and MIMO settings will respond in order to maximize link capability without
compromising reliability.
The system relies upon user traffic to determine the optimal modulation settings. When ACM is
enabled, user traffic must be available in order to bring link performance up to its maximum
capability.
ACM is a feature that is enabled on a per-radio basis. It is not necessary for both radios to
share the same state ACM enable/disable configuration.
ACM seeks to optimize the TX modulation of the radio on which it has been enabled. Since RF
conditions may not be the same on either side of the link, due to impairments such as
interference, the system may not select the same TX modulation/MIMO settings for each side.
The RF power settings will not be adjusted by the ACM system.
If the RF power is set above one of the power/modulation thresholds listed in the Transmit
Power section, the ACM system will not likely reach higher order modulations. For example, if
the radio power is set to 23dBm, then the ACM will not be capable of achieving QAM16 or
QAM64 operation.
Tx Streams The power of MIMO technology rests on the ability to define the number of data
streams that are carried across the two (2) RF links. At all times, the XL100t radios utilize a 2x2
dual-chain MIMO format where 2 RF transmit and 2 RF receive chains are enabled and active.
However, these dual chains can be used to carry 1 or 2 data streams. XL100t systems are fixed
to 1 stream operation only.
In a 2 stream configuration, unique data is carried across each RF chain, greatly increasing the
amount of data capacity over a non-MIMO system. The 100 Mbps capability of the product
requires that 2 streams operation be configured.
In contrast, when increased link robustness and noise immunity is desired, MIMO can be used
in a 1 stream configuration. In this scenario, the same information is carried across both RF
chains, increasing the reliability of reception.
It is recommended that both Master unit and Slave unit share the same Modulation and Stream
settings.