User's Manual

Table Of Contents
PMP 450 Planning Guide
Link operation – Dynamic Rate Adapt
PMP 450 Series products offer five levels or speeds of operation 1x (QPSK), 2x (QPSK-MIMO-B), 4x (16QAM-
MIMO-B), 6x (64QAM-MIMO-B), and 8x (256QAM-MIMO-B). If received power is less due to distance between
the AP and the SM or due to obstructions, or if interference affects the RF environment, the system will
automatically and dynamically adjust links to the best operation level.
The system chooses its operation rate dynamically, based on an internal ARQ (Automatic Repeat reQuest) error
control method. With ARQ, every data slot of every frame sent over the air (except downlink broadcast) is expected
to be acknowledged by the receiver, and if acknowledgement is not received, the data is resent. The sending unit
monitors these resends, and adjusts the operation rate accordingly. A normal system may have links that change
levels of operation as the RF environment changes. Furthermore, the links operate independently; normal operation
can have a downlink running at 6x while the uplink RF environment only supports 2x.
Optimal sector utilization involves having as many links as possible running at 8x. This provides as much capacity
as possible for the sector.
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pmp-0047 (March 2014)