User Guide

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)