Motorola PMP 58430 User Manual page 55

PMP 400/430 and PTP 200/230 Series
PMP 400 Series networks use a cyclic prefix of 1/4 that is not configurable by the operator.
PMP 430 and PTP 230 Series networks use a default cyclic prefix of 1/4 that is configurable by
the operator to 1/8 or 1/16. The Cyclic Prefix is set on the Configuration => Radio page on the
AP. Changing the default from 1/4 to 1/8 can increase throughput by ~2 Mbps (assuming 75%
duty cycle in PMP 430 networks) in installations with low multipath conditions. It is recommended
to test 1/8 or 1/16 cyclic prefix to determine actual performance based on RF conditions.
PTP 200 Series modules (OFDM BHs) are settable for either 1/8 or 1/4 cyclic prefix. The use of
1/8 cyclic prefix provides about 11% higher maximum throughput, and is recommended for
backhaul operations in most cases.
The Cyclic Prefix is set on the Configuration => Radio page of the BHM.
The default on a new unit or when the unit is reset to factory defaults is 1/4 Cyclic Prefix.
In most deployments, 1/8 or 1/16 Cyclic Prefix will provide a high quality, higher
throughput link. In cases with severe multi-pathing or obstructions, 1/4 Cyclic Prefix may
give better overall results.
Procedure for setting the Cyclic Prefix
Set the Cyclic Prefix on the Configuration => Radio page of both the BHM and the BHS
to 1/8 before deployment.
IMPORTANT!
The Cyclic Prefix must be set the same on both the BHM and the BHS.
If they don't match, the BHS will not register to the BHM.
During installation use Link Tests to confirm link quality per standard installation and
alignment procedures.
If a Link Test shows low throughput or efficiency, consider changing the Cyclic Prefix to
1/4 on both the BHM and the BHS along with other standard installation
troubleshooting procedures such as re-aiming, off-axis aiming, changing location,
raising or lowering the height of the radio, adjusting Transmission Power up or
down, or identifying and mitigating sources of interference.
Issue 6.0 May 2011
Motorola PMP Solutions User Guide Supplement
Page 54 of 77