Motorola 5440AP - Canopy 5.4 GHz AP User Manual Supplement page 14

Canopy 400 Series OFDM AP and SM
3.5.2 Frame Calculations and Configuration Settings
Interference between collocated Canopy systems can be avoided by following two practices:
1. Use a CMM. This synchronizes frame start, so that all collocated APs begin
transmitting at the same time each 2.5 millisecond frame.
2. Use the frame calculators in each module, OFDM and FSK (the frame calculators are
different, as frame details are different) to select Downlink Data %, Range, and
Control Slots for each system that produce "Rec SEQ Start" values that are within
300 bit times. This ensures that all collocated APs end transmission each frame
before any collocated AP begins to receive.
When collocating only Canopy OFDM APs together, or collocating only Canopy hardware-
scheduled FSK APs together, the simple practice of setting the Downlink Data %, Range, and
Control Slots the same on all APs ensures they won't interfere with each other. (These
parameters are set on the "Configuration => Radio" page of the AP.) However, due to the
different "physical" layer between Canopy OFDM and Canopy FSK, this doesn't necessarily work
when collocating OFDM and FSK together.
You will need to use frame calculators on both the OFDM and FSK modules, as they are different
frame calculators. For the same Downlink Data %, Range, and Control Slots, the frame
calculators give different results. Use of the frame calculators is similar to the previous use when
collocating software-scheduled and hardware-scheduled APs.
Procedure 1: Finding collocation values using Frame Calculators
1. Using the "Tools => Frame Calculator" on an OFDM module, enter the desired
Downlink Data %, Range, and Control Slot settings, click Calculate, and observe the
"Rec SEQ Start" value.
2. Using the "Tools => Frame Calculator" on an FSK module, enter the desired
Downlink Data %, Range, and Control Slot settings, click Calculate, and observe the
"Rec SEQ Start" value.
3. Iterate, usually adjusting the FSK Downlink Data % and the OFDM Downlink Data %
values by a few percent each time, until the "Rec SEQ Start" times of all collocated
modules are within 300 bit times of each other.
4. Configure the OFDM modules using the resulting OFDM values, and the FSK
modules using the resulting FSK values.
=========================== end of procedure ======================
Version 1, April 2008
User Guide
Page 14 of 40