Cambium Networks PMP 450 Series, Installation Manual

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Chapter 3: System planning 153
frame time Downlink Data is selected as a percentage, between 15% and 85%.
l
Contention Slots: time symbols reserved in the uplink portion of the frame for random access,
registration and bandwidth request Contention Slots is a number between 1 and 15.
The Channel Bandwidth can be configured under Configuration > Radio > Radio Configuration, as shown in
below figure.
All other parameters can be configured under Configuration > Radio > Frame Configuration, as shown in
below figure.
PMP – LTE co- locat ion t ool
The configuration parameters that affect the frame structure need to be selected in order to avoid any
overlap between transmit and receive times.
In order to help with the selection of system parameters, Cambium Networks offers a PMP – LTE co-
location tool, available at
https://support.cambiumnetworks.com/files/colocationtool/
The PMP and LTE configuration parameters are entered in the spreadsheet, and the frame structure for the
two systems is displayed on the right side.
The tool checks that there is no overlap between one AP transmitting and the other receiving.
This translates into two equations:
l
The downlink time of AP1 ends before the uplink time of AP2 starts
l
The downlink time of AP2 ends before the uplink time of AP1 starts
In the example in below figure the second equation is not satisfied, and the two systems cannot be co-
located. The plot to the right also shows that with this frame configuration the LTE AP is still transmitting
when the PMP AP is already receiving. This creates interference at the PMP AP receiver.