Downlink and Uplink huge variation

Dear All

I need your help to this challenge what can cause this type of discrepancies in a Force 200 point to point radio link at a distance of 1.2km.


If your TDD configuration is set to 50/50, you are experiencing a different MCS in the UL compared to the DL. While there is not enough info here, likely your UL noise floor is 6dB or higher than the DL noise floor. Sometimes this is a channel plan issue (channels overlapping), and sometimes you have co-located the UL receive Force 200 to close to other transmitters. The Force 200 should be mounted away from any other transmitters on the tower.

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Dear Dave

Thanks for your prompt response to my request

Yes I quite agree with you the AP(Force200) is currently mounted on a POP(tower) where there are a lot of similar cambium radios mounted on the same tower. There is no other position to relocate or mount this AP because the current height on the tower is the only location that I can have a clear line of sight to the SM(Force 200 at the customer’s end).

Anytime i attempt to shift the current position of the AP(on the tower) there wouldn’t be a clear line of sight to the SM (i.e. no link). So the only choice I have is to maintain the current position so as to have a clear line of sight to the SM(customer’s end)

I have done a spectrum scan at the AP:

Kindly advice me what else can I do. I want to achieve a steady 30Mbps capacity(Uplink and Downlink) on this Point to Point link a Force200 over 1.2km distance link.

Secondly at this same POP(tower) in question what can you advice me to do in-other to reduce or eliminate self interference on the tower where I have over 20 Cambium radios (Force200 on a PTP platform) mounted on the same tower but at different heights and 4-epmp 2000 sectorial base radios antennas(for PTMP links) mounted on the same tower?

This has been affecting any new customer I want to linkup to this tower.

Hope to hear from you soonest.

So if I am understanding you correctly, you have 4 ePMP 2000 AP’s on a tower AND 20 F200 radios all operating as PTP links? If so, I have to say that’s a first for me. Self interference has got to be a killer. If you wanted to sneak in one or two dedicated PTP you could do it using an ePMP 1000 lite with GPS syncwith a dish as an PTP AP and it would play nice with the ePMP 2000.

Not sure what to say except that the deployment as you have described was not a good idea. You would be much better off going with something that can provide much higher throughput, such as the ePMP 3000 solution which has significantly higher AP throughput and would allow you to most likely meet your target bandwidth without all the PTP radios.

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I agree with Riverrat. The unsynchronized PTP radios are causing the problem. There is no way to add synchronization to SM - SM PTP’s, so your best bet is to replace the epmp2K with epmp3K AP’s using the 60 degree dual horn antennas instead of the sector antennas, and move as many, or ideally all, of your PTP links to PtMP links on the higher capacity ePMP3K AP’s. You need to make sure everthing you have co-located on that tower is GPS synchronized, has the same DL/UL TDD ratio, and is running as low power as you can. By your spectral measurement, there is no clean spectrum available for you, so you’ll have to ocnsolodate your links to reduce noise rise, and make your site more efficient.


Dear Dave

After a careful consideration of the current positions of the two radios (Force200). The SM-unit at the customers end was relocated to a new position and similarly the AP unit at the POP was relocated too a clearer position as advised.

It worked perfectly fine and now I can serve the customer perfectly


Customer is fine and happy

Thanks a lot

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