PMP450x Release 20.2 is now available

Cambium is officially releasing the PMP450x Radio 20.2 software.

Radio software and documentation can be found at CBRS procedures that involve both cnMaestro and radio software can be found in the cnMaestro repository at

System Release 20.2 introduces support for Cambium’s CBRS Multigrant feature. Operators are strongly encouraged to upgrade to 20.2 and begin the conversion of their single wideband grants to multigrant in preparation for PAL rollout, which is expected to begin on April 19th.

:warning: WARNING
Upgrade SMs first to System release 20.0 or later and then upgrade the AP, otherwise SMs will connect but at a maximum modulation rate of 2X MIMO-B, until both sides are running System Release 20.2 or later.

System Release 20.0 introduces support for TLS v1.2 and v1.3. TLS v1.1 is no longer supported. CNUT 4.13.3 supports TLS v1.1 only and cannot upgrade PMP/PTP devices running System release 20.0 or later that are configured for HTTPS only web access.

CBRS Multigrant support and PAL rollout support

In System Release 20.1 and prior, the device asks for a single grant regardless of the channel Bandwidth the device is configured for. If a single 10 MHz channel needs to be terminated (for example, a PAL is now protected on that channel), or suspended (for example, a DPA activated on that channel), currently the entire wider channel is affected.

With System Release 20.2, the device has a configuration option to ask for multiple 10 MHz grants

The below figure dispays this configuration option on the AP. Impacts to other UI images are shown in the Configuration Guide and the CBRS Consolidated Procedures Guide. Details on how to use the feature are detailed in the CBRS Consolidated Procedures Guide.

Two other configuration options are also introduced, and their purposes are explained in Configuration Guide and the CBRS Consolidated Procedures Guide.

A 1.6.1 revision of the Consolidated Procedures Guide contains several updates from the 1.6 version that was posted with the 20.2 BETA release on 7th April 2021.

Operators need 3.0.2 cnMaestro for full compatibility with the CBRS Management Tool, such as live CBRS grant status updates to cnMaestro, and the request of new grants as multigrants from the tool. However, conversions to multigrants for existing widegrants can be done with System Release 20.2 on devices still onboarded to 3.0.0/3.0.1 cnMaestro software versions.

The training videos, parts 1 and 2, are available here:

Problems and Limitations corrected in System Release 20.2

Products Affected Tracking Description
All 3 GHz APs CPY-17201 TX Power or EIRP for 450m was not increased as bandwidth was automatically increased when multigrant was in operation.
450m AP CPY-17254 AP sometimes experienced stack lockup after the configuration file was loaded. Traffic still passed, but pings, telnets, https, etc did not respond.

Known Problems or Limitations in System Release 20.2

Products Affected Tracking Workaround/Description
All 3 GHz CBRS SM/AP/BHM/BHS CPY-17257 In previous Software Releases, the “CBRS Staus List” table in the HOME > Session status Page on the AP would show a “TMP” indication if a granted EIRP was a temporary “Same Day Grant” value. This is missing in System Release 20.2. There is a plan to re-introduce this in a future release.
3 GHz 450m CPY-17253 There is an error message that appears roughly every 2 minutes in the event log of a 3 GHz 450m holding a CBRS grant that says “Configured beyond max EIRP, lowering transmit power from xx dBm to xx dBm” This is harmless - there is no actual transmit power issue or lowering taking place, the only negative is that it fills up the event log over time.

Workaround: Until Cambium is able to fix this error in a future release, navigate to the Configuration > Radio page on your AP, lower the EIRP by 1 dB from it’s current setting, then click SAVE. Then immediately raise the EIRP back to it’s previous value and click SAVE again. This workaround will need to be re-applied after every 450m AP reboot.
All 3 GHz AP/BHM CPY-17231 Follow-me is not updating the SM’s in all possible cases in System Release 20.2 when using multigrant.

Workaround: Operators are requested to check and make necessary bandwidth if needed and center frequency additions to their SM scan lists. See the CBRS Consolidated Procedures Guide for more details.
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I applied this release last night to several sites and everything went well. You did an excellent job writing up the CBRS Consolidated procedure guide. The purple text highlighting the critical information was a brilliant idea!

My only tip to others is to wait wait wait for each steps process to finish. You may have to wait 10 minutes +. Especially to start the SM download process after th AP finishes. And the conversion from single to multigrant.

Patience is a virtue well heeded here.

Thank you very much Cambium people!


Has anyone had issues with the wide to multi grant conversion where a few SMs do not come back?

I converted over 1000 radios the other night and a handful of them took awhile to come back (15-45min). This morning I checked and only 1 hadn’t come back online. We think that this was related to the R20.2 firmware update and not the multi-grant process however.

We’re having some issues rolling out 20.2. I’ve seen this occur on several APs: push update out to SMs first, that goes fine. after AP is updated, all SMs reconnect, and then one or two drop offline about 30 seconds later. the customer has to power cycle them to reconnect.
Just resetting the AP seems to cause more to do the same thing. Looking at an SM after it was power cycled, this is always the last message before they go unresponsive:
AP changing from 3610.000 MHz to 3610.000 MHz, adding 3610.000 MHz to frequency configuration.

Downgrading the AP, and issue still occurred (SMs still at 20.2)

Do I have to update cnMaestro first or can I update all the devices to 20.2 and do cnMaestro later? Additionally, is there an STA version of 20.2?

Yes, there is a 20.2 STA-1 available on the Google Drive folder for those that have access.

Sorry, I don’t know the answers to the other questions, but we are working on a 20.2.1 to address field issues such as some SM not establishing session after upgrade.

So should I wait? Do you have an ETA on the 20.2.1 or are you still too deep in the weeds with it?

Thank you for the quick after hours response btw

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Hi, Can we know if CPY-17254 could affect 450m APs with 20.1 already installed, or if it’s an issue that doesn’t concern 20.1? We just scheduled the 20.1 update for Mu-Mimo, it would be best to know now if we have to reschedule, thanks.

CPY-17254 was corrected in 20.2 so It would be safe to assume that with 20.1 you may encounter the issue. I have had 20.1 running on 3 450Ms and one has since been upgraded to 20.2. I did not encounter the issue with any of the three.

Since we appear to now have ability to change channel size and frequency without reboot can we now run a quick spectrum sweep on 5mhz channel width without reboot? The narrower channel allows better view of what spectrum is used etc.

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It’s always hard to give an ETA as you don’t know how long you’ll spend in the weeds until you find what you’re look for. (Personally I’ve been there before in both golfing and engineering…) :slight_smile: But we do have a 20.2.1 BETA-2 coming out soon that we would welcome feedback on.

CPY-17254 specifically applied to 450m and applying a config file over Telnet.
20.2.1 BETA-2 will include a SU-MIMO beamforming fix that is noticeable in low traffic scenarios on multiple SMs.
In addition besides multiple CBRS fixes, we also have a fix for 20.2.1 BETA-2 for rapidly degrading RF links to keep their session up. So for those reason we would love feedback on 20.2.1 BETA-2.

I agree with your request, but running the AP Spectrum Analysis at a different Channel Bandwidth is not supported at this moment from Sector Spectrum Analyzer. Of course as you mentioned it can happen with two reboots but I too agree it is not ideal. Sorry I don’t have an ETA for this feature. As you probably know, it is possible to configure the SMs to run Sector SA at 5 MHz.

I know it’s hard to provide ETA’s, but I appreciate the updates. Keep up the good work :sunglasses: :+1:

I was not able to upgrade a 450M AP running 16.2.3 to 20.2 using CNUT 4.12.8, the process would hang. Updated to the latest CNUT 4.13.3 and I was able to upgrade the AP.

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