PMP450x Release 22.0 is now available

PMP450x System Release 22.0 is now available at


Because of the improvements and enhancements made to the colocation code, Cambium Networks advises any operators using 3 GHz Cambium Networks APs with a 5 ms frame size to upgrade all APs in the same geographic area to System Release 22.0 in a single day; in the same maintenance window. By avoiding running some APs with pre-System Release 22.0 software and other APs with System Release 22.0 software, the possibility of any unexpected self-interference can be avoided. If more than one set of nonoverlapping frequencies is being used by sectors in the same geographic area, those sectors could be upgraded on different days. Note that such self-interference between PMP sectors running different software is unlikely, but cannot be ruled out.

For any operators having sectors configured with the LTE colocation feature enabled, System Release 22.0 software will automatically adjust the operating Downlink Data percentage to avoid any frame overlap with nearby LTE sectors and restrict the range that is allowed to be configured. This automatic adjustment only occurs if the APs configuration is determined by software to potentially cause frame overlap with the collocated LTE configuration.

For any operator running with LTE colocation enabled who is not completely confident they have properly configured their colocation parameters, Cambium Networks advises that the frame configuration Downlink Data percentage in operation be noted before the upgrade to System Release 22.0. Then check again after the upgrade for any possible corrections made by the new software. As mentioned above, possible self-interference concerns can be avoided by upgrading all sectors in the same area at the same time. However, noting any small adjustments made by software to the Downlink Data percentage is useful for operators to understand any changes in downlink vs uplink performance after the upgrades, and possibly adjust the frame configuration as needed to optimize.

First upgrade Subscriber Modules (SMs) to System Release 20.0 or later version and then upgrade the AP. Otherwise, SMs will connect but at a maximum modulation rate of 2X MIMO- B until both sides are running on System Release 20.0 or later version.

New Features

Multiple downlink groups per frame for PMP 450m

This feature is introduced to improve sector throughput, particularly in 5 ms frame or 30 or 40 MHz Channel Bandwidth configurations. With this feature, Cambium Networks PMP 450m AP software can change which SMs are Multi-User MIMO grouped in the middle of the frame, rather than being restricted to one set of grouped SMs through the entire frame, for the traffic in the downlink direction.

A new statistics table has been introduced in the Statistics → Frame Utilization tab called Group Forming Statistics. The Slot Grouping table shown below indicates that 95.3% of the downlink traffic symbols are MU-MIMO grouped, and that grouping is two SMs per group. The Group Forming Statistics table shows that in 40% of our downlink frames, we switch the two SMs being grouped part-way through the frame. In 5.3% of the frames, we made two grouping adjustments in the frame. Some of these frames with MU-MIMO scheduled traffic may have SU-MIMO scheduled traffic also. Only 0.4% of the frames have no MU-MIMO scheduled traffic at all. These frames have only SU-MIMO scheduled traffic, and/or unused symbols.

Link Quality Indicator (LQI) Enhancement

System Release 22.0 introduces an update to the LQI calculation to better reflect the quality of the channel when the interference has an intermittent pattern.

Following are the two changes introduced in this release:

  1. The Downlink LQI is less sensitive to beacon losses
  2. The Uplink LQI now includes information on map losses

The updated LQI value is expected to represent the quality of the channel more closely. In cases of intermittent interference, it is expected that the LQI may be higher with the new calculations compared to previous releases. Consider increasing the LQI threshold for traps if it is currently set low, in order not to miss some alarms if the channel quality starts degrading.

Below two examples show the LQI in System Release 22.0 and prior to System Release 22.0.

Example 1

LQI Prior to System Release 22.0

LQI in System Release 22.0

Example 2

LQI Prior to System Release 22.0

LQI in System Release 22.0

LTE and 5G-NR colocation additions and improvements

LTE colocation feature

LTE colocation feature now automatically adjusts the allowed range of Downlink Data percentage on the APs Configuration → Radio page to ensure no overlap with LTE occurs. In previous releases, PMP 450 APs automatically adjusted the PMP frame start to ensure it aligned with that of LTE. But the selection of a proper downlink data percentage to prevent PMP downlink transmission from overlapping with the LTE uplink transmission from a nearby LTE sector was left up to the operator to use the Cambium tools to calculate and adjust it. In System Release 22.0, this computation is done in software. Also, for any existing PMP sectors already running LTE colocation, when upgrading to System Release 22.0 if the current configuration introduces overlap with LTE, the Downlink Data percentage in the Configuration → Radio page, is automatically adjusted for the operator to the nearest proper value.

To use the above mentioned improvements, an operator additionally needs to specify the LTE subframe configuration in use as well as whether a normal or extended cyclic prefix is used as shown in the screenshot below. Prior to System Release 22.0, only the LTE Frame configuration could be selected.

APs that were already configured for co-location prior to System Release 22.0 upgrade see their cyclic prefix defaulted to Normal and the S Frame Configuration defaulted to 7. This should be checked and changed as needed. Note that there is also a slight possibility that the downlink data percentage might be auto-adjusted based on this SSF value of 7 to an undesired value. This should also be checked and adjusted as needed. These corrections can be done directly on the AP. If a large number of sectors need to be adjusted, a small configuration template can be pushed from cnMaestro. A zip file containing 4 sample templates can be found on the Cambium Networks support site:

This zip file contains, in addition to a template that corrects just the special subframe after the upgrade, a template to enable co-location and set the special subframe configuration after the upgrade, a template to enable co-location prior to the upgrade, and a template to disable/backout co-location.

5G-NR colocation feature

This operates similarly to the LTE colocation feature, with the allowed range of duty cycles selected by the AP based on the 5G-NR configuration selected by the operator in the Configuration → Radio page of the AP.

The configuration selections for the 2.5 ms frame and 5 ms frame are shown in the screenshots below. Note that when selecting 5G-NR colocation for 5 ms frame configurations, the number of Guard symbols in use on the 5G-NR system must also be selected.

Two more detailed technical documents describing co-location between Cambium PMP sectors and LTE and 5G-NR sectors can be found here:

CBRS alternate channel selection improvement

Pre–System Release 22.0 behavior

If more than the configured percentage of SMs are affected by CBRS DPA suspension, the AP triggers the channel hunting algorithm and selects a temporary channel. If on this channel several SMs more than the configured threshold do not reattach to the AP, or several SMs more than this configured threshold also experience a DPA suspension on the temporary channel, the AP keeps operating on this channel and does not attempt to find another channel. The worst case is if none of the SMs can reattach on this channel, and the whole sector has an outage.

System Release 22.0 improvement

If the new temporary channel selected by the channel hunt algorithm also has difficulty authorizing or reattaching the SMs, the AP will attempt to identify another temporary channel while still heartbeating the first temporary channel. This shall be repeated until either a channel is found that supports more than the SM Percentage Threshold for Channel Change or a maximum of 6 grants for the AP is reached. At this point, a decision will be made on which channel is optimal, with the other grants relinquished. The configuration for this feature is unchanged from the pre-System Release 22.0 code, with the same channel change percentage threshold used for both initial and subsequent channel hunts.

Fix Channel Bandwidth for channel hunting when a CBRS event is detected in a Dynamic Protection Area (DPA) causing a grant suspension to occur

For PMP 450m operators who wish to avoid rebooting, they can disable the Reboot for Channel Bandwidth Change feature, leaving the Alternate Channel Selection feature enabled, and hunting only to a channel of the same bandwidth in operation. In System Release 21.1.X Cambium Networks implemented only part of the original operator request. In System Release 21.1.X, for any AP model, if the entire spectrum is suspended due to DPA, a channel hunt is triggered. If only part of the spectrum is suspended, in general, the AP shrinks the bandwidth to the remaining authorized grants. However, for a PMP 450m with Reboot for Channel Bandwidth Change disabled, the AP remains suspended. And then, for any AP model, if part or all of the spectrum is terminated, the radio triggered a channel hunt.

The additional piece that is now added in System Release 22.0 is if only part of the spectrum is suspended due to DPA on a PMP 450m AP. If the reboot flag is disabled, then go ahead and trigger a channel hunt to the operating bandwidth only, rather than just waiting with the AP transmitter disabled until the DPA suspension clears.

Speed Test Prioritization

This feature allows AP and SM to prioritize traffic to/from a unique IP address (Consider A.B.C.D as an IP address of the speed test server). AP prioritizes any packets from A.B.C.D in the downlink direction. SM prioritizes any packets to A.B.C.D in the uplink direction.

This feature requires an SM to have more than one Data Channel configured. Packets to/from A.B.C.D is prioritized by sending over SMs highest priority Data Channel. The traffic to/from A.B.C.D is prioritized over any other traffic from/to an SM.

The operator can configure the Speed Test server’s IP address on the AP, in the Configuration → Quality of Service page, under the Speed Test Prioritization section. This configuration setting on the AP takes effect instantaneously and does not require a reboot.

SMs learn the Speed Test server’s IP address from the AP instantaneously. The IP address information is displayed on the SMs Configuration → Quality of Service page, under the Prioritized Speed Test Servers section.

Prioritized Speed Test Servers

Software upgrade from Graphical User Interface

Prior to System Release 22.0, the PMP 450 family of Radios can only be upgraded either from cnMaestro or CNUT. This feature allows the operator to upgrade software from the Radios Graphical User Interface (GUI). The software can be upgraded from the Tools → Firmware Upgrade page, under the Upload and Update New Firmware Image section, by uploading the cnMaestro Software Package.

PMP 450 AP, PMP 450 SM, and PTP 450 Radios do not have enough resources to support uploading the cnMaestro software package.

The operator can upgrade PMP 450 AP, PMP 450 SM, and PTP 450 Radios from Web GUI by uploading a radio-specific image file. The image that can be uploaded to a Radio is listed under the Image details section, on the Tools → Firmware Upgrade page and is shown in the screenshots below.

Firmware upgrade for PMP 450 AP

Firmware upgrade page for PMP 450 SM

Radio-specific image files can be extracted from the cnMaestro Software Package, using file extractor tools like WinZip, 7-Zip, etc.

The following table lists the image files specific to the Radios and their location in the cnMaestro software package.

Radio Type Image File Location
PMP 450 AP 5x_20_cf200.img \NIOS2\IMAGES\450\AP\SIGNED\
PMP 450 SM 5x_cat120.img \NIOS2\IMAGES\450\SM_BH\SIGNED\
PTP 450 ptp450_c120.img \NIOS2\IMAGES\450\SM_BH\SIGNED\

Disable SNMP agent

This feature allows the operator to disable the SNMP agent, by selecting Disable SNMP option under the SNMP parameter, from the Configuration → Security → Security Mode section. The same SNMP parameter is also available in Configuration- > SNMP → SNMP Settings section.

Disable SNMP agent

Separate RADIUS access levels for AP and SM for the same user

When a user is created in the AAA server, the user now has the same levels of access to both AP and SM. It is not possible to restrict users’ access to AP while providing unrestricted access to SM. With this feature, a user can be assigned access levels for AP that are different from SM access levels.

Following VSAs are added to the dictionary.canopy file, as part of this feature.

ATTRIBUTE Cambium-Canopy-UserLevel-AP 62 integer # Userlevel permission for the User logging in remotely from AP
ATTRIBUTE Cambium-Canopy-UserMode-AP 63 integer  # UserMode permission for the User logging in remotely from AP (1=Read-Only 0=Read-Write)
ATTRIBUTE Cambium-Canopy-UserLevel-SM 64 integer # Userlevel permission for the User logging in remotely from SM
ATTRIBUTE Cambium-Canopy-UserMode-SM 65 integer  # UserMode permission for the User logging in remotely from SM (1=Read-Only 0=Read-Write)

VALUE Cambium-Canopy-UserLevel-AP TECH 1
VALUE Cambium-Canopy-UserLevel-AP INSTALL 2
VALUE Cambium-Canopy-UserLevel-AP ADMIN 3

VALUE Cambium-Canopy-UserMode-AP RO 1
VALUE Cambium-Canopy-UserMode-AP RW 0

VALUE Cambium-Canopy-UserLevel-SM TECH 1
VALUE Cambium-Canopy-UserLevel-SM INSTALL 2
VALUE Cambium-Canopy-UserLevel-SM ADMIN 3

VALUE Cambium-Canopy-UserMode-SM RO 1
VALUE Cambium-Canopy-UserMode-SM RW 0

For example, following is the AAA configuration snippet that restricts AP’s access to TECH level and Read Only mode, while the SMs can be accessed with ADMIN and Read Write mode.

Cambium-Canopy-UserLevel-AP = 1,
Cambium-Canopy-UserMode-AP = 1,
Cambium-Canopy-UserLevel-SM = 3,
Cambium-Canopy-UserMode-SM = 0,

Support for AP Spectrum Analysis at different Channel Bandwidth

Prior to System Release 22.0, when the spectrum scan was triggered, the user can select the scanning Channel Bandwidth for the SM/BHS, but not for the AP/BHM. The AP/BHM always scans at the configured Channel Bandwidth.

From System Release 22.0 onwards, the AP/BHM Spectrum Analyzer provides the option to select scanning bandwidth for the complete sector including AP/BHM. This helps to scan the spectrum with better granularity.

Spectrum Analyzer Options

This feature is not supported on PMP 450m AP.

Additional enhancements in System Release 22.0

Products Affected Tracking Description
All CPY-18022 Support for Spectrum Analysis for cnMaestro.
450m CPY-17857 Provide Heatmap data to cnMaestro.
CBRS CPY-17357 Improved the handling of the CBRS TMP flag indication on the Home → Session Status page of the AP. This improvement refines/corrects when to set and clear this TMP flag, which is an indication of when a CBRS CBSD is operating under a temporary same-day grant.
CBRS CPY-17667 On both the HOME → Session Status page as well as the CBRS → Logs page, a new EIRP In Use field has been added per radio. For SM/BHS devices, this field tracks the smaller of the granted EIRP value and the SM/BHS configured MaxEIRP. See the PMP Configuration Guide or the CBRS Consolidated Procedures Guide for more details.
CBRS CPY-18200 Prior to System Release 22.0, the Configuration → CBRS tab on an SM/BHS was only visible for 3 GHz radios operating in an FCC region. This restriction has been removed to allow operators to clear existing signed data if for some reason a radio is removed from an FCC region.

Problems and limitations corrected in System Release 22.0

Products Affected Tracking Description
450m CPY-18192 A small correction has been made to the computation of the Multiplexing Gain for the Downlink direction reported on the PMP 450m Statistics → Additional Statistics table. As a result, an operator might see a slightly lower reported gain value for the same throughput performance seen in prior releases. For scenarios where the MGPF feature has improved throughput as compared to prior releases, a similar MUX gain value might be seen.
All CPY-18169 Limit the number of configuration change notifications to cnMaestro.
All CPY-18168 Importing a configuration file, with a configuration that is identical to the current Radio configuration, caused the Radio to require a reboot.
Vietnam CPY-18162 Changed the Vietnam country region to follow the 2018 regulatory document.
All CPY-18159 SNMP support for DHCP DNS entries.
RADIUS CPY-18149 Added a retry mechanism if the Radio failed to download a configuration file from an URL received from the RADIUS server.
CBRS CPY-18142 Home → Session Status page incorrectly showed SM state as granted instead of registered after termination.
CBRS CPY-18131 Device Information was not sent from AP if it has multiple grants.
CBRS CPY-1810 55 MHz channel Bandwidth with a center frequency of None was considered an invalid frequency configuration for CBRS.
CBRS CPY-18090 AP should continue/restart heartbeats of original grants if the channel hunt SI response indicates no additional channels available.
CBRS CPY-18089 When making decisions to shrink Bandwidth based on DPA suspensions, SMs with 501 IAP pending suspensions should be treated as if they are authorized for calc purposes.
450m CPY-18076 Spatial Frequencies displayed in Statistics → Sounding page and Statistics → Spatial Utilization page did not match.
CBRS CPY-18069 Modify the handling of TMP channels so we move back to originals in cases where not all SMs came on air on the TMPs.
450m CPY-18059 PMP 450m reported ERROR: Unexpected PHY type ID 0xFFFFFFFF at address 1 for ifnum 0.
CBRS CPY-17977 Channel change and restore time for SM suspension and termination were required in PTP models.


I can not find the Heatmap in cnMaestro. Where is located?

Our cnMaestro X is 3.1.1-r63 version.



First, the device side support is implemented for a cnMaestro feature, next then the cnMaestro feature is developed and deployed. As far as I know, they have not yet implemented and released the cnMaestro part yet, so release 22.0 is laying the groundwork for that.

The same goes for Spectrum Analysis cnMaestro feature.

Ok. I thought all was implemented.

Thanks for your swift answer.


I have recently upgraded my 450m AP and subs to version 22 and I am noticing a higher frame utilization during peak hours since upgrading. I upgraded at 2:30am February 1st and at 11pm January 31st my AP, running version 21, had 65mbps running through the radio with a 44% frame utilization. Since upgrading, my frame utilization has been significantly higher since February 1st and on during peak hours. Last night it was passing 44mbps through the radio with a 80% frame utilization. Also have noticed the cpu is steady at 20-21% on version 22 and prior version, 21, it was steady between 10-12%. Thank you.

Unfortunately there’s not enough details to know if there is an issue just from your post. Downlink traffic you’re talking about and with Downlink SU-MIMO Frame Utilization? We’d have to dive in a bit.

Frame Utilization is complicated, as it depends upon many things like modulation of traffic and number different Data Channels sending traffic at the same time, which impacts the number of Canopy MAC Level Acknowledgements.

And 450m Frame Utilization is even more complicated, as there is both SU-MIMO and MU-MIMO Frame Utilization, and it matters what spatial frequencies need the traffic when and what modulation they are running at.

Note, with the enhancement of Multiple Downlink Groups Per Frame in 22.0, it is possible to get more Data Channel’s traffic through in one frame, which will decrease latency, but could slightly increase Frame Utilization. In addition, it could increase Frame Utilization in the other direction as well as every VC that is sent a packet sends an Acknowledgement in response.

Do you monitor latency, how does it look?

And of course remember that 450m if you have a good distribution of SMs spatially and a good distribution of traffic, a 100% Frame Utilization isn’t the max as it can add more MU-MIMO streams in other directions. For this reason the Heat Map is good to monitor during busy hours to see what spatial groups are maxing out in red for how long.

For this reason, Link Test to Multiple LUIDs is great to see what your 450m could really do if every SM had max traffic at the exact same time.


For future readers, I think the frame utilization question was resolved over here:

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