CBRS SM hangs in the Registration phase


I have 1 AP with a single SM that is hanging in the registration phase at least I think.

The RSSI in the SM is ~ -69 -73 when the link is registering it will the drop to -116, resume scanning, rinse and repeat.

In Maestro this SM is showing heartbeat failure. it is the only one out of 16 APs and 31 SMs that has this issue. Upgraded to 22.0 3 weeks ago no known issues with the upgrade process.
AP /SM are 450 products
I have attempted the following
rebooted AP
rebooted SM
rebooted proxy
rebooted meastro
changed frequency

thank you

So in cnMaestro, have you already added this CBSD and started the SAS process on it? What state does cnMaestro say the new CBSD is in? It will need to be at a ‘granted’ state in order for it to register to the AP, after that it should transition to an ‘authorized’ state.


yes this SM has been in service since 15-16 and rolled up to CBRS whenever that became a thing. it has performed perfectly until it didn’t. The current state is heartbeat failed, I have yet to remove it from the system and try to re-add it back in. Not sure if that would make much difference. I have noticed that on a reboot the link SM will go registered for a few minutes then drop in to the current cycle.


On the AP, if you go to Logs → CBRS Logs, and then select the SM from the drop down list (even if it’s just an IDLE luid), and then press save, what do the CBSD logs say?


below is the CBSD Log

02/15/2023 : 07:12:15 EST : Sending grant information to SM with 1 grants
02/15/2023 : 07:12:15 EST : Enabling session for SM
02/15/2023 : 07:13:06 EST : SM grant version is 1
02/15/2023 : 07:13:06 EST : Grant version 1.1 from cnMaestro
02/15/2023 : 07:13:06 EST : Received GRANT_INFO_RETRIEVED from cnMaestro
02/15/2023 : 07:13:06 EST : Config pull acknowledgement sent to cnMaestro, without config or grant update
02/15/2023 : 07:13:06 EST : CBSD is already registered with SAS
02/15/2023 : 07:13:06 EST : Reusing existing grant with SAS - Frequency = 3665000 kHz
02/15/2023 : 07:13:06 EST : [0] Heartbeat Request : {“cbsdId”: “Z8H89FT00090a003e408e6d”, “operationState”: “AUTHORIZED”, “grantId”: “143496257105932790881676302754”, “grantRenew”: true}
02/15/2023 : 07:13:06 EST : Sent - {“heartbeatRequest”: [{“cbsdId”: “Z8H89FT00090a003e408e6d”, “grantId”: “143496257105932790881676302754”, “grantRenew”: true, “operationState”: “AUTHORIZED”}]}
02/15/2023 : 07:13:06 EST : Sent Heartbeat Request
02/15/2023 : 07:13:06 EST : Recv - {“heartbeatResponse”:[{“cbsdId”:“Z8H89FT00090a003e408e6d”,“grantId”:“143496257105932790881676302754”,“transmitExpireTime”:“2023-02-15T12:16:46Z”,“grantExpireTime”:“2023-02-22T12:13:06Z”,“heartbeatInterval”:190,“response”:{“responseCode”:0}}]}
02/15/2023 : 07:13:06 EST : [0] Received HeartBeat Response
02/15/2023 : 07:13:06 EST : {“cbsdId”: “Z8H89FT00090a003e408e6d”, “grantId”: “143496257105932790881676302754”, “grantExpireTime”: “2023-02-22T12:13:06Z”, “heartbeatInterval”: 190.0, “transmitExpireTime”: “2023-02-15T12:16:46Z”, “response”: {“responseCode”: 0.0}}
02/15/2023 : 07:13:06 EST : Sending grant information to SM with 1 grants
02/15/2023 : 07:13:06 EST : Enabling session for SM
02/15/2023 : 07:13:22 EST : SM not in session hence stopping heartbeat

Hi David. A couple of us took a quick look at the SAS logs and what you have pasted here. Initial reaction is that it looks more like an RF concern than a higher layer CBRS issue. But feel free to open a Cambium ticket for additional assistance. When doing that, include an engineering.xml from both the SM and the parent AP, thanks