Connectivity issues due to temperature

LPWAN Modules / EVBs RAK3172
1

Hi,

We have a few tousands units, with the RAK3172 modules inside, deployed around the world. We are now struggling with connectivity issues on some units that seems related to temperature.

The units are supplies with grid power (no batteries) and are combined in a network of around 900 units on a industial indoor area. We have a custom modified variant of the lora stack to adapt to our application.

The issue we see in the field and also have been able to recreate in an office envirnoment, is that if we increase the ambient temperature around the RAK chipset (to around 50 degree celcius), the communication to the unit from the gateway still works, but communication from the unit to the gateway stops working. We suspect that also the communication to the unit also breaks but at a higher ambient temperature.

All other electronics on the board has been eliminated and the RAK chip has been powered by a lab supply directly with 3.3V. Our suspicions are aimed for the XTAL suppling the frequency to the radio part. Any ideas from you guys?

2

Welcome to RAK forum @JohanRuben ,

Let me share some thoughts.

  1. 50degC is not yet very hot. We have performance test on high temperature and it works ok. We have issues on the XTAL before but it is on the negative temperature side.
  2. When you shared about your modified LoRa stack, is this still based on LoRaWAN? Or you implemented your own protocol? Maybe you can share some features of this like gateway to device communication, bandwidth configuration, etc.
  3. It is good that it can be replicated in office/lab setup. We can do this evaluation as well as whenever you can provide the details for us how we can replicate the issue.
3

Hello @JohanRuben
As you have opened a ticket as well in our Service Center, let us follow up this issue there.

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