reception within a basement?

[Ronald]

For a customer we're trying to see if we can build an IoT solution with nrf9160 to periodically send a status update to the cloud. Unfortunately, the devices are typically in the basement. Connecting from a basement over LTE-M/NB-IoT with nrf9160 has been unsuccessful sofar. We tested in three basements with no luck (normal house basement and two office building garages). As this is one of the main use cases for IoT: stuff in a basement sends a status update once in a long time we were quite surprised that it didn't work. Any hints you can give us? The antenna we tried is an 20 cm tall LTE antenna. Is this a problem with the providers not enabling NB-IoT/LTE-M features for wall-penetration? I failed to find any options to boost the receive or send amplifiers? Are there better antennas that we should try?

[Martin Lesund]

Hi Ronald,
When it comes to IoT devices that are located underground such as basements etc. It is recommended to use the NB-IoT technology since it provide a much better penetration.

From what I read you are using a custom board? Or are you testing with the nRF91DK?

How are you doing these tests?

I would recommend just running the AT Client sample (which is also included as a precompiled .hex file in the .zip folder in the nRF91DK page).
Please make sure you have the latest modem firmware.

Please send a serial output log using the AT Client sample getting a sucessful connection over ground via NB-IoT, and then go underground and follow the same steps.

Best regards,
Martin L.