Giacomo Vianelli

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7 years ago.

Deep Indoor

Hi, I'm working on a prototype of a smart meter using the 868MHz band and a custom PCB based on this board and the processor kl82z.

I started from the LoRaWAN-demo-72 application code and made few adaptions to make it work on my board.

The configuration of the semtech is: - SF12BW125 - +14dB of transmit power - ABP authentication

The distance from the devices and the GW is around 1.5km in a suburban environment. When i send data from the 1st floor the GW receives it. The RSSI ranges from -120 to -111 dB and the SNR from-15.5 to -11.2 dB.

When I try to send data from the basement the GW doesn't receive anything.

My questions are:

1) The parameters I used for my configuration are fine to work in this environment? 2) Do you have any experience/tips to achieve better results in deep indoor environments?

Question relating to:

Last updated: 07 Mar 2019

1 Answer

Jan Jongboom
7 years ago.

Quote:

1) The parameters I used for my configuration are fine to work in this environment?

You can't really do any more than sending with max TX power and lowest data rate, it won't get better than this.

Quote:

2) Do you have any experience/tips to achieve better results in deep indoor environments?

  1. What antennas are you using on both ends? Using an antenna with more gain could help on the device (if allowed).
  2. What's the gateway height? The problem with basements is that the earth gets in the way (fresnel zone), which you can mitigate a little bit (but not completely solve) by placing the other antenna higher. However, you'll lose a *lot* of signal when going underground. Already difference between TX at 1m. vs. 5m. height gives 10 dBm extra path loss (with RX at 30m.) according to Hata model. Putting a small gateway in the building would help more.

Accepted Answer

One other quick note on the antennas, the standard antennas on a lot of things are those thin 2dBi antennas as seen on things like wi-fi hotspots and people generally orient them vertically. Which gives you a nice null in the antenna pattern directly above / below the antennas. I have seen changing the antenna orientation sometimes make a big difference in this sort of situation.

posted by Andy A 08 Nov 2017