EU sub bands used?

[Lawrence Griffiths]

I can’t find any formal documentation which states what sub bands EU mDots use? My understanding is EU LoRaWAN end-nodes must support g1 but does the mDot make use fo g2 & g3 bands? If not will they ever?

I found this on MT Dev site
default: 869500000
range: [863500000 – 867500000]
and [869100000 – 869500000]

868.1
868.3   g1
868.5  

868.85  g2
869.05

869.525 g3

[Roman Ploskon]

Also I would like to hear more on this topic. Presumably mDot is using more then one sub band as I am able to send several messages before starting to receive a response “no free channel”.

[Mike Fiore]

Lawrence,

You are correct. The mDot supports 868.1MHz, 868.3MHz, and 868.5MHz by default.

The other 5 channels are network configured. The device receives this information in the join accept message in OTA join modes. These 5 channels are based on a configured center frequency and spaced 200kHz apart.

The MTS network server defaults this parameter to 869.5MHZ, which yields 869.1MHz, 869.3MHz, 869.5MHz, 869.7MHz, and 869.9MHz as the 5 network channels.

There are 4 different duty cycle bands specified for the 868MHz frequency band. This default configuration spans all 4 bands, which is why it takes a few transmissions in rapid succession before you see the “no free channel” error.

When a channel in a specific duty cycle band is used, all the channels in that band must stay off the air until the time off air requirements for that band have been met. After that, all channels in that band are available for use.

Hope this helps!

-Mike

[Roman Ploskon]

Mike,
Thank you for your repl.y Is it possible to see which channel has been used for transmission of last packet or is going to be used for next one?
Thanks,

[Mike Fiore]

Roman,

Unfortunately, no. The next channel is randomly chosen out of the available channels in order to minimize collisions with other LoRa endpoints. If you enable trace logging, you can probably see what channel is being used, but there isn’t a programatic way to find out.

Can I ask why your application needs to know which channel is being used?

-Mike

[Roman Ploskon]

There is no such application need. I was just a little bit curious 🙂

[Roman Ploskon]

Mike,
could you be please more specific about which channels falls within which band?
From what I have gathered there are:

h1.3 863-870 MHz; 25 mW e.r.p. (0.1%)
h1.4 868-868.6 MHz; 25 mW e.r.p. (1%)
h1.5 868.7-869.2 MHz; 25 mW e.r.p. (0.1%)
h1.6 869.4-869.65 MHz; 500 mW e.r.p. (10%)
h1.7 869.7-870 MHz; 5 mW e.r.p. (no requirement) / 25 mW e.r.p. (1%)

Thanks,

[Jason Reiss]

Roman,

That is exactly how we have the bands setup.

Here is the latest reference doc I could find.
http://www.erodocdb.dk/docs/doc98/official/pdf/rec7003e.pdf

We have noticed that Semtech is following note 5 for h1.3 LoRaMAC-node reference implementation.

Note 5: Duty cycle may be increased to 1% if the band is limited to 865-868 MHz.

This will not allow frequencies that fall between the defined bands above 868 to be used. Making 869.3 invalid.

[Roman Ploskon]

Jason,
thank you for your reply. I looked into the Semtech’s reference implementation.
The difference is that they have center frequency set to 867.5 MHz unlike yours 869.5 MHz.

Center frequency 867.5 MHz leads to 867.1, 867.3, 867.5, 867.7, 867.9 which all falls under the h1.3 (note 5 – 1% duty cycle).

In your case, can I assume that 869.3 MHz is not going to be used at all or it is actually use under a band h1.3 but with 0.1% duty cycle (if that is permissible)?
And what about 869.7 MHz which is right the edge frequency of h1.7?

[Author]

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