LoRa/LoRaWAN tutorial 11: Carrier Frequencies and Bandwidths

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This is part 11 of the LoRa/LoRaWAN tutorial.

In this video series different topics will be explained which will help you to understand LoRa/LoRaWAN.
It is recommended to watch each video sequentially as I may refer to certain LoRa/LoRaWAN topics explained earlier.

In this video I will discuss carrier frequencies, bandwidths, ETSI sub bands, dwell time and hop time.

As mentioned before LoRaWAN uses frequencies in the ISM band.
On The Things Network (TTN) website you can find the carrier frequencies for your country.
First find the frequency plan which applies to your country:
https://www.thethingsnetwork.org/docs...
For example:
Netherlands uses frequency plan EU863-870
If you know your frequency plan, find the corresponding LoRaWAN frequencies:
https://www.thethingsnetwork.org/docs...

Instead of using the The Things Network (TTN) website, checkout the LoRaWAN Regional Parameters document issued by the LoRa Alliance:
https://lora-alliance.org/lorawan-for...
This document contains the approved frequency channel plans for various global regions, and follows the established regulatory constraints in those regions.
In this video I am only focussing on the EU863-870 ISM band, for other ISM bands please consult the LoRaWAN Regional Parameters document.

If your country uses the EU863-870 ISM band, than according to the LoRaWAN Regional Parameters document every EU868MHz end device must implement the following default channels:
- 868.10 MHz, bandwidth = 125 kHz
- 868.30 MHz, bandwidth = 125 kHz
- 868.50 MHz, bandwidth = 125 kHz
and additional 5 frequencies.
The other 5 frequencies can be freely attributed by the network operator.
For example, The Things Network implemented the following frequencies: 867.1, 867.3, 867.5, 867.7 and 867.9.

Earlier the word channel is used.
A channel is just an agreed-upon set of specific frequencies with additional information included in the agreement.
For example when using the TTN freq. plan: EU863-870 the uplink channel 3 refers to:
- carrier frequency: 867.1 MHz
- SF7BW125 to SF12BW125
The LoRaWAN Regional Parameters used by The Things Network can also be found at:
https://github.com/TheThingsNetwork/g...

ETSI divides the 863-870 MHz band (referenced "G") into 5 sub-bands: G, G1, G2, G3 and G4. [5]
Each sub band has different constraints in term of EIRP, duty cycle and channel bandwidth.

LoRaWAN only uses the following bandwidth ranges: 125 kHz, 250 kHz and 500 kHz.
Which of these 3 ranges are actual used depends on the region or frequency plan.
For example in Europe only the bandwidths 125kHz and 250 kHz are used.

An end device changes channel in a pseudo-random fashion for every transmission.
Changing frequencies makes the system more robust to interferences.
For example in Europe for uplink transmissions 8 different frequencies are used.

Dwell time (or transmit time) is the amount of time needed to transmit on a frequency.
Hop time is the amount of time needed to change from one frequency to another in which the radio is not transmitting

Check out all my other LoRa/LoRaWAN tutorial videos:
   • LoRa/LoRaWAN tutorials  

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The presentation used in this video tutorial can be found at:
https://www.mobilefish.com/developer/...

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