We saw in a previous video the comparison between the LoRa modulation and the other protocols of the 1
Internet of Things. 2
We also saw that the LoRa modulation aims to be long range but with a very low bitrate. For transmission, 3
LoRa use free bands. 4
And in Europe, free bands mean that there is no need for authorisation. 5
And there is also no additional fees. 6
I wrote down in the table below a few of these free bands in Europe. 7
They are not all mentioned, but these are the main ones. 8
And among these free bands, we'll try to see where LoRa is located. 9
So first of all, we have the band commonly used for Wi-Fi, Bluetooth BLE and a 2.4 GHz band is 10
also used for Zigbee protocol, which I remind you is used for home automation. 11
The 5 GHz band is also used for Wi-Fi. 12
NFC used for contactless payment is in the 13.56 MHz band, but there is now the 433 MHz potentially 13
used by LoRa. 14
But of course among a lot of other systems, and in that band there is a very well-known one which is 15
the Walkie-Talkie, but obviously not part of the Internet of Things. 16
LoRa also uses 868 MHz band with its competitor Sigfox and again many other protocols. Between 17
868 and 433, 18
how will you make the choice? 19
You can choose 433 MHz if you only use the LoRa modulation for your transmission. 20
But as soon as you want to use LoRaWAN infrastructure, you don't have a choice because the LoRaWAN 21
protocol needs to follow the frequency plan of its network server and it's always 868 MHz in Europe. 22
There is also the possibility to use LoRaWAN in the 2.4 GHz band, but it's not so common yet. 23
The main advantage of that 2.4 GHz band is that it's a world wide free band, which is not the 24
case for 868. 25
Remember also that we have to be careful with high frequencies because the higher the frequency, the 26
lower the range. 27
So, now that we know more about the frequency use, we will try to understand how hundreds, and even thousands 28
of communicating devices will be able to transmit information on the same 868 MHz band 29
while ensuring that at the end, all messages sent are demodulated without errors. 30
And for that, we'll see three techniques that I'm going to explain in the next chapter.