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A LoRa transmission uses 8 frequency channels.
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We also discussed that several devices could transmit at the same time on the same channel, but there
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was only one condition.
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They had to use a different Spreading Factor. But that was not all,
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and we said that the device had to limit its transmission time.
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How exactly?
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There is a rule in the 868 MHz band which says that you can transmit only 1% of the time
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if you transmit during 1 second, then you have to remain silence during 99 seconds.
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What does that mean in our case?
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It means that our device transmitting at SF7 during 46.3 millisecond has to stay silent during
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a minimum of 4.63 seconds.
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And what's the impact on the bitrate ?
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It will be considerably affected because as usual, we are interested in the average bitrate and this
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1% rule simply reduce the average bitrate by 100.
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So for the first case at SF7, the previous 173 bits per second are divided by 100 and are now 1.73
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bits per second.
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And for the second case at SF12, the 6.9 bits per second, are divided by 100 and are now 0.07 bit per second.
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LoRaWAN is an extremely low speed network, much slower than we can imagine when we quickly
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read the documentation.
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So before stepping into LoRaWAN, you have to make a complete evaluation of your use case and to be
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very careful with what LoRaWAN
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can promise in terms of range and low power. In these two domains, it's probably one of the best
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of the market.
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But on the other hand, for the bitrate, we've just seen that it's extremely limited.
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All right, then tell me your application and I will tell you if LoRaWAN is suitable for your
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use case.