[quote=“youngjune0594, post:4, topic:9379, full:true”]
@Epyon
I just wonder about how long transmitter should be silent.
many documents said just “long enough” (a few minutes), however
i want to know which factor mandates transmitter to wait that much and how to calculate the period.
more fundamentally, why LoRaWAN select [/QUOTE]
You should start by reading the wiki, especially the part about duty cycle.
[quote]In my opinion, this kind of communication would be weak for collisions among multiple transmissions from many nodes because each node transmit entire message in one transmission(long air-time).
any advice?[/quote]
Yes. Place more gateways.
LoRaWAN does not scale well if people transmit very long messages on high spread factors very often. In this scenario hundreds of nodes can easily lead to so much collision that communication is practically impossible. LoRaWAN is meant to transmit two, three dozen of bytes every few minutes to a gateway located not that far away (so it can use a low SF). In this scenario it will take thousands of nodes to lead to enough collisions to disrupt communication.
LoRaWAN gateways are commodity priced so it’s very easy to expand the network, making the nodes switch to lower SF (if they support ADR) and freeing up airtime.
See this discussion for more background.