Send picture via LoRaWAN?


#1

Hi,

We want to send picture with LoRaWAN, to cloud of TTN

To send picture we will convert it to string file and then send packets
Our question : with TTN, is there a message limitation per day ?

is it possible to send picture ( series of frame ), with LoRaWAN ?

Thank you


#2

It is possible, but it will be a small picture since LoRa is made for and limited for low bandwith. How ‘much’ data you can send, depends on a few factors which are well explained by @arjanvanb in this post:


#3

Why not say the limitations of LoRaWAN? Small bandwidth, extremely small bandwidth, and no pictures or such, just sensor data. And also actuator data, as switching things on and off. LoRaWAN is not Internet as such, it is small bandwidth in the extremes!

But it is useful and needed for applications within the scopes of the limitations. On, Off, what if, and a lot of important things you want to now, but no pictures and no sound, and no social interactions…


(Arjan) #4

Also, if you have a large file that you split into many pieces, you would want some confirmation that each part has been received. That would need the gateway to confirm each uplink. But the gateway has the same limitations as nodes, but a gateway needs to share that limitations among many, many nodes, and also needs to use it for all kind of administrative tasks. So only a small fraction of the limits of a gateway can be used for your node.

So: no, not possible.


#5

Hello and thank you for your response

But what if we have only one node ( it’s just a demo )

For splite the file, yes it’s possible, but we ask if TTN can accept the large number of packets send ?

thanks


(Leon Schenk) #6

Hi @anisbh,

In the fastest (LoRa) modulation scheme you can send approx. 11000 bps in packets of 250 bytes. The time on air is then 194.69 ms per packet. With the 30 seconds fair access policy of TTN this gives you the possibility to send 38522 bytes per day, which is equivalent to one 700x300 pixel jpeg image per day.
This is not a lot and I discourage the use of the network for these practices, so please reconsider.

So the question is indeed if you want to send such a small amount of data over the TTN network.


(Arjan) #7

…but only in the best situation.

On SF7, one can send about 222 bytes each time, which then takes 368.90 ms and allows for only 81 such packets per day. So then it’s a 17,982 bytes image, assuming all packets are received well.

For SF12 it’s about 51 bytes per message, 2,793.47 ms, maximum 10 packets, hence 510 bytes.

Don’t try this.


(Mohamed Amine GHODHBANE) #8

Hi @arjanvanb

even, we tried to send a very small image ( 3 kbytes), 3 packets from 6 , was lost

so, there is no solution to send image, even it’s a very small image ?

thanks


(Arjan) #9

3 kbytes is not small for LoRaWAN. See the link Knology provided, and also see LoRaWAN Limitations on the Wiki:

The LoRaWAN no list:

  • Sending photos, …

And:

  • Payload should be as small as possible. A good goal is to keep it under 12 bytes. …
  • Interval between messages should be in the range of several minutes, …

#11

not very usefull… and your topic kicking, we don’t like that


#13