xg590
commented
1 year ago According to my understanding of LoRa theory, it is difficult to do collision detection before sending. If two senders contest the same channel, there will be PayloadCrcError. A simple search https://www.thethingsnetwork.org/forum/t/do-lora-wan-nodes-perform-any-activity-detection-and-or-collision-detection/1353/3 led to a similar conclusion. I think we have to do a retransmission if there is a CrcError.
In addition, there is a CAD mechanism for the SX1276 chip but I do not understand how it would be helpful. The datasheet says it listens the preamble of on-going transmission during CAD state but that elusive preamble only lasts for a few milliseconds. If one SX1276 is transmitting (preamble transmission is over), I don't think other SX1276 chips can detect the on-going transmission (payload is being transmitting). What do you think?
Best, Xiaokang.
On Wed, Dec 21, 2022 at 7:17 AM ATONU GHOSH @.***> wrote:
I have setup two or more nodes sending data to a single node. A lot of collisions occur and "PayloadCrcError" shows up. But why does it get stuck at this?
Also, is there a way to receive maximum data from multiple nodes?
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atonughosh
I have setup two or more nodes sending data to a single node. A lot of collisions occur and "PayloadCrcError" shows up. But why does it get stuck at this? In the image below, one node is sending a sequence number and "HelloWorld" and the other is sending "HelloWorld_1".
Also, is there a way to receive maximum data from multiple nodes?