nRF5340 Mesh data transfer speed slow?

[JobMeulenbeld]

I am currently researching the capabilities of Bluetooth Mesh with the nRF5340 DK. I have two DK's which are communicating over Mesh where one sends data (20 bytes) to the other. I turned retransmissions off. I have read on this forum that the speed of Mesh should be around 3.4 kb/s. I can send these 20 bytes with an interval of 200 ms without issue, but when the other DK is receiving the data, there are gaps (missed packets).

On the right is the correct sequence of packets being sent. On the left there is a consistent gap of 6 packets. Which indicates that it takes around 1.2 seconds to handle a packet of 20 bytes (133 b/s)?

 

I tested this with a buffer of 100 bytes as well, this resulted in gaps of 17 packets. Thus indicating that it takes around 3.4 seconds to handle a packet of 100 bytes (235 b/s)?

Maybe I am doing something wrong since I am not getting near the indicated transfer speed. Any tips?

Kind regards,

Job

[JobMeulenbeld]

Hello Elfving,

Elfving said:

If you want to try this test a bit more bare-bones you can try to send something shorter than 15 bytes

I have tested it with different sizes, this time on an nRF 52840, but the problem persists:

- (4 bytes): Works perfectly with an interval of 200 ms

- (10 bytes):  receives 1 out of 4 messages with an interval of 200 ms ( 800 ms per message)

- (20 bytes): Just as before, 1 out of 6 messages with an interval of 200 ms (1200 ms per message)

I have attached the project that I am running. Perhaps you will see something that I am missing 

Nordic_Devzone.zip

The program can be used as listener and sender. Just comment out the looper thread, then it will just listen to the sender.

[Elfving]

JobMeulenbeld said:

- (4 bytes): Works perfectly with an interval of 200 ms

- (10 bytes):  receives 1 out of 4 messages with an interval of 200 ms ( 800 ms per message)

I find it particularly odd that you see a diffence here. No matter the issue, this should essentially be the same test.

Thanks for sending the project. What NCS version are you using for it?

Regards,

Elfving

[JobMeulenbeld]

Elfving said:

What NCS version are you using for it?

I am using the Connect SDK V2.5.2