Beware that this post is related to an SDK in maintenance mode
More Info: Consider nRF Connect SDK for new designs
This post is older than 2 years and might not be relevant anymore
More Info: Consider searching for newer posts

Issue with dropped advertisements using SDK 17.0.2 (SoftDevice 7.2.0)

We experience a 15-20% rate of dropped advertisements from our nRF52840 device. We have used our own application on our device and the ble_app_att_mtu_throughput application on the nRF52840 DK to measure this loss. The devices are advertising once every 10 seconds. We are maxing out the packet size of the advertisements (31 bytes) with manufacturer specific data.

There is noise in our testing environment, and we suspect that may be part of the problem. However, we have performed the same tests outdoors with minimal interference and still continue to see a significant number of dropped advertisements.

We thought maybe using Periodic Advertisements would help us reduce dropped advertisements, but was unable to find support for this in the nRF SDK 17.0.2 (SoftDevice 7.2.0) release.

We also thought that using extended advertisements would reduce the amount of time on the primary channels, (37,38 and 39) and instead transmit the bulk of our data on a secondary channel.

Are Periodic Advertisements supported at this time? If not, when might we expect support? 

Do you have any suggestions that we might use to reduce the number of dropped advertisements, e.g. extended advertisements, periodic advertisements, etc.?

Parents
  • We're now testing an advertisement sent every 5 seconds. The central is running mBedOS 6.11 and setting the scan to 100% duty cycle did offer some improvements to the performance. But, we are still consistently seeing a 15% drop rate.

    We didn't see much improvement between extended and legacy advertisements in our tests.

    Please let me know if you have any other suggestions on proving the drop rate.

Reply
  • We're now testing an advertisement sent every 5 seconds. The central is running mBedOS 6.11 and setting the scan to 100% duty cycle did offer some improvements to the performance. But, we are still consistently seeing a 15% drop rate.

    We didn't see much improvement between extended and legacy advertisements in our tests.

    Please let me know if you have any other suggestions on proving the drop rate.

Children
  • Hi Steven, 

    Please give us some description about your test. 
    You mentioned about ble_app_att_mtu_throughput application but I assume you only count the number of advertising packets you receive, not when they are in a connection ?

    What's the distance between the 2 devices ? 
    Have you tuned the antenna of your custom board ? 
    Could you try to test using 2 DKs instead of your device + our DK. Just so we can compare if it the antenna tunning issue on your board ? 

    For best result, please try to test using a RF chamber or use a antenna cable to connect the 2 devices. 
    I would also suggest to test with short advertising interval (100ms for example) so that we can have more sample and get better statistics. 

Related