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Advertisement packet loss in Coded PHY vs 1 Mb PHY

Using the following:

Rigado BMD-360 nRF52811 development board.

Softdevice S140 7.0.1

SDK 16.0

Using two development boards inches apart, one development board sends a single advertising event every 12 seconds.  The other development board is continuously scanning (interval and window = 7s).  The packets have 30 bytes of data including a sequence number.  I calculated packet loss based on the missing sequence numbers.

Sending and scanning using the 1 MB/s PHY, in a test of approx. 20 minutes  I get 100% reception of packets.

Sending and scanning using the Coded PHY, in the same test I get ~43% reception of packets, ~57% packet loss.

Is this expected behavior, or could I be configuring something wrong when advertising using Coded PHY?

Another behavior I've seen is for the above condition using the Coded PHY to have a repeating pattern of receiving 3 and missing 2.

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  • Hi Kurt

    Packets with a data length of more than 27 bytes in Coded PHY has an increased chance of losing packets. It would be better to transmit two smaller packets than one larger one when using Coded PHY.

    Best regards,

    Simon

  • I've repeated the experiment with 15 fewer data bytes, so now the GAP event structure reports a size of 15 bytes.  I am still getting a packet loss rate of approximately 50%.  I have verified that the advertiser is not reporting errors in sending.

    I have performed another limited experiment where I have sent 15 advertisements with a delay of 100ms between them.  In approximately 50% of those cases, the first advertisement is not detected.  All the remaining advertisements are detected.

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  • I've repeated the experiment with 15 fewer data bytes, so now the GAP event structure reports a size of 15 bytes.  I am still getting a packet loss rate of approximately 50%.  I have verified that the advertiser is not reporting errors in sending.

    I have performed another limited experiment where I have sent 15 advertisements with a delay of 100ms between them.  In approximately 50% of those cases, the first advertisement is not detected.  All the remaining advertisements are detected.

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