https://devzone.nordicsemi.com/f/nordic-q-a/96969/ble-link-layer-retriesOur device is operating as BLE peripheral running NRF5 15.2 and SoftDevice 6.1.1 Our application calls sd_ble_gatts_hvx() to send notifications. If I understand correctly, the SD (or PHY?) will retry the transmission multiple times if necessary. Ifen-USTelligent Community 13Thu, 23 Feb 2023 08:47:48 GMThttps://devzone.nordicsemi.com/thread/411556?ContentTypeID=1Thu, 23 Feb 2023 08:47:48 GMT137ad170-7792-4731-bb38-c0d22fbe4515:7a82f173-3679-42f7-992d-46df48b5aa1aHung Bui<p>Hi Michael,&nbsp;<br />The information about the number of retries is not available to the application. There is no information about an individual packet is send back to the application. The only information is the number of packets has been ACKed in the&nbsp;<a href="https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s132.api.v0.9.0/group___b_l_e___g_a_t_t_s___h_v_n___m_s_c.html?cp=5_7_3_11_2_0_4_0_13">BLE_EVT_TX_COMPLETE </a>event.&nbsp;</p> <p>However, if you want to measure the noise level on each channel of the BLE communication you an use the <a href="https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s132.api.v7.3.0/group___b_l_e___g_a_p___f_u_n_c_t_i_o_n_s.html?cp=5_7_3_1_2_1_3_32#gaebe458be0d54576a131db1c9b2d8ff8b">Softdevice&#39;s Quality of Service channel survey API.<br /></a>You can find the usage in the softdevice migration pdf file:&nbsp;<br /><br /><img style="max-height:240px;max-width:320px;" src="https://devzone.nordicsemi.com/resized-image/__size/640x480/__key/communityserver-discussions-components-files/4/pastedimage1677142001901v1.png" alt=" " /></p><div style="clear:both;"></div>