Issue link: https://read.uberflip.com/i/1428395
LoRaWAN ® L2 1.0.4 Specification © 2020 LoRa Alliance ® Page 84 of 90 The authors reserve the right to change specifications without notice. In this example, the downlink data frames are both unconfirmed frames with the FPending 2511 bit set, and as such, the end-device does not need to transmit an acknowledgement. After 2512 receiving the Data0 unconfirmed downlink data frame with the FPending bit set, the end- 2513 device sends an empty data frame at a time of its own choosing. As this uplink is not received 2514 by the Network, the Network Server is then still waiting for a spontaneous uplink from the end- 2515 device to execute the transfer. The end-device may, at its discretion, offer the Network Server 2516 more transmission opportunities by sending a new empty data frame. 2517 2518 The FPending bit, the ACK bit, and payload data may all be present in the same downlink. 2519 The following frame exchange is a perfectly valid example with NbTrans=1. 2520 2521 2522 Figure 13: Downlink timing diagram for frame-pending frames, example 3 2523 2524 The end-device sends a confirmed uplink data frame. The Network Server may then answer 2525 with a confirmed downlink data frame containing the Data0 application payload, ACK bit set 2526 and FPending bit set. After an arbitrary delay, the end-device then replies with an uplink with 2527 the ACK bit set. The end-device misses next downlink containing Data1, this data was 2528 expected by the end-device because of the previous frame FPending indication. After an 2529 arbitrary delay, it offers the Network Server another opportunity to send the pending data using 2530 an empty frame. This time, Data1 is received by the end-device, and acknowledged. 2531