Issue link: https://read.uberflip.com/i/1428383
LoRaWAN 1.0.3 Specification ©2018 LoRa™ Alliance Page 62 of 72 The authors reserve the right to change specifications without notice. 18 Examples and Application Information 1590 Examples are illustrations of the LoRaWAN spec for information, but they are not part of the 1591 formal specification. 1592 18.1 Uplink Timing Diagram for Confirmed Data Messages 1593 The following diagram illustrates the steps followed by an end-device trying to transmit two 1594 confirmed data frames (Data0 and Data1): 1595 1596 1597 Figure 28: Uplink timing diagram for confirmed data messages 1598 The end-device first transmits a confirmed data frame containing the Data0 payload at an 1599 arbitrary instant and on an arbitrary channel. The frame counter Cu is simply derived by adding 1600 1 to the previous uplink frame counter. The network receives the frame and generates a 1601 downlink frame with the ACK bit set exactly RECEIVE_DELAY1 seconds later, using the first 1602 receive window of the end-device. This downlink frame uses the same data rate and the same 1603 channel as the Data0 uplink. The downlink frame counter Cd is also derived by adding 1 to 1604 the last downlink towards that specific end-device. If there is no downlink payload pending the 1605 network SHALL generate a frame without a payload. In this example the frame carrying the 1606 ACK bit is not received. 1607 If an end-device does not receive a frame with the ACK bit set in one of the two receive 1608 windows immediately following the uplink transmission it MAY resend the same frame with the 1609 same payload and frame counter again at least ACK_TIMEOUT seconds after the second 1610 reception window. This resend MUST be done on another channel and MUST obey the duty 1611 cycle limitation as any other normal transmission. If this time the end-device receives the ACK 1612 downlink during its first receive window, as soon as the ACK frame is demodulated, the end- 1613 device is free to transmit a new frame on a new channel. 1614 The third ACK frame in this example also carries an application payload. A downlink frame 1615 can carry any combination of ACK, MAC control commands and payload. 1616 18.2 Downlink Diagram for Confirmed Data Messages 1617 The following diagram illustrates the basic sequence of a "confirmed" downlink. 1618 1619 1620 gateway End-point Confirmed Data0 {Cu} ACK {Cd} Confirmed Data0 {Cu} ACK {Cd+1} Confirmed Data1 {Cu+1} Data + ACK {Cd+2} ok ok ok ko ok ok Receive slots (diag 1)