Issue link: https://read.uberflip.com/i/1428395
LoRaWAN ® L2 1.0.4 Specification © 2020 LoRa Alliance ® Page 19 of 90 The authors reserve the right to change specifications without notice. The ADR bit MAY be set and unset on demand by the end-device or a Network Server. 554 However, whenever possible, the ADR scheme SHOULD be enabled to increase the battery 555 life of the end-device and maximize the network capacity. 556 557 Note: Even mobile end-devices are immobile most of the time. 558 Depending on its state of mobility, an end-device can request that the 559 Network optimize its data rate using ADR. 560 561 Default TX power is the maximum transmit power allowed for an end-device, considering its 562 capabilities and any applicable regional regulatory constraints. End-devices SHALL use this 563 power level until the Network attempts to change it using the LinkADRReq MAC command, 564 or if the end-device has unset the ADR bit. 565 The default data rate is the minimum data rate allowed for an end-device, considering its 566 capabilities and any applicable regional regulatory constraints. An end-device using Activation 567 By Personalization (ABP, see section 6), with the ADR bit set, SHALL use this data rate until 568 the Network requests a higher data rate through the LinkADRReq MAC command. End- 569 devices which use Over The Air Activation follow a Join Procedure (see section 6) which 570 determines the initial uplink data rate. 571 If an end-device wishes to check for connectivity loss or if an end-device whose data rate is 572 optimized by the Network uses a data rate higher than its default data rate or a TX power 573 lower than its default, the end-device SHALL periodically validate whether the Network is still 574 receiving the uplink frames. Each time the uplink frame counter is incremented (for each new 575 uplink frame, because repeated transmissions do not increment the frame counter), the end- 576 device SHALL increment an ADRACKCnt counter. After ADR_ACK_LIMIT uplinks 577 (ADRACKCnt ≥ ADR_ACK_LIMIT) without receiving a Class A downlink response, the end- 578 device SHALL set the ADR acknowledgment request bit (ADRACKReq) on uplink 579 transmissions. The Network is REQUIRED to respond with a class A downlink frame within 580 the next ADR_ACK_DELAY frames. A Class A downlink frame received following an uplink 581 frame SHALL reset the ADRACKCnt counter. Upon receipt of any Class A downlink, the end- 582 device SHALL clear the ADRACKReq bit. The downlink ACK bit does not need to be set 583 because any Class A downlink frame received by the end-device indicates that the Network 584 has received uplinks from this end-device. If no Class A downlink frame is received within the 585 next ADR_ACK_DELAY uplinks (i.e., after a total of ADR_ACK_LIMIT + ADR_ACK_DELAY 586 transmitted frames), the end-device SHALL try to regain connectivity by first setting the TX 587 power to the default power, then switching to the next lower data rate that provides a longer 588 radio range. The end-device SHALL further lower its data rate step by step every time 589 ADR_ACK_DELAY uplink frames are transmitted. Once the end-device has reached the 590 default data rate, and transmitted for ADR_ACK_DELAY uplinks with ADRACKReq=1 without 591 receiving a downlink, it SHALL re-enable all default uplink frequency channels and reset 592 NbTrans to its default value of 1. Furthermore, if at any point during the backoff the resulting 593 configuration results in an invalid combination of TX power, data rate or channel mask, the 594 end-device SHALL immediately re-enable all default channels and use the maximum TX 595 power permissible for and available to this end-device. 596 597 Note: Other configurations of the end-device by the Network are not 598 modified during ADR backoff. Specifically, configurations that affect 599 downlink connectivity (controlled by RXParamsSetupReq, 600 DlChannelReq, RXTimingSetupReq, and TXParamSetupReq) are 601 not modified during ADR backoff. 602