Issue link: https://read.uberflip.com/i/1428383
LoRaWAN 1.0.3 Specification ©2018 LoRa™ Alliance Page 24 of 72 The authors reserve the right to change specifications without notice. 5.2 Link ADR commands (LinkADRReq, LinkADRAns) 654 655 With the LinkADRReq command, the network server requests an end-device to perform a 656 rate adaptation. 657 658 Size (bytes) 1 2 1 LinkADRReq Payload DataRate_TXPower ChMask Redundancy 659 Bits [7:4] [3:0] DataRate_TXPower DataRate TXPower 660 The requested date rate (DataRate) and TX output power (TXPower) are region-specific and 661 are encoded as indicated in the "LoRaWAN regional physical layer specification" document. 662 The TX output power indicated in the command is to be considered the maximum transmit 663 power the device may operate at. An end-device will acknowledge as successful a command 664 which specifies a higher transmit power than it is capable of using and should, in that case, 665 operate at its maximum possible power. The channel mask (ChMask) encodes the channels 666 usable for uplink access as follows with bit 0 corresponding to the LSB: 667 668 669 Bit# Usable channels 0 Channel 1 1 Channel 2 .. .. 15 Channel 16 Table 6: Channel state table 670 A bit in the ChMask field set to 1 means that the corresponding channel can be used for uplink 671 transmissions if this channel allows the data rate currently used by the end-device. A bit set 672 to 0 means the corresponding channels should be avoided. 673 674 Bits 7 [6:4] [3:0] Redundancy bits RFU ChMaskCntl NbTrans 675 In the Redundancy bits the NbTrans field is the number of transmissions for each uplink 676 message. This applies only to "unconfirmed" uplink frames. The default value is 1 677 corresponding to a single transmission of each frame. The valid range is [1:15]. If NbTrans==0 678 is received the end-device should use the default value. This field can be used by the network 679 manager to control the redundancy of the node uplinks to obtain a given Quality of Service. 680 The end-device performs frequency hopping as usual between repeated transmissions, it 681 does wait after each repetition until the receive windows have expired. . Whenever a downlink 682 message is received during the RX1 slot window, it SHALL stop any further retransmission of 683 the same uplink message. For class A devices, a reception in the RX2 slot has the same 684 effect. 685 The channel mask control (ChMaskCntl) field controls the interpretation of the previously 686 defined ChMask bit mask. It controls the block of 16 channels to which the ChMask applies. 687 It can also be used to globally turn on or off all channels using specific modulation. This field 688