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TC23-00017 The LoRa Alliance © 2019 2 1. Discussion As LinkAdrReq commands also control the nbTrans (number of retransmissions) and this field is an integral component to how the network manages (in conjunction with data-rate and transmit-power) the effective performance of the end-device, the field must also be controlled during ADR back-off. This change will require the end-device to reset nbTrans to its default value of one during the last step of ADR back-off. This point of control was chosen as nbTrans typically improves performance (unlike typical data-rate and transmit-power controls) and the last step of the ADR back-off algorithm is to revert all ADR controlled variables to defaults. The AdrAckReq bit is required be set by the end-device in all cases after ADR_ACK_LIMIT has been reached and is only cleared upon successful reception of a downlink message. Previously the AdrAckReq bit was cleared once default data-rate and transmit power conditions were reached. This change provides additional, valuable information to the network (specifically that the end-device is still unable to receive downlinks) even in these default conditions. Treatment of ADR parameters in response to Join-Accept messages are described in each of the four cases where Join-Accept messages are successfully processed by the end-device. 2. Proposed changes (normative/informative) ************************** Start of proposed change 1 ********************************* 4.3.1.1 Adaptive data rate control in frame header (ADR, ADRACKReq in FCtrl) LoRa network allows the end-devices to individually use any of the possible data rates and Tx power. This feature is used by the LoRaWAN to adapt and optimize the number of retransmissions, the data rate and the Tx power of static end-devices. This is referred to as Adaptive Data Rate (ADR) and when this is enabled the network will be optimized to use the fastest data rate possible. Adaptive Data Rate control may not be possible when the radio channel attenuation changes fast and constantlyrapidly and/or continuously. When the network is unable to control the data rate of a device , the device's application layer should SHOULD control it. It is recommended to use a variety of different data rates in this case. The application layer should always try to minimize the aggregated air time used given the network conditions. If the uplink ADR bit is set, the network will control the number of retransmissions, the data rate and the Tx power of the end-device through the appropriate MAC commands. If the ADR bit is not set, the network will not attempt to control the number of retransmissions, the data rate nor the transmit power of the end-device regardless of the received signal quality. The network MAY still send commands to inform the end-device of the recommended configuration

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