Issue link: https://read.uberflip.com/i/1428395
LoRaWAN ® L2 1.0.4 Specification © 2020 LoRa Alliance ® Page 12 of 90 The authors reserve the right to change specifications without notice. 3 Physical Packet Formats 366 The physical layers used by LoRaWAN are defined in [RP002]. 367 The LoRaWAN terminology distinguishes between uplink and downlink frames. 368 3.1 Uplink Packets 369 Uplink packets are sent by end-devices to a Network Server relayed by one or many 370 gateways. 371 3.2 Downlink Packets 372 Downlink packets are sent by a Network Server to only one end-device and are transmitted 373 by a Network Server through one or more gateways. 2 374 3.3 Receive Windows 375 Following each uplink transmission, the end-device SHALL open one or two receive windows 376 (RX1 and RX2); if no packet destined for the end-device is received in RX1, it SHALL open 377 RX2. The receive windows start times are defined using the end of the transmission as a 378 reference, see Figure 2. 379 380 381 Figure 2: End-device receive-slot timing 382 383 3.3.1 Receiver activity during receive windows 384 If a preamble is detected during one of the receive windows, the radio receiver SHOULD stay 385 active until the downlink frame is demodulated. If a frame was detected and subsequently 386 demodulated during the first receive window, and the frame was intended for this end-device 387 after address and MIC (message integrity code) checks, the end-device SHALL NOT open 388 the second receive window. 389 2 This specification does not describe the transmission of multicast frames from a Network Server to many end-devices.