Issue link: https://read.uberflip.com/i/1507762
Enabling CSMA for LoRaWAN TR013-1.0.0 ©2023 LoRa Alliance ® Page 9 of 18 The authors reserve the right to change specifications without notice. 4.2 State Transitions 247 248 Figure 1 illustrates the state transitions when an end-device follows CSMA: 249 250 251 252 Figure 1: LoRaWAN CSMA state transition diagram 253 4.2.1 State Transitions of an End-Device Adopting DIFS without BO 254 255 This section explains state transitions for an end-device that follows DIFS phase only. Such 256 a device does not have the BO phase enabled and can typically be deployed under low- 257 contended environments. To disable BO phase, BACKOFF_MAX is set to 0. 258 259 The simplest scenario is where the selected CH/SF combination by the end-device is not 260 contended by another. In this case, the end-device entering the DIFS state will successfully 261 complete two CADs, indicating a clear channel. This completes a successful DIFS phase. 262 The end-device then transitions to transmission state. When the frame is transmitted, the end- 263 device decrements NumAvailableCh by one. At the same time, the end-device marks the 264 channel as used in AvailableCh. 265 In cases where the end-device identifies a busy channel during DIFS state, the end-device 266 configures the radio to a different random channel from AvailableCh before starting a new 267 DIFS phase. The key reason to hop to a different channel upon finding a busy channel is 268