Issue link: https://read.uberflip.com/i/1428395
LoRaWAN ® L2 1.0.4 Specification © 2020 LoRa Alliance ® Page 9 of 90 The authors reserve the right to change specifications without notice. 2 Introduction to LoRaWAN Options 326 LoRa ® is a wireless modulation for long-range, low-power, low-data-rate applications 327 developed by Semtech. End-devices implementing more than Class A are generally called 328 "higher Class end-devices" in this document. 329 2.1 LoRaWAN Classes 330 A LoRaWAN network distinguishes between a basic LoRaWAN (called Class A) and optional 331 features (Class B, Class C …) as shown in Figure 1. 332 333 334 335 Figure 1: LoRaWAN Classes 336 337 Bi-directional end-devices (Class A): Class A end-devices allow bi-directional 338 communications, whereby each end-device's uplink transmission is followed by two short 339 downlink receive windows. The transmission slot scheduled by the end-device is based on 340 its own communication needs, with a small variation based on a random time basis (ALOHA- 341 type protocol). Class A operation is the lowest-power end-device system for applications 342 that require only downlink communication from the server shortly after the end-device has 343 sent an uplink transmission. Downlink communications from the server at any other time will 344 have to wait until the next uplink initiated by the end-device. 345 Bi-directional end-devices with scheduled receive slots (Class B): Class B-capable 346 end-devices allow more receive slots. In addition to Class A receive windows, Class B- 347 enabled end-devices open extra receive windows at scheduled times. In order for the end- 348 device to open its receive windows at a scheduled time, it receives a time-synchronized 349 beacon from the gateway. This allows the Network Server to know when the end-device is 350 listening. 351