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LoRaWAN 1.0.3 Specification ©2018 LoRa™ Alliance Page 7 of 72 The authors reserve the right to change specifications without notice. 1 Introduction 226 This document describes the LoRaWAN™ network protocol which is optimized for battery- 227 powered end-devices that may be either mobile or mounted at a fixed location. 228 LoRaWAN networks typically are laid out in a star-of-stars topology in which gateways 1 relay 229 messages between end-devices 2 and a central network server at the backend. Gateways 230 are connected to the network server via standard IP connections while end-devices use single- 231 hop LoRa™ or FSK communication to one or many gateways. 3 All communication is generally 232 bi-directional, although uplink communication from an end-device to the network server is 233 expected to be the predominant traffic. 234 Communication between end-devices and gateways is spread out on different frequency 235 channels and data rates. The selection of the data rate is a trade-off between communication 236 range and message duration, communications with different data rates do not interfere with 237 each other. LoRa data rates range from 0.3 kbps to 50 kbps. To maximize both battery life 238 of the end-devices and overall network capacity, the LoRa network infrastructure can manage 239 the data rate and RF output for each end-device individually by means of an adaptive data 240 rate (ADR) scheme. 241 End-devices may transmit on any channel available at any time, using any available data rate, 242 as long as the following rules are respected: 243 • The end-device changes channel in a pseudo-random fashion for every transmission. 244 The resulting frequency diversity makes the system more robust to interferences. 245 • The end-device respects the maximum transmit duty cycle relative to the sub-band 246 used and local regulations. 247 • The end-device respects the maximum transmit duration (or dwell time) relative to the 248 sub-band used and local regulations. 249 Note: Maximum transmit duty-cycle and dwell time per sub-band are 250 region specific and are defined in the LoRaWAN ¨regional phyLayer 251 definition document 252 1.1 LoRaWAN Classes 253 All LoRaWAN devices implement at least the Class A functionality as described in this 254 document. In addition they MAY implement options named Class B, Class C as also described 255 in this document or others to be defined. In all cases, they must remain compatible with Class 256 A. 257 1 Gateways are also known as concentrators or base stations. 2 End-devices are also known as motes. 3 Support for intermediate elements – repeaters – is not described in the document, however payload restrictions for encapsulation overhead are included in this specification. A repeater is defined as using LoRaWAN as its backhaul mechanism.