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by the device and does not require any
other periodical transmission, this allows the
device to be in a constant sleep mode, saving batteries, and communicating only when
necessary.
B class devices are designed for applications where additional downlink is required. A
periodical beacon message is in fact sent by the gateway to the IoT device to schedule
additional downlink windows without the need to previous successful uplink communica-
tions. Device battery lifetime is impacted due to the receiving of the additional synchro-
nization messages.
Class C communications ensure a low-latency communication as, as opposite of class
A devices, class C devices are always listening for downlink traffic. Gateway is able to
know the status of the device and start the sending data to the device at any time.
Battery optimization in such cases is achieved by switching the device from class A to
class C when necessary.
Apart from the downlink limitation for the lower class devices the LoRaWAN biggest per-
formance issue is due to the duty-cycle limitation imposed in the ISM bands regulation.
[15] Typically the regulations, for instance in Europe [16], dictates that only 1% of the
time the device is allowed to transmit in each sub-band. This limits the traffic for each
device but also add extra complexity to the network when big amount of device are con-
nected to the same network.
