0 1 00:00:00,870 --> 00:00:06,120 When you deploy end devices, you have to select the power and the spreading factor. 1 2 00:00:06,810 --> 00:00:08,790 This is really not an easy task. 2 3 00:00:09,090 --> 00:00:14,820 If you choose a high transmission power and a high spreading factor, then obviously you have more chances 3 4 00:00:14,820 --> 00:00:19,200 to reach your gateway, but you are also considerably reducing your device battery life. 4 5 00:00:19,740 --> 00:00:25,470 So the trick is to find the closest value so the device can reach a gateway without wasting power. 5 6 00:00:26,070 --> 00:00:34,410 So what we need to do is to place the end device at its final location, then go on the gateway logs and 6 7 00:00:34,410 --> 00:00:37,890 check the power received, which is what we call the RSSI. 7 8 00:00:38,100 --> 00:00:44,220 You can also check the SNR and depending on the margin you apply, then the LoRa transmission will have a 8 9 00:00:44,220 --> 00:00:45,450 certain robustness. 9 10 00:00:45,540 --> 00:00:51,600 Then once you are done with the specific end device, you check another one and you apply the same process. 10 11 00:00:52,110 --> 00:00:57,270 Obviously that can't be done for a large fleet because it will take ages. 11 12 00:00:57,900 --> 00:01:04,680 So what we can do is to use the network intelligence and the network intelligence for that is called 12 13 00:01:04,680 --> 00:01:05,730 the ADR. 13 14 00:01:06,210 --> 00:01:13,170 ADR stands for Adaptive Data Rate, and adaptive data rate is a little algorithm which runs on the network 14 15 00:01:13,170 --> 00:01:13,690 server. 15 16 00:01:13,980 --> 00:01:20,850 If the end device is set up to use ADR, then that's the network server which will give the information 16 17 00:01:20,850 --> 00:01:23,250 of the power and the spreading factor. 17 18 00:01:23,610 --> 00:01:29,610 So the device will be able to transmit with the most optimized power and spreading factor values. 18 19 00:01:30,090 --> 00:01:33,270 So how does the adaptive data rate works? 19 20 00:01:33,810 --> 00:01:36,780 The first thing we need to do is to activate it. 20 21 00:01:36,990 --> 00:01:38,250 It's very simple. 21 22 00:01:38,250 --> 00:01:42,240 We just have to enable the ADR flag in the uplink frame. 22 23 00:01:42,240 --> 00:01:48,690 When the networks server sees the ADR flags, then it runs the ADR algorithm. And as soon as it finds 23 24 00:01:48,690 --> 00:01:53,130 a better value for power and spreading factor, then it transmit to the end device. 24 25 00:01:53,490 --> 00:01:55,440 To transmit the ADR value. 25 26 00:01:55,440 --> 00:02:02,430 The network server uses a MAC command called LinkADRReq and when the end device receives and accepts the new 26 27 00:02:02,430 --> 00:02:05,340 parameters then it will answer with a 27 28 00:02:05,370 --> 00:02:06,690 LinkADRAns. 28 29 00:02:06,690 --> 00:02:07,620 That's it. 29 30 00:02:07,620 --> 00:02:08,340 Great. 30 31 00:02:08,340 --> 00:02:11,850 Now there is one last thing that we need to explain. 31 32 00:02:11,850 --> 00:02:15,840 It's when exactly the network server will send a request with the values. 32 33 00:02:15,840 --> 00:02:19,200 When this ADR Link MAC command will be sent. 33 34 00:02:19,500 --> 00:02:25,830 Of course it will be great to send a value right after the algorithm has calculated them, but sometimes 34 35 00:02:25,830 --> 00:02:28,290 the network server just can't send them. 35 36 00:02:28,290 --> 00:02:34,410 That's the case if the end-device has been moved outside of the Gateway coverage, imagine you're using 36 37 00:02:34,470 --> 00:02:38,730 SF7 and your device is moved to the other side of the lake. 37 38 00:02:38,760 --> 00:02:44,010 If the device can't reach the gateway, obviously the network server won't even know that it transmits. 38 39 00:02:44,490 --> 00:02:50,760 To explain the ADR behavior, we're going to make three demonstrations for the ADR algorithm, and that's what 39 40 00:02:50,760 --> 00:02:52,440 we're going to do in the next video.