Wiki source code of LoRaWAN Communication Debug

Version 39.2 by Xiaoling on 2023/03/23 17:08

version	line-number	content
32.2	1	~ Table of Contents:
1.1	2
	3	{{toc/}}
	4
	5
30.2	6
37.2	7	= 1.(% style="display:none" %) (%%) OTAA Join Process Debug =
1.1	8
32.3	9
1.1	10	These pages are useful to check what is wrong on the Join process. Below shows the four steps that we can check the Join Process.
2.1	11	\\If user has checked below steps and still can't solve the problem, please send us (support @ dragino.com) the sceenshots for each step to check. They include:
1.1	12
	13	* End node console to show the Join freuqency and DR. (If possible)
37.3	14
1.1	15	* Gateway (from gateway UI) traffic to show the packet got from end node and receive from Server. (If possible)
37.3	16
1.1	17	* Gateway traffic (from server UI) to shows the data exchange between gateway and server. (Normaly possible)
37.3	18
1.1	19	* End Node traffic (from server UI) to shows end node activity in server. (Normaly possible)
37.3	20
1.1	21	* End Node Keys screen shot shows in end node and server. so we can check if the keys are correct. (In most case, we found keys doesn't match, especially APP EUI)
	22
32.14	23	(% style="color:blue" %)1. End Device Join Screen shot, we can check:
	24
1.1	25	* If the device is sending join request to server?
37.3	26
1.1	27	* What frequency the device is sending?
	28
37.2	29	[[image:image-20220526164956-15.png\|\|height="591" width="1153"]]
1.1	30
	31	Console Output from End device to see the transmit frequency
	32
	33
32.16	34
32.14	35	(% style="color:blue" %)2. Gateway packet traffic in gateway web or ssh. we can check:
1.1	36
	37	* If the gateway receive the Join request packet from sensor? (If this fail, check if the gateway and sensor works on the match frequency)
37.3	38
1.1	39	* If the gateway gets the Join Accept message from server and transmit it via LoRa?
	40
10.2	41	[[image:image-20220526163608-2.png]]
1.1	42
	43	Console Output from Gateway to see packets between end node and server.
	44
	45
35.2	46
32.14	47	(% style="color:blue" %)3. Gateway Traffic Page in LoRaWAN Server
1.1	48
	49	* If the Join Request packet arrive the gateway traffic in server? If not, check the internet connection and gateway LoRaWAN server settings.
37.3	50
1.1	51	* If the server send back a Join Accept for the Join Request? if not, check if the keys from the device match the keys you put in the server, or try to choose a different server route for this end device.
37.3	52
1.1	53	* If the Join Accept message are in correct frequency? If you set the server to use US915 band, and your end node and gateway is EU868, you will see the Join Accept message are in US915 band so no possible to Join success.
	54
13.2	55	[[image:image-20220526163633-3.png]]
1.1	56
	57	The Traffic for the End node in the server, use TTN as example
	58
	59
35.2	60
32.14	61	(% style="color:blue" %)4. Data Page in LoRaWAN server
1.1	62
	63	* If this data page shows the Join Request message from the end node? If not, most properly you have wrong settings in the keys. Keys in the server doesn't match the keys in End Node.
	64
13.2	65	[[image:image-20220526163704-4.png]]
1.1	66
	67	The data for the end device set in server
	68
35.2	69
13.2	70	[[image:image-20220526163732-5.png]]
1.1	71
	72	Check if OTAA Keys match the keys in device
	73
	74
2.1	75	= 2. Notice of US915/CN470/AU915 Frequency band =
1.1	76
32.3	77
4.2	78	(((
1.1	79	If user has problem to work with lorawan server in band US915/AU915/CN470, he can check:
4.2	80	)))
1.1	81
4.2	82	* (((
	83	What sub-band the server support ?
	84	)))
	85	* (((
	86	What is the sub-band the gateway support ?
	87	)))
	88	* (((
	89	What is the sub-band the end node is using ?
	90	)))
1.1	91
4.2	92	(((
1.1	93	All of above should match so End Node can properly Join the server and don't have packet lost.
4.2	94	)))
1.1	95
4.2	96	(((
	97
	98	)))
	99
	100	(((
1.1	101	In LoRaWAN protocol, the frequency bands US915, AU915, CN470 each includes at least 72 frequencies. Many gateways support only 8 or 16 frequencies, and server might support 8 frequency only. In this case, the OTAA join time and uplink schedule is long and unpredictable while the end node is hopping in 72 frequencies, because the end node will send data in many frequency that the gateway or server doesn,t support.
4.2	102	)))
1.1	103
4.2	104	(((
	105
	106	)))
	107
	108	(((
1.1	109	Here are the freuqency tables for these bands as reference:
4.2	110	)))
1.1	111
14.2	112	[[image:image-20220526163801-6.png]]
1.1	113
	114	US915 Channels
	115
35.2	116
18.2	117	[[image:image-20220526163926-7.png]]
1.1	118
	119	AU915 Channels
	120
32.3	121
18.2	122	[[image:image-20220526163941-8.png]]
1.1	123
4.4	124	(((
1.1	125	CN470 Channels
32.3	126
	127
4.4	128	)))
1.1	129
4.3	130	(((
1.1	131	If we look at the [[TTN network server frequency plan>>url:https://www.thethingsnetwork.org/docs/lorawan/frequency-plans.html]], we can see the US915 frequency band use the channel 8~~15.So the End Node must work at the same frequency in US915 8~~15 channels for TTN server.
4.3	132	)))
1.1	133
18.2	134	[[image:image-20220526164052-9.png]]
1.1	135
4.4	136	(((
1.1	137	TTN FREQUENCY PLAN
32.3	138
37.2	139	(% style="display:none" %) (%%)
4.4	140	)))
1.1	141
4.3	142	(((
1.1	143	In dragino end node, user can use AT+CHE command to set what frequencies set the end node will use. The default settings for Dragino end node are preconfigure for TTN server, so use 8~~15 channels, which is AT+CHE=2. (AT+CHE=1 for first 8 channels, AT+CHE=2 for second 8 channels.. etc, and AT+CHE=0 for all 72 channels. )
4.3	144	)))
1.1	145
37.2	146	(% style="display:none" %) (%%)
1.1	147
2.1	148	= 3. Why i see data lost/unperiocially uplink data? Even the signal strength is good =
1.1	149
32.3	150
1.1	151	In this case, we can check if the frequency band matches in End Node, Gateway and LoRaWAN server. A typical case is using US915 in ChirpStack server as below:
	152
37.2	153	* (% style="color:blue" %)End node (%%) ~-~-> Use Sub-band2 (Channel 8,9,10,11,12,13,14,15) for Dragino Sensor. ADR is also enable, this is the default settings for dragino sensors.
1.1	154
37.2	155	* (% style="color:blue" %)Gateway (%%) ~-~-> Use Sub-band2 (Channel 8,9,10,11,12,13,14,15) for Dragino Gateway. this is the default settings for dragino sensors.
	156
	157	* (% style="color:blue" %)LoRaWAN server (%%) ~-~-> ChirpStack default installation and use Sub-band1, enabled_uplink_channels=[0, 1, 2, 3, 4, 5, 6, 7] in the file chirpstack-network-server.toml.
	158
4.3	159	(((
1.1	160	When Sensor power on, it will use sub-band2 to join the network, the frequency matches the settings in gateway so all Join Request will be passed to the server for Join. Server will ask the sensor to change to Sub-band1 in the Join Accept downlink message. Sensor will change to sub-band1 for data upload. This cause the sensor and gateway have different frequencies so user see lost of most data or even no data.
4.3	161	)))
1.1	162
4.3	163
	164	(((
1.1	165	Use Subband2 as a default subband cause the sensor to have problem to work with the LoRaWAN server which use other subband, and use need to access to the end node to change the subband by console. that is not user frendily,. So since Dragino LoRaWAN Stack version DLS-005(release on end of 2020), we have changed the device to use All Subbands for OTAA join, for example, device will use the first frequency in Sub-Band1 as firt OTAA join packet, then use the first frequency in Sub-Band 2 , then first frequency in sub-band 3, and so on. LoRaWAN server will normally provide the required subband in the OTAA accept process, so end node will know what subband it use after join. If LoRaWAN server doesn't provide subband info in OTAA join, end node will use the subband which join success as the working subband. So the new method cause a longer OTAA Join time but will be compatible with all LoRaWAN server. And new method won't affect the normal uplink after Join Success.
4.3	166	)))
1.1	167
	168
2.1	169	= 4. Transmision on ABP Mode =
1.1	170
32.3	171
4.3	172	(((
1.1	173	In ABP mode, there is a Frame Counter Checks. With this check enabled, the server will only accept the frame with a higher counter. If you reboot the device in ABP mode, the device will start from count 0, so you won't be able to see the frame update in server.
4.3	174	)))
1.1	175
4.3	176	(((
1.1	177	So in ABP mode, first check if the packet already arrive your gateway, if the packet arrive gatewat but didn't arrive server. Please check if this is the issue.
4.3	178	)))
1.1	179
4.3	180	(((
1.1	181	To solve this, disable the Frame Counter Check will solve this issue , or reset the frame counter in the device page.
4.3	182	)))
1.1	183
18.2	184	[[image:image-20220526164508-10.png]]
1.1	185
	186	Disable Frame Counter Check in ABP Mode
	187
	188
2.1	189	= 5. Downstream Debug =
1.1	190
2.1	191	== 5.1 How it work ==
1.1	192
32.3	193
1.1	194	LoRaWAN End node will open two receive windows to receive the downstream data. If the downstream packets arrive the end node at these receive windows, the end node will be able to get this packet and process it.
	195
4.3	196	(((
1.1	197	Depends on Class A or Class C, the receive windows will be a little difference,
4.3	198	)))
1.1	199
31.2	200	[[image:image-20220531161828-1.png]]
1.1	201
	202	receive windows for Class A and Class C
	203
32.3	204
1.1	205	Below are the requirement for the End Device to receive the packets.
	206
	207	* The End Device must open the receive windows: RX1 or RX2
37.2	208
1.1	209	* The LoRaWAN server must send a downstream packet, and the gateway forward this downstream packet for this end node.
37.2	210
1.1	211	* This downstream packet must arrive to the end node while RX1 or RX2 is open.
37.2	212
1.1	213	* This packet must match the frequency of the RX1 or RX2 window.
37.2	214
32.3	215	* This packet must match the DataRate of RX1(RX1DR) or RX2 (RX2DR). (% style="color:red" %)This is the common fail point, because different lorawan server might use different RX2DR and they don't info End Node via ADR message so cause the mismatch. If this happen, user need to change the RX2DR to the right value in end node. In OTAA, LoRaWAN Server will send the RX2DR setting in Join Accept message so the end node will auto adjust. but ABP uplink doesn't support this auto change.
1.1	216
39.2	217
	218
2.1	219	== 5.2 See Debug Info ==
1.1	220
32.3	221
4.6	222	(((
32.3	223	(% style="color:blue" %)For LoRaWAN Server
4.6	224	)))
1.1	225
4.6	226	(((
1.1	227	We can check if there is downlink message for this end node, use TTN for example:
4.6	228	)))
1.1	229
4.6	230	(((
1.1	231	Configure a downstream to the end device
4.6	232	)))
1.1	233
22.2	234	[[image:image-20220526164623-12.png]]
1.1	235
4.6	236	(((
1.1	237	Set a downstream in TTN and see it is sent
4.6	238	)))
1.1	239
	240
4.3	241	(((
1.1	242	This downstream info will then pass to the gateway downstream list. and include the DR which is used (SF9BW125) in EU868 is DR3
4.3	243	)))
1.1	244
22.2	245	[[image:image-20220526164650-13.png]]
1.1	246
4.6	247	(((
1.1	248	Gateway Traffic can see this downstream info
4.6	249	)))
1.1	250
	251
32.16	252
4.6	253	(((
32.3	254	(% style="color:blue" %)For LoRaWAN Gateway
4.6	255	)))
1.1	256
4.3	257	(((
1.1	258	When the downstream packet appear on the traffic of Gateway page. The LoRaWAN gateway can get it from LoRaWAN server and transmit it. In Dragion Gateway, this can be checked by runinng "logread -f" in the SSH console. and see below:
4.3	259	)))
1.1	260
22.2	261	[[image:image-20220526164734-14.png]]
1.1	262
4.6	263	(((
1.1	264	Gateway Sent out this packet
4.6	265	)))
1.1	266
	267
32.16	268
4.6	269	(((
32.3	270	(% style="color:blue" %)For End Node
4.6	271	)))
1.1	272
4.8	273	(((
1.1	274	we can use AT Command (AT+CFG) to check the RX1 configure and RX2 configure. as below:
4.8	275	)))
1.1	276
4.9	277	(((
37.3	278	* (% style="color:#037691" %)AT+RX2FQ=869525000 (%%) ~-~--> The RX2 Window frequency
32.4	279
37.3	280	* (% style="color:#037691" %)AT+RX2DR=3 (%%) ~-~--> The RX2 DataRate
32.16	281
37.3	282	* (% style="color:#037691" %)AT+RX1DL=1000 (%%) ~-~--> Receive Delay 1
	283
	284	* (% style="color:#037691" %)AT+RX2DL=2000 (%%) ~-~--> Receive Delay 2
4.9	285	)))
	286
	287	(((
32.3	288	(% style="color:blue" %)when the device running, we can see below info:
4.7	289	)))
1.1	290
4.8	291	{{{ [12502]*** UpLinkCounter= 0 ***
	292	[12503]TX on freq 868500000 Hz at DR 0
	293	[13992]txDone
4.13	294	[15022]RX on freq 868500000 Hz at DR 0 --> RX1 window open at frequency: 868500000, DR0, after 15022-13992= 1030ms of txdone
	295	[15222]rxTimeOut --> no packet arrive in RX1 window. (duration: 200ms)
	296	[15987]RX on freq 869525000 Hz at DR 3 --> RX2 window open at frequency: 869525000, DR3, after 15987-13992= 1995ms of txdone
	297	[16027]rxTimeOut --> no packet arrive in RX2 window. (duration: 40 ms)}}}
1.1	298
4.3	299	(((
4.5	300
32.16	301
	302
4.5	303	)))
	304
4.7	305	(((
32.3	306	(% style="color:blue" %)Another message:
4.7	307	)))
4.5	308
4.8	309	{{{ [12502]*** UpLinkCounter= 0 ***
	310	[12503]TX on freq 868100000 Hz at DR 0
	311	[13992]txDone
	312	[15022]RX on freq 868100000 Hz at DR 0
	313	[15222]rxTimeOut
	314	[15987]RX on freq 869525000 Hz at DR 3
4.13	315	[16185]rxDone --> We have got the downstream packet.
4.8	316	Rssi= -64
	317	Receive data
	318	1:0012345678}}}
4.5	319
22.2	320
32.6	321	== 5.3 If problem doesn't solve ==
1.1	322
32.6	323
23.2	324	(% style="color:red" %)If user has checked below steps and still can't solve the problem, please send us (support @ dragino.com) the sceenshots for each step to check. They include:
1.1	325
	326	* End node console to show the transmit freuqency and DR.
37.3	327
1.1	328	* Gateway (from gateway UI) traffic to show the packet got from end node and receive from Server.
37.3	329
1.1	330	* Gateway traffic (from server UI) to shows the data exchange between gateway and server.
37.3	331
1.1	332	* End Node traffic (from server UI) to shows end node activity in server.
	333
37.4	334
39.2	335
2.1	336	= 6. Downlink Issue ~-~- Packet REJECTED, unsupported frequency =
1.1	337
32.7	338
4.5	339	(((
1.1	340	In LoRaWAN, the gatewat will use the frequency specify by the server to transmit a packet as downlink purpose. Each Frequency band has different downlink frequency. and the gateway has a frequency range limited to transmit downlink.
4.5	341	)))
1.1	342
4.5	343	(((
	344
	345	)))
	346
	347	(((
1.1	348	So if the LoRaWAN server is an AS923 server which ask the gateway to transmit at 923.2Mhz frequency, but the gateway is IN868 frequency band (support 865~~867Mhz to transmit). In the gateway log it will show something like below:
4.5	349	)))
1.1	350
4.7	351	{{{Sat Nov 21 08:04:17 2020 daemon.info lora_pkt_fwd[1680]: ERROR~ Packet REJECTED, unsupported frequency - 923200000 (min:865000000,max:867000000)}}}
1.1	352
4.5	353	(((
4.6	354
	355	)))
	356
	357	(((
1.1	358	In this case, please double check the gateway frequency and the server frequency band.
4.5	359	)))
1.1	360
	361
2.1	362	= 7. Decrypt a LoRaWAN Packet =
1.1	363
	364
32.7	365	(% style="color:blue" %)1. LHT65 End device configure:
1.1	366
32.7	367	Change to ABP Mode: AT+NJM=0
37.3	368
32.7	369	Change to fix frequency: AT+CHS=904900000
37.3	370
32.7	371	Change to fix DR: AT+DR=0
	372
32.12	373
29.2	374	[[image:image-20220526165525-16.png]]
1.1	375
29.2	376
32.16	377
32.7	378	(% style="color:blue" %)2. In LG02 , configure to receive above message
1.1	379
29.2	380	[[image:image-20220526165612-17.png]]
1.1	381
29.2	382
1.1	383	In LG02 console, we can see the hex receive are:
	384
29.2	385	[[image:image-20220526171112-21.png]]
1.1	386
29.2	387
32.16	388
32.7	389	(% style="color:blue" %)3. Decode the info in web
1.1	390
	391	[[https:~~/~~/lorawan-packet-decoder-0ta6puiniaut.runkit.sh>>url:https://lorawan-packet-decoder-0ta6puiniaut.runkit.sh/]]
	392
	393	Need these three fields:
	394
	395	LoRa packet hex format: 40c1190126800100024926272bf18bbb6341584e27e23245 (from LG02)
	396
	397	AT+NWKSKEY=00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 11 (End node Network Session Key)
	398
	399	AT+APPSKEY=00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 11 (End Node App Session Key)
	400
32.9	401
1.1	402	[[https:~~/~~/lorawan-packet-decoder-0ta6puiniaut.runkit.sh/?data=40c1190126800100024926272bf18bbb6341584e27e23245&nwkskey=00000000000000000000000000000111&appskey=00000000000000000000000000000111>>url:https://lorawan-packet-decoder-0ta6puiniaut.runkit.sh/?data=40c1190126800100024926272bf18bbb6341584e27e23245&nwkskey=00000000000000000000000000000111&appskey=00000000000000000000000000000111]]
	403
29.2	404	[[image:image-20220526171029-20.png]]
1.1	405
4.10	406	(((
4.11	407	The FRMPayload is the device payload.
4.10	408	)))
1.1	409
	410
2.1	411	= 8. Why i see uplink 0x00 periodcally on the LHT65 v1.8 firmware =
1.1	412
32.9	413
1.1	414	Since firmware v1.8, LHT65 will send MAC command to request time, in the case if DR only support max 11 bytes, this MAC command will be bundled to a separate uplink payload with 0x00.
	415
29.3	416
2.1	417	= 9. Why do I see a "MIC Mismatch" error message from the server? =
1.1	418
32.9	419
4.7	420	(((
32.9	421	1) If the user receives a "MIC Mismatch" message after registering the node on the server.
4.7	422	)))
1.1	423
4.7	424	(((
1.1	425	It is likely that the user filled in the wrong APPKEY when registering the node. Many users fill in "APPSKEY".
4.7	426	)))
1.1	427
4.7	428	* (((
	429	Please note the distinction between "APPKEY" and "APPSKEY".
	430	)))
1.1	431
4.7	432	(((
1.1	433	2）If the node works on the server for a period of time, the device stops working and receives a "MIC Mismatch" message.
4.7	434	)))
1.1	435
4.7	436	(((
1.1	437	The user needs a USB-TTL adapter to connect the serial port to modify the node APPKEY.
4.7	438	)))
1.1	439
4.7	440	* (((
	441	If a node is registered with multiple servers, it may also cause the "mic mismatch" error.
39.1	442	)))
5.1	443
39.1	444	(% class="wikigeneratedid" %)
	445	3）Wrong Regional Parameters version selected
	446	We generally use versions above 1.0.2
32.9	447
39.1	448	(% class="wikigeneratedid" %)
	449	[[image:image-20230322163227-1.png]]
1.1	450
39.1	451	(% class="wikigeneratedid" %)
	452	4）We have had cases where it was automatically fixed the next day despite no manual changes, probably a server side issue
	453
39.2	454
2.1	455	= 10. Why i got the payload only with "0x00" or "AA~=~="? =
1.1	456
32.9	457
37.3	458	(% style="color:blue" %)Why this happen:
35.1	459
34.1	460	For US915, AU915 or AS923 frequencies.It is possible because: .
1.1	461
33.1	462	When using the frequency mentioned above, the server sometimes adjusts the Data Rate (DR) of the node, because the end node has Adaptive Data Rate (ADR) Enabled.
1.1	463
34.1	464	When the server adjusts end node data rate to 0, the maximum payload length is 11 bytes. The server sometimes sends an ADR packet to the end node, and the node will reply to the server after receiving the ADR packet, but the number of payload bytes exceeds the limit, so it will send a normal uplink packet, and following an additional 00 data packet to handle this MAC command response.
1.1	465
33.1	466
37.3	467	(% style="color:blue" %)How to solve:
35.1	468
	469	Solution: Use the decoder to filter out this 0x00 packet.
	470
34.1	471	Some node decoders may not have the filter function, or you need decoders of other servers and formats. Please send an email to [[support@dragino.com>>mailto:support@dragino.com]]
6.1	472
32.9	473
5.1	474	= 11. Why my Dev EUI and APP EUI is 0x000000000000, how to solve? =
	475
32.9	476
29.4	477	(((
7.1	478	It is possible the keys is erased during upgrading of firmware. and the console output shows below after AT+CFG
29.4	479	)))
5.1	480
29.4	481	(((
5.1	482	AT+APPKEY=00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
29.4	483	)))
5.1	484
29.4	485	(((
5.1	486	AT+NWKSKEY=00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
29.4	487	)))
5.1	488
29.4	489	(((
5.1	490	AT+APPSKEY=00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
29.4	491	)))
5.1	492
29.4	493	(((
5.1	494	AT+APPEUI=00 00 00 00 00 00 00 00
29.4	495	)))
5.1	496
29.4	497	(((
	498
	499	)))
5.1	500
29.4	501	(((
5.1	502	You can get the keys from the box sticker or send mail to Dragino Support to check keys with the provided SN number.
29.4	503	)))
5.1	504
29.4	505	(((
5.1	506	You can rewrites the keys by running commands in AT Console
32.9	507
	508
29.4	509	)))
5.1	510
29.4	511	(((
	512	For example：
	513	)))
5.1	514
29.4	515	(((
8.1	516	AT+APPKEY=85 41 47 20 45 58 28 14 16 82 A0 F0 80 0D DD EE
29.4	517	)))
5.1	518
29.4	519	(((
8.1	520	AT+NWKSKEY=AA CC B0 20 30 45 37 32 14 1E 14 93 E2 3B 20 11
29.4	521	)))
8.1	522
29.4	523	(((
8.1	524	AT+APPSKEY=11 23 02 20 30 20 30 60 80 20 20 30 30 20 10 10
29.4	525	)))
8.1	526
29.4	527	(((
8.1	528	AT+APPEUI=2C 45 47 E3 24 12 23 24
29.4	529	)))
8.1	530
29.4	531	(((
8.1	532	(Any combination of 16 bit codes can be used）
32.1	533
	534
	535	= 12. I set my device is LoRaWAN Class C mode, why i still see Class A after boot? =
29.4	536	)))
8.1	537
	538
32.1	539	Class C only refers to status after OTAA Join successfully. The OTAA Join Process will use Class A mode.
	540
	541
37.1	542	= 13. Why it takes longer time for OTAA joined in US915/CN470/AU915 band? =
32.1	543
37.1	544
	545	In US915, AU915 or CN470 frequency band, there are 8 subbands, totally 72 channels. and LoRaWAN server normally use only one sub-band, for example Subband 2 in TTN. The gateway also configured to Subband 2 and cover eight channels in this subband. If the end node transfer data in Subband 2, it will reach to gateway and to the LoRaWAN server. If the end node transfer packets in other subbands, for example subband 1, the packet won't arrive both gateway or LoRaWAN server.
	546
	547
	548	In Dragino Sensors old version firmware (before early 2022), the subband is fixed the subband to 2 , but this cause a problem, the end node is hard to use in other subband and need program. So the new logic is as below:
	549
	550	We have improved this, the end node will use frequency 1 from sub-band1, then frequency 1 from sub-band2, then frequency 1 from sub-band3, etc to process the OTAA join, In this case, In this case, the end node can support LoRaWAN servers with different subbands. To make sure the end node will only transmit the proper sub-band after OTAA Joined successfully, the end node will:
	551
	552	* (((
	553	Check what sub-band the LoRaWAN server ask from the OTAA Join Accept message and switch to that subband
	554	)))
	555	* (((
	556	Use the Join successful sub-band if the server doesn't include subband info in the OTAA Join Accept message ( TTN v2 doesn't include)
	557	)))
	558
	559	This change will make the activation time a littler longer but make sure the device can be used in any subband.
	560
	561
	562	Below is a photo to show why it takes longer time for OTAA Join. We can see in 72 channels mode, why it takes more time to join success. If users want to have faster OTAA Join success, he can change default CHE to the subband he use.
	563
	564
	565	[[image:image-20221215223215-1.png\|\|height="584" width="1280"]]
	566
29.3	567	(% class="wikigeneratedid" %)
	568

Wiki source code of LoRaWAN Communication Debug

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