RAK4200 OTAA Join Request for AS923 uses wrong channels and CFList not being used

John_NZ · October 18, 2020, 10:30pm

Issue: Join request is not being initiated on Channel 0 or 1 as per specification

Setup: RAK4200 version:3.2.0.14
at+get_config=lora:status
OK Work Mode: LoRaWAN
Region: AS923
MulticastEnable: false
DutycycleEnable: false
Send_repeat_cnt: 1
Join_mode: OTAA
DevEui: 60C5…1D0A
AppEui: 60C5…4200
AppKey: 60C5…4200
Class: A
Joined Network:true
IsConfirm: unconfirm
AdrEnable: true
EnableRepeaterSupport: false
RX2_CHANNEL_FREQUENCY: 923200000, RX2_CHANNEL_DR:2
RX_WINDOW_DURATION: 3000ms
RECEIVE_DELAY_1: 1000ms
RECEIVE_DELAY_2: 2000ms
JOIN_ACCEPT_DELAY_1: 5000ms
JOIN_ACCEPT_DELAY_2: 6000ms
Current Datarate: 2
Primeval Datarate: 2
ChannelsTxPower: 0
UpLinkCounter: 0
DownLinkCounter: 0
Server: Chirpstack (Private)

Details:
When RAK4200 set to region AS923 does OTAA join request, it is using any of the 8 channels that it has available to it. My understanding is that the Join request should only be done on channel 0 or 1 as per the specification as these are the only guaranteed frequencies under AS923

For example, here is join request at 923.6MHz

John_NZ · October 19, 2020, 10:49am

Some additional information.

I have checked that Chirpstack is sending the CFList to the RAK4200 with the Join Accept, which it is.

I have also compared this with an Multitech xDot using mbed with the Semtech Lorawan stack.
Before the OTAA join the xDot is showing just the 2 join channels, 923.2Mhz and 923.4Mhz.
After the join accept, the xDot is showing 5 more channels as per the CFList message sent from Chirpstack with the join accept.

With the RAK4200, if I do a at+get=lora:channels before the join, it shows 8 channels already assigned. This is definitely not correct.

velev · October 21, 2020, 3:31pm

Hi @John_NZ Yes, this is a “bug” that all channels are defined. To propper operate you need to close all other channels, only 0 and 1 by the specification should be opened. The dev team will fix this in the next FW release.

John_NZ · October 21, 2020, 8:35pm

@velev, thank you. Also the other channels should be set as per the frequencies in the CFList data (if it exists) in the Join Accept packet, do you know if this is the case already?

John_NZ · October 27, 2020, 5:03am

@velev I have been checking on whether the RAK4200 stack is honouring the CFList packet.
I have turned off channels 2,3,4,5,6 & 7 and then done a join.
After the join, channels 8,9,10,11 & 12 are turned on and have the channels as per the CFList

For example, after join I see this

at+get_config=lora:channel
**OK * 0,on,923200000,2,5; * 1,on,923400000,2,5; 2,off,923600000,2,5; 3,off,923800000,2,5; 4,off,924000000,2,5; 5,off,924200000,2,5; 6,off,924400000,2,5; 7,off,924600000,2,5; * 8,on,923600000,0,5; * 9,on,922200000,0,5; *10,on,922400000,0,5; 11,on,922600000,0,5; 12,on,922800000,0,5; 13,off,0,0,0; 14,off,0,0,0; 15,off,0,0,0

I then monitored the gateway packets while sending from the RAK4200 module and I do see it cycling through the channels that are turned on.

However, after about 10 or so sends, I see that several sends from the RAK4200 module are not being seen by the gateway.

I then check the channel assignment and I see that channels 2,3,4,5 & 6 have been re-enabled

at+get_config=lora:channel
OK * 0,on,923200000,2,5; * 1,on,923400000,2,5; * 2,on,923600000,2,5; * 3,on,923800000,2,5; * 4,on,924000000,2,5; * 5,on,924200000,2,5; * 6,on,924400000,2,5; 7,off,924600000,2,5; 8,off,923600000,0,5; 9,off,922200000,0,5; 10,off,922400000,0,5; 11,off,922600000,0,5; 12,off,922800000,0,5; 13,off,0,0,0; 14,off,0,0,0; 15,off,0,0,0

Obviously this is the reason I am not seeing the activity on the gateway from this point on for many sends as the gateway is not listening to all the frequencies in channels 3,4,5 & 6

I think that is also a bug with the stack.

velev · October 27, 2020, 7:44am

Thank you for this feedback. I will inform the dev team of this also. Your input is appreciated.

kasun_vega · March 8, 2022, 4:06pm

Hi Velev, im having similar problem with OTAA joining.for OTAA requests my gateway reply back with 923.3MHz and 923.9MHz.but my RAK4200(H) module has only 2 channels which is 923.2Mhz and 923.4Mhz.any solution for this??may be firmware update for rak4200 module?? please help

beegee · March 9, 2022, 3:32am

In AS923, only two channels are enabled during the join process. The other channels are enabled via the CFlist command from the LoRaWAN server.

After the RAK4200 has joined the network, the other channels should be available.

More info ==> RP2-1.0.3 LoRaWAN® Regional Parameters - LoRa Alliance®

kasun_vega · March 9, 2022, 3:46am

thank you beegee for your response.but the problem is gateway reply to joining requests with only 923.3MHz and 923.9Mhz.so at that point rak4200 has only 923.2 and 923.4 channels working.so it cant receive the reply from the gateway and never connect.

beegee · March 9, 2022, 4:09am

What gateway and what LoRaWAN server are you using?

The LoRaWAN server must answer the Join request on the same frequency, if it doesn’t then there is something wrong in the setup.

kasun_vega · March 9, 2022, 4:14am

im using rak5146 with thethingsnetwork.channel plan AS_923
this is the global config we use

github.com

manolovm/rak_common_for_gateway/blob/master/lora/rak5146/global_conf_uart/global_conf.as_920_923.json

{
    "SX130x_conf": {
        "com_type": "SPI",
        "com_path": "/dev/spidev0.0",
        "lorawan_public": true,
        "clksrc": 0,
        "antenna_gain": 0, /* antenna gain, in dBi */
        "full_duplex": false,
        "fine_timestamp": {
            "enable": false,
            "mode": "all_sf" /* high_capacity or all_sf */
        },
        "sx1261_conf": {
            "rssi_offset": 20, /* dB */
            "spectral_scan": {
                "enable": true,
                "freq_start": 921400000,
                "nb_chan": 8,
                "nb_scan": 2000,
                "pace_s": 10

This file has been truncated. show original

RAK4200 module we have only has these channels

at+get_config=lora:channel
OK * 0,on,923200000,0,5; * 1,on,923400000,0,5; * 2,on,0,0,0; 3,off,0,0,0; 4,off,0,0,0; 5,off,0,0,0; 6,off,0,0,0; 7,off,0,0,0; 8,off,0,0,0; 9,off,0,0,0; 10,off,0,0,0; 11,off,0,0,0; 12,off,0,0,0; 13,off,0,0,0; 14,off,0,0,0; 15,off,0,0,0
any idea how to get this solved??

I tried everything.only working plan I got is Asia 920-923 group 2.other settings wont reply to OTAA request.no matter what request frequency is,response only get with 923.3MHz or 923.9Mhz

beegee · March 9, 2022, 4:19am

Your gateway channel plan looks correct.
I am always struggling with TTN and AS923, I am in a worse situation than you, my regional settings are AS923-3 which uses different frequencies than AS923.

On TTN, what channel plan did you try? They have a confusing long list of channels for Asia

Did you try other regional settings in TTN?

Dumindu · March 9, 2022, 5:03am

I tried everything.only working plan I got is Asia 920-923 group 2.other settings wont reply to OTAA request.no matter what request frequency is,response only get with 923.3MHz or 923.9Mhz.
new users only allowed for 3 replies.so I used another account

beegee · March 9, 2022, 5:32am

There is nothing wrong with the RAK4200. You need to ask this question to TTN.
We are implementing the LoRa Alliance regional settings and they say 923.2 and 923.4 MHz.