How to manage Channel Mask

I have one question about the channel mask. In fact there are a few topc about this, but I did not find my answer, so ask here again.

I used regin CN470,
1)in loraserver.toml, enabled_uplink_channels=[80,81,82,83,84,85,86,87]
2)In Gateway, global_conf.json defined from 472.3MHz, up to 8 channels, channel number index is 10~17.
3)In Gateway Profile, Enabled channels * 12, 13, 14, 15, 16, 17, 18, 19
I changed 3) to different channel nubmer, expected to get different chnnel mask in downlink message, but the channel mask seemed always 10~17.

Is this behavior correct?
If want to change channel mask to 12~19, what actions need to do?


First of all, forget about the Gateway Profiles! It is not important in this case. This feature was never clear to users and will be removed in the next major version. See also: Who is using the Gateway Profile / how are you using it?.

What you need to configure is 2 things (this is not specific to the CN channel-plan):

  1. Your gateways: make sure they are listening on the frequencies that you want to use (you will find the frequencies in the LoRaWAN Regional Parameters specification).
  2. Your network-server: this to make sure that it will send the correct channel-mask to your devices. This channel-mask must match the channels as defined by the LoRaWAN Regional Parameters. This configuration configured by the enabled_uplink_channels setting.
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Hi Brocarr,

Thanks for your information first.
I will confirm this.
BTW, with such role, does one NS just support one Region file? I mean if one GW just support 8 channels, then under this NS just support these 8 channels only? Could not support GW 1 to use one 8 channels, GW 2 use another different 8 channels?

Hi Brocarr,

Channel mask is working as you said.
But this lead to another two questions:

  1. It seemed one NS could not support two or more different regions, for example, one EU868 and one CN470.

2)Assume one NS just worked at CN470, in CN470 band, totally there are 96 channels, assume GW1 used channel 10~17, GW2 used channel 20~27, one NS could not support GW1 and GW2 together.

Are these description Correct?


If you use two gateways each listening to 8 channels (e.g. 0 - 7 and 8 - 15), then you can configure the enabled uplink channels to 0 - 15 in your ChirpStack Network Server configuration :slight_smile:

In order to support multiple regions, you need to setup multiple NS instances. Note that you can still link them to a single ChirpStack Application Server.


Hi Brocarr,
For case:
If you use two gateways each listening to 8 channels (e.g. 0 - 7 and 8 - 15), then you can configure the enabled uplink channels to 0 - 15 in your ChirpStack Network Server configuration.

If enabled ADR, is LinkADRReq working? For one downlink message, which channel mask will it use?


It uses the enabled_uplink_channels for the channel-mask.

Hi Brocaar,

Assume enabled_uplink_channels = [0,1,…14,15], and GW1 used 0~7, GW2 used 8~15, and GW1 located in City A, GW located in City B.

After NS received one uplink message, assume enabled ADR funciton, then NS will send LinkADRReq command in downlink message. If one end device under GW1, received such command, will enable channel 0~15, but GW1 could not listen channel 8~15, correct?

I think the key point is one NS just have one channel mask, up to 16 channels.


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This will not work the ChirpStack Network Server assumes that your network has one channel-plan. If you have two gateways where GW1 listens on channels 0 - 7, and GW on channels 8 - 15, then they should cover the same area.


Hi Brocaar,

Ok, I see.


WIll you please give a hint or help me out how to do that?
I’m struggling with this for 3 days.

i have one instance where network, application, and gatway server running. and I’ve added a 868 gateway there and also a device on that. Everything working fine.

But i needed to add AS923 gateway. As one configuration only supports one gateway. I had to create another instance where i installed network and gateway server.

on the application server i’ve added my new AS923 gateway. But not able to do connect it. FYI, gateway is sending join requests.