Issues with Downlinks

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1

Hi All,

I’m having issues with downlinks (confirmed uplinks) with my nodes/gateways, e.g. I’m not getting any. My uplinks are working fine. This has been reported by some of our partners as well which is why i’m looking at it.

Using an Arduino UNO + Dragino board, with a test script which is sending static data “Hello World” on SF12. I can see my up-links and attempted down-links on the TTN Console (both in the App and Gateway). However the Down-links are never received, I noticed that the down-links are being sent of SF10. I was expecting them on SF12 (rx1) or SF9 (rx2). (note: I can transmit successfully on SF10 as well, and doesn’t change the down-link spread-factor)

Other info,
Gateway: Cisco with the Semtech Forwarder
Freq Plan: AS923 (920-923)
Router: Meshed-router

Does anyone have any insights as to why the downlinks aren’t coming through to my node? Or where to look?

2

I switched libraries to use AU915, and immediately saw Acks from another local gateway (at a local university, not one I manage). So I’m confident that the node hardware is ok.

@Maj, any thoughts on the issue or where to look? This is in Brisbane

3

Hi @DanielT1. Are OTAA joins working OK, but confirmed downlinks are not?

I see some intermittent downlink failures, but these can be caused by a variety of reasons. Most common is that a device is on the edge of coverage and is receiving uplinks but not downlinks.

4

Thanks, I’ll be trying closer to our gateways and the northshore gateway later this week.

5

OTAA activation works fine, or we would have picked up issues earlier.

I’ve found part of my issue, my AS923 sensor was configured for SF9 on RX2, when it should have been SF10. I think the reason I didn’t see results in my earlier testing, was as you point out, range related.

Still not seeing anything on RX1 though.

Can you confirm what Spread Factor the EDQ gateways use? Both for AS923 and AU925 ranges

6

Spreading factor is commanded by the network server in accordance with the LoRaWAN regional parameters; the gateways merely do as they are told.

For RX1 in most regions the downlink spreading factor would be the same as whatever was actually used on the triggering uplink (though an offset is possible). RX2 usually uses a fixed downlink SF; in some cases (like EU868) that used by TTN is different than the default.