No answer to mac command LinkCheckReq when uplink use LR-FHSS
Achichig opened this issue · 7 comments
- The issue is present in the latest release.
- I have searched the issues of this repository and believe that this is not a duplicate.
What happened?
When I ask my device, configured to use LR-FHSS modulation only, to send a LinkCheckReq, Chirpstack network server does not generate a LinkCheckAns.
What did you expect?
I am expecting chirpstack ns to generate a LinkCheckAns when we are using LR-FHSS modulation for sending LinkCheckReq, the same way as when using the lora modulation.
Steps to reproduce this issue
Steps:
- Configure the device to use LR-FHSS modulation
- Send a LinkCheckReq
Could you share your log output?
gateway/…/event/up topic:
gateway/acacacacacacac11/event/up {"phyPayload":"QBBKrAAAHQAAfnyRIzE=","txInfo":{"frequency":904600000,"modulation":"LR_FHSS","lrFHSSModulationInfo":{"operatingChannelWidth":1523000,"codeRate":"1/3","gridSteps":52}},"rxInfo":{"gatewayID":"rKysrKysrBE=","time":null,"timeSinceGPSEpoch":null,"rssi":-38,"loRaSNR":0,"channel":1,"rfChain":0,"board":0,"antenna":0,"location":null,"fineTimestampType":"NONE","context":"h1tAAA==","uplinkID":"9Eda8C97RYGP5zvuVO/qsA==","crcStatus":"CRC_OK"}}
Nothing shows up on the gateway/…/command/down and gateway/…/event/ack topics
Your Environment
| Component | Version |
|---|---|
| Application Server | v3.17.6 |
| Network Server | v3.16.1 |
| Gateway Bridge | v3.13.2 |
| Chirpstack API | X |
| Geolocation | X |
| Concentratord | X |
Hi @Achichig,
I'm keen to test the LR-FHSS too.
How should we set the gateway-profile to support LR-FHSS?
We need to add bandwidth 137kHz, 336kHz and 1.523MHz in the gateway-profile?
Hello IoTThinks,
I did not configure a gateway-profile in my case.
I force the end-device to use LR-FHSS modulation by configuring a mobile ADR profile with all DR5 and I have configured the packet forwarder of my gateway to use LR-FHSS modulation (US915 frequency plan):
"lr_fhss_conf": {
"enable": true,
"rf_chain": 0,
"center_freq": 904600000,
"syncword": "2C0F7995",
"chan_cfg": [
{ "freq_hz": 903000000, "ocw": 1523000 },
{ "freq_hz": 904600000, "ocw": 1523000 },
{ "freq_hz": 906200000, "ocw": 1523000 },
{ "freq_hz": 907800000, "ocw": 1523000 },
{ "freq_hz": 909400000, "ocw": 1523000 },
{ "freq_hz": 911000000, "ocw": 1523000 },
{ "freq_hz": 912600000, "ocw": 1523000 },
{ "freq_hz": 914200000, "ocw": 1523000}
]
},
For EU868, the configuration should be:
"lr_fhss_conf": {
"enable": true,
"rf_chain": 0,
"center_freq": 868000000,
"syncword": "2C0F7995",
"chan_cfg": [ /* 16 virtual channels maximum */
{ "freq_hz": 867200000, "ocw": 137000 }, /* 200kHz channel */
{ "freq_hz": 867400000, "ocw": 137000 }, /* 200kHz channel */
{ "freq_hz": 867600000, "ocw": 137000 }, /* 200kHz channel */
{ "freq_hz": 867800000, "ocw": 137000 }, /* 200kHz channel */
{ "freq_hz": 868000000, "ocw": 137000 }, /* 200kHz channel */
{ "freq_hz": 868200000, "ocw": 137000 }, /* 200kHz channel */
{ "freq_hz": 868600000, "ocw": 336000 } /* 400kHz channel */
]
},
I believe the issue is since the NS can't return the margin for LR-FHSS:
For LoRa uplinks, ChirpStack uses the SNR reported by the gateway to derive the margin above demodulation floor. Unfortunately, gateways don't report any SNR (yet?) for the LR-FHSS modulation.
@brocaar So the issue is at gateway?
I'm keen to test lf-fhss with ChirpStack.
Is there any hint how to implement a node to use lr-fhss?
Thanks a lot.
@IoTThinks I think we are mixing two things in this discussion, what is needed to test LR-FHSS and the LinkCheckReq issue. My answer was related to the latter as the current LR-FHSS implementation does not report any SNR for a received uplink (as far as I'm aware). I think this is not related to a a specific gateway but to the LR-FHSS implementation itself.
If you want to test out LR-FHSS, see https://github.com/Lora-net/LoRaMac-node. According to the README it supports LR-FHSS. Please note you also need a LR-FHSS capable gateway.