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LoRa | Geolocation

  • 4 november 2016
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@Tim A quick question:

Supposing my sensor is well within range of loc-enabled stations, could it be possible that I am not guaranteed to receive an update on each transmission because, for instance, the backend hasn't quality data to compensate for external factors (e.g issues of multi path or whatever the DTOA issue might occur).

My question boils down to understand if more than one transmission might still be required even in optimal network coverage of location-based gateways.
THX
@Tim and @rharte
Thanks for the information. I can't wait to test with the geolocation funtionality. What can I expect from geolocation inside buildings? I am looking for an indoor solution that performs better than gps location.
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@rharte thanks so much for your detailed explanation about Geolocation! 😃

@Gijs at this moment, we don't offer Geolocation test accounts anymore for the developer portal. This is because we are busy launching the feauture globally! You may expect to use it on the developer portal within a few weeks from now. This also applies for Thingpark, the subscription portal.
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@Gijs you need a LoRa subscription with the feature Geolocation activated. Then you need an application that sends some data (even if it is a dummy payload, so no specific changes needed in your application), then you need to make sure that at least 3 gateways can pick up your signal for triangulation, so you need to check your antenna effectivity, TX-power and SF, and then you will receive a new message type on your backend server, the DevEUI_location message that you need to decode. That's basically it 😉
I would like to test with geolocation. Is this possible? What do I need to do for that?
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However, if one gateway receives your signal quite strong, it will ask the device to tune down

Why do you think so?

BTW, a gateway typically is just unable to send a MAC command to a node, as it doesn't have access to NwkSKey.


Or then more generally speaking: the network functionality as a whole (ADR) is aimed at preserving link budget; the way it works does not change anything to the nature of my question, or does it?
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However, if one gateway receives your signal quite strong, it will ask the device to tune down

Why do you think so?

BTW, a gateway typically is just unable to send a MAC command to a node, as it doesn't have access to NwkSKey.
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I have another question about geolocation: I guess for the best results and accuracy, it's beneficial if as much gateways receive your signal as possible. At least more than 3. However, if one gateway receives your signal quite strong, it will ask the device to tune down, meaning that less gateways will receive the signal, and the geolocation accuracy will deteriorate if at all enough gateways recieve the signal for a position determination. I guess in the long run KPN doesn't want any devices that ignore mac commands and keep sending at SF12 and max power to get the best geolocation results. How are these mechanisms planned to co-exist in a sort of optimum configuration?
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I have geolocation provisioned and sending with SF12 and ADR off as advised by KPN in this thread. I find that quite regular my signal is received by 3 or 4 gateways, but only occasionally the geo position is updated. I can send dozens of messages per day and still find that my calculated position may be two days old! Is my observation correct that there is not always a position update when a signal is received by 3 or more gateways? Or am I doing something wrong?

Why are moving objects not supported ?


Accuracy of the fine timestamps which are used for LoRa TDoA positioning is disappointing, and multipath propagation brings even more troubles. So you need a (huge) number of messages to feed the filter/solver with their ts and other metadata to get not-too-disasterous positioning accuracy.

Actually, that's why Actility had gave up and bought Abeeway which provides assisted GPS solutions.

Thanks for your reply!
Some more questions arised...
-Is this filter already implemented ?
-Is each calculated loacation indpendendly calculated from the timestamps? Or does it take into account previous locations?
-Are there algorithms implemented which assume the node is non moving ?
-What would be the best way to have location updates for moving objects ? Send 'frequently' on SF11 ?

Thanks!
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Why are moving objects not supported ?


Accuracy of the fine timestamps which are used for LoRa TDoA positioning is disappointing, and multipath propagation brings even more troubles. So you need a (huge) number of messages to feed the filter/solver with their ts and other metadata to get not-too-disasterous positioning accuracy.

Actually, that's why Actility had gave up and bought Abeeway which provides assisted GPS solutions.
"Tests are only available in a limited number of locations and only valid for stationary cases. Moving objects are not supported yet."

Can someone explain if this is still the case ? Why are moving objects not supported ? Any details ?

Thanks!
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Hi Tim,

Could you help me get in touch with a KPN contact to get access and test Geolocation?

Many thanks

Gertjan

Sure! Can you sent me a PM with your DevEUI?
Hi Tim,

Could you help me get in touch with a KPN contact to get access and test Geolocation?

Many thanks

Gertjan
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No problem! Hope you find out what is causing this, please share your findings on the forum 🙂
Hi @Tim,

Strange! I will look into it. Thanks for your time.

Jan
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Hi @jankappe,

We cannot reproduce this! I have fetched the JSON message trough the developer portal, but if I send the message in uppercase letters, it will look like this again. The message is not changed on the way.
Therefore we think the problem should be found within your application server.
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Sorry for the delay @jankappe,

Thanks for sharing! I've forwarded your message to my colleagues. Hope we'll find the cause soon, I'll let you know. 🙂
Hi @Tim,

Here is a location type message:

code:
{
"Token": "04cc6dbfe61991208d58b9537b66c263befbe48ef605150733eb506e5a0278e8",
"LrnFPort": "0",
"DevEUI_location": {
"DevAltRadius": "0.000000",
"DevEUI": "0059AC00001830C8",
"DevAddr": "15293375",
"DevLON": "5.411983",
"DevLAT": "51.479717",
"DevAcc": "0.000000",
"Time": "2017-03-31T12:24:49.0+02:00",
"NxGeolocAlgo": "0",
"NwGeolocTdoaOpt": "0",
"DevAlt": "0.000000",
"DevLocTime": "2017-03-31T12:24:49.0+02:00",
"DevLocRadius": "0.000000",
"CustomerID": "100006334",
"Lrcid": "0059AC01"
},
"timeReceived": "2017-03-31T10:24:49Z",
"Time": "2017-03-31T12:24:49.61+02:00",
"LrnInfos": "TWA_100006334.683.AS-1-33061",
"LrnDevEui": "0059ac00001830c8",
"AS_ID": "asidsalvo"
}


And here the normal one:

code:
{
"Token": "df0bee9e60bbfd47e3f527be1c3cf739351ce4bd223ee69688cba547722bc6a4",
"LrnFPort": "4",
"DevEUI_uplink": {
"AckRequested": "1",
"DevLrrCnt": "6",
"rawMacCommands": "",
"Late": "0",
"ADRbit": "1",
"LrrLON": "5.440173",
"payload_hex": "00346b3a03c814af1e9500480900000000",
"Channel": "LC7",
"FPort": "4",
"DevAddr": "15293375",
"CustomerData": {
"alr": {
"pro": "Nomadic",
"ver": "1"
}
},
"FCntDn": "11",
"CustomerID": "100006334",
"Lrcid": "0059AC01",
"LrrSNR": "0.000000",
"FCntUp": "11",
"mic_hex": "17a1e29c",
"MeanPER": "0.041866",
"Lrrid": "FF010328",
"DevEUI": "0059AC00001830C8",
"Time": "2017-03-31T12:24:48.314+02:00",
"ModelCfg": "0",
"LrrRSSI": "-111.000000",
"MType": "4",
"Lrrs": {
"Lrr": [{
"LrrSNR": "0.000000",
"Lrrid": "FF010328",
"LrrESP": "-114.010300",
"LrrRSSI": "-111.000000",
"Chain": "0"
}, {
"LrrSNR": "-12.000000",
"Lrrid": "FF010381",
"LrrESP": "-127.265724",
"LrrRSSI": "-115.000000",
"Chain": "0"
}, {
"LrrSNR": "-17.000000",
"Lrrid": "FF01047D",
"LrrESP": "-132.085800",
"LrrRSSI": "-115.000000",
"Chain": "0"
}]
},
"LrrLAT": "51.477493",
"SpFact": "12",
"InstantPER": "0.090909",
"SubBand": "G2"
},
"timeReceived": "2017-03-31T10:24:49Z",
"Time": "2017-03-31T12:24:49.60+02:00",
"LrnInfos": "TWA_100006334.683.AS-1-33058",
"LrnDevEui": "0059AC00001830C8",
"AS_ID": "asidsalvo"
}


I hope this will help!
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Hi @jankappe, can you share a JSON message with us? If possible, one normal, and one location type.
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Hello @jankappe, we are currently looking into this problem. I'll post an update if we make any progress.
Hi,

While looking through my LoRa Data I noticed the "LrnDevEui" of an uplink messages is in capital letters and the "LrnDevEui" of a location message is not. This caused some unexpected problems while sorting my data by "LrnDevEui".

Are you aware of this difference and is there any reason for it?

Thanks in advance, I hope this will be changed in the near future.

Jan
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Will do Amine, please check your PM inbox 🙂
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Hello Amine,

Do you have a contact at KPN for LoRa? Geolocation is as far as I know not yet accessible. If you're interested I can get you in touch to get access. Tests are only available in a limited number of locations and only valid for stationary cases.
Hi Tim. Please connect me with someone from KPN to test. Cheers!
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Hello Amine,

Do you have a contact at KPN for LoRa? Geolocation is as far as I know not yet accessible. If you're interested I can get you in touch to get access. Tests are only available in a limited number of locations and only valid for stationary cases.

Reageer