GCI search & multiple cell location

[barbiz]

Hello,

since location accuracy is not enough for us with single cell, we are trying to use multiple cell location.

We tries with %NCELLMEAS = 2 but we don't get multiple cells. Maybe the serving cell has good signal?

Then we tried with GCI search and fw 1.3.4.

%NCELLMEAS = 3,3

and we got those 3 cells (I added newlines for easiness of reading):

%NCELLMEAS: 0,

"0AAE62A2","22201","92B9",65535,0,6254,243,62,19,178936,0,0,

"0319AFA2","22201","92B8",65535,0,6254,295,62,18,178936,0,0,

"0094586F","22210","69D9",65535,0,6354,105,77,29,178973,0,0

so we tried to inject this data into the nrfCloud API:

{
  "lte": [
    {
      "mcc": 222,
      "mnc": 1,
      "eci": 179200674,
      "tac": 37561,
      "earfcn": 6254,
      "adv": 65535,
      "rsrp": -78,
      "rsrq": -10,
      "nmr": [
        {
          "earfcn": 6254,
          "pci": 295,
          "eci": 52015010,
          "rsrp": -78,
          "rsrq": -10.5
        },{
          "earfcn": 6354,
          "pci": 105,
          "eci": 9721967,
          "rsrp": -63,
          "rsrq": -5
        }
      ]
    }
  ]
}

and this is the response:

{
	"lat": 45.39999247,
	"lon": 11.90999508,
	"uncertainty": 2472,
	"fulfilledWith": "MCELL"
}

which does not give any improvement on the original location with SCELL.

Can you help us? Are we formatting the data the wrong way?

Marco

[Cole Hafner]

Hi Marco,

Your formatting is correct. What is the device ID? I can look into the logs and see if I can help you get a better result. 

Thanks,

Cole

[barbiz]

Actually, I am directly calling the API cloud-to-cloud so there is no device id. How can I make my call trackable?

Also, I was wondering: what is the difference between my formatting and passing an array of cells direcly in the "lte" object?

[barbiz]

Dear Andrew,

first of all, thank you for your detailed explanation!!

I am having too issues in finding my cells in cellmapper. Thay are in the same eNodeb as your example, but in different sectors which are not in the cellmapper database. however, this is what the radio returns.

On other hand, I am unable to reproduce your results with nrfCloud.

For example, this query:

{
 	"lte": [
		{
			"mcc": 222,
			"mnc": 1,
			"tac": 17211,
			"eci": 179200573
		}
	]
}

returns a different result:

{
	"lat": 45.4146033,
	"lon": 11.9093139,
	"uncertainty": 1201.109,
	"fulfilledWith": "SCELL"
}

Also the second query:

{
 	"lte": [
		{
			"mcc": 222,
			"mnc": 1,
			"tac": 17211,
			"eci": 179200573
		},
		{
			"mcc": 222,
			"mnc": 1,
			"eci": 179200575,
			"tac": 17211
		}
	]
}

does not give any accuracy improvement:

{
	"lat": 45.4146033,
	"lon": 11.9093139,
	"uncertainty": 1201.109,
	"fulfilledWith": "MCELL"
}

Can you help me understand why I am getting different results by calling the API?

thanks much,

Marco

[AndrewKostka]

Hi Marco:

I now see the same result that you do for that data. It is to be expected that results will sometimes change slightly over time, as data sources get refreshed and updated. However, I'm also seeing what you are seeing, that the second cell no longer changes the accuracy. I'm going to look into this in our data sources to gather more information.

[barbiz]

Hello,

yes I understand that data can change but this seems really a suspicious concidence. Consider I never got improvement by adding multiple cells in this way.

Waiting for updates

Marco

[AndrewKostka]

Hi, Marco: I've looked more into why my initial results were different from what I see now on nrfcloud. We have multiple data sources for some areas, and we continuously do performance evaluation in order to rank those data sources. The environment where I did my initial test had slightly outdated rankings. While these rankings in general improve our success rate, in very specific cases like this it can decrease accuracy.

This edge case has given our team some ideas for improvement of this ranking procedure, including checking SCELL vs. MCELL results for uncertainty decreases. I'm sorry if this isn't the answer you were hoping for, but these cases help us improve our service over time.

[barbiz]

Hello,

thanks.

At this point, we are stuck... do you have any idea on when this implementation can be improved?

Or perhaps can you tell us who the location provider is behind?

It's quite anoying to know that the solution is there but cannot access to it...

Marco

[AndrewKostka]

Hi, Marco: Unfortunately we're not able to give out the exact source of a specific data point. We're going to address this issue within the next couple of months, as part of a larger set of improvements to LTE Location Services.

However, I'd encourage you to test more than just this one data point, as you may get more accurate results from other towers when your device completes handover.