Xmonitor to get current cellid

[Johan]

Hi!

I use XMONITOR to get the current cellid but it seems strange.

%XMONITOR: 5,"","","24008","2725",7,20,"01ADF70B",215,6400,50,35,"","11100000","11100000","01001001"

I did take the field "01adf70b" and filter out lower 2 bytes, to get cellid, but it still gives me a position extremely far away (391km) from my current location (most south sweden)- using opencellid.org. Not correct.

What am I interpreting wrong in what you return with xmonitor?

/Johan

[Heidi]

Hi!

I think you're converting the cellid incorrectly, which is giving you the wrong cell. 

I have asked the modem team how to accurately interpret this parameter, and I'll let you know when I hear back.

Best regards,

Heidi

[Heidi]

We're not familiar with opencellid.org, but our first impression is that it is meant for GSM towers.

Could you verify whether the cell is correct if you use https://www.cellmapper.net/?

This is a site that can be used to verify the correct eNB for this case.

• Cell tower can be found with these steps*
  • eNB ID can be found using https://www.cellmapper.net/enbid
  • 01ADF70B -> 28178187 in decimal -> eNB ID: 110071
• Then on the main page of https://www.cellmapper.net
  • Provider: Telenor - 2408. We return PLMN ID "24008" (240, 08) in %XMONITOR, but the site seems to omit the '0' prior '8'
  • Network: 4G - LTE. We return AcT (7) in %XMONITOR, 7 = E-UTRAN -> means LTE-M
  • Band: 20. We return band in %XMONITOR
  • Cell Tower search: 110071, note: This is the result from the eNB ID calculator

The CellIdentity ("01ADF70B") we return in response is defined in 3GPP 36.331 ch. 6.3.4:

– CellIdentity
The IE CellIdentity is used to unambiguously identify a cell within a PLMN.

CellIdentity ::= BIT STRING (SIZE (28))

Decoding the content of CellIdentity may not be straightforward.

I found this statement from the 3GPP 23.003, v. 13.10.0:

19.6 E-UTRAN Cell Identity (ECI) and E-UTRAN Cell Global Identification
(ECGI)
The E-UTRAN Cell Global Identification (ECGI) shall be composed of the concatenation of the PLMN Identifier
(PLMN-Id) and the E-UTRAN Cell Identity (ECI) as shown in figure 19.6.1 and shall be globally unique:
Figure 19.6.1: Structure of E-UTRAN Cell Global Identification
The ECI shall be of fixed length of 28 bits and shall be coded using full hexadecimal representation. The exact coding
of the ECI is the responsibility of each PLMN operator.
For more details on ECI and ECGI, see 3GPP TS 36.413 [84].

[Johan]

All right, thank you Heidi.
I'll take a look at it now.