Editing My 5G lawful interception notes (section)

== 5G location info notes ==

Cell site information can be manual or automatic. 33 127 and 33 128 discuss automatic reporting.

When automatic, when the cell identity is present within an xIRI the MDF2 that receives the xIRI may retrieve the cell site information for that cell from a CSP database and deliver the same to the LEMF either within the IRI message generated from the received xIRI or in a separate IRI message containing the MDFCellSiteReport record.

I recommend the separate IRI message containing the MDFcellSiteReport record, specifically, asynchronously requesting cell info from a CSP database and delivering original IRI to LEMF without delay or additional modification. Modifying an existing xIRI delays delivery of associated IRI and introduces additional processing steps to convert xIRI to IRI that increases the chances to introduce a software bug.

The MDFCellSiteReport record shall be delivered as an IRI REPORT (see ETSI TS 102 232-1 clause 5.2.10) and allocated the same CIN, if any, as the IRI message that caused the retrieval.

=== ASN.1 notes ===

The use of <code>--...</code> in my ASN.1 notes indicate portions of ASN.1 above or below are omitted. See 3GPP specification for full ASN.1.

==== Location Info ====

<pre>-- ===================
-- Location parameters
-- ===================

Location ::= SEQUENCE
{
    locationInfo                [1] LocationInfo OPTIONAL, 
    positioningInfo             [2] PositioningInfo OPTIONAL,  
    locationPresenceReport      [3] LocationPresenceReport OPTIONAL 
}

CellSiteInformation ::= SEQUENCE
{
    geographicalCoordinates     [1] GeographicalCoordinates,
    azimuth                     [2] INTEGER (0..359) OPTIONAL,
    operatorSpecificInformation [3] UTF8String OPTIONAL
}

-- TS 29.518 [22], clause 6.4.6.2.6
LocationInfo ::= SEQUENCE
{
    userLocation                [1] UserLocation OPTIONAL,
    currentLoc                  [2] BOOLEAN OPTIONAL, 
    geoInfo                     [3] GeographicArea OPTIONAL,
    rATType                     [4] RATType OPTIONAL,
    timeZone                    [5] TimeZone OPTIONAL,
    additionalCellIDs           [6] SEQUENCE OF CellInformation OPTIONAL
}

-- TS 29.571 [17], clause 5.4.4.7
UserLocation ::= SEQUENCE
{
    eUTRALocation               [1] EUTRALocation OPTIONAL,
    nRLocation                  [2] NRLocation OPTIONAL,
    n3GALocation                [3] N3GALocation OPTIONAL
}</pre>

==== MDF Cell Site Report ====
<pre>-- ===============
-- HI2 IRI payload
-- ===============

IRIPayload ::= SEQUENCE
{
    iRIPayloadOID       [1] RELATIVE-OID,
    event               [2] IRIEvent,
    targetIdentifiers   [3] SEQUENCE OF IRITargetIdentifier OPTIONAL
}

IRIEvent ::= CHOICE
{
    -- ...
    -- MDF-related events, see clause 7.3.4
    mDFCellSiteReport                                   [16] MDFCellSiteReport,
    -- ...
}
MDFCellSiteReport ::= SEQUENCE OF CellInformation

CellInformation ::= SEQUENCE 
{
    rANCGI                      [1] RANCGI,
    cellSiteinformation         [2] CellSiteInformation OPTIONAL,
    timeOfLocation              [3] Timestamp OPTIONAL
}

RANCGI ::= CHOICE
{
    eCGI                        [1] ECGI,
    nCGI                        [2] NCGI
}

CellSiteInformation ::= SEQUENCE
{
    geographicalCoordinates     [1] GeographicalCoordinates,
    azimuth                     [2] INTEGER (0..359) OPTIONAL,
    operatorSpecificInformation [3] UTF8String OPTIONAL
}

-- TS 29.572 [24], clause 6.1.6.2.4
GeographicalCoordinates ::= SEQUENCE
{
    latitude                            [1] UTF8String,
    longitude                           [2] UTF8String,
    mapDatumInformation                 [3] OGCURN OPTIONAL
}

-- TS 29.571 [17], clause 5.4.4.5
ECGI ::= SEQUENCE
{
    pLMNID                      [1] PLMNID,
    eUTRACellID                 [2] EUTRACellID,
    nID                         [3] NID OPTIONAL
}

-- TS 29.571 [17], clause 5.4.4.6
NCGI ::= SEQUENCE
{
    pLMNID                      [1] PLMNID,
    nRCellID                    [2] NRCellID,
    nID                         [3] NID OPTIONAL
}

PLMNID ::= SEQUENCE
{
    mCC [1] MCC,
    mNC [2] MNC
}

MCC ::= NumericString (SIZE(3))

MNC ::= NumericString (SIZE(2..3))

-- TS 38.413 [23], clause 9.3.1.9
EUTRACellID ::= BIT STRING (SIZE(28))

-- TS 38.413 [23], clause 9.3.1.7
NRCellID ::= BIT STRING (SIZE(36))

-- TS 23.003 [19], clause 12.7.1 encoded as per TS 29.571 [17], clause 5.4.2
NID ::= UTF8String (SIZE(11))

</pre>

=== References ===

* 33 127 § 7.3.4
* 33 128 § 7.3.2