How it Works

This section describes how this feature works.

cnSGW-C relays the instructions received from PGW towards MME and the information thus reported by MME towards PGW.

To pass the information, two IEs are defined on GTPC interface as per 3GPP TS 29274 V15.4.0. The following section shows the IE support implemented in cnSGW-C.

Presence Reporting Area Action

Presence Reporting Area Action

Octets

Bits

8

7

6

5

4

3

2

1

1

Type = 177

2–3

Length = n

4

SPARE

Instance

5

SPARE

INAPRA

Action

6–8

Presence Reporting Area Identifier

Action Values

Action

Value (Decimal)

Start Reporting changes of UE presence in the Presence Reporting Area (PRA)

1

Stop Reporting changes of UE presence in the Presence Reporting Area (PRA)

2

  • The Action value 1 (Start Reporting change) is used to request to start reporting changes of UE presence in the Presence Reporting Area identified by the Presence Reporting Area Identifier and, if present, the Presence Reporting Area elements composing the Presence Reporting Area.

  • The Action value 2 (Stop Reporting change) is used to request to stop reporting changes of UE presence in a Presence Reporting Area.

  • The Inactive PRA (INAPRA) flag in the Octet 5 is set to 1 on the S10/S16/S3 interface if the PRA is inactive in the source MME/SGSN during an inter MME/SGSN mobility procedure, i.e. the reporting change of UE presence in this Presence Reporting Area was requested by the PGW/PCRF/OCS but it was deactivated by the source MME/SGSN.

  • The Presence Reporting Area Identifier shall be present if the Action value requests to start, stop, or modify reporting changes of UE presence in a Presence Reporting Area. If so, the Presence Reporting Area Identifier shall contain an identifier of the Presence Reporting Area and encoded using full hexadecimal representation.

Presence Reporting Area Information

Presence Reporting Area Information

Octets

Bits

8

7

6

5

4

3

2

1

1

Type = 178

2–3

Length = n

4

SPARE

Instance

5–7

PRA Identifier

8

SPARE

INAPRA

SPARE

OPRA

IPRA

  • The PRA Identifier in octets 5–7 is present and contains the identifier of the PRA the UE is entering or leaving. It’s encoded using full hexadecimal representation (binary, not ASCII encoding). The PRA Identifier is defined in 3GPP TS 23.003 [2], Clause 19.10.

  • The Inside PRA (IPRA) flag is set to 1 if the UE is inside or enters the Presence Reporting Area identified by the PRA Identifier.

  • The Outside PRA (OPRA) flag is set to 1 if the UE is outside or leaves the Presence Reporting Area identified by the PRA Identifier.

  • The Inactive PRA (INAPRA) flag in octet 8 is set to 1 if the PRA is inactive in the MME/SGSN, i.e. the reporting of change of UE presence in this PRA is currently deactivated in the MME/SGSN, e.g. due to an overload situation.

  • Either the IPRA or the OPRA flag or the INAPRA is set to 1, not several ones, for a given Presence Reporting Area Identifier.