6.4 Sx Reporting Procedures

23.2143GPPArchitecture enhancements for control and user plane separation of EPC nodesRelease 17TS

6.4.1 General

The Sx reporting procedure is used by the UP function of SGW, PGW or TDF to report events to the CP function.

The following Sx reporting procedures exist: Sx session level reporting and Sx node level reporting. Both are initiated by the CP function.

6.4.2 Sx Session Level Reporting Procedure

This procedure is used by the UP function to report events related to an Sx session for an individual PDN connection IP-CAN session, TDF session or TDF in unsolicited reporting mode. The triggers for event reporting were configured on the UP function during Sx session management procedures by the CP function (excluding the Sx session termination procedure).

Figure 6.4.2-1: Sx Session Level Reporting procedure

1. The UP function detects that an event has to be reported. The reporting triggers involve the following cases:

(1) Usage report (by SGW-U, PGW-U and TDF-U).

Usage information shall be collected in the UP function and reported to the CP function as defined in clause 5.3 and clause 7.4.

(2) Start of traffic detection (by PGW-U and TDF-U).

When traffic detection is requested by PGW-C/TDF-C, and the start of traffic is detected for a PDR, the PGW-U/TDF-U shall report the start of traffic detection to the PGW-C/TDF-C and indicate the PDR rule ID.

(3) Stop of traffic detection (by PGW-U and TDF-U).

When traffic detection is requested by PGW-C/TDF-C, and the end of traffic is detected for a PDR, the PGW-U/TDF-U shall report the stop of traffic detection to the PGW-C/TDF-C and indicate the PDR rule ID.

(4) Detection of 1st Downlink Data for Idle-Mode UE (by SGW-U)

When SGW-U receives the downlink packet but no S1-bearer for transmission and the buffering is performed by SGW-U, it shall report the detection of 1st downlink data to SGW-C, for the purpose of paging the UE. SGW-U shall also report the DSCP of the packet when instructed by SGW-C (e.g. in case the Paging Policy Differentiation function as described in TS 23.401 [2] is enabled at the SGW-C).

2. The UP function sends an Sx report message (Session ID, list of [Reporting trigger, Measurement information]) to the CP function.

The Reporting trigger parameter contains the name of the event which triggered the report and the Measurement information parameter contains the actual information the CP function requested to be informed about.

3. The CP function identifies the Sx session context based on the received Session ID and applies the reported information for the corresponding PDN connection IP-CAN session, TDF session or TDF in unsolicited reporting mode. The CP function responds with an Sx report ACK message.