5.4 Dedicated Bearer Procedures for E-UTRAN Access with PMIP-based S5/S8

23.4023GPPArchitecture enhancements for non-3GPP accessesRelease 18TS

5.4.1 General

The procedure given in Figure 5.4.1-1 applies to all dedicated resource allocation operations for E-UTRAN which are triggered by PCRF, with the only exception of MME-initiated Dedicated Bearer Deactivation procedure which is covered in clause 5.4.5.3 The procedures initiated by the S‑GW in the E-UTRAN differ for each case.

The procedure described in Figure 5.4.1-1 shows only the steps, due to PMIP based S5/S8, that are different from the GTP variant of the procedure given in TS 23.401 [4].

Figure 5.4.1-1: Dedicated Resource Allocation Procedure, UE in Active Mode

This procedure applies to the Non-Roaming (Figure 4.2.1-1), Roaming (Figure 4.2.1-2) and Local Breakout (Figure 4.2.3-4) cases. For the Roaming and Local Breakout cases, the vPCRF forwards messages between the Serving GW and the hPCRF. In the Local Breakout case, the vPCRF forwards messages between the PDN GW and the hPCRF.

If dynamic policy provision is not deployed, the steps shown in the figure are not taken. Instead, a configured static policy may be applied.

A.1) The PCRF initiates the Gateway Control and QoS Rules Provision Procedure specified in TS 23.203 [19] by sending a message with the QoS rules and Event Trigger information to the S‑GW.

Steps between A.1 and B.1 are described in TS 23.401 [4], clauses 5.4.{1, 2.1, 3, 4.1}.

NOTE 1: For a PMIP‑based S5/S8, before procedure steps (step 3 of TS 23.401 [4], clause 5.4.1), the PCRF sends a PCC decision provision (QoS policy) message to the S‑GW and not to the P‑GW as done for GTP‑based S5/S8. The S‑GW uses this QoS policy to determine that traffic flow(s) shall be aggregated to or removed from an active bearer. The S‑GW generates the TFT and updates the EPS Bearer QoS to match the aggregated set of traffic flows. It is possible that the S-GW bearer binding function will result in the modification, creation or removal of bearers at this point. For modification, the S‑GW sends an Update Bearer Request (PTI, EPS Bearer Identity, EPS Bearer QoS, TFT) message to the MME. For creation of a dedicated bearer, the S-GW sends a Create Bearer message and for removal, the S-GW sends a Delete Bearer Request.

B.1) The Serving GW indicates to the PCRF whether the requested QoS Policy Rules Provision could be enforced or not thus completing the GW Control and QoS Rules Provision procedure started in step A.1. The Serving GW indicates User Location Information and/or UE Time Zone Information to the PCRF as an Event Report if the corresponding event trigger is set.

B.2) The PCRF initiates the PCC Rules Provision Procedure as specified in TS 23.203 [19]. The PCRF provides updated PCC rules to the PCEF for enforcement by means of an PCC Rules Provision procedure specified in TS 23.203 [19].

NOTE 2: Step B.2 may occur before step A.1 or performed in parallel with steps A.1‑B.1 if acknowledgement of resource allocation is not required to update PCC rules in PCEF. For details please refer to TS 23.203 [19].

Interactions between PCRF initiated dedicated bearer procedure and handover are described in clauses 5.7.1 and 5.7.2.

5.4.2 Dedicated Bearer Activation

When the QoS Policy rules provided by the PCRF to the Serving Gateway in Step A.1 of Figure 5.4.1-1 above result in the Serving Gateway to decide to activate a dedicated bearer, this procedure is applied.

The procedure depicted in Figure 5.4.1-1 applies for this case. On receiving message A.1, the Serving GW decides that a new bearer needs to be activated, the Serving GW uses this QoS policy to assign the EPS Bearer QoS, i.e., it assigns the values to the bearer level QoS parameters (excluding AMBR); see TS 23.401 [4] clause 4.7.3. The Serving GW follows the procedure shown in TS 23.401 [4], clause 5.4.1 by sending a Create Bearer Request message (EPS Bearer QoS, TFT, S1 TEID) to the MME.

The message descriptions for A.1, B.1 and B.2 in clause 5.4.1 apply to this case as well. The steps between A.1 and B.1 are described in TS 23.401 [4], clause 5.4.1.

5.4.3 Bearer Modification with Bearer QoS Update

5.4.3.1 PCC Initiated Bearer Modification with Bearer QoS Update

When the QoS Policy rules provided by the PCRF to the Serving Gateway in step A.1 of Figure 5.4.1-1 above results in the Serving Gateway to decide to modify the QoS of an already existing bearer, this procedure is applied. QoS modification may result in a bearer modification in the E-UTRAN access.

The procedure depicted in Figure 5.4.1-1 applies to this case as well. On receiving message A.1, the Serving GW uses this QoS policy to determine that traffic flow(s) shall be aggregated to or removed from an active bearer. The Serving GW generates the TFT and updates the EPS Bearer QoS to match the aggregated set of traffic flows. The Serving GW then follows the procedure shown in TS 23.401 [4], clause 5.4.2 by sending the Update Bearer Request (EPS Bearer QoS, TFT) message to the MME.

The message descriptions for A.1, B.1 and B.2 in clause 5.4.1 apply to this procedure as well. The steps between A.1 and B.1 are described in TS 23.401 [4], clause 5.4.2.1.

5.4.3.2 HSS-Initiated Subscribed QoS Modification

The HSS Initiated Subscribed QoS Modification for a PMIP-based S5/S8 is depicted in Figure 5.4.3.2-1.

Figure 5.4.3.2-1: HSS-initiated Subscribed QoS Modification

A.1. The Serving GW initiates the Gateway Control and QoS Policy Rules Request Procedure with the PCRF as specified in TS 23.203 [19]. The S‑GW provides the updated default EPS Bearer QoS for the default bearer to the PCRF and the PCRF responds with updated QoS rules. The PCRF makes a PCC decision as a result of the Gateway Control and QoS policy request and provides the updated QoS Rules to the Serving GW.

A.2. The PCRF initiates the PCC Rules Provision Procedure with the PDN GW as specified in TS 23.203 [19] to updates the rules in the PDN GW.

After Step A.1, the Serving GW follows the procedure shown in TS 23.401 [4], clause 5.4.2.1 by sending the Update Bearer Request message to the MME. The procedure is completed when the Serving GW receives a Update Bearer Response from the MME in Step 10 of TS 23.401 [4] clause 5.4.2.1.

B.1. The Serving GW indicates to the PCRF whether the requested QoS Policy Rules Provision could be enforced or not and thus completing the GW Control and QoS Rules Provision procedure started in step A.1.

B.2. The PCRF executes the Policy and Charging Rules Provision Procedure as specified in TS 23.203 [19] to update the PCC rules in the PDN GW.

NOTE: Step B.2 may be performed in parallel with steps A.1‑B.1 if acknowledgement of resource allocation is not required at the PCRF to update PCC rules in PCEF. For details please refer to TS 23.203 [19].

5.4.4 Dedicated Bearer Modification without Bearer QoS Update

When the QoS Policy rules provided by the PCRF to the Serving Gateway in step A.1 of figure 5.4.1-1 above results in the Serving Gateway to decide to only update the set of TFTs corresponding to an already existing dedicated bearer, this procedure is applied.

NOTE: If neither the contents of the TFT nor the APN-AMBR are modified, this procedure does not apply.

The procedure depicted in Figure 5.4.1-1 applies to this case as well. On receiving message A.1, the Serving GW uses this QoS policy to determine that traffic flow(s) shall be aggregated to or removed from an active dedicated bearer. The Serving GW generates the TFT and determines that no update of the EPS Bearer QoS is needed. The Serving GW then follows the procedure shown in TS 23.401 [4], clause 5.4.3 by sending the Update Bearer Request (TFT) message to the MME.

The message descriptions for A.1, B.1 and B.2 in clause 5.4.1 apply to this procedure as well. The steps between A.1 and B.1 are described in TS 23.401 [4], clause 5.4.3.

5.4.5 Dedicated Bearer Deactivation

5.4.5.1 PCC-initiated Dedicated Bearer Deactivation

When the QoS Policy rules provided by the PCRF to the Serving Gateway in step A.1 of figure 5.4.1-1 above results in the Serving Gateway to decide to deactivate an existing dedicated bearer, this procedure is applied.

The procedure depicted in Figure 5.4.1-1 applies to this case as well. On receiving message A.1, the Serving GW uses this QoS policy to determine that a dedicated bearer needs to be deactivated, the Serving GW follows the procedure shown in TS 23.401 [4], clause 5.4.4 by sending the Delete Bearer Request message to the MME. If the S‑GW determines that the default bearer needs to be deactivated, the S‑GW follows the procedure specified in clause 5.6.2.1.

The message descriptions for A.1, B.1 and B.2 in clause 5.4.1 apply to this procedure as well. The steps between A.1 and B.1 are described in TS 23.401 [4], clause 5.4.4.1.

5.4.5.2 Void

5.4.5.3 MME-initiated Dedicated Bearer Deactivation

This clause contains the procedure steps that vary between the GTP and PMIP variant of S5 and S8 for the procedure defined in TS 23.401 [4], clause 5.4.4.2 for -MME initiated dedicated bearer deactivation.

Figure 5.4.5.3-1: MME-initiated Dedicated Bearer Deactivation

This procedure applies to the Non-Roaming (Figure 4.2.1-1), Roaming (Figure 4.2.1-2) and Local Breakout (Figure 4.2.3-4) cases. For the Roaming and Local Breakout cases, the vPCRF forwards messages between the Serving GW and the hPCRF. In the Local Breakout case, the vPCRF forwards messages between the PDN GW and the hPCRF.

The optional interaction steps between the gateways and the PCRF in the procedures in Figure 5.4.5.3-1 only occur if dynamic policy provisioning is deployed. Otherwise policy may be statically configured with the gateway.

Before Step A.1, the procedure shown in TS 23.401 [4], clause 5.4.4.2 is followed and the Serving GW receives a Delete Bearer Command message from the MME.

A.1) The Serving GW decides to deactivate the bearers and initiates the Gateway Control and QoS Policy Rules Request Procedure with the PCRF as specified in TS 23.203 [19]. The Serving GW informs the PCRF about the deleted QoS Rules and indicates User Location Information and/or UE Time Zone Information to the PCRF as an Event Report if the corresponding event trigger is set.

A.2) The PCRF initiates the PCC Rules Provision Procedure with the PDN GW as specified in TS 23.203 [19] to updates the rules in the PDN GW. The PCC rules provide the PDN GW with information required to enforce the remaining dedicated resource allocation policy, after removing PCC rules corresponding to the QoS rules deactivated by step A.1.

After step A.1, the Serving GW follows the procedure shown in TS 23.401 [4], clause 5.4.4.2 by sending the Delete Bearer Request message to the MME. The Serving GW does not need to wait for step A.1 to complete to proceed with the deactivation of bearers with the MME. The procedure is completed when the Serving GW receives a Delete Bearer Response from the MME in Step 8 of TS 23.401 [4], clause 5.4.4.2.