6.2.5.1.1 QoS rules

6.2.5.1.1.1 General

In a PDU session of IPv4, IPv6, IPv4v6 and Ethernet PDU session type, the NAS protocol enables different forwarding treatments of UL user data packets in one or more QoS flows based on signalled QoS rules, derived QoS rules or any combination of them.

In a PDU session of Unstructured PDU session type, all UL user data packets are associated with the same QoS flow.

6.2.5.1.1.2 Signalled QoS rules

The NAS protocol enables the network to provide the UE with signalled QoS rules associated with a PDU session.

The network can provide the UE with one or more signalled QoS rules associated with a PDU session at the PDU session establishment or at the PDU session modification.

Each signalled QoS rule contains:

• an indication of whether the QoS rule is the default QoS rule;
• a QoS rule identifier (QRI);
• a QoS flow identifier (QFI);
• optionally, a set of packet filters; and
• a precedence value.

NOTE 1: The default QoS rule indication (DQR) of a signalled QoS rule cannot be changed.

For case d) above:

• If the QoS rule is the default QoS rule of a PDU session of IPv4, IPv6, IPv4v6 or Ethernet PDU session type, the set of packet filters contains zero or more packet filters for DL direction, and may additionaly contain one of the following:

A) a match-all packet filter for UL direction;

B) a match-all packet filter for UL and DL directions;

C) zero or more packet filters for UL direction (other than the match-all packet filter for UL direction);

D) zero or more packet filters for UL and DL directions (other than the match-all packet filter for UL and DL directions); or

E) one or more packet filters for UL direction (other than the match-all packet filter for UL direction) and one or more packet filters for UL and DL directions (other than the match-all packet filter for UL and DL directions).

The set of packet filters for the default QoS rule shall not be empty. If the default QoS rule contains a match-all packet filter, then the highest precedence value shall be used for the default QoS rule.

NOTE 1a: Set of packet filters for the default QoS rule can contain only packet filters for DL direction e.g. for determination that local preconditions are met in an IMS session (see 3GPP TS 24.229 [14]) with a receive only media.

• If the QoS rule is a QoS rule of a PDU session of IPv4, IPv6, IPv4v6 or Ethernet PDU session type and is not the default QoS rule, the set of packet filters contains zero or more packet filters for the DL direction, and may additionally contain one of the following:

A) zero or more packet filters for UL direction (other than the match-all packet filter for UL direction); and

B) zero or more packet filters for both UL and DL directions (other than the match-all packet filter for UL and DL directions).

The set of packet filters for a QoS rule which is not the default QoS rule shall not be empty.

NOTE 1b: Set of packet filters for a QoS rule which is not the default QoS rule can contain only packet filters for DL direction e.g. for determination that local preconditions are met in an IMS session (see 3GPP TS 24.229 [14]) with a receive only media.

• For PDU session of unstructured PDU session type, there is only one QoS rule associated with it and the set of packet filters of that QoS rule is empty.

If the UE requests a new QoS rule, it shall assign a precedence value for the signalled QoS rule which is not in the range from 70 to 99 (decimal).

NOTE 2: In this release of the specification, there is no support for a match-all packet filter for DL direction.

NOTE 3: In order to support QoS differentiation in case of access to PLMN services via an SNPN, the UE, within the SNPN, can construct packet filters based on the destination IP address to reach the N3IWF in the PLMN and the security parameters index (SPI) for the IPsec SA.

NOTE 4: In order to support QoS differentiation in case of access to SNPN services via a PLMN, the UE, within the PLMN, can construct packet filters based on the destination IP address to reach the N3IWF in the SNPN and the security parameters index (SPI) for the IPsec SA.

NOTE 5: The above described condition of assigning a precedence value for the signalled QoS rule is applied to the UE when the UE requests a QoS rule for network to bind service data flows described by the QoS rule to a dedicated QoS flow by setting the segregation bit to 1.

In NB-N1 mode, there is only one QoS rule associated with a PDU session and that is the default QoS rule. As described in 3GPP TS 23.501 [8], when the SMF determines that the UE has:

• moved from a tracking area in WB-N1 mode into a tracking area in NB-N1 mode;
• moved from a tracking area in WB-S1 mode into a tracking area in NB-N1 mode; or
• moved from a tracking area in NR connected to 5GCN into a tracking area in NB-N1 mode;

the SMF shall, for each PDU session that is kept active, initiate the PDU session modification procedure (see clause 6.3.2.2) to delete every QoS rule that is not the default QoS rule, if any.

Within a PDU session:

• each signalled QoS rule has a unique QRI;
• there is at least one signalled QoS rule;
• one signalled QoS rule is the default QoS rule; and
• there can be zero, one or more signalled QoS rules associated with a given QFI.

6.2.5.1.1.3 Derived QoS rules

Derived QoS rules are applicable only for PDU session of IPv4, IPv6, IPv4v6 or Ethernet PDU session type.

The reflective QoS in the UE creates derived QoS rules associated with a PDU session based on DL user data packets received via the PDU session.

Each derived QoS rule contains:

• a QoS flow identifier (QFI);
• a packet filter for UL direction; and
• a precedence value of 80 (decimal).

NOTE: On the network side, the corresponding PCC rule can be associated with a different precedence value in the range from 70 to 99 (decimal).

Within a PDU session:

• there can be zero, one or more derived QoS rules associated with a given QFI; and
• there can be up to one derived QoS rule associated with a given packet filter for UL direction.

In the UE, a timer T3583 runs for each derived QoS rule.

Reflective QoS is not supported in NB-N1 mode. Reflective QoS is not applicable for a PDU session with control plane only indication.

6.2.5.1.1.4 QoS flow descriptions

The network can also provide the UE with one or more QoS flow descriptions associated with a PDU session at the PDU session establishment or at the PDU session modification.

Each QoS flow description contains:

• a QoS flow identifier (QFI);
• if the flow is a GBR QoS flow:
• Guaranteed flow bit rate (GFBR) for UL;
• Guaranteed flow bit rate (GFBR) for DL;
• Maximum flow bit rate (MFBR) for UL;
• Maximum flow bit rate (MFBR) for DL; and
• optionally averaging window, applicable for both UL and DL;
• 5QI, if the QFI is not the same as the 5QI of the QoS flow identified by the QFI; and
• optionally, an EPS bearer identity (EBI) if the QoS flow can be mapped to an EPS bearer as specified in clause 4.11.1 of 3GPP TS 23.502 [9].

If the averaging window is not included in a QoS flow description for a GBR QoS flow with a 5QI indicated in 3GPP TS 23.501 [8] table 5.7.4-1, the averaging window associated with the 5QI in 3GPP TS 23.501 [8] table 5.7.4-1 applies for the averaging window.

If the averaging window is not included in a QoS flow description for a GBR QoS flow with a 5QI not indicated in 3GPP TS 23.501 [8] table 5.7.4-1, the standardized value of two seconds is used as the averaging window.