4.1 Service Description

29.5123GPP5G SystemRelease 18Session Management Policy Control ServiceStage 3TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

4.1.1 Overview

The Session Management Policy Control Service performs provisioning, update and removal of session related policies and PCC rules by the Policy Control Function (PCF) to the NF service consumer (e.g. SMF). The Session Management Policy Control Service can be used for charging control, policy control, application detection and control and/or access traffic steering, switching and splitting within a MA PDU Session. Session Management Policy Control Service applies to the cases where the SMF interacts with the PCF in the non-roaming scenario, the SMF interacts with the V-PCF in the local breakout roaming scenario and the H-SMF interacts with the H-PCF in the home-routed scenario.

4.1.2 Service Architecture

The Session Management Policy Control Service is provided by the PCF to the consumer and shown in the SBI representation model in figure 4.1.2-1 and in the reference point representation model in figure 4.1.2-2. The overall Policy and Charging Control related 5G architecture is depicted in 3GPP TS 29.513 [7].

The only known NF service consumer is the SMF.

Figure 4.1.2-1: Reference Architecture for the Npcf_SMPolicyControl Service; SBI representation

Figure 4.1.2-2: Reference Architecture for the Npcf_SMPolicyControl Service; reference point representation

NOTE: The PCF represents the V-PCF in the local breakout scenario. The SMF represents the H-SMF and the PCF represents the H-PCF in the home routed scenario.

4.1.3 Network Functions

4.1.3.1 Policy Control Function (PCF)

The PCF is responsible for policy control decisions and flow based charging control functionalities. The PCF provides the following:

– policies for application and service data flow detection, gating, QoS, flow based charging, traffic steering control, usage monitoring control, access traffic steering, switching and steering within a MA PDU Session, access network information report, UMIC, PMIC and TSCAI input container and RAN support information to the SMF.

The policy decisions made by the PCF may be based on one or more of the following:

– Information obtained from the AF, e.g. the session, media and subscriber related information;

– Information obtained from the UDR;

NOTE: For local breakout roaming, session management policy data for the UE as defined in 3GPP TS 29.519 [15] is not available in the VPLMN and V-PCF uses locally configured information according to the roaming agreement with the HPLMN operator. All interactions to the UDR in this document are subject to this restriction.

– Information obtained from the AMF, e.g. UE related and access related information;

– Information obtained from the SMF;

– Information obtained from the NWDAF;

– Information obtained from the NEF;

– Information from the CHF;

– Information from the TSCTSF or TSN AF; and

– PCF pre-configured policy context.

4.1.3.2 NF Service Consumers

The SMF is responsible for the enforcement of session management related policy decisions from the PCF, related to service flow detection, QoS, charging, gating, traffic usage reporting, traffic steering and access traffic steering, switching and splitting within a MA PDU Session.

The SMF shall support:

– sending the PDU session related attributes to the PCF;

– requesting and receiving the PCC rule(s) from the PCF;

– binding of service data flows to QoS flow as defined in 3GPP TS 29.513 [7];

– deriving rule(s) from the PCC rule(s) and then providing those rules to the user plane function or remove the rule(s) from the user plane as defined in 3GPP TS 29.244 [13];

– deriving the QoS rules towards the UE;

– deriving the QoS profile towards the access network;

– deriving the ATSSS rules towards the UE if applicable;

– transferring the DS-TT PMIC transparently towards/from the UE/DS-TT and transferring the NW-TT U/PMIC transparently towards/from the UPF/NW-TT, if applicable;

– adapting received TSCAI input information (TSC assistance container) to 5GS GM and transferring the TSCAI to the AN-RAN;

– handling the policy control request trigger; and

– handling the PDU session related policy information.

NOTE: SMF functionality related to event exposure is defined in 3GPP TS 29.508 [12].

4.1.4 Rules

4.1.4.1 General

A rule is a set of policy information elements associated with a PDU session, or with service data flows (i.e., with a PCC rule).

Two types of rules are defined:

– Session rule; and

– PCC rule.

Both Session rules and PCC rules are composed of embedded information elements as well as information elements that are part of the referenced objects (e.g. condition data, or usage monitoring policy data type) by the rule.

PCC rule is defined in clause 4.1.4.2. Session rule is defined in clause 4.1.4.3.

4.1.4.2 PCC rules

4.1.4.2.1 PCC rules definition

A PCC rule is a set of information elements enabling the detection of a service data flow and providing parameters for policy control and/or charging control. There are two different types of PCC rules as defined in 3GPP TS 23.503 [6]:

– Dynamic PCC rules: PCC rules that are dynamically provisioned by the PCF to the SMF. These PCC rules may be either predefined or dynamically generated in the PCF. Dynamic PCC rules can be installed, modified and removed at any time.

– Predefined PCC rules: PCC rules that are preconfigured in the SMF. Predefined PCC rules can be activated or deactivated by the PCF at any time. Predefined PCC rules within the PCF may be grouped allowing the PCF to dynamically activate a set of PCC rules.

Additionally, predefined PCC rules may be grouped within the SMF as predefined PCC rule bases which allow the PCF to dynamically activate these sets of rules. In this case, the PCC rule identifier is used to hold the predefined PCC rule base identifier.

NOTE 1: When the SMF interacts with the PCF for a PCC rule base, the PCF has no way of knowing which individual PCC rule of the PCC rule base caused the interaction. If such knowledge is required for specific PCC rules, then these PCC rules need to be implemented either as dynamic PCC rules or as predefined PCC rules that are not grouped in a PCC rule base. The SMF decision logic for interacting (or not) with the PCF about an event related to a PCC rule base is up to implementation and depends on the specific issue that triggered this interaction.

NOTE 2: The operator can define a predefined PCC rule, to be activated by the SMF. Such a predefined rule is not explicitly known in the PCF.

A PCC rule consists of:

Table 4.1.4.2.1-1: PCC rule information elements

Information name	Description	Category
Rule identifier	Uniquely identifies the PCC rule, within a PDU Session. It is used between PCF and SMF for referencing PCC rules.	Mandatory
	Service data flow detection
Precedence	Determines the order, in which the service data flow templates are applied at service data flow detection, enforcement and charging.	Mandatory
Service Data Flow Template	For IP PDU traffic: Either a list of service data flow filters or an application identifier that references the corresponding application detection filter for the detection of the service data flow. For Ethernet PDU traffic: Combination of traffic patterns of the Ethernet PDU traffic.	Mandatory
Mute for notification	Defines whether application’s start or stop notification is to be muted.	Optional
	Charging
Charging key	The charging system (CHF) uses the charging key to determine the tariff to apply to the service data flow.	Optional
Service identifier	The identity of the service or service component the service data flow in a rule relates to.	Optional
Sponsor Identifier	An identifier, provided from the AF, which identifies the Sponsor, used for sponsored flows to correlate measurements from different users for accounting purposes.	Optional
Application Service Provider Identifier	An identifier, provided from the AF, which identifies the Application Service Provider, used for sponsored flows to correlate measurements from different users for accounting purposes.	Optional
Charging method	Indicates the required charging method for the PCC rule. Values: online or offline or none.	Optional
Service Data flow handling while requesting credit	Indicates whether the service data flow is allowed to start while the SMF is waiting for the response to the credit request. Only applicable for charging method online.	Optional
Measurement method	Indicates whether the service data flow data volume, duration, combined volume/duration or event shall be measured. This is applicable to reporting, if the charging method is online or offline. Note: Event based charging is only applicable to predefined PCC rules and PCC rules used for application detection filter (i.e. with an application identifier).	Optional
Application Function Record Information	An identifier, provided from the AF, correlating the measurement for the Charging key/Service identifier values in this PCC rule with application level reports.	Optional
Service identifier level reporting	Indicates that separate usage reports shall be generated for this Service identifier. Values: mandated or not required.	Optional
	Policy control
5QI	Identifier of the authorized QoS parameters for the service data flow.	Mandatory
ARP	The Allocation and Retention Priority for the service data flow consisting of the priority level, the pre-emption capability and the pre-emption vulnerability.	Mandatory
Gate status	The gate status indicates whether the service data flow, detected by the service data flow template, may pass (Gate is open) or shall be discarded (Gate is closed).	Optional
QoS Notification Control (QNC)	Indicates whether notifications are requested from 3GPP NG-RAN when the GFBR can no longer (or again) be guaranteed for a QoS Flow during the lifetime of the QoS Flow.	Optional
Reflective QoS Control	Indicates to apply reflective QoS for the SDF.	Optional
MBR (UL/DL)	The uplink/downlink maximum bitrate authorized for the service data flow.	Optional
GBR (UL/DL)	The uplink/downlink guaranteed bitrate authorized for the service data flow.	Optional
UL sharing indication	Indicates resource sharing in uplink direction with service data flows having the same value in their PCC rule.	Optional
DL sharing indication	Indicates resource sharing in downlink direction with service data flows having the same value in their PCC rule.	Optional
Redirect	Redirect state of the service data flow (enabled/disabled).	Optional
Redirect Destination	Controlled Address to which the service data flow is redirected when redirect is enabled.	Optional
Bind to default QoS Flow	Indicates that the dynamic PCC rule shall always have its binding with the default QoS Flow.	Optional
Priority Level	Indicates a priority in scheduling resources among QoS Flows.	Optional
Averaging Window	Represents the duration over which the guaranteed and maximum bitrate shall be calculated.	Optional
Maximum Data Burst Volume	Denotes the largest amount of data that is required to be transferred within a period of 5G-AN PDB.	Optional
Disable UE notifications at changes related to Alternative QoS Profiles	Indicates to disable QoS flow parameters signalling to the UE when the SMF is notified by the NG-RAN of changes in the fulfilled QoS situation. The fulfilled situation is either the QoS profile or an Alternative QoS Profile.	Optional
Precedence for TFT packet filter allocation	Determines the order of TFT packet filter allocation for PCC rules	Optional
	Access Network Information Reporting
User Location Required	The UE location(s) (e.g. the serving cell of the UE) is to be reported. When the corresponding QoS flow is deactivated, and if available, information on when the UE was last known to be in that location is also to be reported.	Optional
UE Timezone Required	The time zone of the UE is to be reported.	Optional
	Usage Monitoring Control
Monitoring key	The PCF uses the monitoring key to group services that share a common allowed usage.	Optional
	N6-LAN Traffic Steering Enforcement Control
Traffic steering policy identifier(s)	Reference to a pre-configured traffic steering policy at the SMF.	Optional
	AF influenced Traffic Steering Enforcement Control
Data Network Access Identifier	Identifier of the target Data Network Access.	Optional
Per DNAI: Traffic steering policy identifier	Reference to a pre-configured traffic steering policy at the SMF.	Optional
Per DNAI: N6 traffic routing information	Describes the information necessary for traffic steering to the DNAI.	Optional
Information on AF subscription to UP path changes events	Indicates whether a notification in case of UP path change is requested, as well as the destination(s) for where to provide the notification.	Optional
Indication of UE IP address preservation	Indicates UE IP address should be preserved.	Optional
Indication of traffic correlation	Indicates that the target PDU Sessions should be correlated via a common DNAI in the user plane. (NOTE 5)	Optional
Information on User Plane Latency requirements	Indicates the user plane latency requirements.	Optional
EAS IP replacement information	Contains EAS IP replacement information (i.e. IP addresses and port numbers of source and target EAS).	Optional
Indication for simultaneous connectivity at edge relocation	Indicates request from the AF for temporary simultaneous connectivity over source and target PSA at edge relocation. It may provide AF guidance to determine when the connectivity over the source PSA can be removed.	Optional
Indication of EAS rediscovery.	Indicates the rediscovery of EAS.	Optional
	RAN support information
UL Maximum Packet Loss Rate	The maximum rate for lost packets that can be tolerated in the uplink direction for the service data flow.	Optional
DL Maximum Packet Loss Rate	The maximum rate for lost packets that can be tolerated in the downlink direction for the service data flow.	Optional
	MA PDU Session Control
Application descriptors	Identifies the application traffic for which MA PDU Session control is required based on the Steering functionality, the Steering mode, the Steering mode indicator and the Threshold values.	Optional
Steering Functionality	Indicates the applicable traffic steering functionality.	Optional
Steering mode (UL/DL)	Indicates the UL and/or DL traffic distribution rules between the 3GPP and Non-3GPP accesses together with associated parameters (when applicable) for the traffic matching the service data flow.	Optional
Steering mode indicator	Indicates either autonomous load-balance operation or UE-assistance operation, if the steering mode is set to "LOAD_BALANCING".	Optional
Threshold values	Indicates the threshold value(s) for maximum RTT and/or maximum Packet Loss Rate.	Optional
Charging for Non-3GPP access	Indicates parameters used for charging packets carried via Non-3GPP access for a MA PDU Session. The same set of parameters as for the Charging information above applies. If a parameter is not included here, the value provided in the Charging information above applies.	Optional
Usage Monitoring for Non-3GPP access	Indicates parameters used to monitor usage of the packets carried via Non-3GPP access for a MA PDU Session. The same set of parameters as for the Usage Monitoring information above applies. If a parameter is not included here, the value provided in the Usage Monitoring information above applies.	Optional
	IPTV (NOTE 1)
IP Multicast traffic control information	Indicates whether the service data flow, corresponding to the service data flow template, is allowed or not allowed.	Optional
	QoS Monitoring for URLLC
QoS parameter(s) to be measured	UL packet delay, DL packet delay or round trip packet delay.	Optional
Reporting frequency	Defines the frequency for the reporting, such as event triggered, periodic, or when the PDU Session is released.	Optional
Target of reporting	Defines the target of the QoS Monitoring reports, it can be either the PCF and/or the AF, decided by the PCF.	Optional
Indication of direct event notification	Indicates that the QoS Monitoring event shall be reported by the UPF directly to the AF or Local NEF indicated by the Target of reporting.	Optional
	Alternative QoS Parameter Sets (NOTE 2)
Packet Delay Budget	Indicates the packet delay budget in this Alternative QoS Parameter Set.	Optional
Packet Error Rate	Indicates the packet error rate in this Alternative QoS Parameter Set.	Optional
GBR (UL/DL)	The uplink/downlink guaranteed bitrate authorized for the service data flow in this Alternative QoS Parameter Set.	Optional
	TSCAI Input container
Burst Arrival Time	Indicates the burst arrival time in reference to TSN GM for TSN or external GM for non-TSN applications at ingress port.	Optional
Periodicity	The time period (in reference to TSN GM for TSN or external GM for non-TSN applications) between start of two bursts.	Optional
Flow Direction	Direction of the flow.	Optional
Survival Time	It refers to the time period an application can survive without any burst. It is expressed in reference to the TSN GM for TSN and external GM for non-TSN applications.	Optional
Time Domain	Indicate the (g)PTP domain the (TSN)AF is located in.	Optional
NOTE 1: Only applicable to the 5G-RG connecting to the 5GC via NG-RAN as defined in Annex C. NOTE 2: Only applicable for GBR service data flow with QoS Notification Control enabled. NOTE 3: The parameter "Bind to QoS Flow associated with the default QoS rule and apply PCC rule parameters" defined in table 6.3.1 of 3GPP TS 23.503 [6] is implemented as follows: a default QoS with a GBR type or delay critical GBR type 5QI and a PCC rule bound to the default QoS flow are provisioned as defined in clause 4.2.6.2.1. NOTE 4: The parameter "Indication of exclusion from session level monitoring" defined in table 6.3.1 of 3GPP TS 23.503 [6] is implemented as follows: a PCC rule identifier is included within the "exUsagePccRuleIds" attribute of the UsageMonitoringData instance of PDU session level usage monitoring to indicate that the service data flow shall be excluded from PDU Session usage monitoring as defined in clause 4.2.6.5.3. NOTE 5: The indication of traffic correlation shall be provided only when all the PDU sessions related to the 5G VN group member UEs should be correlated by a common DNAI in the user plane for the traffic as described in 3GPP TS 23.501 [2], clause 5.6.7.1 and clause 5.29.

The above information is organized into a set of decision data objects as defined in clause 4.1.4.4. The exact encoding of PCC rules is defined in clause 5.6.2.6.

4.1.4.2.2 PCC rules operation

For dynamic PCC rules, the following applies:

– Installation: to provision the PCC rules.

– Modification: to modify the PCC rules.

– Removal: to remove the PCC rules.

For predefined PCC rules, the following operations are available:

– Activation: to activate the PCC rules.

– Deactivation: to deactivate the PCC rules.

4.1.4.3 Session rule

4.1.4.3.1 Session rules definition

A session rule consists of policy information elements associated with PDU session. A session rule is dynamically provisioned by the PCF to the SMF (i.e., there are only dynamic session rules). The encoding of the SessionRule data type is defined in clause 5.6.2.7.

A session rule shall include:

– Session Rule Identifer.

A session rule may include:

– Authorized Session-AMBR;

– Authorized Default QoS;

– Reference to Usage Monitoring Data;

– Reference to Usage Monitoring Data for Non-3GPP access of MA PDU session; and

– Reference to Condition Data.

4.1.4.3.2 Session rules operation

For Session rules, the following applies:

– Installation: to provision the session rules.

– Modification: to modify the session rules.

– Removal: to remove the session rules.

4.1.4.4 Policy Decision types

4.1.4.4.1 General

A policy decision is a grouping of cohesive information elements describing a specific type of decision, e.g. QoS, Charging data, etc. A policy decision can be linked to one or more PCC rules or one or more Session rules. A PCC rule or session rule can at most refer to one instance of the policy decision for each type.

The following types of policy decision are defined:

– Traffic control data;

– QoS data;

– Charging data;

– Usage Monitoring data; and

– QoS Monitoring data.

4.1.4.4.2 Traffic control data definition

Traffic control data defines how traffic data flows associated with a rule are treated (e.g. blocked, redirected). The traffic control data encoding table is defined in clause 5.6.2.10.

Traffic control data shall include:

– Traffic Control Data ID.

Traffic control data may include:

– Flow status;

– Redirect Information;

– Mute Notification;

– Traffic Steering Policy ID UL;

– Traffic Steering Policy ID DL;

– Routing requirements;

– UP path change event subscription from the AF;

– Information on User Plane Latency requirements;

– EAS IP replacement information;

– Indication of traffic correlation;

– Indication of simultaneous connectivity temporarily maintained for source and target PSA during edge relocation and guidance about when the connectivity over the source PSA can be removed;

– Access Traffic Steering Functionality;

– Access Traffic Steering Mode DL;

– Access Traffic Steering Mode; and

– Optionally, Access Traffic Steering Mode Indicator or Access Traffic Steering Mode Threshold;

– Access Traffic Steering Mode UL; and

– Access Traffic Steering Mode; and

– Optionally, Access Traffic Steering Mode Indicator or Access Traffic Steering Mode Threshold;

– Multicast Access Control.

4.1.4.4.3 QoS data definition

QoS data defines QoS parameters (e.g. bitrates) associated with a rule. The QoS data encoding table is defined in clause 5.6.2.8.

QoS data shall include:

– QoS Data ID;

QoS data may include:

– 5QI;

– ARP;

– QNC;

– Maximum Packet Loss Rate UL;

– Maximum Packet Loss Rate DL;

– Maximum Bit Rate UL;

– Maximum Bit Rate DL;

– Guaranteed Bit Rate UL;

– Guaranteed Bit Rate DL;

– 5QI Priority Level;

– Averaging window;

– Maximum Data Burst Volume;

– Bound to default QoS flow indication;

– Resource Sharing Key UL;

– Resource Sharing Key DL;

– Reflective QoS attribute;

– Packet Delay Budget; and

– Packet Error Rate.

NOTE: Either 5QI and ARP combination or Bound to default QoS flow indication is provided.

4.1.4.4.4 Charging data definition

Charging data defines charging related parameters (e.g. rating group) associated with a rule. The charging data encoding table is defined in clause 5.6.2.11.

Charging data shall include:

– Charging Data ID;

– Rating Group.

Charging data may include:

– Metering Method;

– Charging Method;

– Service Data flow handling while requesting credit;

– Reporting Level;

– Service ID;

– Sponsor ID;

– Application Service Provider ID; and

– AF Charging ID.

4.1.4.4.5 UsageMonitoring data definition

UsageMonitoring data defines usage monitoring information associated with a rule. The UsageMonitoring data encoding table is defined in clause 5.6.2.12.

Usage Monitoring Data shall include:

– Usage Monitoring ID.

NOTE: A Usage Monitoring ID corresponds to a valid Monitoring Key.

Usage Monitoring Data may include:

– Volume Threshold;

– Volume Threshold UL;

– Volume Threshold DL;

– Time Threshold;

– Monitoring Time;

– Next Volume Threshold;

– Next Volume Threshold UL;

– Next Volume Threshold DL;

– Next Time Threshold;

– Inactivity Time; and

– PCC rule identifier(s) corresponding to the service data flow(s) which need to be excluded from PDU session level usage monitoring.

4.1.4.4.6 QoS Monitoring data definition

QoS Monitoring data defines QoS Monitoring related parameters (e.g. request QoS monitoring parameters to be measured) associated with a rule. The QoS Monitoring data encoding table is defined in clause 5.6.2.40.

QoS Monitoring data shall include:

– QoS Monitoring Data ID;

– requested QoS monitoring parameters to be measured;

– reporting frequency.

QoS monitoring data may include:

– reporting thresholds;

– wait time;

– reporting period;

– target of reporting; and

– indication of direct event notification.

4.1.5 Policy control request trigger

A policy control request trigger is a condition pre-configured in the SMF (i.e. always report) or provisioned by the PCF to the SMF, which defines when the SMF shall interact again with PCF for further policy decision related to a PDU session.

The policy control request trigger is designed as an Enumeration type defined in clause 5.6.3.6.

The PCF can provide an array of policy control request triggers in a policy decision to subscribe to the associated triggers in the SMF.

When the SMF interacts with the PCF when the condition(s) associated with policy control request triggers are met, the SMF shall send the related attributes that have changed together with the corresponding triggers.

4.1.6 Requested rule data

Requested rule data consists of requested information by the PCF associated with one or more PCC rules.

The requested rule data is designed as a subresource of the policy decision within an attribute called "lastReqRuleData". The PCF only records the last requested rule data.

When requesting rule data, the PCF shall include the types of data requested for the rules within the "reqData" array of the "lastReqRuleData" and shall also provide the corresponding policy control request triggers if the triggers are not yet set.

The encoding of the requested rule data is further specified in clause 5.6.2.24.

When the SMF receives the requested rule data, the SMF shall report the corresponding information to the PCF for the associated PCC rule(s).

4.1.7 Requested usage data

Requested Usage data consists of the requested accumulated usage reports by the PCF for one or more instances of Usage Monitoring data decision.

The requested usage data is designed as a sub resource of the policy decision within an attribute called "lastReqUsageData". The PCF only records the last requested usage data.

The encoding of the requested usage data is further specified in clause 5.6.2.25.

When the SMF receives the requested usage data attribute, the SMF shall report to the PCF the corresponding accumulated usage reports for the corresponding Usage Monitoring data decision(s). Requested usage data shall not be valid anymore for these Usage Monitoring data decision(s) after the reporting.

4.1.8 Condition data

Condition data defines the condition(s) where the PCC rules or session rules are applicable and/or not applicable. The condition data encoding is defined in clause 5.6.2.9.

Condition data shall include:

– Condition Data ID.

Condition data may include:

– Activation Time;

– Deactivation Time;

– Access Type; and

– RAT Type

NOTE: Access type and RAT type are only applicable to the session rule.