Content for  TS 23.402  Word version:  18.3.0

The ANDSF contains data management and control functionality necessary to provide network discovery and selection assistance data as per operators' policy. The ANDSF shall respond to UE requests for access network discovery information (pull mode operation) and may be able to initiate data transfer to the UE (push mode operation), based on network triggers or as a result of previous communication with the UE. The ANDSF shall comply with regulatory requirements pertaining to the privacy and confidentiality of user location information. Subject to operator's configuration, the ANDSF may obtain the permanent UE identity, e.g. based on the security solution specified in TS 33.402. The H-ANDSF in the subscriber's home operator network may interact with other databases such as the HSS user profile information residing in subscriber's home operator network. Details of such interaction with these databases are not described in this Release of the specifications. The ANDSF shall be able to provide various types of information, e.g. inter-system mobility policy, network access discovery information, etc. These types of information are specified in the following clauses. The ANDSF may provide to UE all types of information or only one of them. The H-ANDSF selects the types of information to be delivered to the UE according to the operator requirements and the roaming agreements. If the permanent UE identity is known to the H-ANDSF, and subject to operator's configuration, the available subscription data (e.g. the list of access networks, or access technology types, the UE is authorized to use, etc.) may also be used by the H-ANDSF for selecting the inter-system mobility policies, the access network discovery information, the inter-system routing policies and the inter-APN routing policies. The V-ANDSF selects the types of information to be delivered to the UE according to the operator requirements and the roaming agreements. However, the V-ANDSF shall not deliver IARP policy (see clause 4.8.2.1.5) to a roaming UE. The ANDSF shall be able to limit the amount of information provided to the UE based e.g. on the UE's current location, UE capabilities, etc. The ANDSF shall be able to limit the load caused by the UE initiated requests towards the ANDSF. The information provided by ANDSF may also be pre-configured by the home operator on the ME or provisioned on the UICC. The UE shall use the ANDSF information in the following order:

1. ANDSF information provided by the ANSDF server to the ME;
2. ANDSF information configured on the UICC;
3. ANDSF information pre-configured on the ME.

The visited operator cannot pre-configure ANDSF information in the UE.

The Inter-System Mobility Policy (ISMP) is a set of operator-defined rules that affect the inter-system mobility decisions taken by the UE. The UE uses the inter-system mobility policy when it can route IP traffic only over a single radio access interface at a given time (e.g. is neither IFOM nor MAPCON capable or its IFOM and MAPCON capabilities are disabled) in order to select the most preferable access technology type or access network that should be used to connect to EPC. The inter-system mobility policy may be provisioned in the UE and may be updated by the ANDSF based on network triggers or after receiving a UE request for network discovery and selection information. Each ISMP rule includes the following information:

• Validity conditions, i.e. conditions indicating when the rule is valid (such conditions may include e.g. a time duration, a location area, etc.).
• A prioritized list of access technologies or access network that indicate the order in which they are preferred or restricted for EPC connectivity.
• A rule priority that indicates the priority of this rule with respect to other ISMP rules provided by the same PLMN.

For example, an ISMP rule may indicate that 3GPP access is preferable to WLAN access for EPC connectivity. When this rule is applied, inter-system handover from 3GPP access to WLAN access is not allowed. The rule may also indicate e.g. that WiMAX access is more preferable to WLAN access. The home operator may provide ISMP rules to UE via the H-ANDSF or may pre-configure the UE with ISMP rules. The ISMP rules provided to UE via the H-ANDSF shall take precedence over the pre-configured ISMP rules in the UE.

Upon UE request, the ANDSF may provide a list of access networks available in the vicinity of the UE for all the access technology types requested by the UE (if any requested). The ANDSF provides information for access networks that are available to the UE including:

• the access technology type (e.g. WLAN, WiMAX).
• the radio access network identifier (e.g. the SSID of a WLAN).
• other technology specific information, e.g. one or more carrier frequencies.
• validity conditions, i.e. conditions indicating when the provided access network discovery information is valid (such conditions may include e.g. a location).

The UE may retain and use the access network discovery information provided by the ANDSF until new/updated information is retrieved.

The Inter-System Routing Policy (ISRP) is a set of operator-defined rules that determine how the UE should route IP traffic across multiple radio access interfaces. The ANDSF may provide a list of ISRP rules to the UE independently of the UE capability to route IP traffic simultaneously over multiple radio access interfaces. The UE uses the ISRP rules when it can route IP traffic simultaneously over multiple radio access interfaces (e.g. it is an IFOM capable UE with the IFOM capability enabled or a MAPCON capable UE with the MAPCON capability enabled) in order to meet the operator routing / offload preferences by:

(i) deciding when an access technology type / access network is restricted for a specific IP traffic flow and/or a specific APN; and
(ii) selecting the most preferable access technologies / access networks which should be used by the UE when available to route IP traffic that matches specific criteria (e.g. all traffic to a specific APN, or all traffic belonging to a specific IP flow, or all traffic of a specific application, etc).

The inter-system routing policy may be provisioned in the UE and may be updated by the ANDSF based on network triggers or after receiving a UE request for network discovery and selection information. Each ISRP rule includes the following information:

• Rules for IFOM: Each one of these rules identifies a prioritised list of access technologies / access networks which should be used by the UE when available to route traffic that matches specific IP traffic filters on a specific APN or on any APN. A rule for IFOM can also identify which radio accesses are restricted for traffic that matches specific IP traffic filters on aspecific APN (e.g. WLAN is not allowed for RTP/RTCP traffic flows on APN-x) or on any APN;
  • Each rule for IFOM contains one or more IP traffic filters (to match specific IP traffic), a prioritised list of access technologies / access networks, a rule priority and, optionally, validity conditions that indicate when the rule is valid. Each IP traffic filter may identify traffic based on destination address, transport protocol, destination/source port numbers, DSCP or Traffic Class, destination domain name and application identity.
• Rules for MAPCON: Each one of these rules identifies a prioritised list of access technologies / access networks which should be used by the UE when available to route PDN connections to specific APNs. A rule for MAPCON can also identify which radio accesses are restricted for PDN connections to specific APNs (e.g. WLAN is not allowed for PDN connection to APN-x);
  • Each rule for MAPCON contains an APN value, a prioritised list of access technologies / access networks, a rule priority and, optionally, validity conditions that indicate when the rule is valid. When no APN value is contained, the rule applies to any APN.
• Rules for Non-seamless WLAN Offload (NSWO) specified in clause 4.1.5: Each one of these rules identifies which traffic shall or shall not be non-seamlessly offloaded to a WLAN when available. It shall be possible to restrict certain traffic from using non-seamless WLAN offload only in specific WLAN access networks or in all WLAN access networks. Similarly, it shall be possible to permit certain traffic to use non-seamless WLAN offload only in specific WLAN access networks or in all WLAN access networks.
  • Each rule for NSWO contains one or more IP traffic filters (to match specific IP traffic), a rule priority and, optionally, validity conditions that indicate when the rule is valid. Each IP traffic filter may identify traffic based on destination address, transport protocol, destination/source port numbers, DSCP or Traffic Class, destination domain name and application identity.

The prioritised list of access technologies included in the rules for IFOM and MAPCON may contain 3GPP access, WLAN access as well as specific 3GPP RATs such as GERAN, UTRAN and E-UTRAN. The order of the access technologies in this list allows the operator to prioritize specific 3GPP RATs with respect to WLAN access. The UE shall use the prioritised list of access technologies in these rules only for IP routing and PDN connection establishment. The UE shall not use this prioritised list for 3GPP RAT selection. If more than one valid rule for IFOM and non-seamless WLAN offload match a specific IP traffic flow, the UE applies the rule with the highest rule priority. The home operator may provide ISRP rules to UE via the H-ANDSF or may pre-configure the UE with ISRP rules. The ISRP rules provided to UE via the H-ANDSF shall take precedence over the pre-configured ISRP rules in the UE.

The Inter-APN Routing Policy (IARP) is a set of operator-defined rules that determine which traffic should be routed across different PDN connections and which traffic should be non-seamlessly offloaded to WLAN (as defined in clause 4.1.5). These rules can be provisioned by the H-ANDSF only. If the UE receives IARP rules from the V-ANDSF, the UE shall ignore them. An Inter-APN routing capable UE selects an existing IP interface to route IP flows based on the received / provisioned IARP rules and user preferences. This IP interface is either associated with a specific APN or is used for non-seamless WLAN offload (NSWO). Each IARP rule includes the following information:

• Rules for APN: Each one of these rules identifies a prioritised list of APNs which should be used by the UE to route traffic that matches specified IP traffic filters. A rule for APN can also identify which APNs are restricted for traffic that matches specified IP traffic filters.
  • Each rule for APN contains one or more IP traffic filters (to match specific IP traffic), a prioritized list of APNs, a rule priority and, optionally, validity conditions that indicate when the rule is valid. Each IP traffic filter may identify traffic based on destination address, transport protocol, destination/source port numbers, DSCP or Traffic Class, destination domain name and application identity. The rule priority indicates the priority of the rule for APN with respect to other rules inside the same IARP rule.
• Rules for NSWO: Each one of these rules identifies which traffic shall or shall not be non-seamlessly offloaded to a WLAN when available. It shall be possible to restrict certain traffic from using non-seamless WLAN offload only in specific WLAN access networks or in all WLAN access networks. Similarly, it shall be possible to permit certain traffic to use non-seamless WLAN offload only in specific WLAN access networks or in all WLAN access networks.
  • Each rule for NSWO contains one or more IP traffic filters (to match specific IP traffic), a rule priority and, optionally, validity conditions that indicate when the rule is valid. Each IP traffic filter may identify traffic based on destination address, transport protocol, destination/source port numbers, DSCP or Traffic Class, destination domain name and application identity. The rule priority indicates the priority of the rule for NSWO with respect to other rules inside the same IARP rule.

An IARP for APN rule can be applied only when it steers IP traffic to an existing (i.e. already established) PDN connection. When no APN in the IARP for APN rule is associated with an existing PDN connection, then the rule shall not be applied. When the UE has simultaneously an active IARP rule and an active ISRP rule, the UE evaluates first the rules for APN and for NSWO inside the active IARP rule (in priority order) to determine how to route an IP flow.

• If the IP flow matches a rule for NSWO inside the active IARP rule, then the IP flow is routed to an IP interface used for NSWO and the rules inside the active ISRP rule are not evaluated.
• If the IP flow matches a rule for APN inside the active IARP rule that prefers a certain APN, then the IP flow is routed to the IP interface corresponding to this APN. If IFOM procedures are applied on this IP interface, then the rules for IFOM inside the active ISRP rule are also evaluated and used to further route the flow. The rules for NSWO inside the active ISRP rule are not evaluated (thus the IP flow is not offloaded to WLAN if it also matches a rule for NSWO inside the active ISRP rule).
• If the IP flow matches a rule for APN inside the active IARP rule that forbids one or more APNs, then the UE evaluates the rules inside the active ISRP rule (in priority order) to determine how to route the IP flow. If the IP flow matches a rule for NSWO inside the active ISRP rule that forbids the use of the selected WLAN (or any WLAN) for routing the IP flow, then the UE may select, in an implementation dependent way, a non-forbidden APN to route the IP flow.
• If the IP flow does not match any rule inside the active IARP rule, then the UE evaluates the rules inside the active ISRP rule (in priority order) to determine how to route the IP flow.

The above order of rule evalution applies to both non-roaming and roaming scenarios and independently of whether the active IARP rule and the active ISRP rule are provided by the same or by different PLMNs. The home operator may provide IARP rules to UE via the H-ANDSF or may pre-configure the UE with IARP rules. The IARP rules provided to UE via the H-ANDSF shall take precedence over the pre-configured IARP rules in the UE.

The WLAN Selection Policy (WLANSP) is a set of operator-defined rules that determine how the UE selects and reselects a WLAN access network. When not operating in SNPN access mode (as defined in TS 23.501) the UE may be provisioned with WLANSP rules from multiple PLMNs. The UE operating in SNPN access mode may be provisioned with WLANSP rules from the subscribed SNPN, Credential Holder or registered SNPN (as defined in TS 23.501). Each WLANSP rule includes the following information:

• Validity conditions, i.e. conditions indicating when the provided rule is valid. The validity conditions can include the time of day, geolocation, network location (e.g. PLMN, Location Area), etc.
• One or more groups of WLAN selection criteria in priority order. Each group contains one or more criteria that should be fulfilled by a WLAN access network in order to be eligible for selection. Such criteria are based on the following and only the following WLAN attributes:
  1. Attributes defined in the HS2.0 Rel-2 specification [75]:
     • PreferredRoamingPartnerList,
     • MinimumBackhaulThreshold,
     • MaximumBSSLoad,
     • RequiredProtoPortTuple.
     • A list of SSIDs as defined in the SPExclusionList.
  2. Additional attributes:
     • PreferredSSIDList: A prioritized list of SSIDs preferred for selection.
     • HomeNetwork: When the HomeNetwork is set in a group of selection criteria, it indicates that the group of selection criteria applies only to WLAN access networks that directly interwork with the home operator. When the HomeNetwork is not set or is not present in a group of seletion criteria, it indicates that the group of selection criteria applies to all WLAN access networks. The UE determines which WLAN access networks directly interwork with the home operator as follows:
       • for UE not operating in SNPN access mode by discovering which WLAN access networks advertise the HPLMN identity or the home network realm or a service provider realm equivalent to the HPLMN. The home network realm is derived by the UE from IMSI as specified in TS 23.003 (e.g. wlan.mnc015.mcc234.3gppnetwork.org).
       • for UE operating in SNPN access mode by discovering which WLAN access networks advertise the SNPN identity of the subscribed SNPN or the home network domain of the SNPN as defined in clause 28.2 of TS 23.003.

For example, a WLANSP rule may include the following groups of selection criteria:

• Group of selection criteria with priority 1:
  • PreferredRoamingPartnerList = Priority 1: partner1.com, Priority 2: partner2.com
  • MaximumBSSLoad = 60
• Group of selection criteria with priority 2:
  • PreferredSSIDList = Priority 1: myoperator1, Priority 2: myoperator2
  • MinimumBackhaulThreshold = 2Mbps in the downlink

A WLAN access network meets a group of selection criteria when it concurrently fulfills all the criteria in the group. The home operator may provide WLANSP rules to UE via the H-ANDSF or may pre-configure the UE with WLANSP rules. The WLANSP rules provided to UE via the H-ANDSF shall take precedence over the pre-configured WLANSP rules in the UE.

The "VPLMNs with preferred WLAN Selection" Rules is a list of PLMNs that is used by the UE when roaming. When the UE is roaming to one of the PLMNs in the list, the UE is configured to prefer the WLANSP rules provided by this PLMN over the WLANSP rules provided by the HPLMN. When the UE is roaming to any other PLMN, the UE is configured to prefer the WLANSP rules provided by the HPLMN. How the UE uses this list of PLMNs for WLAN selection is specified in more detail in clause 4.8.2a.1. The home operator may provide "VPLMNs with preferred WLAN Selection" rules to UE via the H-ANDSF or may pre-configure the UE with "VPLMNs with preferred WLAN Selection" rules. The "VPLMNs with preferred WLAN Selection" rules provided to UE via the H-ANDSF shall take precedence over the pre-configured "VPLMNs with preferred WLAN Selection" rules in the UE.

The Home Network Preferences may be provided by the UE's home operator and include information that assists the UE to select a WLAN access network and to select a PLMN for 3GPP-based authentication over WLAN. The Home Network Preferences may be provided by the HPLMN or an equivalent HPLMN or may be statically provisioned in the UE. The UE shall ignore the Home Network Preferences if provided by any other PLMN. The Home Network Preferences may contain the following information:

• Equivalent Home Service Providers (EHSP): Contains a list of service providers which are equivalent to the UE's HPLMN. Each service provider in EHSP is identified with a domain name, which may contain a PLMN identity (e.g. wlan.mncXYZ.mccABC.3gppnetwork.org) or may not contain a PLMN identity (e.g. example.com). The EHSP is used by the UE for PLMN selection over WLAN as specified in clause 4.8.2b.
• Preferred Service Provider List (PSPL): Contains a prioritized list of service providers which are preferred for WLAN roaming. Each service provider in PSPL is identified with a domain name, which may contain a PLMN identity (e.g. wlan.mncXYZ.mccABC.3gppnetwork.org) or may not contain a PLMN identity (e.g. example.com). The UE uses the PSPL for WLAN selection and PLMN selection as specified in clause 4.8.2b.
• "S2a connectivity preference": The "S2a connectivity preference" indicates if the home operator prefers the UE to establish PDN connections over WLAN by using the applicable S2a procedures specified in clause 16. It is used by the UE during the WLAN selection procedure as specified in clause 4.8.2b.
• "Prefer 3GPP RPLMN" indication: This indication specifies how a roaming UE selects a PLMN in order to perform 3GPP-based authentication over WLAN access. If the "prefer 3GPP RPLMN" indication is not set, the UE attempts to select the HPLMN, or a service provider included in EHSP, or a service provider included in PSPL for authentication over WLAN access. If the "prefer 3GPP RPLMN" indication is set, the UE attempts to select the Registered PLMN (RPLMN) or a service provider included in EVSP of the RPLMN (see clause 4.8.2.1.10) for authentication over WLAN access. Further details about the use of "prefer 3GPP RPLMN" indication are provided in clause 4.8.2b.

The home operator may provide Home Network Preferences to UE via the H-ANDSF or may pre-configure the UE with Home Network Preferences. The Home Network Preferences provided to UE via the H-ANDSF shall take precedence over the pre-configured Home Network Preferences in the UE.

The Visited Network Preferences may be provided by a PLMN-x, which is different from the UE's HPLMN and all equivalent HPLMNs. They include information that assists the UE (when roaming to PLMN-x) to select a PLMN for authentication over WLAN. The UE shall ignore the Visited Network Preferences if provided by HPLMN or any equivalent HPLMN. The Visited Network Preferences may contain the following information:

• Equivalent Visited Service Providers (EVSP): Contains a list of service providers which are considered equivalent to the PLMN which provided the EVSP. Each service provider in EVSP is identified with a domain name, which may contain a PLMN identity (e.g. wlan.mncXYZ.mccABC.3gppnetwork.org) or may not contain a PLMN identity (e.g. example.com). The EVSP is used by the UE for PLMN selection over WLAN as specified in clause 4.8.2b.