3GPP TS 23501-g51 中英文对照 | 4.2.8 Support of non-3GPP access

Posted 2021-09-07 COCOgsta

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4.2.8 Support of non-3GPP access

4.2.8.0 General

In this Release of the specification, the following types of non-3GPP access networks are defined:

- Untrusted non-3GPP access networks;

- Trusted non-3GPP access networks; and

- Wireline access networks.

The architecture to support Untrusted and Trusted non-3GPP access networks is defined in clause 4.2.8.2. The architecture to support Wireline access networks is defined in 4.2.8.2.4 and in TS 23.316 [84].

4.2.8.1 General Concepts to Support Trusted and Untrusted Non-3GPP Access

The 5G Core Network supports connectivity of UEs via non-3GPP access networks, e.g. WLAN access networks.

5G Core Network支持通过non-3GPP接入网络（例如WLAN接入网络）连接UE。

Only the support of non-3GPP access networks deployed outside the NG-RAN is described in this clause.

本条款仅描述了对部署在NG-RAN之外的non-3GPP接入网络的支持。

The 5G Core Network supports both untrusted non-3GPP access networks and trusted non-3GPP access networks (TNANs).

5G Core Network支持不受信任的non-3GPP接入网络和受信任的non-3GPP接入网络（TNAN）。

An untrusted non-3GPP access network shall be connected to the 5G Core Network via a Non-3GPP InterWorking Function (N3IWF), whereas a trusted non-3GPP access network shall be connected to the 5G Core Network via a Trusted Non-3GPP Gateway Function (TNGF). Both the N3IWF and the TNGF interface with the 5G Core Network CP and UP functions via the N2 and N3 interfaces, respectively.

不受信任的non-3GPP接入网络应通过non-3GPP InterWorking Function（N3IWF）连接到5G Core Network，而受信任的non-3GPP接入网络应通过Trusted non-3GPP Gateway Function（TNGF）连接到5G Core Network。N3IWF和TNGF分别通过N2和N3接口与5G Core Network的CP和UP功能进行接口。

A non-3GPP access network may advertise the PLMNs for which it supports trusted connectivity and the type of supported trusted connectivity (e.g. "5G connectivity"). Therefore, the UEs can discover the non-3GPP access networks that can provide trusted connectivity to one or more PLMNs. This is further specified in clause 6.3.12 (Trusted Non-3GPP Access Network selection).

Non-3GPP接入网络可以公布其支持可信连接的plmn和支持的可信连接的类型（例如“5G连接”）。因此，UE可以发现能够向一个或多个PLMN提供可信连接的非3GPP接入网络。

The UE decides to use trusted or untrusted non-3GPP access for connecting to a 5G PLMN by using procedures not specified in this document. Examples of such procedures are defined in clause 6.3.12.1.

UE决定通过使用本文档中未指定的过程来使用受信任或不受信任的non-3GPP接入来连接到5G PLMN。

When the UE decides to use untrusted non-3GPP access to connect to a 5G Core Network in a PLMN:

- the UE first selects and connects with a non-3GPP access network; and then

- the UE selects a PLMN and an N3IWF in this PLMN. The PLMN/N3IWF selection and the non-3GPP access network selection are independent. The N3IWF selection is defined in clause 6.3.6.

-UE在该PLMN中选择PLMN和N3IWF。PLMN/N3IWF选择和non-3GPP接入网络选择是独立的。

When the UE decides to use trusted non-3GPP access to connect to a 5G Core Network in a PLMN:

- the UE first selects a PLMN; and then

- the UE selects a non-3GPP access network (a TNAN) that supports trusted connectivity to the selected PLMN. In this case, the non-3GPP access network selection is affected by the PLMN selection.

-UE选择支持到所选PLMN的可信连接的non-3GPP接入网络（TNAN）。在这种情况下，non-3GPP接入网络选择受PLMN选择的影响。

A UE that accesses the 5G Core Network over a non-3GPP access shall, after UE registration, support NAS signalling with 5G Core Network control-plane functions using the N1 reference point.

通过non-3GPP接入访问5G Core Network的UE应在UE注册后，使用N1参考点支持具有5G Core Network control-plane功能的NAS信令。

When a UE is connected via a NG-RAN and via a non-3GPP access, multiple N1 instances shall exist for the UE i.e. there shall be one N1 instance over NG-RAN and one N1 instance over non-3GPP access.

当UE通过NG-RAN和non-3GPP接入连接时，UE应存在多个N1实例，即，NG-RAN上应有一个N1实例，non-3GPP接入上应有一个N1实例。

A UE simultaneously connected to the same 5G Core Network of a PLMN over a 3GPP access and a non-3GPP access shall be served by a single AMF in this 5G Core Network.

通过3GPP接入和non-3GPP接入同时连接到PLMN的相同5G Core Network的UE应由该5G Core Network中的单个AMF服务。

When a UE is connected to a 3GPP access of a PLMN, if the UE selects a N3IWF and the N3IWF is located in a PLMN different from the PLMN of the 3GPP access, e.g. in a different VPLMN or in the HPLMN, the UE is served separately by the two PLMNs. The UE is registered with two separate AMFs. PDU Sessions over the 3GPP access are served by V-SMFs different from the V-SMF serving the PDU Sessions over the non-3GPP access. The same can be true when the UE uses trusted non-3GPP access, i.e. the UE may select one PLMN for 3GPP access and a different PLMN for trusted non-3GPP access.

当UE连接到PLMN的3GPP接入时，如果UE选择N3IWF并且N3IWF位于与3GPP接入的PLMN不同的PLMN中，例如位于不同的VPLMN或HPLMN中，则UE由两个PLMN分别服务。UE向两个单独的AMF注册。通过3GPP接入的PDU Session由V-SMF服务，不同于通过non-3GPP接入服务PDU Session的V-SMF。当UE使用受信任的non-3GPP接入时，也可以是这样，即UE可以选择一个PLMN用于3GPP接入，而选择另一个PLMN用于受信任的non-3GPP接入。

The PLMN selection for the 3GPP access does not depend on the PLMN that is used for non-3GPP access. In other words, if a UE is registered with a PLMN over a non-3GPP access, the UE performs PLMN selection for the 3GPP access independently of this PLMN.

3GPP接入的PLMN选择不依赖于用于non-3GPP接入的PLMN。换句话说，如果UE通过非3GPP接入向PLMN注册，则UE独立于该PLMN执行3GPP接入的PLMN选择。

A UE shall establish an IPsec tunnel with the N3IWF or with the TNGF in order to register with the 5G Core Network over non-3GPP access. Further details about the UE registration to 5G Core Network over untrusted non-3GPP access and over trusted non-3GPP access are described in clause 4.12.2 and in clause 4.12.2a in TS 23.502 [3], respectively.

UE应与N3IWF或TNGF建立IPsec隧道，以便通过non-3GPP接入向5G Core Network注册。

It shall be possible to maintain the UE NAS signalling connection with the AMF over the non-3GPP access after all the PDU Sessions for the UE over that access have been released or handed over to 3GPP access.

在UE通过non-3GPP接入的所有PDU Session被释放或移交给3GPP接入后，应能够通过non-3GPP接入保持UE NAS与AMF的信令连接。

N1 NAS signalling over non-3GPP accesses shall be protected with the same security mechanism applied for N1 over a 3GPP access.

Non-3GPP接入上的N1 NAS信令应使用适用于N1 over a 3GPP接入的相同安全机制进行保护。

User plane QoS differentiation between UE and N3IWF is supported as described in clause 5.7 and TS 23.502 [3] clause 4.12.5. QoS differentiation between UE and TNGF is supported as described in clause 5.7 and TS 23.502 [3] clause 4.12a.5.

支持UE和N3IWF之间的用户平面QoS区分。支持UE和TNGF之间的QoS区分。

4.2.8.1A General Concepts to support Wireline Access

Wireline 5G Access Network (W-5GAN) shall be connected to the 5G Core Network via a Wireline Access Gateway Function (W-AGF). The W-AGF interfaces the 5G Core Network CP and UP functions via N2 and N3 interfaces, respectively.

Wireline 5G Access Network（W-5GAN）应通过Wireline Access Gateway Function（W-AGF）连接到5G Core Network。W-AGF分别通过N2和N3接口连接5G Core Network CP和UP功能。

For the scenario of 5G-RG connected via NG RAN the specification for UE defined in this TS, TS 23.502 [3] and TS 23.503 [45] are applicable as defined for UE connected to 5GC via NG RAN unless differently specified in this TS and in TS 23.316 [84].

When a 5G-RG is connected via a NG-RAN and via a W-5GAN, multiple N1 instances shall exist for the 5G-RG i.e. there shall be one N1 instance over NG-RAN and one N1 instance over W-5GAN.

当5G-RG通过NG-RAN和W-5GA连接时，5G-RG应存在多个N1实例，即NG-RAN上应有一个N1实例，W-5GA上应有一个N1实例。

A 5G-RG simultaneously connected to the same 5G Core Network of a PLMN over a 3GPP access and a W-5GAN access shall be served by a single AMF in this 5G Core Network.

通过3GPP接入和W-5GAN接入同时连接到PLMN的相同5G Core Network的5G-RG应由该5G Core Network中的单个AMF提供服务。

5G-RG shall maintain the NAS signalling connection with the AMF over the W-5GAN after all the PDU Sessions for the 5G-RG over that access have been released or handed over to 3GPP access.

5G-RG应在该接入的5G-RG的所有PDU Session被释放或移交给3GPP接入后，通过W-5GAN保持与AMF的NAS信令连接。

The 5G-RG connected to 5GC via NG-RAN is specified in TS 23.316 [84].

For the scenario of FN-RG, which is not 5G capable, connected via W-5GAN to 5GC, the W-AGF provides the N1 interface to AMF on behalf of the FN-RG.

对于不支持5G的FN-RG场景，通过W-5GAN连接到5GC，W-AGF代表FN-RG向AMF提供N1接口。

An UE connected to a 5G-RG or FN-RG can access to the 5GC via the N3IWF or via the TNGF where the combination of 5G-RG/FN-RG, W-AGF and UPF serving the 5G-RG or FN-RG is acting respectively as Untrusted Non-3GPP access network or as a Trusted Non-3GPP access network defined in clause 4.2.8.2; for example a UE is connecting to 5G-RG by means of WLAN radio access and connected to 5GC via N3IWF. The detailed description is specified in TS 23.316 [84].

连接到5G-RG或FN-RG的UE可以通过N3IWF或TNGF访问5GC，其中服务于5G-RG或FN-RG的5G-RG/FN-RG、W-AGF和UPF的组合分别充当Untrusted Non-3GPP接入网络或Trusted Non-3GPP接入网络；例如，UE通过WLAN无线接入连接到5G-RG，并通过N3IWF连接到5GC。

The roaming architecture for 5G-BRG, FN-BRG, 5G-CRG and FN-CRG with the W-5GAN is not specified in this Release. The Home Routed roaming scenario is supported for 5G-RG connected via NG RAN, while Local Breakout scenario is not supported.

本Release中未指定带W-5GAN的5G-BRG、FN-BRG、5G-CRG和FN-CRG的漫游架构。通过NG RAN连接的5G-RG支持Home Routed漫游方案，而不支持Local Breakout方案。

5G Multi-Operator Core Network (5G MOCN) is supported for 5G-RG connected via NG RAN as defined in clause 5.18

5G Multi-Operator Core Network（5G MOCN）支持通过NG RAN连接的5G-RG

4.2.8.2 Architecture Reference Model for Trusted and Untrusted Non-3GPP Accesses

4.2.8.2.1 Non-roaming Architecture

 

Figure 4.2.8.2.1-1: Non-roaming architecture for 5G Core Network with untrusted non-3GPP access

 

Figure 4.2.8.2.1-2: Non-roaming architecture for 5G Core Network with trusted non-3GPP access

NOTE 1: The reference architecture in Figure 4.2.8.2.1-1 and in Figure 4.2.8.2.1-2 only shows the architecture and the network functions directly connected to non-3GPP access, and other parts of the architecture are the same as defined in clause 4.2.

注1：图4.2.8.2.1-1和图4.2.8.2.1-2中的参考架构仅显示直接连接到non-3GPP接入的架构和网络功能，架构的其他部分与第4.2条中的定义相同。

NOTE 2: The reference architecture in Figure 4.2.8.2.1-1 and in Figure 4.2.8.2.1-2 supports service based interfaces for AMF, SMF and other NFs not represented in the figure.

注2：图4.2.8.2.1-1和图4.2.8.2.1-2中的参考体系结构支持AMF、SMF和图中未显示的其他NFs的基于服务的接口。

NOTE 3: The two N2 instances in Figure 4.2.8.2.1-1 and in Figure 4.2.8.2.1-2 terminate to a single AMF for a UE which is simultaneously connected to the same 5G Core Network over 3GPP access and non-3GPP access.

注3：图4.2.8.2.1-1和图4.2.8.2.1-2中的两个N2实例终结于一个UE的单个AMF，该UE同时通过3GPP接入和non-3GPP接入相同的5G Core Network

NOTE 4 The two N3 instances in Figure 4.2.8.2.1-1 and in Figure 4.2.8.2.1-2 may terminate to different UPFs when different PDU Sessions are established over 3GPP access and non-3GPP access.

注4：当通过3GPP接入和non-3GPP接入建立不同的PDU Session时，图4.2.8.2.1-1和图4.2.8.1-2中的两个N3实例可能会终止到不同的UPF。

4.2.8.2.2 LBO Roaming Architecture

 

Figure 4.2.8.2.2-1: LBO Roaming architecture for 5G Core Network with untrusted non-3GPP access - N3IWF in the same VPLMN as 3GPP access

 

Figure 4.2.8.2.2-2: LBO Roaming architecture for 5G Core Network with untrusted non-3GPP access - N3IWF in a different PLMN from 3GPP access

 

Figure 4.2.8.2.2-3: LBO Roaming architecture for 5G Core Network with trusted non-3GPP access using the same VPLMN as 3GPP access

 

Figure 4.2.8.2.2-4: LBO Roaming architecture for 5G Core Network with trusted non-3GPP access using a different PLMN than 3GPP access

NOTE 1: The reference architecture in all above figures only shows the architecture and the network functions directly connected to support non-3GPP access, and other parts of the architecture are the same as defined in clause 4.2.

注1：所有上图中的参考架构仅显示了直接连接以支持non-3GPP接入的架构和网络功能，架构的其他部分与第4.2条中的定义相同。

NOTE 2: The reference architecture in all above figures supports service based interfaces for AMF, SMF and other NFs not represented in the figures.

注2：上图中的参考体系结构支持AMF、SMF和图中未显示的其他NFs的基于服务的接口。

NOTE 3: The two N2 instances in Figure 4.2.8.2.2-1 and in Figure 4.2.8.2.2-3 terminate to a single AMF for a UE which is connected to the same 5G Core Network over 3GPP access and non-3GPP access simultaneously.

注3：图4.2.8.2.2-1和图4.2.8.2.2-3中的两个N2实例终结于一个UE的单个AMF，该UE同时通过3GPP接入和non-3GPP接入相同的5G Core Network

NOTE 4: The two N3 instances in Figure 4.2.8.2.2-1 and in Figure 4.2.8.2.2-3 may terminate to different UPFs when different PDU Sessions are established over 3GPP access and non-3GPP access.

注4：当通过3GPP接入和non-3GPP接入建立不同的PDU会话时，图4.2.8.2.2-1和图4.2.8.2.2-3中的两个N3实例可能会终止到不同的UPF。

4.2.8.2.3 Home-routed Roaming Architecture

 

Figure 4.2.8.2.3-1: Home-routed Roaming architecture for 5G Core Network with untrusted non-3GPP access - N3IWF in the same VPLMN as 3GPP access

 

Figure 4.2.8.2.3-2: Home-routed Roaming architecture for 5G Core Network with untrusted non-3GPP access - N3IWF in a different VPLMN than 3GPP access

 

Figure 4.2.8.2.3-3: Home-routed Roaming architecture for 5G Core Network with untrusted non-3GPP access - N3IWF in HPLMN

 

Figure 4.2.8.2.3-4: Home-routed Roaming architecture for 5G Core Network with trusted non-3GPP access using the same VPLMN as 3GPP access

NOTE 1: The reference architecture in all above figures only shows the architecture and the network functions directly connected to support non-3GPP access, and other parts of the architecture are the same as defined in clause 4.2.

注1：所有上图中的参考架构仅显示了直接连接以支持non-3GPP接入的架构和网络功能，架构的其他部分与第4.2条中的定义相同。

NOTE 2: The two N2 instances in Figure 4.2.8.2.3-1 and in Figure 4.2.8.2.3-4 terminate to a single AMF for a UE which is connected to the same 5G Core Network over 3GPP access and non-3GPP access simultaneously.

注2：图4.2.8.2.3-1和图4.2.8.2.3-4中的两个N2实例终结于一个UE的单个AMF，该UE同时通过3GPP接入和non-3GPP接入相同的5G Core Network。

4.2.8.3 Reference Points for Non-3GPP Access

4.2.8.3.1 Overview

The description of the reference points specific for the non-3GPP access:

N2, N3, N4, N6: these are defined in clause 4.2.

Y1 Reference point between the UE and the untrusted non-3GPP access (e.g. WLAN). This depends on the non-3GPP access technology and is outside the scope of 3GPP.

UE和不受信任的non-3GPP接入（例如WLAN）之间的参考点。这取决于non-3GPP接入技术，并且不在3GPP的范围内。

Y2 Reference point between the untrusted non-3GPP access and the N3IWF for the transport of NWu traffic.

不受信任的non-3GPP接入和N3IWF之间的参考点，用于传输NWu流量。

Y4 Reference point between the 5G-RG and the W-AGF which transports the user plane traffic and the N1 NAS protocol. The definition of this interface is outside the scope of 3GPP.

5G-RG和W-AGF之间的参考点，用于传输用户平面流量和N1 NAS协议。此接口的定义不在3GPP的范围内。

Y5 Reference point between the FN-RG and the W-AGF. The definition of this interface is outside the scope of 3GPP.

FN-RG和W-AGF之间的参考点。此接口的定义不在3GPP的范围内。

Yt Reference point between the UE and the TNAP. See e.g. Figure 4.2.8.2.1-2.

Yt' Reference point between the N5CW devices and the TWAP. It is defined in clause 4.2.8.5.

NWu Reference point between the UE and N3IWF for establishing secure tunnel(s) between the UE and N3IWF so that control-plane and user-plane exchanged between the UE and the 5G Core Network is transferred securely over untrusted non-3GPP access.

UE和N3IWF之间的参考点，用于在UE和N3IWF之间建立安全隧道，以便在UE和5G Core Network交换的control-plane和use-plane通过不受信任的non-3GPP接入安全地传输。

NWt Reference point between the UE and the TNGF. A secure NWt connection is established over this reference point, as specified in TS 23.502 [3], clause 4.12a.2.2. NAS messages between the UE and the AMF are transferred via this NWt connection.

UE和TNGF之间的参考点。在该参考点上建立安全NWt连接。UE和AMF之间的NAS消息通过此NWt连接传输。

Ta A reference point between the TNAP and the TNGF, which is used to support an AAA interface. Ta requirements are documented in clause 4.2.8.3.2.

TNAP和TNGF之间的参考点，用于支持AAA接口。

Tn A reference point between two TNGFs, which is used to facilitate UE mobility between different TNGFs (inter-TNGF mobility).

两个TNGF之间的参考点，用于促进不同TNGF之间的UE移动性（inter-TNGF移动性）。

Tn and inter-TNGF mobility are not specified in this Release of the specification.

4.2.8.3.2 Requirements on Ta

Ta shall be able to

- Carry EAP-5G traffic and user location information before the NWt connection is established between the UE and the TNGF.

-在UE和TNGF之间建立NWt连接之前，携带EAP-5G流量和用户位置信息。

- Allow the UE and the TNGF to exchange IP traffic.

In deployments where the TNAP does not allocate the local IP addresses to UE(s), Ta shall be able to:

在TNAP不向UE分配本地IP地址的部署中，Ta应能够：

- Allow the UE to request and receive IP configuration from the TNAN (including a local IP address), e.g. with DHCP. This is to allow the UE to use an IP stack to establish a NWt connection between the UE and the TNGF.

-允许UE从TNAN请求和接收IP配置（包括本地IP地址），例如使用DHCP。这是为了允许UE使用IP堆栈在UE和TNGF之间建立NWt连接。

NOTE: The "local IP address" is the IP address that allows the UE to contact the TNGF; the entity providing this local IP address is part of TNAN and out of 3GPP scope

注：“本地IP地址”是允许UE联系TNGF的IP地址；提供此本地IP地址的实体是TNAN的一部分，不在3GPP范围内

In this Release of the specification, Ta is not specified.

4.2.8.4 Architecture Reference Model for Wireline Access network

 

Figure 4.2.8.4-1: Non- roaming architecture for 5G Core Network for 5G-RG with Wireline 5G Access network and NG RAN

The 5G-RG can be connected to 5GC via W-5GAN, NG RAN or via both accesses.

NOTE 1: The reference architecture in figure 4.2.8.4-1 only shows the architecture and the network functions directly connected to Wireline 5G Access Network, and other parts of the architecture are the same as defined in clause 4.2.

注1：图4.2.8.4-1中的参考架构仅显示了直接连接到Wireline 5G Access Network的架构和网络功能，架构的其他部分与第4.2条中定义的相同。

NOTE 2: The reference architecture in figure 4.2.8.4-1 supports service based interfaces for AMF, SMF and other NFs not represented in the figure.

注2：图4.2.8.4-1中的参考体系结构支持AMF、SMF和图中未显示的其他NFs的基于服务的接口。

NOTE 3: The two N2 instances in Figure 4.2.8.4-1 apply to a single AMF for a 5G-RG which is simultaneously connected to the same 5G Core Network over 3GPP access and Wireline 5G Access Network.

注3：图4.2.8.4-1中的两个N2实例适用于5G-RG的单个AMF，该5G-RG通过3GPP接入和Wireline 5G Access Network同时连接到同一个5G Core Network。

NOTE 4 The two N3 instances in Figure 4.2.8. 4-1 may apply to different UPFs when different PDU Sessions are established over 3GPP access and Wireline 5G Access Network.

注4：图4.2.8 4-1中的两个N3实例。当通过3GPP接入和Wireline 5G Access Network建立不同的PDU会话时，可能适用于不同的UPF。

 

Figure 4.2.8.4-2: Non- roaming architecture for 5G Core Network for FN-RG with Wireline 5G Access network and NG RAN

The N1 for the FN-RG, which is not 5G capable, is terminated on W-AGF which acts on behalf of the FN-RG.

不支持5G的FN-RG的N1端接在代表FN-RG的W-AGF上。

The FN-RG can only be connected to 5GC via W-5GAN.

NOTE 5: The reference architecture in figure 4.2.8.4-2 only shows the architecture and the network functions directly connected to Wireline 5G Access Network, and other parts of the architecture are the same as defined in clause 4.2.

注5：图4.2.8.4-2中的参考架构仅显示直接连接到Wireline 5G Access Network的架构和网络功能，架构的其他部分与第4.2条中定义的相同。

NOTE 6: The reference architecture in figure 4.2.8.4-1 supports service based interfaces for AMF, SMF and other NFs not represented in the figure.

注6：图4.2.8.4-1中的参考体系结构支持AMF、SMF和图中未显示的其他NFs的基于服务的接口。

4.2.8.5 Access to 5GC from devices that do not support 5GC NAS over WLAN access

4.2.8.5.1 General

The devices that do not support 5GC NAS signalling over WLAN access are referred to as "Non-5G-Capable over WLAN" devices, or N5CW devices for short. A N5CW device is not capable to operate as a 5G UE that supports 5GC NAS signalling over a WLAN access network, however, it may be capable to operate as a 5G UE over NG-RAN.

不支持通过WLAN接入的5GC NAS信令的设备被称为“Non-5G-Capable over WLAN”设备，简称N5CW设备。N5CW设备不能作为通过WLAN接入网络支持5GC NAS信令的5G UE运行，但是，它可以作为通过NG-RAN的5G UE运行。

Clause 4.2.8.5 specifies the 5GC architectural enhancements that enable N5CW devices to access 5GC via trusted WLAN access networks. A trusted WLAN access network is a particular type of a Trusted Non-3GPP Access Network (TNAN) that supports a WLAN access technology, e.g. IEEE 802.11. Not all trusted WLAN access networks support 5GC access from N5CW devices. To support 5GC access from N5CW devices, a trusted WLAN access network must support the special functionality specified below (e.g. it must support a TWIF function).

第4.2.8.5条规定了5GC体系结构增强功能，使N5CW设备能够通过受信任的WLAN接入网络访问5GC。可信WLAN接入网络是支持WLAN接入技术（例如IEEE 802.11）的特定类型的Trusted non-3GPP Access Network（TNAN）。并非所有受信任的WLAN接入网络都支持N5CW设备的5GC接入。要支持N5CW设备的5GC访问，受信任的WLAN访问网络必须支持以下指定的特殊功能（例如，它必须支持TWIF功能）。

When a N5CW device performs an EAP-based access authentication procedure to connect to a trusted WLAN access network, the N5CW device may simultaneously be registered to a 5GC of a PLMN. The 5GC registration is performed by the TWIF function (see next clause) in the trusted WLAN access network, on behalf of the N5CW device. The type of EAP authentication procedure, which is used during the 5GC registration to authenticate the N5CW device, is specified in TS 33.501 [29].

当N5CW设备执行EAP-based的接入认证过程以连接到可信WLAN接入网络时，N5CW设备可同时注册到PLMN的5GC。5GC注册由TWIF功能（见下一条）代表N5CW设备在受信任的WLAN接入网络中执行。

4.2.8.5.2 Reference Architecture

The architecture diagram below is based on the general 5GS architecture diagrams in clause 4.2 and shows the main network functions required to support 5GC access from N5CW devices. Other network functions are not shown for simplicity.

以下架构图基于第4.2条中的通用5GS架构图，显示了支持N5CW设备5GC接入所需的主要网络功能。为简单起见，未显示其他网络功能。

 

Figure 4.2.8.5.2-1: Non-roaming and LBO Roaming Architecture for supporting 5GC access from N5CW devices

4.2.8.5.3 Network Functions

Trusted WLAN Access Point (TWAP): It is a particular type of a Trusted Non-3GPP Access Point (TNAP) specified in clause 4.2.8.2, that supports a WLAN access technology, e.g. IEEE 802.11. This function is outside the scope of the 3GPP specifications.

Trusted WLAN Access Point（TWAP）：它是第4.2.8.2条中规定的一种特定类型的Trusted Non-3GPP Access Point（TNAP），支持WLAN接入技术，例如IEEE 802.11。此功能不在3GPP规范的范围内。

Trusted WLAN Interworking Function (TWIF): It provides interworking functionality that enables N5CW devices to access 5GC. The TWIF supports the following functions:

Trusted WLAN Interworking Function（TWIF）：它提供互通功能，使N5CW设备能够访问5GC。TWIF支持以下功能：

- Terminates the N1, N2 and N3 interfaces.

- Implements the AMF selection procedure.

- Implements the NAS protocol stack and exchanges NAS messages with the AMF on behalf of the N5CW device.

-实现NAS协议栈，并代表N5CW设备与AMF交换NAS消息。

- On the user plane, it relays protocol data units (PDUs) between the Yw interface and the N3 interface.

-在用户平面上，它在Yw接口和N3接口之间中继协议数据单元（PDU）。

- May implement a local mobility anchor within the trusted WLAN access network.

4.2.8.5.4 Reference Points

The Yt' and Yw reference points are both outside the scope of the 3GPP specifications. The Yt' reference point transports WLAN messages (e.g. IEEE 802.11 messages), while the Yw reference point:

Yt'和Yw参考点都不在3GPP规范的范围内。Yt参考点传输WLAN消息（例如IEEE 802.11消息），而Yw参考点：

- Shall be able to transport authentication messages between the TNAP and the TWIF for enabling authentication of a N5CW device;

-应能够在TNAP和TWIF之间传输认证消息，以实现N5CW设备的认证；

- Shall allow the N5CW device to request and receive IP configuration from the TWIF, including an IP address, e.g. with DHCP.

-应允许N5CW设备从TWIF请求和接收IP配置，包括IP地址，例如使用DHCP。

- Shall support the transport of user-plane traffic for the N5CW device.

The N1, N2 and N3 reference points are the same reference points defined in clause 4.2.7.