【5G核心网】 PCF之Access and Mobility Policy

女爷i 2022-11-25 11:43 821阅读 0赞

本文分析 PCF 中的 Access and Mobility Policy Control Service 接入与移动性策略控制服务

接入与移动策略控制服务由策略控制功能（PCF）提供

该服务向 AMF 提供与 AMF 接入控制和移动性管理相关的策略，并提供以下功能：

>     -  在 UE 注册期间基于从 AMF 请求的策略创建
> 
>     -  通知 AMF 已订阅的更新策略
> 
>     -  UE 策略上下文的删除

# 1. 服务架构 #

接入与移动策略控制服务（Npcf\_AMPolicyControl）是策略控制功能（PCF）的基于 Npcf 服务的接口的一部分。

Npcf\_AMPolicyControl 服务的使用者是访问和移动性管理功能（AMF）。

AMF 通过 N15 参考点访问 PCF 上的接入和移动策略控制服务。 在漫游方案中，N15 参考点位于受访网络中的 V-PCF 和 AMF之间。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70][]**Figure 4.1.2-1: Reference Architecture for the Npcf\_AMPolicyControl Service; SBI representation**

**                 **

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 1][]**Figure 4.1.2-2** **:** ** Non-roaming Reference Architecture for the Npcf\_AMPolicyControl Service; reference point representation**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 2][]**Figure 4.1.3-2** **:** ** Roaming reference Architecture for the Npcf\_AMPolicyControl Service; reference point representation**

###    1.1 PCF 策略控制功能 ###

>     -  支持统一的策略框架来保证网络的行为
> 
>     -  向实施这些策略的 AMF 提供与接入和移动管理相关的策略

在漫游情况下，访问策略控制功能（V-PCF）向访问网络提供本小节中描述的功能。

向 AMF 提供服务：

>     - Registration management;
> 
>     - Connection management;
> 
>     - Reachability management; and
> 
>      - Mobility Management.

# 2. 服务操作 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 3][]** Table** ** 4.2.1** **-1: Operations of the Npcf\_AMPolicyControl Service**

### **   2.1** Npcf\_AMPolicyControl\_Create ###

AM 策略关联的创建仅适用于正常注册的 UE，即不适用于紧急注册的 UE。

\{apiRoot\}/npcf-am-policy-control/v1/policies

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 4][] Figure 4.2.2.1-1: Creation of a policy association

**    当 UE 注册并建立 UE 上下文时，AMF 可以在更新位置过程中从 UDM 获取服务区域限制，RFSP 索引和 GPSI，并应基于本地策略决定是否向 PCF 请求策略。**

为了从 PCF 请求策略，NF 服务使用者（例如AMF）必须发送 HTTP POST 请求，其中资源 URI 为

“ ***\{apiRoot\} / npcf-am-policy-control / v1 / policies”***，请求为 ***PolicyAssociationRequest*** 数据结构，其包括：

>     - Notification URI encoded as "***notificationUri***" attribute; and
> 
>     - SUPI encoded as "***supi***" attribute,

当可用时包括参数：

>     - GPSI encoded as "***gpsi***" attribute;
> 
>     - Access type encoded as "***accessType***" attribute;
> 
>     - Permanent Equipment Identifier (PEI) encoded as "***pei***" attribute;
> 
>     - User Location Information encoded as "***userLoc***" attribute;
> 
>     - UE Time Zone encoded as "***timeZone***" attribute;
> 
>     - Serving PLMN Identifier encoded as "***servingPlmn***" attribute;
> 
>      - RAT type encoded as "***ratType***" attribute;
> 
>      - Service Area Restriction s (see subclause 4.2.2.3.1) derived from the Service Area Restrictions obtained from the UDM by mapping any service areas denoted by geographical information into Tracking Area Identities (TAIs) and encoded as "***servAreaRes***" attribute;
> 
>     - RFSP index (see subclause 4.2.2.3.2) as obtained from the UDM encoded as "***rfsp***" attribute;
> 
>     - A list of Internal Group Identifiers encoded as "***groupIds***" attribute;
> 
>     - if the NF service consumer is an AMF, the GUAMI encoded as "***guami***" attribute;
> 
>     - if the NF service consumer is an AMF, the name of a service produced by the AMF that expects to receive information within Npcf\_AMPolicyControl\_UpdateNotify service operation encoded as "***serviceName***" attribute;
> 
>     - Alternate or backup IPv4 Address(es) where to send Notifications encoded as "***altNotifIpv4Addrs***" attribute;
> 
>     - Alternate or backup IPv6 Address(es) where to send Notifications encoded as "***altNotifIpv6Addrs***" attribute; and
> 
>     - trace control and configuration parameters information encoded as "***traceReq***" attribute.

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 5][]

\{"notificationUri":"http://127.0.0.1:8080/namf-xxxx/v1/am-policy/","supi":"imsi-4069300007908","gpsi":"msisdn-0900000000","accessType":"3GPP\_ACCESS","pei":"imeisv-1110000000000000","servingPlmn":\{"mnc":"93","mcc":"406"\},"guami":\{"plmnId":\{"mcc":"406","mnc":"93"\},"amfId":"xxxx"\},"suppFeat":""\}

**  PCF 接收 HTTP POST 请求如下处理：**

>     -  将分配一个策略关联 ID
> 
>     -  应确定适用的策略（考虑并可选地修改可能收到的服务区限制和/或 RFSP 索引）
> 
>     -  对于成功的应在“位置”头字段中发送 HTTP “ 201 Created” 响应以及所创建资源的 URI

### **   2.2 **Npcf\_AMPolicyControl\_Update ###

当 NF 服务使用者修改现有的 AM 策略关联时（包括 AMF 重新定位且新的 AMF 选择保持与旧 PCF 的策略关联并更新 Notification URI 的情况）

###    2.3 Npcf\_AMPolicyControl\_UpdateNotify ###

###    2.4 Npcf\_AMPolicyControl\_Delete ###

# 3. Npcf\_AMPolicyControl API #

**\{apiRoot\}/\{apiName\}/\{apiVersion\}/\{apiSpecificResourceUriPart\}**

> **    **\- The \{apiRoot\} shall be set as described in 3GPP TS 29.501 \[6\].
> 
>     - The \{apiName\}** **shall be "npcf-am-policy-control".
> 
>     - The \{apiVersion\} shall be "v1".
> 
>     - The \{apiSpecificResourceUriPart\} shall be set as described in subclause 5.3.

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 6][] Table 5.3.1-1: Resources and methods overview

###    3.1 AM Policy Associations ###

**\{apiRoot\}/npcf-am-policy-control/v1/policies**

![20200808170751404.png][] Table 5.3.2.3.1-2: Data structures supported by the POST Request Body on this resource

![20200808170849838.png][]  Table 5.3.2.3.1-3: Data structures supported by the POST Response Body on this resource

**     3.1.1 AM Policy Association Establishment**

此过程涉及以下情形：

>      -  UE初始向网络注册
> 
>      -  与 PCF 一起进行的 AMF 重新分配在切换过程和注册过程中发生了变化
> 
>      -  在没有现有 AM 策略关联的情况下，在 UE 从 EPS迁 移到 5GS 的过程中，UE 向 5GS 注册

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 7][] Figure 5.1.1-1 AM Policy Association Establishment procedure

# 4. Data Model 数据模型 #

本节指定 API 支持的应用程序数据模型。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 8][] Table 5.6.1-1: Npcf\_AMPolicyControl specific Data Types

###    4.1 PolicyAssociationRequest ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 9][] Table 5.6.2.3-1: Definition of type PolicyAssociationRequest

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 10][]

### 参考： ###

3GPP TS 29.507: "5G System; Access and Mobility Policy Control Service; Stage 3"

3GPP TS 29.513: “5G System; Policy and Charging Control signalling flows and QoS parameter mapping;Stage 3"

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