5G PCF策略控制三阶段与PCC规则授权信令拆解

stateDiagram-v2
    [*] --> Idle: PDU会话不存在

    Idle --> Establishing: SMF发起\nSM Policy Association\nEstablishment

    Establishing --> Active: PCF返回\nSmPolicyDecision\n(初始PCC规则)

    Active --> Active: SMF/PCF发起\nSM Policy Association\nModification

    Active --> Terminating: SMF发起\nSM Policy Association\nTermination

    Terminating --> [*]: PCF确认\n策略关联释放

    note right of Active
        持续监控Policy Control
        Request Trigger条件
        - QoS Flow状态变化
        - 位置变化
        - PLMN变化
        - 用量阈值
    end note

sequenceDiagram
    participant UE
    participant AMF
    participant SMF
    participant PCF
    participant UDR
    participant UPF

    UE->>AMF: PDU Session Establishment Request
    AMF->>SMF: Nsmf_PDUSession_CreateSMContext
    Note over SMF: 1. 获取UDM签约数据
    Note over SMF: 2. 判断需要PCC授权

    SMF->>PCF: POST /npcf-smpolicycontrol/v1/sm-policies<br/>SmPolicyContextData
    Note right of SMF: 关键IE:<br/>supi, dnn, snssai,<br/>ipv4Addr/ipv6Prefix,<br/>ratType, userType,<br/>subscribedQos,<br/>online/offlineCharging

    PCF->>UDR: GET /nudr-dr/v1/policy-data<br/>获取用户策略数据
    UDR-->>PCF: 签约策略规则

    Note over PCF: 策略决策引擎:<br/>1. 匹配签约策略
    Note over PCF: 2. 生成动态PCC规则
    Note over PCF: 3. 设定Policy Control<br/>   Request Trigger
    Note over PCF: 4. 确定QoS参数(5QI/ARP)

    PCF-->>SMF: 201 Created<br/>SmPolicyDecision
    Note left of PCF: 关键IE:<br/>pccRules(安装/激活),<br/>sessRules(会话规则),<br/>qosDecs(QoS决策),<br/>chgDecs(计费决策),<br/>policyCtrlReqTriggers,<br/>umDecs(用量监控)

    Note over SMF: QoS Flow Binding:<br/>PCC规则 → QFI映射

    SMF->>UPF: N4 Session Establishment<br/>(PDR/QER/FAR/URR)
    SMF-->>AMF: Nsmf_PDUSession_CreateSMContext Response
    AMF-->>UE: PDU Session Establishment Accept

sequenceDiagram
    participant UE
    participant SMF
    participant PCF
    participant UPF

    Note over SMF: Trigger触发场景举例:<br/>1. QoS Flow释放<br/>2. RAT类型变化<br/>3. 位置变化<br/>4. 应用检测报告<br/>5. 用量阈值到达

    SMF->>PCF: POST /npcf-smpolicycontrol/v1<br/>/sm-policies/{polAssoId}/update<br/>SmPolicyUpdateContextData

    Note right of SMF: 关键IE:<br/>repPolicyCtrlReqTriggers<br/>(报告已触发的Trigger)<br/>accuUsageReports(用量报告)<br/>userLocationInfo(新位置)<br/>ratType(新RAT类型)<br/>appDetectionInfos<br/>(应用检测结果)

    Note over PCF: 评估上报事件:<br/>1. 重新计算PCC规则<br/>2. 调整QoS参数<br/>3. 更新计费决策<br/>4. 设定新Trigger

    PCF-->>SMF: 200 OK<br/>SmPolicyDecision
    Note left of PCF: 可能的决策输出:<br/>- 安装新PCC规则<br/>- 修改现有规则QoS<br/>- 去活/删除规则<br/>- 更新用量监控阈值

    SMF->>UPF: N4 Session Modification
    Note over SMF: 更新PDR/QER/FAR/URR

    opt 需要UE配合修改QoS
        SMF->>UE: PDU Session Modification Command<br/>(QoS规则更新)
    end

sequenceDiagram
    participant AF
    participant PCF
    participant SMF
    participant UPF

    AF->>PCF: POST /npcf-policyauthorization/v1<br/>/app-sessions/{appSessionId}/modify<br/>(AF请求QoS变更)
    Note over PCF: 场景:IMS VoNR视频通话<br/>AF请求增加视频媒体流

    Note over PCF: 策略决策:<br/>1. 创建新PCC规则(视频流)<br/>2. 设置5QI=2(Video)<br/>3. 分配GBR/MBR

    PCF->>SMF: POST {notificationUri}<br/>SmPolicyNotification
    Note right of PCF: SmPolicyDecision包含:<br/>pccRules: [新安装视频PCC规则]<br/>qosDecs: [5QI=2, ARP, GBR]<br/>policyCtrlReqTriggers更新

    SMF-->>PCF: 204 No Content

    Note over SMF: QoS Flow Binding:<br/>5QI=2 → 新建QoS Flow<br/>或绑定到已有同类型Flow

    SMF->>UPF: N4 Session Modification<br/>(新增PDR/QER)

    SMF->>SMF: 触发PDU Session<br/>Modification流程
    Note over SMF: 通过AMF向UE下发<br/>新的QoS Rule

SMF → PCF: POST /npcf-smpolicycontrol/v1/sm-policies/{polAssoId}/delete
           SmPolicyDeleteData {
               userLocationInfo,    // 释放时位置
               usageReports,        // 最终用量报告
               rupUsageReports      // RUP用量报告
           }

PCF → SMF: 200 OK
          SmPolicyDeleteResponse {
              // 可选: 最终策略决策
              // 通常为空,直接确认释放
          }

PCC Rule ::= {
    pccRuleId:           "rule-001",              // 规则唯一标识
    precedence:          10,                       // 优先级(越小越高)
    flowInformation: [                            // SDF模板
        {
            flowDirection:   "BIDIRECTIONAL",     // 方向: UL/DL/BIDI
            flowDescription: "permit out ip from <UE-IP> to <Server-IP> <port>"  
        }
    ],
    flowStatus:          "ENABLED",               // ENABLED/DISABLED
    qosFlowIdentifier:   5,                        // 绑定到QFI=5的QoS Flow
   _qosData: [                                    // 引用的QoS决策
        {
            5qi:             1,                    // 5QI=1 (IMS Conversational Voice)
            arp: {
                priorityLevel:         1,          // 最高优先级
                preemptCap:   "MAY_PREEMPT",      // 可抢占
                preemptVuln:  "NOT_PREEMPTABLE"   // 不可被抢占
            },
            maxbrUl:         "100 Mbps",          // 上行最大速率
            maxbrDl:         "100 Mbps",          // 下行最大速率
            gbrUl:           "50 Mbps",           // 上行保证速率(GBR类型)
            gbrDl:           "50 Mbps"            // 下行保证速率(GBR类型)
        }
    ],
    _chargingPolicyData: [                         // 计费策略引用
        {
            chargingKey:     "rg-001",             // 计费键/Rate Group
            meteringMethod:  "VOLUME_BASED",      // 基于流量计费
            isOffline:       true,                 // 离线计费
            isOnline:        false                 // 非在线计费
        }
    ],
    _monitoringKey:      "mk-001",                 // 用量监控键
    _trafficControlData: [                         // 流量控制
        {
            flowStatus:      "ENABLED",            // 门控状态
        }
    ],
    appDetectionResult:   null                     // 应用检测结果
}

flowchart TD
    A[SMF收到新PCC规则] --> B{已有QoS Flow<br/>匹配5QI+ARP?}
    B -->|是| C[绑定到已有QoS Flow<br/>复用QFI]
    B -->|否| D{是否为GBR类型<br/>5QI?}
    D -->|是, GBR| E[建立新QoS Flow<br/>分配新QFI<br/>需RAN资源预留]
    D -->|否, Non-GBR| F{默认QoS Flow<br/>可承载?}
    F -->|是| G[绑定到默认<br/>QoS Flow]
    F -->|否| H[建立新Non-GBR<br/>QoS Flow]

    C --> I[生成N4规则:<br/>PDR匹配SDF→QER执行QoS]
    E --> I
    G --> I
    H --> I

    I --> J{需要修改<br/>AN资源?}
    J -->|是| K[触发PDU Session<br/>Modification<br/>更新QoS Rule]
    J -->|否| L[仅更新N4规则<br/>无需UE参与]

    style A fill:#e1f5fe
    style I fill:#fff3e0
    style K fill:#fce4ec

AF → PCF: POST /npcf-policyauthorization/v1/app-sessions
          EventsNotification {
              mediaComponents: [
                  {
                      medCompN: 1,           // 媒体组件编号
                      medType: "AUDIO",      // 音频
                      flowDesc: [            // IP流描述
                          "permit in ip from <UE-IP> <port> to <GW-IP> <port>"
                      ],
                      marBwDl: "64 kbps",    // 最大下行带宽
                      marBwUl: "64 kbps",    // 最大上行带宽
                      rrBwDl: "32 kbps",     // 保证下行带宽
                      rrBwUl: "32 kbps"      // 保证上行带宽
                  }
              ],
              ueAddr: "10.1.1.100",         // UE IP地址
              dnn: "ims",                    // DNN
              snssai: {sst: 1, sd: "010203"} // S-NSSAI
          }

# 基于HTTP/2头部的SBI URI过滤
tcpdump -i eth0 -A -s 0 \
  'tcp port 8080 and (tcp[((tcp[12:1]>>4):4)] != 0x00000000)' | \
  grep -E "(sm-policies|npcf-smpolicycontrol)"

# Wireshark显示过滤器
http2.header.value contains "npcf-smpolicycontrol"

输入: SmPolicyContextData (SUPI, DNN, S-NSSAI, subscribedQos...)
      + UDR策略数据 (策略模板, 用户签约策略)
      + AF请求 (如存在, 媒体组件)
      + NWDAF分析 (如配置)

策略决策流程:
├── Step 1: 匹配用户签约策略
│   └── 从UDR获取 subscriber policy (default 5QI, ARP, session-AMBR)
├── Step 2: 生成会话级规则 (Session Rule)
│   └── 默认QoS Flow参数: session-AMBR, default 5QI, default ARP
├── Step 3: 评估AF请求
│   └── 每个media component → 生成一条PCC规则
├── Step 4: 策略冲突解决
│   └── 基于precedence值排序, 高优先级规则匹配后不再继续
├── Step 5: 计费策略绑定
│   └── 每条PCC规则绑定chgDecs (online/offline/both)
├── Step 6: 设定监控触发器
│   └── 基于运营商配置设定Policy Control Request Trigger
└── Step 7: 输出 SmPolicyDecision

1. UE → P-CSCF(AF): SIP INVITE (SDP: m=audio 49152 RTP/AVP 96)
                    [codec: EVS, bw: 24-64kbps]

2. P-CSCF(AF) → PCF: POST /npcf-policyauthorization/v1/app-sessions
                    mediaComponent: {AUDIO, rrBw=24kbps, marBw=64kbps}
                    ueAddr: 10.1.1.100, dnn: "ims"

3. PCF: Session Binding → 匹配到PDU Session (SUPI=..., DNN=ims)

4. PCF → SMF: POST {notificationUri} (SmPolicyNotification)
              新PCC规则: {
                pccRuleId: "voice-rule-1",
                flowInfo: "permit out ip from 10.1.1.100 to <MRFP-IP>",
                5qi: 1,   // Conversational Voice
                arp: {priority: 1, preemptCap: MAY_PREEMPT},
                gbrUl: "24 kbps", gbrDl: "24 kbps",
                maxbrUl: "64 kbps", maxbrDl: "64 kbps"
              }

5. SMF: QoS Flow Binding → 新建QFI=5 (GBR Flow, 5QI=1)

6. SMF → UPF: N4 Session Modification (PDR: 匹配RTP流, QER: QFI=5, GBR限制)

7. SMF → gNB: PDU Session Resource Setup (QFI=5, 5QI=1, GBR参数)
   [gNB预留无线资源]

8. UE ← SMF: PDU Session Modification Command (QoS Rule: QFI=5, SDF filter)

9. 语音RTP流建立，QoS保障生效