5G Paging三触发源与PF/PO寻呼时机博弈

flowchart TB
    subgraph 触发源
        T1["触发源1: CN-initiated<br/>SMF/AMF → NGAP Paging<br/>UE在CM-IDLE/RRC_IDLE"]
        T2["触发源2: RAN-initiated<br/>Last gNB → Xn/Uu Paging<br/>UE在RRC_INACTIVE"]
        T3["触发源3: Short Message<br/>gNB → DCI 1_0 ShortMsg<br/>ETWS/CMAS/SI更新"]
    end

    subgraph 空口寻呼
        P1["Paging Frame计算<br/>SFN mod T = T/N × UE_ID mod N"]
        P2["Paging Occasion计算<br/>i_s = floor UE_ID/N mod Ns"]
        P3["PDCCH监听<br/>P-RNTI加扰 DCI 1_0"]
    end

    subgraph UE响应
        R1["Service Request<br/>RRC_IDLE→CONNECTED"]
        R2["RRC Resume<br/>RRC_INACTIVE→CONNECTED"]
        R3["系统信息更新<br/>重新读取SIB"]
    end

    T1 --> P1
    T2 --> P1
    T3 --> P2
    P1 --> P2
    P2 --> P3
    P3 --> R1
    P3 --> R2
    P3 --> R3

sequenceDiagram
    participant UPF
    participant SMF
    participant AMF
    participant gNB1 as gNB-1
    participant gNB2 as gNB-2
    participant UE

    UPF->>SMF: DL Data Notification<br/>(N4 Downlink Data Report)
    Note over SMF: 检测UE在CM-IDLE<br/>无N3隧道活跃
    SMF->>AMF: Namf_Communication<br/>_N1N2MessageTransfer<br/>(含PDU Session ID, N2 SM Info)
    Note over AMF: 查询UE注册区域<br/>确定TAI List for Paging
    AMF->>gNB1: NGAP Paging<br/>(5G-S-TMSI, TAI List,<br/>Paging Priority, DRX)
    AMF->>gNB2: NGAP Paging<br/>(5G-S-TMSI, TAI List)
    Note over gNB1,gNB2: 计算PF/PO<br/>在对应空口时机发送
    gNB1->>UE: RRC Paging<br/>(P-RNTI DCI 1_0 + PDSCH)
    gNB2->>UE: RRC Paging<br/>(同步发送)
    UE->>gNB1: RRC Setup Request<br/>(含Service Request NAS Msg)
    gNB1->>AMF: NGAP Initial UE Message<br/>(Service Request)
    Note over AMF: UE转为CM-CONNECTED
    AMF->>SMF: Nsmf_PDUSession<br/>_UpdateSMContext<br/>(N2 SM Info)
    SMF->>UPF: N4 Session Modification<br/>(恢复DL隧道)
    UPF->>UE: Downlink Data

sequenceDiagram
    participant UPF
    participant gNB_A as Last gNB<br/>(Anchor)
    participant gNB_B as Neighbor gNB
    participant UE

    UPF->>gNB_A: DL Data<br/>(N3隧道仍存在)
    Note over gNB_A: 检测UE在RRC_INACTIVE<br/>AS Context保留
    gNB_A->>gNB_B: Xn RAN Paging<br/>(I-RNTI, RNA范围)
    gNB_A->>UE: RRC Paging<br/>(在Anchor小区)
    gNB_B->>UE: RRC Paging<br/>(在RNA内邻区)
    UE->>gNB_B: RRC Resume Request<br/>(含Resume ID / I-RNTI)
    gNB_B->>gNB_A: Retrieve UE Context<br/>(Xn接口)
    gNB_A->>gNB_B: UE Context Response<br/>(完整AS上下文)
    Note over gNB_B: 恢复DRB/SRB配置
    UE->>gNB_B: RRC Resume Complete
    gNB_B->>UPF: Path Switch<br/>(N3路径切换)
    UPF->>UE: Downlink Data

graph LR
    A["NGAP Paging Message"] --> B["UE Paging Identity"]
    A --> C["TAI List for Paging"]
    A --> D["Paging Priority<br/>(Optional)"]
    A --> E["UE Radio Capability<br/>for Paging<br/>(Optional)"]
    A --> F["Assistance Data<br/>for Paging<br/>(Optional)"]
    A --> G["Paging DRX<br/>(Optional)"]

    B --> B1["5G-S-TMSI<br/>(常规寻呼)"]
    B --> B2["Full IMSI<br/>(紧急寻呼/未分配TMSI)"]

    C --> C1["TAI 1"]
    C --> C2["TAI 2"]
    C --> C3["TAI N"]

    D --> D1["Priority Level 1-8<br/>1=最高 8=最低"]

    F --> F1["UE Identity Index Value<br/>(用于PF/PO计算)"]
    F --> F2["Recommended Cells<br/>(建议优先寻呼小区)"]
    F --> F3["Location Indication<br/>(UE大致位置)"]

    G --> G1["32/64/128/256<br/>radio frames"]

SFN mod 128 = floor(128/64) × (961 mod 64)
           = 2 × (961 mod 64)
           = 2 × 1
           = 2

i_s = floor(961/64) mod 1 = 15 mod 1 = 0

sequenceDiagram
    participant UE
    participant gNB

    Note over UE: DRX休眠中...
    Note over UE: PF到达，唤醒RF链路

    rect rgb(230, 245, 255)
    Note over UE,gNB: Step 1: PDCCH监听
    gNB->>UE: PDCCH DCI 1_0<br/>(P-RNTI加扰)<br/>频域: PagingSearchSpace<br/>时域: PO对应的PDCCH监听时机
    Note over UE: 解码DCI → 获取PDSCH调度信息
    end

    rect rgb(255, 245, 230)
    Note over UE,gNB: Step 2: PDSCH接收
    gNB->>UE: PDSCH Paging Message<br/>含pagingRecordList<br/>或Short Message指示
    Note over UE: 检查pagingRecord中<br/>是否有自己的5G-S-TMSI
    end

    alt 寻呼到本UE
        UE->>UE: 记录accessType<br/>(1=NR, 0=EUTRA)
        UE->>gNB: RRC Setup/Resume Request
    else 未寻呼到
        Note over UE: 回到DRX休眠
    end

PagingRecord ::= SEQUENCE {
    ue-Identity                  CHOICE {
        ng-5G-S-TMSI             BIT STRING (SIZE(48)),
        fullI-RNTI               BIT STRING (SIZE(40))
    },
    accessType                   ENUMERATED {nr, eutra},
    ...
}

stateDiagram-v2
    [*] --> RRC_IDLE: 开机注册后

    RRC_IDLE --> RRC_CONNECTED: CN Paging响应<br/>RRC Setup + Service Request
    RRC_IDLE --> RRC_CONNECTED: UE主叫<br/>RRC Setup + Registration/Service Request

    RRC_CONNECTED --> RRC_INACTIVE: RRC Release<br/>(suspendConfig)
    RRC_CONNECTED --> RRC_IDLE: RRC Release<br/>(无suspendConfig)

    RRC_INACTIVE --> RRC_CONNECTED: RAN Paging响应<br/>RRC Resume
    RRC_INACTIVE --> RRC_IDLE: RNAU失败/定时器超时<br/>隐式回退

    RRC_INACTIVE --> RRC_INACTIVE: RAN Paging<br/>(RNA范围内移动)

    note right of RRC_IDLE
        CM-IDLE状态
        NAS连接已释放
        AMF按TA级别跟踪
    end note

    note right of RRC_INACTIVE
        CM-CONNECTED状态
        NAS连接保持
        gNB按RNA级别跟踪
    end note

    note right of RRC_CONNECTED
        CM-CONNECTED状态
        全部连接活跃
    end note

sequenceDiagram
    participant UE
    participant gNB

    Note over UE: DRX休眠中...

    rect rgb(200, 255, 200)
    Note over UE,gNB: PEI Occasion（PO之前）
    gNB->>UE: DCI 2_7<br/>(PEI-RNTI加扰)<br/>含subgroup bitmap
    Note over UE: 检查自己所在subgroup位<br/>0=无寻呼 1=有寻呼
    end

    alt PEI指示=0（无寻呼）
        Note over UE: 立即回睡，跳过PO
    else PEI指示=1（有寻呼）
        rect rgb(230, 245, 255)
        Note over UE,gNB: 正常Paging流程
        gNB->>UE: PDCCH DCI 1_0 (P-RNTI)
        gNB->>UE: PDSCH Paging Message
        end
    end

# 过滤NGAP Paging消息
ngap.procedureCode == 17

# 过滤特定5G-S-TMSI的Paging
ngap.paging && ngap.UEPagingIdentity

# 过滤高优先级Paging
ngap.paging && ngap.PagingPriority

# 过滤RRC Paging
rrc.pcch

# 查看pagingRecord中的UE标识
rrc.pagingRecord.*