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ETSI C-ITS Protocol Stack Integration

rustv2xsimulator integrates natively with rustflexstack, providing a memory-safe, zero-copy implementation of European Telecommunications Standards Institute (ETSI) Cooperative Intelligent Transport Systems (C-ITS) protocol standards.

1. Protocol Architecture

The communication stack mirrors the European C-ITS architecture (ETSI EN 302 665):

flowchart TD
    subgraph FacilitiesLayer ["Facilities Layer (ETSI TS 103 900 / TS 103 898)"]
        CAM["Cooperative Awareness Basic Service (CAM, Port 2001)"]
        DENM["Decentralized Environmental Notification Service (DENM, Port 2002)"]
        LDM["Local Dynamic Map (LDM Facility)"]
    end

    subgraph TransportLayer ["Transport Layer (ETSI EN 302 636-5-1)"]
        BTP["BTP Router (BTP-A / BTP-B)"]
    end

    subgraph NetworkLayer ["Network Layer (ETSI EN 302 636-4-1)"]
        GN["GeoNetworking Router (SHB, GBC, Location Table)"]
        Security["ETSI TS 103 097 Security (ECDSA P-256, Certificates)"]
    end

    subgraph Adapter ["Simulator Link-Layer Adapter"]
        SLL["SimulatorLinkLayer (Bridge channels)"]
    end

    subgraph MACPHY ["Simulator Wireless Layer"]
        MAC["EdcaChannelAccess / WirelessTechnology"]
    end

    CAM & DENM <--> BTP
    CAM -.->|Updates Neighbours| LDM
    BTP <--> GN
    GN <--> Security
    GN <--> SLL
    SLL <--> MAC

2. Standards Compliance

Layer / Service ETSI Specification Implementation Details
Facilities Layer ETSI TS 103 900 (CAM)
ETSI TS 103 898 (DENM)		 Dynamic kinematic triggers ($
Transport Layer ETSI EN 302 636-5-1 (BTP) BTP-B for CAM broadcasts (Port 2001); BTP-A for port-directed packets.
Network Layer ETSI EN 302 636-4-1 (GeoNet) Single-Hop Broadcast (SHB), GeoBroadcast (GBC), Long Position Vector (LPV) location tables.
Security Subsystem ETSI TS 103 097 / IEEE 1609.2 ECDSA P-256 signing, certificate verification backend, SHA-256 digest calculation.
Local Dynamic Map ETSI EN 302 895 (LDM) High-speed spatial hash map tracking neighbor vehicle kinematics and Age of Information (AoI).

3. The SimulatorLinkLayer Bridge

In a physical vehicle, the GeoNetworking router communicates with the wireless network interface card (NIC) over Linux raw sockets (AF_PACKET via libpnet).

Inside the discrete-event simulator, SimulatorLinkLayer bridges rustflexstack to the DES channel without OS socket overhead:

  • Outbound Frames: GeoNetworking packets ready for wireless broadcast are queued in gn_to_ll_rx. The simulation engine polls them via drain_outbound_frames(), maps them to the appropriate Access Category (AC_BE for CAM, AC_VO for DENM), and submits them to the MAC contention engine.
  • Inbound Frames: When a wireless packet is successfully decoded by the PHY layer, the engine calls inject_rx(&payload_bytes). The frame enters the GeoNetworking router, updates the receiver's location table, passes through BTP, and reaches the facility layer (updating the Local Dynamic Map).