Supply Chain > ADAS/AV Stack > Compute Platform
EV External Vehicle Communications
External Vehicle Communications covers the hardware systems that connect a vehicle to the cloud, fleet systems, and surrounding infrastructure. This stack is distinct from the In-Vehicle Network (IVN), which is the vehicle’s internal communication fabric. External communications enable telemetry, OTA (Over-the-Air) updates, remote commands, positioning, and (where equipped) vehicle-to-everything (V2X) connectivity.
External communications vs IVN (internal networking)
Vehicles have both internal and external networking. Conflating them causes confusion.
| Stack | What it connects | Primary purpose | Typical technologies |
|---|---|---|---|
| In-Vehicle Network (IVN) | Sensors, compute, controllers, actuators inside the vehicle | Real-time internal data transport and control | Automotive Ethernet, CAN/CAN-FD, LIN |
| External Vehicle Communications | Vehicle ? cloud / fleet / infrastructure | Telemetry, OTA, remote commands, positioning, V2X (where used) | LTE/5G, GNSS, C-V2X, RF front-end, secure elements |
What this stack enables
- Telemetry: vehicle health, diagnostics, usage metrics, event reporting
- Remote commands: lock/unlock, HVAC, charging control, wake/sleep (capabilities vary)
- OTA updates: firmware/software delivery and update staging (vehicle-side)
- Location: GNSS positioning and geofencing
- Emergency services: eCall and related functions (market-dependent)
- V2X: communications with vehicles and infrastructure (where equipped)
Hardware
Most of these elements are integrated into or closely coupled with the TCU (Telematics Control Unit), but they are listed separately to clarify the supply chain.
| Element | What it is | What it does | Typical integration |
|---|---|---|---|
| Telematics Control Unit (TCU) | Connectivity ECU/module | Vehicle-side hub for telemetry, OTA transport/staging, and remote commands | Standalone ECU; sometimes combined with gateway functions |
| Cellular modem (LTE / 5G) | Wide-area radio | Primary uplink/downlink for connected services | Usually inside TCU; sometimes separate module |
| GNSS receiver | Positioning receiver | Location and timing for fleet, navigation support, logging | Usually inside TCU; sometimes shared with infotainment |
| V2X radio (C-V2X) | Short-range comms radio | Vehicle-to-vehicle and vehicle-to-infrastructure messaging (where used) | Optional; integrated with TCU or separate unit |
| RF front-end | Filters, amplifiers, tuners | Determines real-world radio performance | Coupled to modem and antenna system |
| Antenna system | External antennas and cabling | Provides RF coupling for cellular/GNSS (and V2X) | Roof/shark-fin or distributed antennas depending on OEM |
| SIM / eSIM | Carrier identity and provisioning | Enables connectivity provisioning and multi-market deployments | Inside TCU; may be remotely provisioned (eSIM) |
| Secure element / HSM | Hardware root of trust | Key storage, crypto operations, secure boot, signed OTA verification | Inside TCU or security module on main board |
| Storage (flash) | Non-volatile memory | Buffers logs and stages OTA images for reliable updates | Inside TCU; capacity varies by use case |
Interfaces to the vehicle
External communications hardware must interface to internal vehicle systems through one or more IVN links.
- Ethernet: common in modern platforms; supports higher bandwidth and richer internal routing
- CAN/CAN-FD: common for diagnostics and command/control compatibility
- Gateway functions: may be separate ECU or integrated with the TCU depending on OEM
OTA (Over-the-Air) hardware responsibilities
OTA is a system spanning cloud and vehicle hardware. On the vehicle side, the External Communications stack commonly provides:
- Secure boot and signed update verification (via secure element/HSM)
- Download transport, buffering, and retry behavior
- Update staging to target ECUs (architecture dependent)
- Power-fail safe handling (rollback strategies vary by OEM)
Fleet-grade vs consumer-grade connectivity
Fleet deployments stress connectivity differently than consumer-only use.
- Higher telemetry volume and more frequent operational events
- Stronger buffering and fault handling expectations
- More frequent OTA cycles and staged rollouts
- Greater importance of auditability and key management
