Hybrid eCall verification

Your task

It is mandatory for modern vehicle eCall systems to support next generation (NG) eCalls (IP multimedia subsystem (IMS) based voice and minimum set of data (MSD) over 4G/5G) and strongly recommended that they remain compatible with legacy eCall systems that use circuit-switched networks (2G/3G) as a fallback. Manufacturers need to validate hybrid implementations to make sure they trigger calls, transmit the minimum set of data (MSD), maintain GNSS positioning and deliver intelligible voice quality across all network combinations (voice over New Radio (VoNR)/voice over LTE (VoLTE) – circuit-switched (CS) fallback). Tests must demonstrate that a system remains robust when faced with handovers, degraded radio conditions and standard compliance (CEN/ETSI/3GPP and national rules).

Rohde & Schwarz solution

Rohde&Schwarz offers a testing system for hybrid eCall modules (see „Hybrid eCall test setup“). This system uses:

• CMX500 radio communication tester
• CMW500 wideband radio communication tester
• R&S®SMBV100B vector signal generator (as GNSS simulator)
• R&S®CMX-KA099, comprehensive eCall verification software for hybrid eCall
• R&S®CMX-KF672B, R&S®CMWrun test package for automated end-to-end (E2E) conformance testing of hybrid eCall

The Rohde&Schwarz test platform enables comprehensive verification of both legacy eCalls and NG eCalls in a single, controlled lab environment with the CMX500 and CMW500. By emulating IMS‑based VoNR/VoLTE calls, circuit‑switched fallbacks and realistic GNSS conditions, manufacturers can validate MSD delivery, call continuity, handovers and position accuracy across all network combinations. This capability increases safety and coverage resilience by ensuring faster, more reliable public safety answering point (PSAP) connections, reducing the number of missed or delayed emergency calls and providing measurable evidence for certification and functional safety assessments.

Benefits for original equipment manufacturers (OEM)

• Reproducible lab verification of legacy, next‑generation and hybrid eCall behavior reduces the need for extensive field testing
• Early identification of CS/IMS integration, handover and GNSS issues shortens debugging cycles
• Accelerated development cycles and reliable, auditable evidence for regulatory approval and homologation
• Scalable, automated test suites span development, validation and production phases for repeatable regression testing
• Testing a real eCall in a controlled test network environment

Application

Hybrid eCall test specification EN18052 states that a hybrid system must combine different transmission paths and protocols to make sure an eCall reliably reaches its destination. In practice this means a vehicle will use NG eCall functions (IP/IMS‑based voice and data over 4G/5G) but can automatically fall back to available classic CS eCall (2G/3G) transport paths when coverage or service quality degrades. The hybrid approach provides redundancy with automatic domain selection and seamless fallback between NG (IP/IMS over 4G/5G) and legacy CS (2G/3G) transport paths supporting call handovers.

A hybrid system enables parallel or repeated delivery of the MSD, supports alternative MSD transfer with an in‑band modem in the packet-switched (PS) domain when access layer acknowledgement (AL‑ACK) is negative or missing, and defines reattempt behavior, domain changes and rejection/time-out scenarios. The system includes self‑testing and fault indication, allows call backs after domain changes, and maintains registration for the required periods (including limited service and eCall‑only) to ensure robust position reporting, higher fault tolerance and improved reachability for emergency services during the transition from legacy to NG networks.

Summary

The Rohde & Schwarz modular test platform enables com prehensive verification of hybrid, NG and legacy eCall in a controlled lab environment. Combining cellular and GNSS simulation with PSAP emulation and automated test sequencing, the system ensures robust emergency calling, reliable MSD delivery and demonstrable compliance with applicable standards.