# The Development of Teleoperated Driving to Cooperate with the Autonomous Driving Experience
## 2 Literature Review on 5G Teleoperation and Fallback Systems for Autonomous Vehicles  
Despite significant progress, most autonomous vehicles (AVs) remain at SAE Levels 2-4 and continue to rely on human oversight in unpredictable or edge-case scenarios [2; 21]. This dependence has driven the adoption of teleoperation--where trained human operators intervene remotely through high-speed communication networks--as a vital fallback mechanism, especially for Level 4 vehicles. Recent field trials conducted in Ref. [22] demonstrated that remote drivers were able to resolve complex real-world traffic situations such as construction detours. However, the study also identified practical challenges related to operator readiness, latency compensation, and legal/regulatory frameworks that remain unresolved. Reliable teleoperation is underpinned by fast and stable network connections. The 5G-Blueprint project [23] showed that sub-6 GHz 5G deployments can deliver round-trip times (RTTs) between 40 and 60 ms under normal conditions, although handover events caused occasional latency spikes up to 300 ms. In another trial, Ref. [24] demonstratedaverage glass-to-glass (G2G) latency of 202 ms and RTT of 47 ms in a Kia Soul EV pilot, revealing that even modest latency can significantly degrade response accuracy. At a speed of approximately 8.33 m/s (equivalent to 30 km/h), for example, the added braking distance from a 200 ms delay can exceed one meter, undermining safe operation [24; 25]. To mitigate these latency issues, researchers have developed predictive human-machine interface (HMI) technologies. [PERSON]. [25] proposed a future-image generation method based on GAN-ConvLSTM models which can anticipate driving scenes and reduce operator lag under high-latency conditions. Similarly, [PERSON]. [26] described the implementation of a Kalman filter-based predictive display system that masked 0.5 s delays, enabling smoother control in curved road scenarios. These systems enhance perceived responsiveness but also introduce new challenges related to system calibration and user trust. Interface design itself remains a crucial element in effective teleoperation. In a public transport context, the authors of Ref. [27] developed a multi-camera dashboard UI, enhancing spatial awareness and decision-making during remote operation. Complementing this, the authors of Ref. [28] compared traditional car-like control layouts to optimized HMI alternatives, concluding that task-specific layouts can reduce cognitive workload, albeit sometimes at the expense of maneuver efficiency. Nevertheless, teleoperation remains vulnerable to severe network disruptions. Latencies exceeding 500 ms can render remote control impractical or even unsafe [24; 29; 30; 31; 32]. For this reason, onboard fallback strategies such as minimal risk maneuvers (MRMs) are essential. [PERSON]. [33] proposed a fallback strategy based on differential braking and linear quadratic regulation (LQR) that can bring a vehicle to a safe stop within its lane even on curved roads. Standards bodies like ISO and NIST reinforce these needs by promoting robust architectural paradigms--particularly the door/checker/fallback model, which ensures layered redundancy in safety-critical systems [30]. Recent trends in integration further enhance teleoperation and fallback viability. On the communication front, [PERSON]. [34] modeled 5G NR radio-layer latency under ultra-reliable low-latency communication (URLLC) conditions, while [PERSON]. [35] extended this to a cross-layer latency framework tailored for V2X and remote driving. These models are vital for anticipating and bounding delay profiles in real-time applications. In positioning, urban navigation can benefit from fusing 5G mmWave signals with inertial navigation systems (INSs). [PERSON]. [36; 37] demonstrated that UKF-based fusion techniques could achieve \(<\)30 cm positioning accuracy over 97% of the time in dense environments like downtown Toronto, making them promising for teleoperated vehicles in GPS-degraded areas.