## 4 Impact of Network Latency on Teleoperation
### Wireless Technologies Used in Teleoperation  
Wireless technologies play a pivotal role in teleoperation systems by enabling seamless control and communication between the operator and the teleoperation station. It is crucial to maintain the safety and security of the teleoperation communication systems, as these systems should be uninterrupted and transmit data in real-time [9]. The wireless technologies used in teleoperation with their performance and latency requirements are listed in Table 2. These are technologies that have been used across various domains. The technology performance is determined by various network parameters, including frequency, bandwidth, coverage, data rate, throughput, and latency. The most influential factors for a general teleoperation use case include latency, throughput (user data rate), data rate (maximum capacity), and coverage. Hence, only these parameters are mentioned in the table. There has been a drastic evolution in network technologies over time, with each iteration achieving improved performance and unlocking new applications, in turn, decreasing the effects of latency. A standout example is the evolution of cellular networks, which have revolutionised the way we communicate and access data. They have evolved from first-generation 1G (from 1980) to fifth-generation 5G (from 2020 onwards) networks, where  
Figure 5: System architecture of CAV teleoperation control loop. each generation is an improvement on the previous one [20], providing better coverage, higher frequencies, faster data transfers, lower latency, higher reliability, and mobility, among other improvements. The main factors for network data traffic growth are increasing populations with smart devices, applications, and sensors, leading to the Internet of Everything (IoE) [20]. The statistics of the International Telecommunication Union (ITU) state that just global cellular traffic will rise to 607 exabytes (EBs) per month by 2025 and 5016 EB by 2030 [20]. With the continuous demand for network traffic and emerging applications (e.g., CAVs), the current technologies will have difficulty sustaining the requirements. Latency can cause disruptions to applications relying on communication technologies. Different technologies for teleoperation exhibit various levels of latency based on their QoS factors. For example, experimental results have shown that 3G networks have a mean latency of 217 ms and 205 ms for vehicle control and video streaming, respectively. Whereas the next generation showed a slight improvement, with 4G networks having a mean latency of 183 ms for video streaming and 107.2 to 110.3 ms for vehicle controls [21]. The present and future generations of networks, including 5G and sixth generation, are expected to have much lower latency and better network quality (e.g., high frequencies, fast data transfers, high reliability, mobility) [20], satisfying the requirements and leading to efficient teleoperations. For example, teleoperation using 5G networks can have latency as low as 60 ms but as high as 260 ms in some cases [22]. As inferred from the table, the wireless technologies used in teleoperation can be broadly classified as cellular and non-cellular. Cellular technologies, especially the recent advances, provide reliable and high-speed connectivity over large geographical areas. Many studies that have used 3G, 4G, and 5G networks for teleoperation have demonstrated that latency and bandwidth requirements could be met for teleoperation applications, particularly for CAVs and remote scenarios requiring long-distance operations. In such scenarios, wired connections are infeasible. However, they have limitations in extremely remote areas such as rural areas or due to heavy traffic and congestion in urban areas, which can lead to potential latency or signal degradation. Some studies have revealed that there is an evident difference between 4G and 5G networks for teleoperation [23]. The 4G networks are just able to support the necessary infrastructure for basic remote driving capabilities [10].