## 2 Requirements from Autonomy and Remote Control in Smart Farms
### Requirements for Communications Networks  
The communication needs of remote control depend on the autonomy level of the vehicle, where no driving automation will be most demanding for remote control, and full driving automation may not need any remote control support.  
A remote control system with control services, including cameras, sensors, and control devices, may involve many other services, such as weather forecasts, engine remote maintenance, cultivation plans, navigation, collision avoidance, and logistic information services. However, the most demanding service in terms of wireless communication is remote control in which the tractor is operated by a person from a remote area based on data from tractor cameras and sensors. For the scenario of remote control of the tractor, the communication medium must meet the requirements of latency and bandwidth for video and control data transfer.  
Control data include steering-related information as well as feedback information. The status information from different tractor subsystems is also included in the transmission, such as temperature and battery levels. In the current trial, the tractor control was based on the CAN bus [33]. The CAN protocol specification allows bit rates of up to 1 Mbps. Our implementation optimized CAN communication by filtering CAN frames so that the tunneled network traffic utilized a 85-kbps bitrate from the tractor and a 53-kbps bitrate to the tractor. These bitrates were from measurements that may involve small amounts of other data traffic. The trialed tractor had five cameras: the forward-facing camera required a minimum of 2 Mbps constant bit rate, while the forward side-cameras, which did not need as good a video quality, could use 1 Mbps. In total, the five cameras required an uplink bitrate of 8 Mbps. A forward-moving tractor requires a minimum view of three cameras.  
Concerning human remote control based on video camera views, humans will need 100 ms to recognize or become aware of stimuli, and a minimum 180 ms to see an object and make movements such as pressing a key [34]. Thus, the end-to-end latency of the system can have 180 ms in human intervention remote control. The end-to-end system latency consists of information processing delays, such as video processing and packet transmission delays, where video processing will have a dominant role [30].  
When vehicle-to-everything (V2X) remote control involves autonomous services without human interaction, different latencies [35] and quality requirements apply. 5 GAA Automotive Association [36]  specified that the maximum latency tolerable for gaining awareness of pedestrians in danger is 100 ms, of which the recommended latency for communication is 20 ms when the assumed vehicle speed is 50 km/h. This indicates that the vehicle will move an additional 28 cm due to a network delay. 3 GPP has also specified V2X requirements for cellular networks, as listed in Table 1, which vary between 5 ms and 100 ms (video stream to a remote cabin and CAN messages to the tractor). The trialed scenario did not involve use cases with close cooperation with other vehicles, such as platooning interactions, but it supported pedestrian safety, and 10 ms was the minimum latency caused by a network for one directional packet. If we assume a tractor with a velocity of 15 km/h and a safety limit due to a network delay of 28 cm, the allowed latency is 67.2 ms (33.6 ms in one direction). However, when tractors are equipped with sensors that can autonomously prevent collisions or when tractors are not used in road traffic, but in private fields without external pedestrians, these requirements may be more relaxed.