# Enhanced High-Definition Video Transmission for Unmanned Driving in Mining Environments
## 3 Design and Implementation of Video Transmission
### Video Transmission Strategies  
The video is produced using the visual retention principle [35] of the human eye, which essentially involves playing a series of pictures. Through video compression technology, the vehicle-mounted video transmission system eliminates duplicate information contained in consecutive frames at the transmitting end (vehicle video transmission 5G terminal) and restores it at the receiving end (remote monitoring subsystem). The H.264 video compression encoding [36; 37; 38] includes three types of frame data: I, P, and B, which together form a picture group. Here, the I-frame is a key frame containing all the information and can be independently decoded. P-frames, also known as inter-frame predictive encoding frames, require referencing the previous I-frames for encoding. B-frames, also known as bidirectional predictive coding frames, record the difference between this frame and the previous and subsequent frames. By utilizing H.264 video compression technology and its I-, P-, and B-frame structures, in-vehicle video transmission provides highly reliable and low-latency guarantees from three dimensions:  
Generally, there is a direct relationship between latency and network utilization:  
\[D=D_{0}/(1-U) \tag{7}\]  
where \(D_{0}\) is the latency when the network is idle, \(U\) is the network utilization, and \(D\) is the current latency. When network utilization exceeds 50%, the latency will increase rapidly. Once the utilization rate approaches 100%, the latency will approach infinity. The original data size of 4K video per 1 s (resolution: 3840 \(\times\) 2160, minimum frame rate: 25 fps, 24-bit true color) is as follows: 3840 \(\times\) 2160 \(\times\) 24 bit \(\times\) 25/(1024 \(\times\) 1024 \(\times\) 8) = 593.27 MB. Direct transmission would consume a large number of network resources, or even cause crashes. By using H.264 video compression technology for vehicle video transmission, a compression ratio of up to 100:1 can be achieved, significantly reducing the amount of data transmitted end-to-end, reducing network utilization, and providing low-latency protection.  
To improve user perception, the 5G core network can differentiate service categories and implement differentiated resource scheduling strategies. However, due to the broad classification of services on the core network side, conventional solutions struggle to accurately locate video transmission services. By utilizing special flag bits in I-frame data from H.264 video compression coding, the 5G system can accurately identify video transmission services on the wireless side (5G base station) and provide priority scheduling and resource allocation, thereby offering targeted low-latency guarantee.  
By utilizing the I-, P-, and B-frame structure of H.264, the vehicle video transmission system can ensure low-latency characteristics through dynamic frame chasing. In situations of network congestion, the system prioritizes dropping B-frames based on frame decoding priority (I > P > B). If the bandwidth remains limited, P-frames are appropriately dropped. As each frame group is transmitted from the I-frame, in case of stuttering, all current frames are directly discarded. However, when the next I-frame is received, a new frame group is sent by skipping the discarded frames, as depicted in Figure 7.