Nowadays, high mobility scenarios have become increasingly common. The widespread adoption of High-speed Rail (HSR) in China exemplifies this trend, while more promising use cases, such as vehicle-to-everything, continue to emerge. However, the Internet access provided in high mobility environments still struggles to achieve seamless connectivity. The next generation of wireless cellular technology 5 G further poses more requirements on the end-to-end evolution to fully utilize its ultra-high band-width, while existing network diagnostic tools focus on above-IP layers or below-IP layers only. We then propose HiMoDiag, which enables flexible online analysis of the network performance in a cross-layer manner, i.e., from the top (application layer) to the bottom (physical layer). We believe HiMoDiag could greatly simplify the process of pinpointing the deficiencies of the Internet access delivery on HSR, lead to more timely optimization and ultimately help to improve the network performance.

Continuous advancements in visible-light communication (VLC) technology have paved the way for future high-capacity communication links that can simultaneously provide data transmission and illumination. VLC is being accepted as a potential complementary technology in 5G networks, and standardization efforts through IEEE 802.15.7 are on their way. Today, vehicular networking applications have become increasingly complex with tight power and performance requirements. Consequently, devices and systems that can meet diverse vehicular networking applications are in great demand. In this article, we discuss three alternatives for vehicular networking applications in (1) LED–photodiode-based active VLC, (2) VLC with a multicamera array receiver, and (3) passive VLC based on decoding information from optical backscatter. We also present our recent experimental and modeling work using our camera-based and passive VLC prototype implementations.