The First 5G-LTE Comparative Study in Extreme Mobility

5G claims to support mobility up to 500 km/h according to the 3GPP standard. However, its field performance under high-speed scenes remains in mystery. In this paper, we conduct the first large-scale measurement campaign on a high-speed railway route operating at the maximum speed of 350 km/h, with full coverage of LTE and 5G (NSA and SA) along the track. Our study consumed 1788.8 GiB of cellular data in six months, covering the three major carriers in China and the recent standardized QUIC protocol. Based on our dataset, we reveal the key characteristics of 5G and LTE in extreme mobility in terms of throughput, RTT, loss rate, signal quality, and physical resource utilization. We further develop a taxonomy of handovers in both LTE and 5G and carry out the link-layer latency breakdown analysis. Our study pinpoints the deficiencies in the user equipment, radio access network, and core network which hinder seamless connectivity and better utilization of 5G's high bandwidth. Our findings highlight the directions of the next step in the 5G evolution.