Performance of LTE in a high-velocity environment

The performance of LTE at high velocities (larger than $100$ km/h) is badly understood. Operators have largely deployed LTE in urban environments where velocities are low and the benefits of LTE core features, for instance MIMO, are well demonstrated. With the proliferation of smartphones and tablets, mobile Internet access became ubiquitous and the pressure of rising traffic demands on operator infrastructures is increasing. Furthermore, mobile users now expect access to audio and HD video streams or IPTV while traveling in cars, public transports or intercity trains. Expectations evolve and high-quality connectivity is desired anywhere. To address these demands, operators are expanding their LTE deployments to semi-urban and rural areas of importance, typically along main transportation axes. However, it is unclear (1) how much LTE still benefits from MIMO spatial multiplexing or link adaptation at velocities above a few tens of kilometer per hours; and (2) how overall performance degrades with higher velocities. This paper presents results of a measurement study of a live LTE system at velocities up to $200$ km/h. The results show that while velocity has an effect on performance, its influence remains limited if the SNR coverage is well dimensioned. The percentage of spatial multiplexing usage can exceed 65% from $100$ to 200 km/h.