Massive MIMO channel measurements for a railway station scenario

In this paper we present dual-band massive multiple-input multiple-output (MIMO) channel measurements for a railway station scenario. The massive MIMO link shall provide an ultra-reliable low-latency communication link from the control center to the locomotive. In the measurement campaign the locomotive moves from line-of-sight (LOS) to non line-of-sight. We present dual frequency band measurements, where the massive MIMO array at the base station has 24 receive antenna elements at 1890 MHz and 8 receive antenna elements at 748 MHz. The measurement bandwidth is 20 MHz and we use a repetition rate of 1 ms to acquire the time-variant channel frequency response from the locomotive to all 32 antenna elements in parallel. We provide a first analysis of the root mean square (RMS) delay spread, the path loss coefficients and the channel hardening in both frequency bands. The measurements show that the RMS delay spread at lower frequencies is slightly smaller compared to higher frequencies, due to a stronger LOS component at lower frequencies. Furthermore, the results indicate that increasing the number of receive antennas in vertical domain, does not allow for better channel hardening and that lower frequencies allow for better channel hardening with the same amount of antennas.