Measuring the V2I channel in cell-free vehicle networks using the MaMIMOSA distributed channel sounder

In this paper, we present a small but realistic vehicular cell-free massive MIMO (multiple input, multiple output) architecture deployed at the University of Lille in a typical suburban environment, under both line-of-sight (LOS) and obstructed LOS (OLOS) shadowing conditions.

The radio channels were acquired using a distributed RF-over-fiber (RoF) upgrade of the MaMIMOSA real-time channel sounder. The system operates at 5.89 GHz with a bandwidth of 80 MHz, corresponding to the ITS frequency band offered by ITS-G5 and CV2X technologies. Four omnidirectional receiving antennas were placed on the roof of a van travelling at a speed of 25 km/h. The propagation channel was measured for different transmission antenna configurations, ranging from co-located antennas to fully distributed antennas. The measurement results show a significant gain in signal-to-noise ratio (SNR), as well as more uniform coverage and lower delay spread values with distributed scenarios than with centralized ones.

Finally, the path loss measurement results obtained for the cell-free network provided guidelines for the deployment of distributed antennas.

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