Characterization of Non-Wide-Sense Stationarity for Distributed Massive MIMO Channels

Distributed massive multiple-input multiple-output (MIMO) communication is envisioned as one of the key paradigms of future MIMO systems. To investigate non-widesense stationarities (non-WSSs) in distributed massive MIMO channels, this paper first presents an indoor channel measurement campaign, where distributed arrays with a total of 128 elements were implemented. Then relying on the correlation matrix distance (CMD) method, the stationary distance and stationary frequency of the measured channels are estimated. Results show that the space non-WSS in the measured channels is significantly affected by locations of the distributed arrays. However, the impact of array locations on the measured frequency non-WSSs is marginal. Besides, even for a specific channel, the estimated stationary distances at the base station (BS) and user equipment (UE) side are different. The results provide insights from the perspective of channel non-WSS for future modelling of distributed massive MIMO channels and deployment of distributed antennas in practical systems.