Channel Measurements and Modelling for Large Antenna Arrays

This paper presents Massive MIMO measurements conducted in Kista, Sweden utilizing one receiving base station antenna array with 448 ports in a typical Urban Macro deployment and 48, 4-port, transmitters located in mixed indoor and outdoor conditions. The measurement data is analyzed and compared to the 3GPP UMa channel model to provide insights on requirements for channel modelling for very large antenna arrays. In general, the UMa model, given its 20 clusters, is too sparse to jointly model both the angular and delay characteristics as seen in measurements for antenna arrays larger than what is commonly deployed today. Further, the analysis of scenarios where part of the array is blocked indicates that the power variation experienced over the array, seems to be sufficiently well captured by a simple knife edge diffraction model when applied per cluster for the dominant directions.