On the Spatial Separation of Multi-user channels Using 73 GHz   Statistical Channel Models
  This paper focuses at the investigation of the degree of orthogonality of channels of multiple users in densely populated indoor and outdoor scenarios. For this purpose, a statistical millimeter wave (mmwave) MIMO channel simulator is carefully designed using state of the art channel models. At the mmwave frequencies, human/vehicular mobility around the mobile users may partially or completely block the communication link. This give rise to the consideration of new channel modeling parameter i.e. probability of a user to be in LOS dynamics. Higher line of sight (LOS) probabilities may increase the spatial correlation among the multiuser channels. Therefore, quantification of the spatial separation of users in different scenarios with distinct LOS probabilities is crucial and it is the subject of investigation of this paper. Additionally, the mutual orthogonality of channels by changing the number of base station (BS) antennas and inter antenna element distance (IED) have also been investigated. Analysis shows that LOS blockage of certain scenario has more impact at the degree of orthogonality among users as compared to the number of BS antennas and the spacing between the antenna elements. 
Geamel Alyami and Ivica Kostanic
cs.IT math.IT