Characterizing spatial correlation of blockage statistics in urban mmWave systems

Abstract

Millimeter-wave (mmWave) systems suffer from a significant loss in performance when the line-of-sight (LoS) path between the transmitter and the receiver is obstructed due to blockage caused by humans or other obstacles. However, due to blocker or user motion, the mmWave receiver may transition between the LoS and non-LoS (nLoS) states. Following the recent 3GPP requirements on spatial consistency for channel modeling, this paper aims to analyze the spatial correlation of blockage statistics and characterize their evolution due to user mobility in a static field of blockers in urban mmWave systems. In particular, we derive conditional probabilities of residing in LoS or nLoS state at a given time t1, provided that a user was in LoS/nLoS state at a prior time t0. We demonstrate that for realistic values of user speed, the angle of motion, height of transmitter and receiver, as well as the density of blockers, there always is a significant correlation between user channel states at time t0 and t1, across the time scales relevant for mmWave resource scheduling. Hence, our model can serve as an important tool for optimizing system performance in the presence of blockage.