Abstract: To improve the performance of some wireless technologies, which are susceptible to line of sight (LOS) and non line of sight (NLOS), LOS/NLOS identification in 3D massive multi-input multi-output (MIMO) system is studied. Based on channel correlation, an improved identification algorithm, TSFCI-1, is proposed, which uses actual channel information instead of the normally assumed ideal accurate channel. The process includes:defining measurement based on time-space-frequency properties of LOS/NLOS; in view of the unsteady spatial channel correlation for 3D massive MIMO systems, finding the expectation of measurement on the spatial interval; using channel information to construct the statistical identification model. Considering the influence of antenna dual-polarization, TSFCI-2 with better evaluation index is proposed. It is shown that the identification error of TSFCI-1 and TSFCI-2 is as low as 1.92% and 1.72%, with over 6% better than a previous study. Besides, the effects of signal to noise ratio and the taps number on TSFCI-2 with the best performance is discussed.

Key words: line of sight/non line of sight identification, time-space-frequency channel correlation, 3D massive multiple-input multiple-output, channel estimation