Measurements and analyses of 28 GHz indoor channel propagation based on a synchronized channel sounder using directional antennas

This paper presents measurements and analyses of channel propagation to investigate the channel characteristics of the millimeter wave for the indoor mobile communication system. The candidate for the promising carrier frequency is 28 GHz. We conducted the measurements considering conditions for the line of sight and the obstructed line of sight. The measurement points are located in a typical office room that is one of the main scenarios for the channel model. For channel propagation analysis, a novel channel sounder with a time synchronization scheme is introduced to combine channel measurements from different directions using an automatic scanning measurement system. With this system, omni-like power delay profiles of 28 GHz communication was successfully obtained. Furthermore, we analyze the spatial-temporal channel characteristics of an indoor environment such as path loss, delay and angular distributions, delay and angular spreads, and cross-correlation between the large-scale channel parameters.