The Effects of the Rotating Step on Analyzing the Virtual Multi-Antenna Measurement Results at 28 GHz

The millimeter-wave communication is a key component in future broadband cellular networks. In this paper,a virtual multi-antenna measurement was conducted in an indoor line-of-sight scenario using a broadband channel sounder with 400 MHz bandwidth at 28 GHz. In the measurement,with an omni- directional antenna located in a fixed position at transmitter, horn antenna at receiver is rotated 360° in azimuth with the step of 2°, 3°, 5°, 8° and 10°, respectively. Then, the space- alternating generalized expectation-maximization (SAGE) algorithm was utilized to extract channel parameters from the measured results, including number of multipath components (MPCs) in azimuth domain, power azimuth spectrum (PAS) and root mean square azimuth spread of arrival angles (ASA). Finally, we compare these estimated parameters. This work aims to reveal the effects of the rotating step on the estimated results using SAGE algorithm in the virtual multi- antenna measurement. It is found that the number of estimated MPCs in azimuth domain decreases obviously as the rotating step rises, which further affects PAS and ASA. When with the step of 5°, the estimated ASA value is closest to the reference value of 3GPP TR 38.900.