Channel Measurements, Modeling, Simulation and Validation at 32 GHz in Outdoor Microcells for 5G Radio Systems

In this paper, based on outdoor microcellular channel measurements at 32 GHz for 5G radio systems, a comprehensive channel modeling, simulation, and validation are performed. The directional-scan-sounding measurements using a horn antenna rotated with an angular step at the receiver are carried out, which constitutes a virtual array to form a single-input multiple-output radio channel. The directional- and omni-directional path-loss models are developed by using close-in and floating-intercept methods. Non-parametric and parametric methods are applied to extract large-scale channel parameters (LSPs). The non-parametric method is based on the definition of a channel parameter, whereas the parametric method is derived by the space-alternating generalized expectation-maximization (SAGE) algorithm, which can de-embed an antenna pattern. It is found that the LSPs in the angular domain are significantly different by using the two methods; however, the LSPs in the delay domain almost stay the same. By comparing the LSPs with the parameter table at 32 GHz with 3GPP standard, it is found that 3GPP LSPs should be corrected at the International Telecommunications Union-assigned millimeter wave (mmWave) frequencies for 5G. In this paper, the channel simulation is implemented by using the quasi-deterministic radio channel generator (QuaDRiGa) platform recommended by 3GPP. By comparing the LSPs with the simulated and measured results, it is found that QuaDRiGa is a good platform at the mmWave band, even if it is originally developed for channel simulation below 6 GHz. The results of this paper are important and useful in the simulations and design of future 5G radio systems at 32 GHz.