Ray-tracing Based 28 GHz Channel Characterization for Outdoor Millimeter Wave Communications

With the rapid development of mobile Internet and Internet of Things technologies, it is considered as the main driving force for the fifth generation (5G) mobile communication technology to improve data transmission rate in wireless communication system. Due to the much higher transmission bandwidth, the millimeter wave has received wide attention. However several problems such as small coverage areas and large frequency differences are founded in the millimeter wave wireless communication systems. Therefore, research on the millimeter wave propagation characteristics in different scenarios and complete the channel measurement and modeling is important for millimeter wave wireless system. This paper first introduces the current development of 5G millimeter wave technology and summarizes the current 5G millimeter wave candidate frequency bands, application scenarios, channel measurement and modeling methods. And the 28 GHz frequency band is selected for the outdoor scenario propagation research in this paper. Then, based on the ray-tracing simulation tools, an outdoor street scenario with dense trees is built, and the propagation characteristics of the millimeter wave for the outdoor scenario across multiple frequency channels are studied. Finally, the statistical distribution of path loss and time delay parameters in outdoor street scenario is analyzed, and the influence of vegetation distribution on the channel is focused on. According to the results of millimeter wave wireless channel measurement and modeling in this paper, it is helpful to deepen the understanding of millimeter wave propagation, determine the commercial frequency band of millimeter wave applied in 5G system, and promote the standardization of high frequency channel model and the development of wireless communication technology.