Mitigating People Blockage by Angular Diversity at Millimeter Wave 5G Bands Miguel Riobó, Manuel García Sanchez, Iñigo Cuiñas, Isabel Exposito Dept. Teoría do Sinal e Comunicacións, atlanTTic Universidade de Vigo Vigo, Spain miriobo, manuel.garciasanchez, inhigo, iexpositop@uvigo.es Jo Verhaevert, Rob Hofman IDLab, Department of Information Technology Ghent University/imec Ghent, Belgium Jo.Verhaevert, Rob.Hofman@UGent.be Abstract—A measurement campaign was carried out in order to characterize the channel response when people are passing between transmitter and receiver in the 5G Frequency Range 2 and beyond (40 GHz and 60 GHz). We also studied the possibility of using angular diversity to compensate for the resultant fading. After analyzing the data, interesting results are obtained: fading values over 25 dB were measured at both bands; the level crossing rate is very similar in value and distribution at both frequencies, and the average duration of the resultant fadings is almost double at 60 GHz. It was also observed that the fading depth seems to be related to the stature of the person obstructing the radio link. A deeper fading is observing with taller individuals. Keywords—attenuation; narrowband; propagation; diversity I. INTRODUCTION The fifth generation of mobile communications (5G) is just around the corner and will require higher data rates and lower latency times. There is no doubt that a very important part of the new services will be used in indoor environments, where the antennas are located very close to each other. The possibility of people passing between the end antennas will lead to a radio link that can be considered challenging at best, if not unstable. In order to develop a diversity technique able to mitigate or even eliminate deep fading points, it is necessary to know how people interrupt the line of sight (LoS) and hence affect the performance of the system. With this objective, a campaign of narrowband measurements was carried out, and results are presented in this paper. In contrast, some studies focused on the effect of the people on the attenuation of the radio waves around WiFi frequencies [1] [2]. The most similar study is presented in [3], where the effect of people on the signal is characterized at different bands. II. MEASUREMENT SETUP Measurements were performed with the intention to simulate a radio link for the 5G Frequency Range 2 in an indoor environment. One transmitting and two receiving antennas were used. The transmitting antenna was directive with a beamwidth of 20º, with an amplifier connected to it when working at 40 GHz. On the other hand, the receiving antennas were omnidirectional, amplified in the case of the measurements at 60 GHz and passive at 40 GHz. The transmit antenna and the two receiving ones were placed in a large corridor, as depicted in Fig. 1. The heights were 1.2 m and 2.5 m above ground level for the transmitting and receiving antennas, respectively. Then, the linear distance between the transmitting and each of the receiving antennas was 3.09 m. The receiving omnidirectional antennas were made by Flann Microwave, models: MD249-AA and MD249-AC for the 60 GHz and 40 GHz measurements, respectively. The transmitting horn antenna used at 40 GHz was also a Flann Microwave model 23240-20, whereas it was a Q-par QSH25F20 at 60 GHz. Fig. 1. Zenithal view of antennas’ collocation. All dimensions are in meters. All antennas were connected to a four port Rohde & Schwarz ZVA67 vector network analyzer (VNA) configured in time sweep mode, transmitting by port 1 and receiving by ports 2 and 3, measuring both S21 and S31 parameters. During the chosen sweep time of 20 s, the VNA sampled 20,001 and 2,001 points, at 40 GHz and 60 GHz bands, respectively. Thus, the sampling rates were 1 kHz for the former and 100 Hz for the latter. A standard test was carried out, repeated at both bands. Two different persons passed at walking speed, one at a time, between the transmitting and receiving antennas. Person 1 was 185 cm tall and person 2, 173 cm. When each person interrupted the LoS, a deep fading was observed in the channel response. 1237 978-1-7281-6670-4/20/$31.00 ©2020 IEEE APS 2020 brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Ghent University Academic Bibliography