Measured 21.5 GHz Indoor Channels With User-Held Handset Antenna Array

For mobile systems involving hand-held devices, the influence of the user on system performance has to be considered. Extensive studies below 6 GHz have demonstrated large effects on system performance. However, the impact of user influence at potential frequency bands for upcoming 5G mobile networks is still to be investigated. This paper investigates how the user affects the performance of a 5G handset mock-up. The user impact is studied by channel sounding in an indoor scenario, with and without the presence of different users. The mock-up handset has a uniform linear array of receive (Rx) antennas operated at 21.5 GHz. A dual-polarized horn antenna with a wide beamwidth is transmit antenna and a fast channel sounder is used, allowing for dynamic and realistic channels. The results show that the mean influence of the user on the power varies considerably depending on the scenario, with more than 12 dB loss in some cases, while a gain of 4 dB is seen in other. An important finding is that the mean power among the seven Rx branches may be very different. Branch power ratios in the typical range of 2-10 dB were found, depending on the user and scenario.