Hand Grip Impact on 5G mmWave Mobile Devices

This paper contributes a comprehensive study on the effect of the user hand grip on the design of 5G millimeter-wave (mmWave) mobile handsets, specifically in terms of the antenna module placement and the beamforming codebook. The high-frequency structure simulator (HFSS) is used to characterize the radiation fields for different antenna placements and 14 possible handgrip profiles based on the experiments that we conducted. The loss from hand blockage on the antenna gains can be up to 20-25 dB, which implies that the possible hand grip profiles need to be taken into account while designing the antenna module placement and beamforming codebook. Specifically, we consider three different codebook adaption schemes: a grip-aware scheme, where perfect knowledge of the hand grip is available; a semi-aware scheme, where just the application (voice call, messaging, and so on) and the orientation of the mobile handset is known; and a grip-agnostic scheme, where the codebook ignores the hand blockage. Our results show that the ideal grip-aware scheme can provide more than 50% gain in terms of the spherical coverage over the agnostic scheme, depending on the grip and orientation. Encouragingly, the more practical semi-aware scheme that we propose provides performance approaching the fully grip-aware scheme. Overall, we demonstrate that the 5G mmWave handsets are different from pre-5G handsets: the user grip needs to be explicitly factored into the antenna placement and the codebook design.