Wearable Antennas for Virtual Reality Cross-Body Links

Abstract

Cross-body link refers to the wireless connection between two wearable devices when they are both worn or near the body, such as that of a virtual reality (VR) headset and its controllers. It is one of the most challenging wireless scenarios in terms of link budget, due to severe shadowing effects when controllers are placed at the back side of the body. This is especially true when the users are in an outdoor environment where there is less reflection from the surrounding. This paper investigates the wireless propagation mechanism, including line-of-sight, ground reflection, and creeping waves. Based on that, through simulation and measurement experiments, this work analyzes the impact of different antenna designs on the cross-body link of VR/AR devices, including one novel compact low-profile antenna named Distributed Monopole (DM), and two conventional antennas. Due to the polarization advantages, both the novel DM antenna and the patch antenna shows significantly better performance than the dipole antenna. The DM antenna also shows a 2-4 dB advantage over the patch antenna due to its omni-directional field pattern. Time-domain analysis and statistical approaches are suggested to fully characterize the cross-body link of VR/AR antennas and body propagation.