  Virtual reality (VR) enables mobile wireless users to experience multimodal
perceptions in a virtual space. In this paper we investigate the problem of
concurrent support of visual and haptic perceptions over wireless cellular
networks, with a focus on the downlink transmission phase. While the visual
perception requires moderate reliability and maximized rate, the haptic
perception requires fixed rate and high reliability. Hence, the visuo-haptic VR
traffic necessitates the use of two different network slices: enhanced mobile
broadband (eMBB) for visual perception and ultra-reliable and low latency
communication (URLLC) for haptic perception. We investigate two methods by
which these two slices share the downlink resources orthogonally and
non-orthogonally, respectively. We compare these methods in terms of the
just-noticeable difference (JND), an established measure in psychophysics, and
show that non-orthogonal slicing becomes preferable under a higher target
integrated-perceptual resolution and/or a higher target rate for haptic
perceptions.
