  Proactive tile-based virtual reality (VR) video streaming employs the current
tracking data of a user to predict future requested tiles, then renders and
delivers the predicted tiles to be requested before playback. The quality of
experience (QoE) depends on the overall performance of prediction, computing
(i.e., rendering) and communication. All prior works neglect that users may
have privacy requirement, i.e., not all the current tracking data are allowed
to be uploaded. In this paper, we investigate the privacy-aware VR streaming.
We first establish a dataset that collects the privacy requirement of 66 users
among 18 panoramic videos. The dataset shows that the privacy requirements of
360$^{\circ}$ videos are heterogeneous. Only 41\% of the total watched videos
have no privacy requirement. Based on these findings, we formulate the privacy
requirement as the \textit{degree of privacy} (DoP), and investigate the impact
of DoP on the proactive VR streaming. First, we find that with DoP, the length
of the observation window and prediction window of a tile predictor should be
variable. Then, we jointly optimize the durations for computing and
transmitting the selected tiles as well as the computing and communication
capability, aimed at maximizing the QoE given arbitrary predictor and
configured resources. From the obtained optimal closed-form solution, we find a
resource-saturated region where DoP has no impact on the QoE and a
resource-unsaturated region where the two-fold impacts of DoP are
contradictory. On the one hand, the increase of DoP will degrade the prediction
performance and thus degrade the QoE. On the other hand, the increase of DoP
will improve the capability of computing and communication and thus improve the
QoE. Simulation results using two predictors and a real dataset validate the
analysis and demonstrate the overall impact of DoP on the QoE.
