Efficient Caching for 360° Videos with Dynamic View Selection

Due to the emergence of 3D video applications like virtual reality, network storage management for 360 degrees videos is expected to play an important role. In comparison with traditional videos, it is envisaged that a 360 degrees video requires larger space to store multiple views. Nevertheless, efficient storage schemes for 360 degrees videos in a proxy have not been explored in the literature. In this paper, therefore, we first observe that the storage space can be effectively reduced by leveraging real-time image-based generation schemes to synthesize the desired views in 360 degrees videos. We then formulate a new optimization problem, named Dynamic View Synthesis and Selection Problem (DVSSP), to minimize the total network cost over time, which includes the cost of synthesis, local transmission, and fetching views from the remote server. Since the current storage influences the cost spent in the future, we then devise an online algorithm based on the dynamic programming technique to carefully examine the correlation between nearby views that are most likely to be requested in the following time slots. Simulation results manifest that the proposed algorithm can significantly improve the hit rate by more than 50% and reduce more than 45% total cost compared with various baseline algorithms.