Simulation of content-aware caching policies for tiled 360 videos

Abstract: Video streaming is used daily by people around the world, plays a big role in many Internet users daily lives, and are today responsible for the majority of the Internet traffic. As 360 video streaming services become increasingly popular and each such user session requires much higher bandwidths than traditional video streaming, optimized solutions for this type of video is becoming increasingly important. One method that has been proposed to reduce the bandwidth usage is the usage of proxy servers. In this thesis, we evaluate custom-adapted prefetching policies that tries to improve the users Quality of Experience (QoE). Defining a prefetching policy for something adaptive as 360 video brings challenges that need to be simulated before release in the real world. Without proper testing the prefetch policy can do more harm than good by flooding the network with unnecessary amount of transmissions. Prior research has shown that the QoE of HTTP-based adaptive streaming (HAS) clients can be improved with content-aware prefetching (e.g., Krishnamoothi et al. 2013). However, there have been limited prior work adapting and evaluating such policies in the context of 360 streaming. This thesis presents a simulation-based evaluation of proxy-assisted 360solutions that includes custom designed prefetching polices. The main contributions of the thesis are as follows:First, we implement four types of proxy-assisted prefetching policies and simulate these under two scenarios with different networks conditions. One scenario simulate a network environment with a bottleneck located between the client and proxy while the other scenario simulates a network environment with the bottleneck located between the proxy and server. The cooperation between the client and proxy is evaluated for each scenario and prefetching policy. Second, we evaluate the proxy-assisted prefetching policies in comparison with baselines and each other, in regards of their ability to improve the viewers QoE. Our results show that the bottleneck location has major impact on proxy-performance and that simple prefetching policies can enable clients to download bigger loads of data, which have a significant effect on viewers QoE. Considering that 360 videos require much higher bandwidth then traditional video streaming, service providers may consider integrating prefetching policies for 360 video streaming.