We all know that Microsoft is working on a cloud based gaming service. Last year, they even demoed it during company meeting with a Lumia 520 Windows Phone device running Halo game from the cloud. Recently, Microsoft Research revealed their project DeLorean, which uses speculation to enable low-latency continuous interaction for cloud gaming.
Gaming is very popular. Cloud gaming – where remote servers perform game execution and rendering on behalf of thin clients that simply send input and display output frames – promises any device the ability to play any game any time. Unfortunately, the reality is that wide-area network latencies are often prohibitive; cellular, Wi-Fi and even wired residential end host round trip times (RTTs) can exceed 100ms, a threshold above which many gamers tend to deem responsiveness unacceptable.
In this paper, we present DeLorean, a speculative execution system for mobile cloud gaming that is able to mask up to 250ms of network latency. DeLorean produces speculative rendered frames of future possible outcomes, delivering them to the client one entire RTT ahead of time; clients perceive no latency. To achieve this, DeLorean combines: 1) future input prediction; 2) state space subsampling and time shifting; 3) misprediction compensation; and 4) bandwidth compression.
To evaluate the prediction and speculation techniques in DeLorean, we use two high quality, commerciallyreleased games: a twitch-based first person shooter, Doom 3, and an action role playing game, Fable 3. Through user studies and performance benchmarks, we find that players overwhelmingly prefer DeLorean to traditional thin-client gaming where the network RTT is fully visible, and that DeLorean successfully mimics playing across a low-latency network.
Read the full research paper here.