PNCTS: A Prediction and Network Coding-Based Transmission Scheme for Efficient Screen Updates Delivery in DaaS

Abstract

Desktop as a Service (DaaS) provides users with flexible, customizable and highly secure cloud based virtual desktop access. As the major carrier of execution results in DaaS, screen updates play an important role in users’ quality of experience. In order to bring users the same feelings like manipulating a local device, timeliness and reliability should be balanced. However, a timely but unreliable transmission scheme (i.e. UDP) or a completely reliable transmission scheme (i.e. TCP) is inappropriate for such a transmission scenario, especially under a high-loss network. In this paper, we propose a Prediction and Network Coding based Transmission Scheme (PNCTS) for efficient screen updates delivery in DaaS. As an end-to-end partially reliable transmission scheme, it prioritizes different data obtained by partitioning screen updates and employs network coding and TFRC (TCP Friendly Rate Control) to compensate for data loss and adjust the sending rate of screen updates, respectively. To reduce the overhead of network coding, PNCTS uses a Hidden Markov Model to predict the reliability level of network and makes different encoding strategies for the data with different priorities. Simulation results show that PNCTS can improve display quality and instantaneous goodput effectively while maintaining end-to-end delay and jitter at a relatively low level under the static and time-varying network conditions.