Zero clients are hardware-based devices without a central processing unit (CPU) that deliver virtual desktops (VDs) from remote computing systems to users. We measured the performance of applications accessed through zero clients to study the feasibility of using this approach to provide a desktop-pc experience across a network. Performance evaluation is complicated because monitoring software cannot be downloaded to the zero clients. Therefore, we introduce a new methodology and metric to measure zero-client VD performance that is based on network-traffic analysis. We conducted objective and subjective studies to determine the sensitivity of application-specific metrics to different network conditions. The results show that the packet loss rate (PLR) impacts zero-client performance for some applications such as video streaming. Subjective tests showed a greater user sensitivity to the PLR for video streaming than for image viewing or Skype. A strong correlation was found between the objective and subjective measurements but the rate at which these measurements changed with increasing PLR differed depending on the application. INDEX TERMS Edge-cloud, measurements, objective study, QoE, remote desktops, subjective study, VDI, VDI metrics, virtual desktops, zero clients. I. INTRODUCTION Virtual-Desktop (VD) technologies have been growing in popularity as several remote desktop tools, such as VNC, Microsoft Remote Desktop Services (RDS), and TeamViewer, have been developed to support this paradigm. Remote desktop clients have been implemented in custom Application Specific Integrated Circuits (ASICs) or Field Programmable Gate Arrays (FPGAs). For example, Teradici Tera2321, is used in equipment called zero clients, which include interfaces such as USB, DVI, and HDMI ports to connect keyboard, video, mouse (KVM) terminals, and an Ethernet port for network connectivity. Zero-client hardware has primarily been developed for enterprises, with each user being supported by one Virtual Machine (VM) in an edge-or commercial-cloud host. Thus, zero clients are used in schools, hospitals, libraries, and businesses [1]-[4]. Zero clients have also been used for highperformance graphics applications to allow multiple users to share the more expensive processing engines [5]. Graphics applications frequently exploit co-location of zero clients The associate editor coordinating the review of this manuscript and approving it for publication was Haibo Wu.
