No abstract

Recent communication improvements mainly target increasing bandwidth. However, high bitrate does not necessarily translate to a good Quality of Experience (QoE) for end users. Indeed, the Quality of Service (QoS) criteria that impact the QoE may differ according to the applications. For instance, a high latency impairs the QoE of web browsing users. Satellite networks effectively illustrate this principle. These networks offer major advantages: They can feed a very large number of users, propose a high bandwidth, and have low deployment costs. But they also have one significant disadvantage: Due to their location, users suffer a latency of around 500 ms (we focus on geostationary satellites in our study). This latency has a harmful impact in term of QoE. Satellite end users may be disappointed by their so-called high-speed Internet, when they experience a lack of responsiveness.The competition between the increasing number of over-the-top services has actually led to an escalation towards the best QoE. For these services, a massive use of content delivery networks (CDN) is unavoidable. Content delivery networks solutions mainly rely on caching the content as close as possible to the end user and redirecting users' requests. 1Taking into account CDN capacities in the field of communications satellites (satcom) is a necessary step to improve users' QoE. As we will see, this deployment can match the competitiveness of terrestrial networks. Therefore, we propose in this paper to deploy a CDN in a satellite network and to study its impact on the experience of the end users. We set the study in a backhaul context where the satellite may feed home networks (HNs) or 5G small cells. Although we discuss numerous questions about the location of caches, the targeted applications, the type of stored content or the caching policy, we choose to focus on a proof of concept through measures based on an open-source testbed (OpenSAND) and a real satellite system. The results highlight an increase in QoE for both web browsing and video streaming. Nevertheless, the transparent caching for video streaming over HTTP, ie, dynamic adaptive streaming over HTTP (DASH), may induce poor performances in some cases. Thus, we propose a solution to improve the transparent caching and address cache misuses. The contribution of this paper are summarised as follows:• We study the impact of the use of CDN on the QoE of satellite end users.• We run our evaluation on an emulation and a real satellite testbed to emphasise our conclusions.• We study several applications that reflect the current Internet usages (web browsing, video streaming and peer to peer [P2P]).• We successfully solve a misuse of caching detected during the evaluation.The remaining sections of this paper are organised as follows. In Section 2, we provide some background information and related work. Then Section 3 discusses the different solutions for deploying a CDN in a satellite context, and Section 4 presents the testbeds and the use cases that have been selected for this study. ...

This article proposes a discussion on the strengths, weaknesses, opportunities, and threats related to the deployment of QUIC end-to-end from a satellite-operator point-of-view. The deployment of QUIC is an opportunity for improving the quality of experience when exploiting satellite broadband accesses. Indeed, the fast establishment of secured connections reduces the transmission time of short files.Moreover, removing transport-layer performance-enhancing proxies reduces the cost of network infrastructures and improves the integration of satellite systems.However, the congestion and flow controls at end points are not always suitable for satellite communications due to the intrinsic high bandwidth-delay product. Further acceptance of QUIC in satellite systems would be guaranteed if its performance in specific use cases were increased. Based on an emulated platform and on open-source software, this paper proposes values of performance metrics as one piece of the puzzle. The final performance objective requires consensus among the different actors. The objective should at least provide acceptable performance for satellite operators to allow QUIC traffic but reasonable enough to keep QUIC deployable on the Internet.

Abstract-Unequal protection mechanisms have been proposed at several layers in order to improve the reliability of multimedia contents, especially for video data. The paper aims at implementing a multi-layer unequal protection scheme, which is based on a Physical-Transport-Application cross-layer design. Hierarchical Modulation, in the physical layer, has been demonstrated to increase the overall user capacity of a wireless communications. On the other hand, unequal erasure protection codes at the transport layer turned out to be an efficient method to protect video data generated by the application layer by exploiting their intrinsic properties. In this paper, the two techniques are jointly optimized in order to enable recovering lost data in case the protection is performed separately. We show that the cross-layer design proposed herein outperforms the performance of hierarchical modulation and unequal erasure codes taken independently.

Offering seamless connectivity for Next-Generation Internet (NGI) services has become a widespread concern to achieve global sustainability goals. In this position paper, we focus on the design of a smart connectivity platform that can extend its capabilities beyond the boundaries of what today's 5G architecture can support. The proposed platform encompasses and integrates a wide range of technologies, spanning from Non-Terrestrial Networks, NTNs (GEO/LEO satellites, and airborne) to terrestrial cellular 5G and long-range low-power Internet of Things (IoT) networks. We enhance 5G technology with novel network architectures and network intelligence to meet coverage and capacity requirements; and by strengthening infrastructure management and control components with autonomous capabilities to decouple operational costs from growth in network traffic, cloud computing, and IoT. Finally, we discuss the technical, commercial and market challenges that need to be overcome before the commercial deployment of the designed platform becomes reality.