This paper proposes a quality of service (QoS) management framework for high throughput satellite (HTS) systems using extremely high frequency (EHF) frequency bands, which can achieve high capacity provided that feeder link outage events caused by severe weather conditions can be properly counteracted. To this regard, smart gateway diversity architectures implementing advanced gateway handover procedures are certainly attractive, although they can only partly mitigate the negative effects of adverse weather conditions in terms of packet losses, delays, and jitters, which significantly degrade the performance of delay-sensitive and delay-insensitive traffic flows. To cope with these technical challenges, we propose an incremental rerouting scheme to control congestion events because of capacity reduction during the transient phase, consisting of offloading high-priority QoS traffic flows from the affected gateway towards gateways operating in more favorable conditions. Moreover, we apply inter-flow network coding at the gateways to protect delay-insensitive flows from packet losses occurring during feeder link outage. Finally, extra capacity is reserved at the gateways to handle the additional traffic resulting from gateway handover. The theoretical analysis (validated by simulation campaigns) allowed characterizing network coding performance and confirming the potentialities of our QoS management framework for HTS systems.

This paper explores the network design implications to be taken into account in Smart Gateway Diversity (SGD) satellite systems, where gateway outage events have to be counteracted by efficient handover procedures. In more detail, enabling high data-rate satellite systems in these conditions requires efficient coordination strategies between gateways, upstream routers and Network Control Centre (NCC) to precisely estimate the need of handover and to efficiently manage the satellite resources. To this regard, this paper adopts a simple channel estimation algorithm and applies network coding to cope with packet losses deriving from possible inaccuracies on the prediction of the handover time. The results obtained via simulation confirm the capabilities of network-coding-based approaches and pave the way for further studies in the area of network for SGD satellite systems.

This paper focuses on geostationary satellite scenarios and investigates the performance of several Transmission Control Protocol (TCP) variants in a novel Performance Enhancing Proxy (PEP) architecture solution, whose added value is the use of network coding beneath the transport layer. Comparison of TCP New-Reno, Vegas, Scalable, CUBIC, Hybla, and HTCP and the cases where these transport protocols are used along with network coding is carried out by means of simulation campaigns. The obtained results show the potentials of the proposed network coding technique, resulting in the improvement of TCP connections performance in a wide range of channel conditions and the possible exploitation of future increase of the satellite link capacity.

The most widely used transport protocols (i.e, TCP and UDP) are not suitable for aeronautical services because of the reliability and strict transfer delay requirements that cannot be met by TCP and UDP in such environment. In this respect, the paper proposes a novel message-oriented transport protocol Reliable Aeronautical Services Protocol (RASP) enabling reliable aeronautical services. Simulation campaigns carried out in ns-2 show the superiority of RASP with respect to TCP in terms of end-to-end message transfer delay and number of performed retransmissions.

This work aims at introducing two novel packet retransmission techniques for reliable multicast in the framework of Instantly Decodable Network Coding (IDNC). These methods are suitable for order- and delay-sensitive applications, where some information is of high importance for an earlier gain at the receiver's side. We introduce hence an Unequal Error Protection (UEP) scheme, showing by simulations that the Quality of Experience (QoE) for the end-users is improved even without complex encoding and decoding.

Mitigation of Transmission Control Protocol (TCP) performance degradation over satellite has been extensively studied over the last two decades by the scientific community, which has come up with a large set of protocol and architecture solutions. This paper proposes a novel end-to-end (E2E) transport layer protocol, namely Advanced Transport Satellite Protocol (ATSP), which is built around consolidated control theory concepts already infused in Active Queue Management (AQM) control schemes. ATSP exploits the knowledge of the bandwidth allocated to each terminal, as available from the satellite network operator. Besides, the satellite network property of being completely under control allows the joint collaboration of sender, receiver and routers in order to acquire a complete knowledge of the network status and eventually optimize the overall performance. The performance analysis shows that ATSP achieves a fair bandwidth share for all the satellite users and outperforms TCP Hybla, which is optimized for satellite links, in terms of throughput.

In this paper, we propose a novel proxy caching scheme for video-on-demand (VoD) services. Our approach is based on the observation that streaming video users searching for some specific content or scene pay most attention to the initial delay, while a small shift of the starting point is acceptable. We present results from subjective VoD tests that relate waiting time and starting point deviation to user satisfaction. Based on this relationship as well as the dynamically changing popularity of video segments, we propose an efficient segment-based caching algorithm, which maximizes the user satisfaction by trading off between the initial delay and the deviation of starting point. Our caching scheme supports interactive video cassette recorder (VCR) functionalities and enables cache replacement with a much finer granularity compared to previously proposed segment-based approaches. Our experimental results show a significantly improved user satisfaction for our scheme compared to conventional caching schemes.

In this paper, we derive an analytical model for the evaluation of the performance of a Video on Demand (VoD) system. The model estimates the mean waiting time achievable by the Popularity-Aware Partial cAching (PAPA) algorithm from our previous work. Two approximation strategies are proposed for low computational complexity. Furthermore, we also consider the influence of a starting point shift on the quality of experience and combine the two factors into a universal user satisfaction metric. In order to find the relation between the two impairments, waiting time and starting point shift, sophisticated subjective tests are performed. With the final score model, a more comprehensive evaluation of the system can be obtained with very low computational complexity.