The detection of socialization events is useful to build indicators about social isolation of people, which is an important indicator in e-health applications. On the other hand, it is rather difficult to achieve with non-invasive solutions. This paper reports about the currently work-in-progress on the technological solution for the detection of socialization events adopted in the DOREMI project.

IoT and cloud represent the breakthrough for making concrete the envisioned scenarios for Smart Environments and specifically, those scenarios devoted to the human well-being. Under this respect, we propose a system focused on the quality of the environments where employees work with particular attention to the energy consumption. We describe a long-term monitoring system together with the Stigma algorithm designed to detect the presence or the absence of a worker by exploiting sensing information.

CORDIAL is a collaborative service discovery strategy designed for mobile and opportunistic networks, which takes advantage of some features of human behavior, namely the periodicity of movements, the membership to a restricted number of communities and the sharing of interests among members of a community. CORDIAL exploits these features by adapting the strategies of query and service advertisements by exploiting the cooperation of nodes with higher social centrality in order to improve the chance of finding the desired service. The evaluation of CORDIAL by simulation shows that, as compared with similar approaches, it improves proactivity and accuracy levels, and it reaches performance comparable to the flooding technique but at a much lower cost.

In this work, we discuss the two-ray radio propagation model when an UAV acts as a mobile node belonging to a ground wireless sensor network. Currently, UAVs are attracting attention in the market and in the research field, thus more accurate radio propagation models are needed to properly estimate

RSS-based indoor localization systems are widely accepted in the literature as one of the less invasive localization technique. In fact, this range-based approach does not require any special hardware and is available in most standard wireless devices. Furthermore, judicious use of RSS has not a significant impact on local power consumption, sensor size, and cost. In front of these interesting characteristics, the performance of the RSS approach is worst with respect to some more invasive ad hoc hardware range-based solutions (such as Angle of Arrival, Time of Arrival etc…). In this paper we propose a localization method that leveraging the context information, such as the knowledge of being in a given room, increases the localization accuracy of RSS-based methods. Performance evaluation is done via real measurements in an office environment composed of three adjacent rooms.

This study aims at summarising the work done in the SatNEx project for the development and the performance evaluation of a new access scheme for multimedia data transmissions in digital video broadcasting-return channel via satellite (DVB-RCS)/satellite second generation (S2), applied to a mobile environment. The work has been stimulating because, as far as the authors know, this research topic has not yet been fully addressed in the literature. The authors started thinking about a realistic scenario of mobility, where novel services could be offered; having defined the scenario, the authors developed a satellite access scheme suitable for transmission control protocol (TCP) sessions and video streams in mobility. In this study, the authors present the reference architecture, the access scheme, the choice of the most suitable transmission parameters and the simulation results that are obtained when transmitting the two different types of data.

Satellite link presents peculiar characteristics like no packet reordering and low bit error rate. In this paper we leverage these characteristics combined with watermarking techniques to propose a novel authentication algorithm for multicast video streaming. This algorithm combines a single digital signature with a hash chain pre-computed on the transmitter side; the hash chain is embedded in the video stream by means of a watermarking technique. Our proposal shows several interesting features: authentication is enforced, as well as integrity of the received multicast stream; received blocks can be authenticated on the fly; no storage is required on the receiver side, except for the amount of memory needed to store a single hash; overhead computations required on the receiver sum up to single hash per block, while a digital signature verification is amortized over the whole received stream. Finally, note that the bandwidth overhead introduced is negligible, since the applied watermarking technique introduces virtually no modifications (at least, not recognizable by humans) on the original video stream pictures.

The goodput of long-lived TCP connections can be maximized in error-prone channels by trading bandwidth for Bit Error Rate (BER). This fact can be exploited in the bandwidth and transmission parameters' assignment, by means of Adaptive Coding and Modulation (ACM), in satellite systems; in such a case, multiple source- destination (SD) pairs actually "see" channels with diverse characteristics, owing to unequal weather conditions. However, when dealing with multiple SD assignments, both aspects of goodput-maximization and fairness must be dealt with. Improving the effectiveness of TCP may be relatively easy, but maintaining the effectiveness while maintaining the fairness is a challenge. The paper numerically analyzes the fairness behavior of two bandwidth allocation methods to TCP connections, experiencing diverse fading conditions.

The TCP efficiency degradation in high delay- bandwidth product and error-prone channels is a well-known problem. To reduce this degradation, we utilized a hybrid wireless network architecture, where a geostationary bent-pipe satellite channel is used for forward high bit-rate transmissions, while the return link is realized through a terrestrial 3G segment. The performance of four of the most popular TCP versions are tested and compared via simulations in terms of goodput. Our aim is choosing which version performs better by using an Adaptive Coding and Modulation (ACM) technique, both alone and together with an Automatic Repeat reQuest (ARQ) scheme of the Selective Repeat (SR) type. ARQ is used with and without transmit and receive timeouts. The obtained results show that such a hybrid architecture is advantageous for TCP transmissions in terms of average goodput, and that ACM is effective only if used together with ARQ schemes.

Video-coding techniques that are widely used in videoconferencing and streaming applications over the Internet may face degradation in performance when traversing satellite channels. The aim of the present paper is to provide objective measurements of the quality of video-encoded sequences for two of the most popular video coders in this setting [namely, H.261 and moving picture experts group (MPEG)-2], after transmission over faded satellite channels. In particular, the emphasis is on the Ka band, which is becoming an attractive alternative for commercial applications but is more prone to quality degradation than the currently widely used Ku band. In order to test the behavior of the coders in repeatable experimental conditions and over different data link platforms, two transmission chains have been implemented in the laboratory by careful emulation of the required environment. The data link layer has been based on HDLC-like and direct video broadcasting protocols, respectively. The experiments have been performed in the presence of additive white Gaussian noise (AWGN) and by using fading patterns derived by real-world data. The results obtained highlight some often neglected aspects in the behavior of the coders under examination, both in relation to their comparative performance and to their adaptability to different underlying data link protocols.

This paper shows how the adoption of a dynamic rate shaping (DRS) to variable bit rate (VBR) MPEG-2 (Motion Pictures Expert Group-2) coded video data, in addition to different levels of data protection, adds more flexibility in the way a video data stream can be sent over a faded satellite channel. DRS allows the satellite bandwidth required to be continuously trimmed, within a certain range. Also, some bandwidth can be saved when the video quality is maintained as close as possible to a required level during changing fade conditions. The performance of DRS applied to a VBR MPEG-2 coded video stream is shown. An application of this technique is discussed, and some criteria are given which help the user to choose the most suitable way to send video coded data, according to the service quality requirements.

A description is given of FODA-TDMA (FIFO ordered demand assignment-TDMA), a satellite access scheme designed for mixed traffic (patent N. 9373A/89). The study of the system is presented and the choice of some parameters is justified. A simplified analytic solution is found, describing the steady-state behavior of the system. Some results of the simulation tests for an already existing hardware environment are also presented for channel speeds of 2 and 8 Mb/s, considering both the stationary and the transient cases. The results of experimentation at 2 Mb/s on the EUTELSAT-F2 satellite are also presented and compared with the results of the simulation.>

STELLA (Satellite Transmission Experiment Linking Laboratories) is a European wide-band data transmission experiment. STELLA makes use of the European Orbital Test Satellite (OTS) which provides a 2 Mb/s broadcast data transmission channel. The first phase of the STELLA project (STELLA/I) is summarized. The more important design characteristics of an improved version (STELLA/II) of STELLA/I are emphasized. Collaboration between STELLA/II and UNIVERSE projects in the framework of COST-11Bis is then outlined.