This study analyzes recent changes on the television (TV) market, and the transformation of TV consumption habits, motivated by new transmission and recording technologies. Through an international survey spanning 62 countries and 4 continents, a growing presence of nonlinear TV services and over-the-top (OTT) content offerings is found. A detailed taxonomy of ways of watching TV content on the TV set is proposed to clarify the existing Pay-TV and OTT services, including time-shift and videoon-demand (VoD) terms such as Pause TV, Start-over TV, personal video recorder, Catch-up TV, transaction VoD, and subscription VoD, to name a few. An in-depth literature review is conducted, focusing not only on the technological aspects of nonlinear TV, but also on its business and consumer behavior impacts. The existing research works clearly demonstrate a lack of global reach by mostly concentrating their analyses on specific regions or countries. In addition to the literature review, the survey and taxonomy definition, the impact of nonlinear TV on the complete supply chain is also extensively discussed, indicating structural changes not yet addressed in the current literature. B João Nogueira

As the interest on Network Virtualization continues to grow, so does the awareness of the many technical obstacles to transpose before the envisioned virtualized network environment may become a reality. A significant obstacle lies on the efficient assignment of virtual resources into physical ones. Performing the so-called mapping of a virtual network into a substrate network is a computationally intensive task, due to the dual optimization required for nodes and links placement. The purpose of this paper is to tackle this problem taking into consideration real-life scenarios of network operators, where the limitations imposed by the heterogeneity of the virtual and substrate networks must be accounted for. To that end, this paper proposes a heuristic algorithm for virtual resources mapping in the physical infrastructure that supports the heterogeneity of networks, in both links and nodes. The mapping heuristic was evaluated both through simulation and in a real experimental virtualization platform. Through the simulation results, it is shown that the mapping approach is able to embed a high percentage of the Virtual Network (VNet) requests respecting all links and node constraints. With respect to the experimental results, the proposed algorithm was shown to be fast, requiring a mapping time in the order of low tens of milliseconds, and linearly scalable with the increase in the number of existing VNets.