Convergence of Digital TV Systems and Services

The migration from analog to digital of the broadcasting technologies, already well consolidated for satellite systems, is becoming a reality also for terrestrial transmission. Digital Terrestrial Television (DTT) is also evolving to offer interactive services and a degree of flexibility which can be exploited to offer tailored applications to users which include, for instance interactivity, different levels of personalization, and innovative location-based, as well as context-aware, services. A clear example of this trend is given by the rising success of the Internet Protocol Television (IPTV) which allows for a degree of flexibility on offered services unknown to the traditional broadcasting systems. In this framework, several satellite operators are starting to launch IPTV services using direct satellite links, as well as some terrestrial internet service providers are offering digital TV channels embedded in the IP streaming over XDSL. Furthermore, IPTV services are likely to be broadcast also wirelessly, exploiting advanced broadband access technologies such as WiMAX, LTE, or LTE-A. Last, but not least, TV and broadcast services for mobile users have also been deployed in many countries using DVB-H and will be soon available on an even broader scale thanks to its satellite counterpart, DVB-SH. In the near future, a set of different technologies able to offer personalized and customized services to different classes of users are expected in the area of wireless broadcasting and convergence of technologies is auspicious. This concept entails different levels of convergence, namely, at terminal level (one device fits all), at service level (convergence of traditional fixed, mobile, and broadcast services), and at transport and network level with a common and standardized set of protocols and at access layer thanks to the harmonic coexistence of different radio technologies. This special issue aims to capture the state-of-the-art research work concerning the integration of DTT/Satellite/IPTV systems for the broadcasting of multi-media and interactive services. There are very different directions in which researchers investigate new solutions in order to improve the quality of the rich media content delivered over various network types. In this context, this special issue illustrates some of these avenues and presents some of the most significant and promising results. Papers have been grouped into four thematic sections. The first section is devoted to Mobile Television and Interactive Multimedia Broadcasting Services. The first paper entitled " Converged digital TV services: the role of mid-dleware and future directions of interactive television " provides a brief overview of …