Efficient Transmission of Fixed / Mobile Services and Local Services in First and Second Generation Digital Terrestrial Television Networks
Jaime López Sánchez
The in-band provision of fixed and mobile services and the insertion of local services in Single Frequency Networks (SFN) are two key topics for the optimization of Digital Terrestrial Television (DTT) networks. On one hand, the transmission of mobile TV services requires the allocation of specific bandwidth and dedicated networks to achieve good coverage levels. The costs associated to the deployment of these dedicated networks and the lack of a successful business model have been the main causes of the failure of the first-generation mobile TV technologies. In this sense, the convergence of fixed and mobile paradigms can facilitate the introduction of mobile TV services by allowing the reuse of spectrum, content and infrastructure. On the other hand, neither SFN nor Multi Frequency Network (MFN) topologies used for the current DTT networks are ideally suited for delivery of both global and local services in an efficient way. MFNs enable the efficient transmission of local services but need a significant amount of frequency spectrum. Without violating the SFN principle, local services meant to address sub regions of an SFN must therefore be transmitted throughout the whole network, causing inefficient distribution of local services. Therefore, the efficient provision of global and local TV contents in SFN topologies allow saving bandwidth and guaranteeing an optimal use of the spectrum.