As mobile IP-access is becoming the dominant technology for providing wireless services, the demand for more spectrum for this type of access is increasing rapidly. Since IP-access can be used for all types of services, instead of a plethora of dedicated, single-service systems, there is a significant potential to make spectrum use more efficient. In this paper, the feasibility and potential benefit of replacing the current terrestrial UHF TV broadcasting system with a mobile, cellular data (IP-) network is analyzed. In the cellular network, TV content would be provided as one of the services, here referred to as CellTV. In the investigation we consider typical Swedish rural and urban environments. We use different models for TV viewing patterns and cellular technologies as expected in the year 2020. Results of the quantitative analysis indicate that CellTV distribution can be beneficial if the TV consumption trend goes towards more specialized programming, more local contents, and more on-demand requests. Mobile cellular systems, with their flexible unicast capabilities, will be an ideal platform to provide these services. However, the results also demonstrate that CellTV is not a spectrum-efficient replacement for terrestrial TV broadcasting with current viewing patterns (i.e. a moderate number of channels with each a high numbers of viewers). In this case, it is doubtful whether the expected spectrum savings can motivate the necessary investments in upgrading cellular sites and developing advanced TV receiver required for the success of CellTV distribution.
Using LTE technology to provide over-the-air TV service has been proposed in @cite_32 as a 'tower-overlay' system, where the DTT network employs a modified LTE standard for broadcasting TV content to both mobile and fixed reception. Recent studies have considered using not only LTE technology but also cellular infrastructure for providing TV services. In @cite_23 , the amount of spectrum needed for delivering today's over-the-air TV service is calculated by taking different cities in the USA as reference. Its focus is limited to densely populated (urban) areas where typical inter-site-distance (ISD) of cellular networks is smaller than 2km, which ensures good performance of the eMBMS network. Larger ISD which is typical in rural areas would considerably degrade the spectral efficiency of the SFN due to the long propagation delay as shown in @cite_2 , thus requiring far larger amount of spectrum to provide the same service. Therefore, it is not evident that replacing DTT service with mobile networks is feasible based on the results from urban scenarios alone. Besides, the possibility of employing unicast for less popular TV channels is not exploited in this analysis, although it may reduce the spectrum requirement as indicated by results from earlier studies.
@cite_32 @cite_23 @cite_2
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Wide-spread provisioning of TV services has strongly shaped the cultural development since the last century; terrestrial radio broadcast transmission has been the original form of TV distribution. Although the majority of TV reception is today based on alternative distribution means, like cable or satellite, TV broadcast enjoys still a significant amount of allocated terrestrial spectrum (∼300 MHz). However, it has been identified that TV broadcast does not efficiently use its allocated spectrum. At the same time, other spectrum users like mobile communication systems experience a tremendous growth and demand for spectrum. The scarcity of radio spectrum has led the US FCC rule that additional 500 MHz of spectrum are to be identified for mobile broadband systems in the next decade — out of which 120 MHz are to come from the TV band in the next 5 years. In this paper we identify an alternative transmission architecture for TV distribution based on cellular LTE MBMS, with densely placed low-power transmitters that transmit in a synchronized single frequency network. It is demonstrated that in this way a full frequency reuse at all sites is possible, in contrast to the large reuse distances in high-power high-tower TV transmission. As a result, we show that it is possible to support TV services with 84 MHz of spectrum via LTE MBMS, in contrast to the 300 MHz used by today's ATSC TV broadcast system. This approach can be realized in a cost-effective manner by re-using existing mobile network infrastructure and we also show that the total radiated power can be decreased. TV is regarded as a key service for mobile devices. In the past, Mobile TV was often associated with broadcast transmission. However, unicast technology is sufficient in many cases, especially since mobile users prefer to access content on-demand, rather than following a fixed schedule. In this paper we will focus on 3G mobile networks, which have been primarily optimized for unicast services. Based on a traffic model we will discuss the capacity limits of 3G networks for unicast distribution of Mobile TV. From the results it can be concluded that the capacity is sufficient for many scenarios. In order to address scenarios in which broadcast is a more appropriate technology, 3GPP has defined a broadcast extension, called Multimedia Broadcast Multicast Service (MBMS). MBMS introduces shared radio broadcast bearers and has thus the capabilities of a real broadcasting technology. We will give a short overview about MBMS including a discussion on MBMS capacity. Since MBMS is primarily a new transport technology, additional application and service layer technologies are required, like electronic service guide and service protection. These mechanisms are standardized by the Open Mobile Alliance (OMA) and are favorably combined with MBMS or 3G unicast distribution in order to create complete end-to-end solutions. In order to optimize a system for delivery of broadcast services over 3G networks, the advantages of broadcast and unicast should be combined. We argue that hybrid unicast-broadcast delivery offers the best system resource usage and also the best user experience, and is thus favorable not only for broadcast delivery in 3G networks, but actually also for non-cellular broadcast systems like DVB-H or DMB