 system for the delivery of digital content and services using IP-based mechanisms to handheld devices. An inherent part of the IP Datacast system 7 SFN is a broadcast network where several transmitters simultaneously send the same signal over the same frequency channel. Next Generation Mobile Communications Ecosystem Air Interface Interactive Network Service Content Service Creation Application Manage- Terminal Broadcast Network Figure 9.12 IPDC reference architecture. Reproduced with permission from Kornfeld and May C is that it comprises a unidirectional DVB broadcast path that may be combined with a bidirectional mobile/cellular interactivity path. IP Datacast is thus a platform that can be used for enabling the convergence of services from broadcast/media and telecommunications domains (e.g., mobile/cellular) as shown in Figure 9.13 [17]. 9.12.2.3 DVB-SH It would be unfair if we didn't discuss DVB-SH following DVB-H. DVB-SH is the name of a transmission system standard designed to deliver video, audio and data services to vehicles and handheld devices. The key feature of DVB-SH is that it's a hybrid satellite and terrestrial system that allows the use of a satellite to achieve coverage of large regions or even a whole country. In areas where direct reception Broadcast Service DVB-H Provider Transmitter Broadcast Operator DVB-H Mobile Mediation Terminal Platform Interactive Mobile Operator Network Internet Radio Service Access Network Provider Network Figure 9.13 Cellular and broadcast (DVB-H) systems convergence via IPDC. Reproduced with permission from Reimers C 2006 IEEE [17] IMS, Services and Applications of the satellite signal is not possible, terrestrial gap filler can be used seamlessly to provide coverage. It is designed to use frequencies below 3GHz, typically around 2.2GHz. The system and waveform specifications have been published as ETSI standards (TS 102 584, TS 102 585 and EN 302 583) [22]. 9.12.2.3.1 Technical Overview Like DVB-H, DVB-SH is also based on OFDM, but at the same time it introduce