Chapter 2: Trends Towards Mobility 35 technical areas where cellular has an edge over WLAN (for instance, roaming, charging, and power economy), but for many people WLAN seems to be good enough, at least in urban areas. In the longer term, as all networks converge towards IP protocols, there will be less differences between the various access technologies. WLAN, Wimax, GSM, 3G, and other mobile networks can simply be different ways of connecting to the Internet, the mother of all networks. Well, almost all networks. Except maybe for broadcast TV. 2.6.1 Broadcast Networks Traditional radio and TV networks were designed for the broadcasting model: one source, millions of viewers. The Internet is inherently a many-to-many network, and not ideally suited for mass distribution of broadcast content. For that, it is more economical to use satellites that beam down DVB (digital video broadcast) content. In existing urban areas it is enticing to use the existing TV cabling and terrestrial trans- mitters – and even phone lines. Granted, countless Internet-based casting stations exist, for instance, for the popular Internet radio. However, there the infrastructure is not currently benefi ting of the economy of distributing the same content all over the network. Instead, individual users get their own data stream 20 that is not shared with other users. This does not matter with small numbers of users, but becomes an issue when millions subscribe to the same content. However, it is another matter altogether about what will happen to broadcast media in the longer term. It is possible that broadcasting networks will mutate and join the stream of other Internet data. Mobile TV is now being piloted around the world. Digital TV receiv- ers are being embedded in mobile phones (such as Samsung SGH-910 in Figure 2-8). One of the standards, DVB-H, uses essentially the same MPEG coding technology as satellite TV, but the transmission chain has been modifi ed for mobile terminals. The design allows adaptation into the various quirks of mobile radio links, such as multipath fading and Doppler effects, to name but two. In particular, the content can be economically received with relatively low energy consumption, which, we repeat, is crucial for mobile phones. As the mobile TV pilots are just starting, mass adoption of this tech- nology can be years away. However, from the consumer’s point of 20 Some peer-to-peer designs attempt to change this. It is currently too early to say if those approaches will fl y for broadcast TV.