chapter  6
Mobile TV Using 3G Technologies
Pages 40

It began with the 2.5G networks such as GPRS, EDGE, and cdmaOne in the late 1990s as a service for streaming of short clips. The operators had upgraded the networks from pure voice to being data capable. cdmaOne and GPRS users had “ always-on ” connectivity using packetswitched connections. The Wireless Application Protocol (WAP) was formalized and was intended to be the protocol of choice for accessing wireless applications over the air. However, in the initial period, at least, the data usage of the networks was limited. Internet access, though possible, had limited attraction owing to the tiny screens, limitations of keypads, and indeed of the cellphones themselves. Operators keen to derive maximum benefi t from the networks saw big opportunity in video streaming and music downloads just as was the case over the Internet.

The availability of highly compressed video clips under the new compression algorithms such as Windows Media or MPEG-4 and their progressive standardization under the 3GPP forum made it advantageous for mobile operators to leverage on the capacities for data in their networks and provide video clips. Many GSM-, GPRS-, and CDMA-based networks started offering the clip download services as well as limited video streaming. This was in no small measure facilitated by the increasing power of mobile phones for handling multimedia applications such as audiovisual content. The initial video streaming services were limited to small clips of, say, 30 sec and low frame rates of 7 – 15 fps. As the availability of handsets and the usage grew, the 2.5G networks were already straining the limits of their capacity in terms of streaming or downloading video to a large number of users, and the limitations were quite obvious in the form of frozen frames and interrupted video viewing, as average bit rates on 2/2.5G connections averaged 40 – 50 kbps. This brought the focus back on the 3G networks, which were designed to have a greater capability for data.