Datacasting In The Mobile Environment

Datacasting employs the excess bandwidth from digital television signals for use in one-way data transmission, and it is being used successfully for high-speed downloads at fixed locations. There is considerable interest in extending datacast usage to mobile users, although there are reception challenges in the mobile environment that can significantly impact system performance. To explore the feasibility of using datacasting in this environment, datacasting receivers and data logging equipment were installed in emergency vehicles to record performance characteristics over a wide range of operational conditions. Summary conclusions from that study are described in this paper along with details about the network infrastructure and equipment used. Although datacasting provides only a downlink channel, it can be interfaced with other channels so as to form a twoway link. In the work reported here, datacasting was coupled with a broadband cellular channel to successfully provide a two-way data channel. It is important to note that this paper addresses the use of conventional datacasting, which is particularly sensitive to multipath interference. For example, conventional datacast reception is not possible when the receiver is in motion. Newer forms of datacasting that are less susceptible to multipath are currently under development and should be on the market in the near future. Consequently, some of the limitations of conventional datacasting reported here may not be factors with the newer versions of datacasting.