Exploding mobile wireless broadband services will propel digital broadcasting into a new era, according to network specialist Broadcast Australia. Driven by consumer expectations for next-generation services, including TV, on portable and mobile devices, savvy broadcasters will re-examine network design and operation.
“Our experience suggests that the future of TV viewing will incorporate an increasing range of portable and mobile devices, such as netbooks, high-tech phones and the new breed of low-cost portable TVs,” says Chris Jaeger, managing director of Broadcast Australia International Business.
“Almost every country in the world is experiencing the same massive uptake of mobile wireless broadband services. The average consumer will expect to have access to all multimedia and entertainment services just about anywhere. It also has the potential to introduce TV to a whole new range of viewers — particularly those in less-advantaged communities who can afford the new range of receivers, but also by virtue of exciting new digital content.”
Jaeger warns, however, that adequate network coverage is critical. “Mobile wireless broadband services are designed to penetrate buildings and are often carried by dedicated infrastructure indoors,” he says. “Conventional broadcast TV networks, on the other hand, are typically designed for fixed reception by an external antenna. If reception on a mobile or portable device is achieved in this environment, it is simply fortuitous.”
To address challenges such as reduced antenna height, building penetration, reduced receive antenna gain and higher required location availability, mobile TV trials have shown that field strengths need to be more than 30dB higher than in a fixed-reception environment.
According to Broadcast Australia, the most practical means of achieving this coverage is via a high-density distributed transmission network (DTN), a single-frequency network (SFN) comprising multiple low-power transmission sites that together provide consistently high signal coverage. Because an SFN network delivers signals from multiple directions, it increases location availability and reduces the impact of building clutter.
“There is also a very real argument for deploying SD and HD TV broadcast networks based on the same architecture,” Jaeger says. “This would allow anyone with an appropriate device to receive TV on their portable computers or other portable TV devices now becoming widely available at very low prices.”
A high-density distributed transmission network would also address other digital TV reception challenges, most notably reception in high-density living environments. Multilevel residential condominiums in cities such as Singapore and Hong Kong are typically serviced by master antenna TV systems, which need to be re-engineered to carry digital TV signals, and sometimes completely replaced at significant cost.
If residents could receive digital TV via simple “rabbit ear” antennas or USB receivers, expensive upgrades to master antenna systems wouldn't be needed. A study by Singapore Digital found that the cost to deploy a distributed transmission network in Singapore was less than a quarter of that of upgrading master antenna TV systems across the city-state.
“We are entering a new era of terrestrial broadcasting when the variety of ways in which TV is experienced is escalating dramatically,” Jaeger says. “Viewing habits are changing, and it makes sense to plan for a ‘next-generation’ transmission network that will satisfy all demands simultaneously.”
A distributed transmission network can provide a common network infrastructure for broadcasting HD and SDTV signals for fixed, portable and mobile reception, without the need for external receive antennas. This, Jaeger says, not only paves the way for portable and mobile TV, but will assist the TV broadcasting industry to keep pace with the dynamic services supported by mobile wireless broadband networks.
