 | Issue: | Africa and the Middle East 2005 |
| Article no.: | 11 | |
| Topic: | Video goes mobile – with DVB-H | |
| Author: | Johannes Hofmann | |
| Title: | Managing Director | |
| Organisation: | Rohde & Schwarz, Middle East and Africa | |
| PDF size: | 64KB |
About author
Johannes Hofmann is the Managing Director of Rohde & Schwarz for the Middle East and Africa. Mr Hofmann began working at Rohde & Schwarz in Cologne after having served in the German Air force for six years. During his first years of employment at Rohde & Schwarz, he was promoted to Head of Training for the operation, maintenance and repair all Rohde & Schwarz products. He then moved to Munich where he became Managing Director for Sales for the Middle East and Africa. During the last years he has concentrated his activities on Africa. Mr Hofmann was educated in Cologne, Germany, as a radio and TV Technician. He has also studied Parallel Mathematics at the University of Hagen.
Article abstract
The new DVB-H digital TV standard enables efficient transmission of multimedia content to mobile receivers. DVB-H combines video broadcasting with mobile radio for mobile phone reception. The upgrading of many African analogue broadcast systems to mobile compatible DVB-H digital broadcasting is often quite cost effective. Since DVB-H program content originates as an IP data stream, it is compatible with modern, Internet-enabled mobile phones. DVB-H broadcasts data packets sent in short bursts and the consequent energy consumption of user equipment is low.
Full Article
The new digital TV standard – DVB-H, an expansion of DVB-T – enables you to efficiently transmit multimedia content to mobile receivers. In Europe, DVB-H is already in use and multimedia reception is already a reality. Many European countries will have fully digital broadcasting networks by 2010, after which most analogue networks will be shut down for good. Africa may also take the same path. Numerous high-power analogue TV transmitters that can be easily upgraded to digital (and to DVB-H) have already been installed in South Africa, Ghana, Nigeria, Egypt and Morocco. Several DVB pilot projects are already underway in Africa according to manufacturers of broadcasting and test and measurement equipment for digital TV. Mobile radio and television are converging Digitisation is making it all possible. After maintaining separate lives and development tracks over the decades, some services and technologies are now finding themselves face to face at the bit and byte level. This convergence is the driving force behind many new products, markets and business models. One prime example is the convergence of mobile radio and television. Here, the catch phrase is “DVB-H”. These two worlds coexisted before with practically no contact, but DVB-H is bringing them together in terms of culture and technology. This can be a trying process, but suppliers have expert knowledge of the technologies and experience with what is needed and expected in both camps: a wide range of technical solutions that will be useful in implementing new products and services in the future. The best of both worlds If you are new to DVB-H, get ready to cope with two different cultures: broadcasting and mobile radio. Each has its own traditions, technologies, terminology and market structure. In cross-cultural situations of this kind, you need a “bilingual” partner who can provide the necessary translation services and who offers a complete portfolio of equipment for both sides of the DVB-H equation. During decades of experience in the fields of mobile radio and broadcasting, pioneering and reference solutions have been developed which will simplify the coming merger of these two seemingly quite different fields. Video goes mobile The mobile radio industry and broadcasting network operators want to increase their offerings of multimedia content such as TV and video streaming for mobile receivers. DVB-H is ideal for this purpose, since data is not broadcast continuously, but rather bundled in data packets using IP encapsulation and sent in short bursts. This keeps the energy consumption of user equipment (UE) low. Owing to this timeslot technique, the UE can switch off between data packets, thus saving up to 90 per cent in energy. Additional error correction at the IP level (MPE forward error correction) improves reception quality even in the event of high packet loss. DVB-H, in addition to the modulation modes that are commonly used with DVB-T, offers an additional 4k modulation mode. This compromise between 8k, with its limited speed and large single-frequency networks or SFNs, and 2k, with its very high speed, small SFNs, ensures stable mobile reception even when the speed is very high. Transmission parameter signalling (TPS) bits signal whether the receiver uses DVB-H features and which ones. Implementation of DVB-H networks There are several scenarios describing how DVB-H networks may be implemented. Combined DVB-T/DVB-H networks are especially useful for initial implementations where cost-efficiency is highly important. In such cases, DVB-H services are implemented using the existing DVB-T networks (see Figure 1 – Playout center). Initial DVB-H pilot projects have already been started in various countries, frequently by making existing products compatible with DVB-H. From DVB-T to DVB-H Making DVB-T mobile and Internet-compatible DVB-H is an adaptation of the digital terrestrial TV standard DVB-T – which has enjoyed great success worldwide – to the requirements of mobile applications, particularly using battery-powered handheld equipment. The following were the development objectives pursued, and achieved, with DVB-H: √ Use of Internet technology: DVB-H program content is fed to the playout center in the form of an IP data stream. There, it is transformed into an MPEG-2 transport stream or, in the case of mixed DVB-T and DVB-H operation, mixed with the transport stream for “normal” TV programmes. IP-based video streaming can be implemented relatively easily and cost-effectively using streaming servers. Modern mobile phones make use of TCP/IP protocol stacks that allow direct processing of IP packets; √ Low power consumption: one of the greatest challenges when building battery-powered user equipment is how to extend the amount of time the device can run on a single charge. Video applications tend to be particularly power-hungry. In the case of DVB-H, the solution has been to employ the familiar timeslot technology used by such mobile radio standards as GSM (see Figure 2). Using the timeslot technology, data is not transmitted continuously, but as a series of bursts. During the pauses in transmission, while data is being transmitted for other DVB-H users, the mobile phone can turn off parts of its circuitry and save quite a bit of energy. These pauses are also useful for handling handover procedures; √ Reliability of transmission: although DVB-T was designed with mobile applications in mind, further measures have been taken with DVB-H to ensure reliable reception and good performance even in vehicles moving at high speeds. This includes forward error correction (FEC) and an additional type of modulation (4k mode). All of these measures are specified in the DVB-H standard, but the details of the implementation are left open. In the simplest case – with no time slicing, no FEC, no 4k mode – this means that DVB-H and DVB-T use an identical transmission method. Only time will tell which of these configurations will ultimately be the most practical and popular. Retrofitting DVB-T broadcast equipment is easy The embedding of DVB-H program content in the DVB data stream, and DVB-H signalling, are handled independently of the transmission method. A graphical representation of a playout center for combined DVB-T/H operation shows where DVB-H-specific extensions are required (see Figure 1).
