Thomas Lauterbach

Using DAB and GSM to Provide Interactive Multimedia Services to Portable and Mobile Terminals

The objective of the MEMO project is to design, integrate and operate applications which utilise interactive DAB services, i.e. combining the existing GSM mobile telecommunications network and the Digital Audio Broadcasting system. A first trial with this platform for mobile multimedia services was performed to demonstrate the results achieved after one year of work and cooperation of the European partners involved. The MEMO architecture comprises DAB transmitter equipment and PC-based terminals. During the specification of the first generation prototype and the software/hardware development the following results were achieved: Infrastructure and transmitter equipment (Specification and implementation of a protocol for information interchange between contents providers and the DAB network; design and implementation of the multi-network server (MNS) with an interface to the DAB-network-server (DNS) to feed the DAB transmitter; set-up of a DAB test transmitter at CCETT, Rennes; specification of a protocol for broadcasting Multimedia data on DAB) and Terminal (development of prototype DAB receivers with a data interface and PC plug-in card, notebook PCs and interface equipment to connect the PCs to the DAB receiver for data transfer at data rates up to 256 kbit/s; implementation of the GSM interaction channel between the mobile terminal and the MNS; definition and partial implementation of Application Programming Interfaces (APIs); development of terminal software for the network/system/application service layer and adaptation of publishing and construction industry applications to demonstrate mobile, interactive services). For the trial, the transmission chain from GSM request to DAB download was successfully completed and operated, including the connection between information provider and network operator. Three interactive applications were implemented and tested — a specialised software for the building construction industry, a system to download issues of a newspaper and a general software to transmit data objects — representing the contrary edges of services MEMO is targeting. Thus, the approach of interactive mobile services at high data rates was presented for the first time to potential customers and users providing valuable results.

Mobile Reception of Digital AM Audio and Data Services Using Long-Range Skywave Propagation

Digitization of AM radio systems promises a revival of the currently underutilized broadcasting bands below 30 MHz. Its prospects are near-FM sound quality, automatic tuning, and interference-free reception. Using skywave propagation in some of the bands, a potentially very large area can be covered by a single transmitter if the appropriate frequency and power are chosen. In this paper, we compare mobile and stationary reception at various frequencies, investigate the correlation between solar sunspot activity and reception quality, and analyze how non-audio data service can efficiently be broadcast with digital radio systems in the AM bands. Restrictions regarding the antenna size together with varying ionospheric conditions and and man-made noise make the reception of radio transmissions below 30 MHz in a car a challenging problem. Using the Digital Radio Mondiale (DRM) system, a total of 58 measurements were conducted both in rural and urban environments in fall 2005, most of them in the 49 m, 41 m and 17 m short wave bands, but also in long wave and medium wave bands. A stationary reference receiver recorded data of the same transmission in parallel with the mobile measurements. Comparison of both data sets allowed for a detailed analysis of the impact of mobility on the reception quality. The results show that particularly in rural areas, mobile reception is indeed reliable and perceived as high quality. Only when ionospheric disturbances push signals to just above the required Signal-to-Noise Ratio (SNR), in-car reception fades more frequently than at a stationary receiver. In urban and industrial areas, shadowing effects (tunnels, large buildings) and man-made noise (power lines, etc.) cause even more frequent dropouts. Thus most of the problems known from analog AM reception in cars will remain the same for digital broadcasting. However, where it works, the digital audio quality is clearly superior to that of analog AM. Therefore, we believe that digital radio in the AM bands is a valuable complement to other digital broadcast services, e.g. by augmenting their coverage in rural areas, where network deployments for higher frequencies may economically not be feasible. Further, the data features-although limited-make digital broadcasting in the AM bands an interesting candidate for telematics and traffic information services covering very large areas.

Multimedia broadcasting to mobile, portable and fixed receivers using the Eureka 147 Digital Audio Broadcasting system

The Digital Audio Broadcasting (DAB) system developed within the Eureka 147 project is well adapted to the requirements of broadcasting audio, programme associated data and general data including, e.g. video, still images and coded traffic messages. The configuration of the DAB multiplex (i.e. data rates and error protection of the different applications) is flexibly adjustable. Having evaluated the performance of DAB data channels in typical mobile reception situations, we conclude that the system will allow multimedia services to be reliably broadcast to mobile, portable and fixed receivers. To demonstrate this capability of DAB, we set up and operated experimental low bitrate video and still image transmissions associated with audio programmes.

Diversity reception for digital audio broadcasting

Antenna Diversity is a method to improve the reliability of DAB reception in mobile environment leading to less spots with undesired audio interruptions and increased coverage areas.