Jörn Thielecke

Convergence of cellular and broadcast networks from a multi-radio perspective

The demand of both the new telecom industry and digital broadcasters for cost-efficient provisioning of mobile multimedia services faces the reality of scarce radio resources. Various digital mobile and broadcast radio technologies have been developed and specifically been optimized. However, existing and emerging multimedia services exhibit challenging requirements in terms of asymmetry, interactivity, real time, and multicast communication. This article describes an evolution of an IP-based infrastructure from todays networks toward a future multi-radio infrastructure, taking into account the implications on the end-user terminal. This multi-radio infrastructure enables the cooperation of existing radio networks to combine their spectrum-efficient capabilities, whereby high-quality mobile multimedia services shall be provided. Furthermore, the need for dynamic allocation of spectrum to radio services is motivated. The basic functionality and architecture of a multi-radio system are outlined, with a special emphasis on cooperation between different radio systems. Also, an evolution path for the convergence of broadcast and new telecom is described, starting from todays systems and leading to a fully coordinated system.

Exploiting the data-rate potential of MIMO channels: multi-stratum space-time coding

There is a high potential with respect to Shannon capacity in having a multiple-input multiple-output (MIMO) channel. In this paper a new MIMO coding approach, called multi-stratum space-time coding (MSSTC) is presented The principle of MSSTC is to partition the data stream and to transmit the substreams on separate strata. The transmission on every stratum is based on space-time block coding (STBC) yielding full diversity. Orthogonal superposition of the strata results in independent transmit symbols and enables therefore a high data rate. Decoding may be done successively stratum by stratum yielding reasonable receiver complexity. The structural properties inherent in MSSTC make it a robust scheme for varying channel conditions. A Shannon capacity comparison to other MIMO schemes like V- and D-BLAST is presented showing the robustness of MSSTC in different environments.

Modulation for HIPERLAN type 2

Currently, standards for wireless multimedia communication with high bit rate in the 5 GHz band are being developed in the US, Europe, and Japan. The available user data rate for these systems is supposed to be significantly greater than 10 Mbps. The high data rate and the channel characteristics are the main challenges for the design of the physical layer and in particular the selection of modulation technique for such a system. In this paper two modulation techniques, single-carrier and multicarrier modulation (implemented by OFDM), are considered as candidates. Both techniques are introduced, individually optimized to some extent and finally compared with regard to link performance and other aspects like coverage and power consumption. It is shown that for the assumed conditions the addressed coherent OFDM scheme provides about 2-3 dB performance gain compared to single-carrier modulation as well as non-coherent OFDM.

Convergence of Broadcast and New Telecom Networks

The demand of the new telecom industry for cost efficient provision of mobile multimedia services is faced with the reality of scarce radio resources. The requirement of spectrum efficiency has driven the development of various digital radio technologies that have been optimized for specific services, namely for broadcast or for mobile communication. However, existing and emerging multimedia services exhibit challenging requirements in terms of asymmetry, interactivity, real-time, and multicast communication. This paper describes an IP based multi-radio infrastructure that enables the co-operation of existing radio networks to combine their capabilities to ensure a spectrum efficient provision of high-quality mobile multimedia services. Further the need for a dynamic allocation of spectrum to radio services is motivated. The basic functionality and the architecture of a multi-radio system is outlined, with a special emphasis on the cooperation between different radio systems. Further an evolution path for the convergence of broadcast and new telecom is desribed, starting from todays systems and leading to a fully coordinated system.