Reinhard Becher

Broadband wireless access and future communication networks

This paper presents a vision for wireless communication systems beyond the third generation, which comprises a combination of several optimized access systems on a common IP-based medium-access and core network platform. These different access systems will interwork via horizontal and vertical handover, service negotiation, and global roaming. The different access systems are allocated to different cell layers in the sense of hierarchical cells with respect to cell size, coverage, and mobility to provide globally optimized seamless services to all users. This vision requires extensive international research and standardization activities to solve many technical challenges. Key issues are the global interworking of different access systems on a common platform, the implementation of multimode and multiband terminals and base stations by software-defined radio concepts as well as advanced antenna concepts.

Decentralized software distribution for SDR terminals

This article describes a novel approach to downloading software in mobile networks. The motivation for a decentralized approach is to cut down the overall download time for all relevant terminals, thereby considering not just over-the-air distribution of software. This work is performed under the European Research project Transparently Reconfigurable Ubiquitous Terminal (IST-TRUST). In particular, we consider terminal-to-terminal upgrades, which must be realized in ad hoc networks or HIPERLAN/2, where a direct mode between terminals can be established. The concept can also be contemplated for base-station-centric networks. For a client-to-client upgrade new security problems are to be resolved, and a suitable security concept is described here. The security concept is independent of the network; that is, even in fixed networks a similar concept can be conceived. Basically, the decentralized concept is not restricted to mobile networks, but the procedures described are mobile-centric.