Optimized network access in heterogeneous wireless networks

In Europe, 2nd Generation mobile communication networks including GSM as well as 2.5G systems like GPRS have achieved coverage close to 100 %. At the same time commercial wireless LAN installations based on 802.11 standards show up at hot spot locations in growing numbers while UMTS, the European 3G system, is being deployed. As a result a heterogeneous environment is created where potentially several radio access technologies could serve a user’s request. To benefit from this plurality the existing radio resource management has to be complemented by multi standard radio resource management (MxRRM) mechanisms that exploit the existence of alternative radio access technologies to improve service availability and quality of service. This thesis describes fundamentals for successful MxRRM considering circuit switched as well as packet switched services and discusses some possible algorithms including performance results. Two further topics being discussed are the use of diffuse infrared links in the field of wireless communication based on a new detector element, the Photonic Mixer Device, and the extension of cellular system by means of mobile ad-hoc relays.