Chapter: Wireless Propagation Channels
Contributed by Peter E. Leuthold and
Modelling of indoor radio channels in the UHF, SHF and EHF range is a key issue for the design of modern wireless local area communication systems. Stochastic radio channel models (SRCM) reveal to be advantageous compared to other simulation schemes. In order to calculate the parameter set of the different target functions for the random variables in the SRCM, i.e. path loss, path delay, incidence directions and Doppler shift of the wave components, the measurement of the complex channel impulse response of the dominant paths is needed. A novel channel sounder concept based on optical millimeter wave generation has been developed to solve this problem at extremely high frequencies. Mathematical methods suitable for the extraction of important parameters from the measured data are discussed briefly.
This contribution gives some insight into the research activities in wireless indoor communications at the Communication Technology Laboratory of ETH Zurich. It deals with the indoor SRCM as a parametric model and describes the way how to acquire the appropriate parameter set. The second section presents the dependence of the model scheme on various effects of the operation scenario, dispersion and transceiver characteristics and considers the possibilities of reducing the model complexity. Subsequently, the model parameters being random to some extent and the relationship to the previously mentioned physical and technical influences are explained. The third section introduces a novel channel sounder concept based on optical millimetre wave generation which permits the measurement of the complex envelopes of the impinging waves and deals with the mathematical problem how to extract significant parameters, e.g. complex amplitude, path delay, incidence direction etc.