Measurement and modeling of wireless propagation channels for MIMO

Ernst Bonek
Retired from Technische Universität Wien, Vienna, Austria


Abstarct: The ultimate performance limits, as well as the performance of practical systems, of any wireless system is limited by the radio propagation channels that the system is operating in. It is thus critical that we understand the channel properties that are relevant for MIMO systems: directional and delay properties of the multipath components. Any such understanding must be based both on the understanding of the physical propagation processes and actual measurements; furthermore, it is very helpful to have good channel models that can be used to test the performance of algorithms and systems. These aspects will be treated in the tutorial.

We start out with an introduction of spatial sounding techniques that form the basis for spatial channel measurements and spatial channel characterization. We will present new measurement results of the directional channel properties as seen from the base station and from the mobile terminal jointly (double-directional propagation characteristics). Both indoor and outdoor scenarios will be treated. We will explain how these measurement results can be utilized and included in spatial channel models, which are required for the design and development of adaptive antenna and MIMO systems. A classification of MIMO models, including their “why?” and “for what?” will be given.

Then, the various methods to model the MIMO channel will be discussed. The relative merits and shortcomings of measurement-based stochastic models, relying on parameter estimation techniques; of geometry-based parametric models, approximating a radio environment by geometry, but adding stochastic processes; and of deterministic models (ray-tracing or measured) will be highlighted. Finally, a review on standardized MIMO channel modeling will be given. It includes the models of 3GPP/3GPP2 for outdoor environments, the IEEE 802.11n models for indoor environments, and the COST 273 model, which is valid for all environments.

Ernst Bonek was born in Vienna, Austria, 1942. He received the Dipl. Ing. and Dr. techn. degrees (with highest honors) from the Technische Universität (TU) Wien. In 1984, he was appointed Full Professor of Radio Frequency Engineering at the TU Wien. Since then, his field of interest has been mobile communications at large. Significant contributions concern the characterization of mobile radio channels and advanced antennas designs, mostly smart antennas. Altogether, he authored or co-authored some 180 journal and conference publications, and contributed to several books, “Wireless Internet Access over GSM and UMTS”, “Advances in UMTS Technology”, “Network Planning and Deployment Issues for MIMO Systems”, “Space-Time Wireless Systems: From Array Processing to MIMO Communications”, and “Adaptive Antenna Arrays. Trends and Applications”. He holds several patents on mobile radio technology. He is a former Chairman of Commission C “Signals and Systems “ within URSI (Union of Radio Scientists). Between 1997 and 2005 he was chairman of the "Antennas and Propagation" working group in the European research initiatives COST 259 "Wireless Flexible Personalised Communications" and COST 273 "Toward Mobile Multimedia Networks”.