34 Demonstrators and testbeds

Since the establishment of the first point-to-point radio communication by GuglielmoMarconi in 1895, the complexity of communication systems has grown dramatically in the continuing search for higher system capacity, higher data rates, and bandwidth efficiency. Research in information theory and digital signal processing has been the foundation for the development of systems that are able to handle millions of users all over the globe. However, the enormous proliferation of systems such as GSM or IS-95 has only become possible through the additional significant advances in integrated circuits technology. The ability to integrate complex algorithms and systems in a small, low-power device at a reasonable price has been the key factor for the success of mobile communication. While modern ASIC technology allows for the integration of systems, the cost factor is largely dependent on the development effort and time to market. As systems become larger and more complex, the majority of the development effort is spent on its verification and performance analysis [1, 2]. With the necessity to introduce standards as the basis for enormous future development efforts, important decisions need to be made very early in the design cycle of a new system. At this point the actual implementation of a product is often not an immediate issue or might even not yet be feasible at reasonable cost. Erroneous decisions at this point can have significant impact on the success of a future system. An example of this is the introduction of HIPERLAN/1, where after many years of successful standardization, only one product came on the market, see http://www.proxim.com. At the time of standardization, it was believed that an equalizer would solve all observed transmission problems. Although equalizer algorithms are well explored in literature and showed very promising behavior in simulations, once the equalizer was to be implemented, the realization became very difficult. Particular solutions had to be investigated [3, 4, 5] in order to meet the stringent requirements, which finally turned out to be far too expensive to become a successful product.