For the sake of new radio devices to conform to respective standards, implementing functionality such as cognitive radio, Long Term Evolution beyond 2x2, or Global Navigation Satellite Systems, a demand for extensive testing arises. A promising solution is the validation inside an Over-the-Air testbed that creates a virtual electromagnetic environment using wave-field synthesis. This paper analyzes the polarimetric accuracy of a wave field generated by a hemispheric (3D) antenna arrangement. As most radio devices have a flat shape (e. g. smart phones, tablets, compact cognitive radio antennas) or a metallic backplane along a defined surface, the complexity of the optimization problem can be reduced. Analyzing the wave-field synthesis accuracy, it has to be kept in mind that for most radio devices the signal-to-noise ratio is limited in a range between 0-30 dB, which indirectly defines the upper limits of the required wave-field synthesis accuracy

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This paper provides an overview of ongoing research in over-the-air (OTA) testing for next-generation communication and data transmission devices with special consideration of cognitive radio (CR). Existing state-of-the-art techniques and their merits and limitations are discussed. We identify the requirements and issues for the OTA test in a virtual electromagnetic environment (OTAinVEE) which needs to address the more complex scenario of future networks, where interference emulation becomes a highly challenging task. A complex interference scenario arises due to the attempt to simultaneously utilize several opportunity dimensions such as frequency, time, direction (space), and polarization, in a dynamic manner in a multiuser scenario. Although MIMO-OTA testing addresses many limitations of single antenna-conducted test systems, more dimensions and parameters to be addressed in the new scenarios imply further increase in cost and complexity. Closed-loop OTA test setups for CR evaluation are discussed along with an overview of other test scenarios.

With the development of advanced communication systems such as ITS-G5 (C2C, C2I), mobile, and in-car communication systems, more and more systems are operating simultaneously. To verify their reliability in a coexistence scenario, all systems have to be tested under realistic conditions. The so-called two-stage method provides a test procedure for such systems. Unfortunately, it does not consider self or inter-system interference for which the radiated two-stage method was developed. Based on this method, this contribution proposes an approach which allows to test large objects with multiple antennas/antenna-systems under realistic propagation conditions. It is realized in an over-the-air setup for wide-band applications by creating orthogonal wireless channels, a technique also known as wireless cable