Wireless Channel Sounding using Distributed and Synthetic Arrays

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As wireless systems have adopted increasing complex methods and techniques to achieve greater capacity, reliability and energy efficiency, their performance has become increasingly sensitive to a broader range of propagation impairments and channel models have become evermore complex. We propose to develop novel and improved methods for characterizing wireless channels using either synthetic or distributed arrays and thereby support the design and deployment of next generation wireless systems in new and challenging scenarios. Anticipated outcomes include: 1) more cost effective channel sounder architectures, 2) better methods for extracting channel characteristics from raw signal data, 3) better methods for capturing the channel characteristics in the form of channel models.******Distributed Array Channel Sounders. We propose to replace the mechanical switches used in current distributed antenna channel sounders with optical-delay-line multiplexers. By eliminating the high cost, slow switching speeds and poor reproducibility of fast mechanical switches and providing simultaneous sampling, ultra-fast multiplexing (microsecond delays) and excellent reproducibility, such channel sounders have the potential to revolutionize work in this area. ******We will focus on developing better methods for extracting channel characteristics from raw signal data produced by such a channel sounder and better methods for capturing the measured channel characteristics in the form of DAS channel models. Ultimately, more effective DAS channel sounders and standardization of DAS channel models will facilitate fair comparison between alternative architectures and protocols and spur advances in DAS performance enhancement and cost reduction. ******Synthetic Array Channel Sounders. Spatial channel models play a crucial role in predicting the performance of multiple-input multiple-output (MIMO)-based wireless communication systems in mobility environments including high speed rail. Current approaches to characterizing spatial channels require either mechanically steerable directional antennas or virtual / physical antenna arrays at both the transmitter and receiver, but these are generally unsuitable for use in mobility environments. ******We suggest that a spatial channel measurement system suitable for mobility environments can be simplified considerably by casting it as a bistatic synthetic aperture radar (BiSAR) with a stationary transmitter and a mobile receiver that moves with respect to the environment. The hardware required is trivial compared to conventional spatial channel sounders and lends itself to routine use by operators. Ultimately, more efficient and effective spatial channel sounders will improve both academic and practical understanding of the factors that affect MIMO system performance.