MRI: Development of a Matrix Channel Measurement System

Ohio State University Research Foundation -Do Not Use, Columbus OH

Investigators

Abstract

Abstract A matrix channel is the set of NT NR impulse responses (subchannels) that completely characterize the propagation between NT > I transmit antennas and NR > I receive antennas. The Ohio State University ElectroScience Laboratory (ESL) will develop a matrix channel measurement system (MCMS), consisting of a mobile multichannel transmitter (MCT) and a portable multichannel receiver (MCR) capable of any form of modulation with bandwidth up to 40 MHz at any frequency between 250 MHz and 6 GHz. The MCT will consist of 4 independent, coherent channels. Each transmit channel will consist of an arbitrary waveform generator and an upconverter. The MCR will consist of 16 channels, with each channel consisting of a downconverter/digitizer, 75 ms capture at 40 MHz bandwidth (proportionally longer for smaller bandwidths), on-the-fly data processing, and long-term storage of results. Both the MCT and MCR will be battery-powered and built into transit cases suitable for two-person carry to allow measurements anywhere, including indoors, outdoors, and from vehicles. The MCMS will be employed in continuing ESL research programs including: (1) Measurements of capacity in matrix channels, (2) Development and evaluation of open loop forward link array processing techniques for frequency division duplex (FDD) systems, (3) Refinement of angle-of-arrival (AOA) estimation techniques for beamforming and mobile radio geolocation, and (4) Evaluation of interference mitigation techniques for GPS receivers. In each case, the superior tuning range, bandwidth, capture time, and portability of the MCMS will greatly enhance the quality of data relative to that obtained from previous systems developed by ESL and others. For example, in topic 1, the MCMS will be used to obtain improved and more thorough measurements of matrix channels to support development of the next generation of communications technologies, such as BLAST, that exploit antenna arrays to dramatically increase spectral efficiency. Of particular interest is learning under what conditions matrix channel systems significantly outperform vector (NT = 1) channel methods, and how to design antenna arrays (element geometry and polarization) to optimize this performance. The MCMS will possess unprecedented flexibility by virtue of its modular, software-defined architecture, and thus will be of great value for other research efforts as well. Despite the urgent need, no system with comparable features exists commercially, nor can such a system be assembled from off-the-shelf equipment at a reasonable cost. Instead, the project team will design the MCMS from the bottom up, bringing to bear its extensive previous experience in developing similar systems. To ensure the success of this project, ESL will partner with Aeroflex Lintek - a world-renowned developer of custom RF test equipment - to codevelop the MCMS. In this partnership, ESL will be responsible for design concept, requirements, proof-of-concept, and prototyping of hardware and software. Aeroflex Lintek will participate in the design effort and will be responsible for systems engineering and development of the final system. Aeroflex Lintek will perform this work for a small fraction of it's anticipated costs in return for the opportunity to develop, produce, and market a new generation RE test equipment based on technology developed from this project.