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Random beamforming (RBF) is a practically favorable transmission scheme for multiuser multiantenna downlink systems since it requires only partial channel state information (CSI) at the transmitter. Under the conventional single-cell setup, RBF is known to achieve the optimal sum-capacity scaling law as the number of users goes to infinity, thanks to the(More)
can be roughly estimated in the direction of = cos 01 (=k0), where is the elevation angle from the microstrip, and k 0 is the free space wavenumber. The propagation constants can be derived by solving the spectral domain integral equations with appropriate integral contour of the inverse Fourier transform and the moment method numerical technique [10]. The(More)
—The performance of the maximum ratio combining method for the combining of antenna-diversity signals in correlated Rician-fading channels is rigorously studied. The distribution function of the normalized signal-to-noise ratio (SNR) is expanded in terms of a power series and calculated numerically. This power series can easily take into account the signal(More)
A new concept of using a stacked phased coil array to increase the signal-to-circuit noise ratio (SCNR) in magnetic resonance imaging (MRI) is introduced. Unlike conventional phased coil arrays, the proposed stacked phased coil array is constructed by stacking the coil elements closely together in the vertical direction. Through a proper combination of the(More)
A new method is introduced to increase the signal-to-noise ratio (SNR) in low-field magnetic resonance imaging (MRI) systems by using a vertically stacked phased coil array. It is shown theoretically that the SNR is increased with the square root of the number of coils in the array if the array signals are properly combined to remove the mutual coupling(More)
The random beamforming (RBF) scheme, together with multi-user diversity based user scheduling, is able to achieve interference-free downlink transmission with only partial channel state information (CSI) at the transmitter. The impact of receive spatial diversity on RBF, however, is not fully characterized even under a single-cell setup. In this paper, we(More)
—A new method for calculation of the mutual impedance is introduced for the compensation of mutual coupling effect in a dipole antenna array employed for direction finding. This method uses an estimated current distribution and a different method for the calculation of the open-circuit voltage. It is shown that the new method can significantly improve the(More)
Using the beamspace preprocessing in RF chains, the fast Fourier transform (FFT)-based antenna selection scheme can reduce the performance degradation of traditional antenna selection schemes in correlated multiple-input multiple-output (MIMO) channels. Based on this technique, an antenna selection method in beamspace is developed for MIMO systems using(More)