The derivation of scaling relationship between acoustic and electromagnetic scattering by spheres

The rigorous theory of the conversion between the scattering of uniform plane electromagnetic wave by a perfectly conducting sphere and the scattering of uniform plane acoustic wave by a rigid sphere is studied in this paper. The conversion formula between these two different scattering based on two calibration curves is derived, which describes the quantitative relationship between acoustic and electromagnetic wave scattering at arbitrary frequencies by spheres of arbitrary sizes. In addition, the scaling relationship of the sizes of those two spheres and the corresponding frequencies are discussed in detail, and an indirect method of measurement of electromagnetic scattering by the spheres is proposed

Hybrid precoding based on matrix-adaptive method for multiuser large-scale antenna arrays

<div><p>Massive multiple-input multiple-output (MIMO) is envisioned to offer a considerable improvement in capacity, but it has a high cost and the radio frequency (RF) chain components have a high power consumption at high frequency. To address this problem, a hybrid analog and digital precoding scheme has been studied recently, which restricts the number of RF chains to far less than the number of antenna elements. In this paper, we consider the downlink communication of a massive multiuser multiple-input single-output (MU-MISO) system and propose an iterative hybrid precoding algorithm to approach the capacity performance of the traditional full digital precoding scheme. We aim to attain a large baseband gain by zero-forcing (ZF) digital precoding on the equivalent channel and then minimize the total power to obtain the optimal RF precoder. Simulation results show that the proposed method can approach the performance of the conventional fully digital precoding with a low computational complexity.</p></div

The comparisons among different schemes under different numbers of antennas and users.

<p>The comparisons among different schemes under different numbers of antennas and users.</p

Block diagram of a MU-MISO system with the hybrid precoding architecture at the BS.

<p>Block diagram of a MU-MISO system with the hybrid precoding architecture at the BS.</p

Computational analysis.

<p>Computational analysis.</p

The comparisons among different schemes with 2-bit quantized phase-shifter array.

<p>The comparisons among different schemes with 2-bit quantized phase-shifter array.</p