Zuping Qian

Joint Resource Allocation for Device-to-Device Communications Underlaying Uplink MIMO Cellular Networks

This paper presents a resource allocation framework for device-to-device (D2D) communications underlaying uplink MIMO cellular networks. At first, our aim is to address the sum-rate maximization problem of the cellular network with both D2D and cellular users. An algorithm based on pure random search is presented for obtaining the optimal resource allocation without using an exhaustive search. Then, we propose a noncooperative resource allocation game for the joint self-optimization of channel allocation, power control, and precoding of the D2D users in a more practical setting. The feasibility and existence of the pure strategy Nash equilibrium are then established. An iterative algorithm based on best response dynamic is then proposed to determine the feasible pure strategy Nash equilibrium under specific conditions. As the algorithm may not always converge, we devise a strategy refinement mechanism to tackle this issue based on the sum-rate criterion. Simulation results verify our theoretical analysis and findings.

AN-Aided Secrecy Precoding for SWIPT in Cognitive MIMO Broadcast Channels

In this letter, we study the secrecy precoding problem for simultaneous wireless information and power transfer (SWIPT) in a cognitive multiple-input multiple-output (MIMO) broadcast channel. We adopt an artificial noise (AN)-aided precoding scheme and formulate the problem as a secrecy rate maximization (SRM) problem, which is subject to both an interference power constraint imposed to protect the primary user (PU) and an energy harvesting constraint required by the secondary energy receiver (SER). Since the formulated SRM problem constitutes a difference convex (DC)-type programming problem, we solve it by employing a successive convex approximation (SCA) method. With the SCA method, the nonconvex part of the SRM problem can be locally linearized to its first-order Taylor expansion. Then, relying on solving a series of convexified optimization problems, an iterative precoding algorithm is developed. Numerical simulations are also provided to demonstrate the proposed algorithm. Results show that our algorithm can achieve a near-optimal performance with guaranteed convergence.

Compact Wideband Dual Circularly Polarized Substrate Integrated Waveguide Horn Antenna

In this communication, a compact circularly polarized (CP) substrate integrated waveguide (SIW) horn antenna is proposed and investigated. Through etching a sloping slot on the common broad wall of two SIWs, mode coupling is generated between the top and down SIWs, and thus, a new field component as TE01 mode is produced. During the coupling process along the sloping slot, the difference in guide wavelengths of the two orthogonal modes also brings a phase shift between the two modes, which provides a possibility for radiating the CP wave. Moreover, the two different ports will generate the electric field components of TE01 mode with the opposite direction, which indicates the compact SIW horn antenna with a dual CP property can be realized as well. Measured results indicate that the proposed antenna operates with a wide 3-dB axial ratio bandwidth of 11.8% ranging from 17.6 to 19.8 GHz. The measured results are in good accordance with the simulated ones.

Precoding and Artificial Noise Design for Cognitive MIMOME Wiretap Channels

In this paper, we study the secrecy precoding problem for a cognitive multiple-input-multiple-output multiple-eavesdropper (MIMOME) wiretap system. The problem is studied with an artificial noise (AN)-aided precoding scheme. First, we place AN in the null space of the legitimate receivers channel matrix and formulate a secrecy rate maximization (SRM) problem, which is subject to both an interference power constraint imposed to protect the primary user (PU) and a maximum transmit power constraint available for the secondary transmitter. Second, we drop the null space constraint and reformulate the SRM problem. Because the formulated SRM problems naturally constitute difference-convex-type programming problems, we solve them by employing a successive convex approximation method, where the nonconvex parts of each problem are approximated by their first-order Taylor expansion. Thus, the SRM problems can be iteratively solved through successive convex programming of their convexified versions. Results show that our algorithms can achieve a satisfactory solution with guaranteed convergence.

RAISE: A New Fast Transmit Antenna Selection Algorithm for Massive MIMO Systems

In this paper, we study the problem of transmit antenna selection for massive multiple-input multiple-output systems by maximizing the determinant modulus of the selected channel matrix. Based on the maximum-volume submatrix finding method, we propose a real-time antenna-by-antenna iterative swapping enhancement (RAISE) transmit antenna selection algorithm with low memory cost and low computational complexity. The convergence of the proposed algorithm is proved and the performance of it is evaluated via numerical simulations. Our results show that, compared to the traditional antenna selection algorithms, RAISE can achieve near optimal capacity performance while the computational complexity and the memory cost are significantly reduced.

Distributed precoding for wireless information and power transfer in MIMO DF relay networks

In this paper, we focus on the problem of distributed precoding for simultaneous wireless information and power transfer (SWIPT) in a decode-and-forward (DF) multiple-input multiple-output (MIMO) relay network with two heterogeneous destination nodes, i.e., an information decoding (ID) receiver and a RF energy harvesting (EH) receiver. Since full channel state information (CSI) is usually unavailable in practice, we consider a practical scenario in this paper, where only local transmit CSI is available. Such a scenario is naturally constituted as a noncooperative game. Then, it is proved that the existence and uniqueness of the pure strategy Nash Equilibrium (NE) of this game are both guaranteed. Next, we propose a distributed precoding algorithm based on best response dynamic. Finally, numerical results are provided to evaluate the performance of the proposed algorithm. It is shown that the convergence of the proposed algorithm is very fast.

Game-Theoretic Precoding for SWIPT in the DF-Based MIMO Relay Networks

In this paper, we study the distributed precoding problem for simultaneous wireless information and power transfer (SWIPT) in decode-and-forward (DF)-based multiple-input-multiple-output (MIMO) relay networks. The system model considered here consists of a source, a relay, an information decoding (ID) receiver, and an energy harvesting (EH) receiver, all mounted with multiple antennas. Since full channel state information (CSI) is usually unavailable, a practical scenario, where only local CSI is required, is considered in this paper. Such a practical scenario naturally constitutes a noncooperative game, where the source and the relay can be regarded as two rational game players. With properly designed utilities, it can be further shown that the existence and uniqueness of the pure-strategy Nash equilibrium (NE) of the proposed game can both be guaranteed under some mild conditions. Therefore, a distributed iterative precoding algorithm can be developed based on the best-response dynamic to obtain the unique NE solution for the proposed game. Moreover, a proximal-point-based regularization approach is also pursued to ensure the convergence of the proposed algorithm without requiring special restrictions on the channel ranks. Numerical simulations are also provided to demonstrate the proposed algorithm. Results show that our algorithm can converge quickly to a satisfactory solution with guaranteed convergence.

Optimal precoding for simultaneous information and power transfer in MIMO relay networks

In this paper, we focus on the problem of optimal precoding for simultaneous wireless information and power transfer (SWIPT) in a two-hop decode-and-forward (DF) multiple-input multiple-output (MIMO) relay network, which consists of a source, a relay station, an information decoding (ID) receiver and an energy harvesting (EH) receiver. Each node in this relay network is assumed to employ multiple antennas. In order to better character the optimal tradeoff between simultaneous information and power transfer in MIMO relay networks, a 3D rate-energy (R-E) region is first defined. In addition, an algorithm based on convex programming is proposed to effectively compute the R-E region. Finally, numerical simulations are provided to evaluate the proposed algorithm. It is found that the optimal tradeoff between the maximum information and power transfer locates on the contour of the 3D regions boundary.

Electrically Large Resonant Cavity Loaded With -Negative and -Negative Metamaterials

An electrically large resonant cavity (ELRC) operated at the TM100 dominant mode with unconstrained physical size is proposed in this letter. The rectangular cavity is filled partially by ε-negative metamaterial and μ-negative metamaterial. Modal equation for the dominant mode TM100 of the ELRC is deduced based on the cavity model theory. Numerical results indicate that the resonant frequency can be increased in a much degree in comparison to the cavity composed of normal material. Finally, electric field distributions of the proposed cavity are plotted, and the quality factor is calculated to verify the resonant property of the ELRC, which shows it is a good candidate for the electrically large antenna applications.

Compact SIW Annular Ring Slot Antenna With Multiband Multimode Characteristics

A substrate-integrated waveguide (SIW) cavity-backed annular ring slot antenna with multiband multimode characteristics is proposed in this communication. The antenna consists of an SIW cavity and an annular slot on top surface as the radiator. Two patch-like radiation patterns and one monopolar radiation pattern at three different frequencies are excited by the single fed antenna. Moreover, each operating frequency can be individually adjusted. A prototype is fabricated and measured to validate the theoretical analysis. Good agreement between the simulated and measured results of the input reflection coefficients and radiation patterns is achieved. Compared with other designs, the proposed antenna has features of simple structure, multiband multimode and frequency-tunable characteristics.