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Narrow beamforming solutions for millimeter wave cellular networks require mobile and base stations to exhaustively search all angular space. This scanning is mandatory in order to detect the unique optimum beamforming and combining vectors prior to control and data signaling. However exhaustive search yields large computational complexity and increases beam discovery time and control plane latency...
In this paper, we propose a new beamforming design to maximize energy efficiency (EE) for multiple input single output interfering broadcast channels (IFBC). Under this model, the EE problem is non-convex due to the coupled interference and its fractional form, and thus it is difficult to solve the problem. Conventional algorithms which address this problem have adopted an iterative method for each...
Zero-forcing beamforming (ZFBF) is a popular pre-coding scheme for MIMO systems. Most of the studies in the literature are under total power constraints. However, the perantenna power constraints (PAPC) are more realistic. The state-of-the-art method is interior point method which is expensive to realize in practice due to the high computational complexity. Hence, a low complexity zero-forcing precoding...
To meet the ever growing demand for both high throughput and uniform coverage in future wireless networks, dense network deployment will be ubiquitous, for which cooperation among the access points is critical. Considering the computational complexity of designing coordinated beamformers for dense networks, low-complexity and suboptimal precoding strategies are often adopted. However, it is not clear...
This paper presents a distributed beamforming algorithm with a reduced computational complexity for a wireless relay network, where a source-destination pair is assisted by cooperating amplify-and-forward (AF) relays but suffers from additional interference. The relay weights are obtained by maximizing the signal-to-interference-plus-noise ratio (SINR) at the destination subject to individual relay...
Most of the known robust adaptive beamforming techniques can be unified under one framework. This is to use minimum variance distortionless response principle for beamforming vector computation in tandem with sample covariance matrix estimation and steering vector estimation based on some information about steering vector prior. Motivated by such unified framework, we develop a new robust adaptive...
In this paper, collaborative use of relays to form a beamforming system with the aid of perfect channel state information (CSI) and to provide physical-layer security is investigated. In particular, a decode-and-forward-based relay beamforming design subject to total and individual relay power constraints is studied with the goal of maximizing the secrecy rate. The total power constraint leads to...
MISO-OFDM systems enable the allocation of resources in the frequency and spatial domain to increase the data throughput of wireless systems. In this paper, we initially present a near-optimal solution to the MISO-OFDM Resource Allocation (RA) problem. This solution performs an exhaustive search over all possible user sets and then uses a dual-based approach to optimally assign power to the selected...
A procedure has been recently developed that computes the optimal sensors coordinates of the ambiguity-free antenna array for omnidirectional direction of arrival estimation. The procedure has an exponential complexity, motivating the simplification presented in this paper. This is made possible by exploiting some experimental observations, namely the fact that the optimal omnidirectional array has...
In this paper, we present a semi-closed form solution to the SNR balancing problem, first considered in, in the context of network beamforming design for two-way relay networks. This solution relies on a simple bisection method to obtain the transmit power of one of the two transceivers. Given this transmit power, the relay beamforming weight vector is shown to have a closed-form solution. Simulation...
In this paper, firstly, we introduce regenerative multi-way relaying. A half-duplex multi-antenna relay station (RS) assists multiple nodes which want to communicate to each other. Each node has a message and wants to decode the messages from all other nodes. The number of communication phases is equal to the number of nodes, N, such that when N = 2, we have the well known two-way relaying. In the...
An algorithm with reduced computational complexity for solving the transmit beamforming problem in the case of multiple co-channel multicast groups is considered. A new degree of freedom, which allows a trade-off between the transmission power, the number of antenna array elements and the computational time, is added. The optimization problem is transformed to a lower-dimensional optimization problem,...
In this paper, technique for the array optimization of multiple-input multiple-output (MIMO) radar is investigated. The primacy focus of this study is improved two-way pattern performance of MIMO radar. Genetic algorithms (GA) is applied to the array optimization in order to reduce the peaks of side lobes (PSL) by acting on the elements positions. By using the property that the two-way pattern of...
To improve the spectrum utilization efficiency, cognitive radio (CR) has been proposed by allowing a cognitive radio network (CRN) to coexist with a licensed primary network. The security issues, although critical, have been less explored in the literature of CRN. In this paper, we consider a secure CRN in which a multi-antenna secondary user (SU) transmitter sends confidential information to a SU...
We consider a relay network which consists of two transceivers and r relay nodes. Assuming that the transceivers and the relays are all equipped with single antennas, we devise a two-way amplify-and-phase-adjust relaying scheme. In this scheme, each relay multiplies its received signal by a complex weight and transmits the so-obtained signal thereby participating in a distributed beamforming process...
This paper studies linear transmit filter design for weighted sum-rate (WSR) maximization in the multiple input multiple output broadcast channel (MIMO-BC). The problem of finding the optimal transmit filter is non-convex and intractable to solve using low complexity methods. Motivated by recent results highlighting the relationship between mutual information and Minimum Mean Square Error (MMSE),...
We consider a relay network which consists of two transceivers and r relay nodes. We study a half-duplex two-way relaying scheme. First, the two transceivers transmit their information symbols simultaneously and the relays receive a noisy mixture of the two transceiver signals. Then each relay adjusts the phase and the amplitude of its received signal by multiplying it with a complex beamforming coefficient...
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