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In this paper, the problem of sequential beam construction and adaptive channel estimation based on reduced rank (RR) Kalman filtering for frequency-selective massive multiple-input multiple-output (MIMO) systems employing single-carrier (SC) in time division duplex (TDD) mode are considered. In two-stage beamforming, a new algorithm for statistical pre-beamformer design is proposed for spatially...
In Virtual Antenna Array (VAA) based wireless system, knowledge of users' locations can help the transmitter to achieve interference avoidance by steering the main beam towards the intended recipient. In this work, the idea has been applied to licensed shared access (LSA) based cognitive radio (CR) environment where location aware beam-forming has been implemented on spatially modulated Generalized...
In this paper, a population-based metaheuristic optimization algorithm named Opposition-based Simulated Kalman Filter (OBSKF) is proposed as an adaptive beamforming algorithm. This algorithm is based on Simulated Kalman Filter (SKF), which is a newly introduced optimization algorithm inspired by Kalman filtering. Opposition-based learning is employed in SKF to improve the performance of SKF in adaptive...
Smart Antennas can adaptively adjust their radiation pattern to form nulls towards the interference sources and form maximum radiation towards the desired users. This paper presents an assessment on the effectiveness of an adaptive beamforming algorithm for an electrically steerable parasitic array radiator (ESPAR) smart antenna system by comparing resultant radiation patterns after beamforming process,...
In this paper, we study a joint beam and user scheduling problem in a cooperative cellular network utilizing orthogonal random beamforming technique. This paper aims to minimize total base stations' average energy expenditure while ensuring finite service time for all traffic arrivals in a given set. We leverage Lyapunov optimization technique to transform original long-term problem into short-term...
This paper studies energy-efficient coordinated beamforming in multi-cell multi-user multigroup multicast multiple-input single-output systems. We aim at maximizing the network energy efficiency by taking into account the fact that some of the radio frequency chains can be switched off in order to save power. We consider the antenna specific maximum power constraints to avoid non-linear distortion...
Time-shifted pilot scheme can efficiency combat pilot contamination. However, when the number of base station (BS) antennas is finite, the pilot interference due to the downlink transmission symbols cannot be mitigated in the time-shifted scheme. This paper proposed a novel two-stage channel estimation algorithm based on time-shifted pilot to reduce the effect of pilot interference. In the first stage,...
Joint power control with optimal beamforming design and power control with minimum antenna selection under signal to inference noise ratio constraints have been considered in separate wireless communication scenarios. In power control algorithms, multiple antennas with linear beamforming are used to reduce the interference power, which also minimizes the total transmitted power in uplink/downlink...
In this paper, we consider the problem of enhancing the filtering capacity of single standard beamformers for real base-band signals. Unfortunately, the standard smart arrays are not able to effectively minimize the effects of the complex noise in the array. In order to solve this problem, we analyze a parallel adaptive beamforming system based on complex nonlinear adaptive filters. In this design,...
This paper compares the performance of various beamforming techniques using convex optimization. A new robust beamforming technique is formulated, and its performance is compared with the diagonal loading, robust SOCP techniques and the standard sample matrix inversion technique in different scenarios. The robustness of the proposed technique to errors in the array steering vector is demonstrated...
In this paper, we address the direction-of-arrival (DOA) estimation problem of hybrid completely polarized (CP) and partially polarized (PP) source signals with arbitrary polarimetric arrays. Firstly, oblique projection filtering operators, which are insensitive to the state of polarization of signals, are used to separate potential source signals in the spatial domain. Secondly, the DOA estimates...
Based on the tapped delay-lines (TDL) wideband model, the response variation (RV) constraint is applied to improve the frequency response consistency of the wideband beamforming. The optimization criterion of the proposed algorithm is minimizing the designed sidelobe level utmost and the constraints of the sidelobe level, interference suppression and the response variation while making the direction...
This paper proposes diagonal microphone placement for the landscape/portrait interchangeable mode of a personal computer. Two microphones are diagonally located at a screen corner to provide useful directivity for target-signal enhancement in both landscape and portrait modes. The diagonal microphone placement guarantees a nonzero microphone spacing in either the landscape and the portrait mode along...
This paper focuses on an average robust transmit beamforming optimization problem for the multiuser multiple-input-single-output (MISO) downlink scenario. In this problem, the channels are modeled as Gaussian variables with mean zero and with known covariance at the transmitter. The design criterion is to maximize the sum of the users' average rates with respect to the channels, subject to the total...
We consider the problem of designing hybrid analog-digital beamformers in a downlink multi-user large-scale MIMO system. The objective is to minimize the total transmit power, while fulfilling SINR targets of all users. A dual virtual uplink problem is formulated for the original downlink problem based on the uplink-downlink duality theory, in order to decouple the digital beamformers in the constraints...
This paper considers practical deployment issues of a multi-user MIMO system with full-duplex (FD) base station and half-duplex (HD) user equipment. The aim is to select a set of uplink (UL) and downlink (DL) users at any instant that will provide a satisfactory performance in system resource allocation. Furthermore, it is also necessary to deal with the interference created by the UL users to the...
This paper considers a multicell downlink channel in which multiple base stations (BSs) cooperatively serve users by jointly precoding shared data transported from a central processor over limited-capacity backhaul links. We jointly design the beamformers and BS-user link selection so as to maximize the sum rate subject to user-specific signal-to-interference-noise (SINR) requirements, per-BS backhaul...
In this paper, we study a constructive interference based cognitive radio beamforming optimization problem under perfect channel state information at the transmitter and the knowledge of data information. The beamformers are designed to minimize the worst secondary user's symbol error probability under constraints on the instantaneous total transmit power, and the power of the instantaneous interference...
Millimeter-wave (mmWave) systems require massive antennas at both transmitter and receiver to reach desirable link budget. Analog-digital hybrid beamforming is a promising architecture since it significantly reduces the hardware cost while approaches the performance of digital beamforming. However, the nonlinear power amplifier (PA) introduces intermodulation interference and degrades the spectral...
Non-Orthogonal Multiple Access (NOMA) is a promising multiple access technique for the 5th generation (5G) mobile communication systems. In this paper, an efficient power allocation scheme is derived for multiuser multiple input single output (MISO) downlink beamforming NOMA system to guarantee that successive interference cancellation (SIC) detection can remove completely the intra-cluster interference...
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