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Exponentially increasing demands for higher data rates and quality of service cannot be satisfied by delivering more power as higher power levels may reduce Signal-to-Interference-plus-Noise Ratio (SINR) with negative impact on overall system performances. Simultaneously, the continuous shrinking in transistors size for denser circuits integration, following Moore's law, will be constrained by the...
The emerging 5G mobile communication standard aims to increase the throughput and, in the same time, to considerably increase the number of users serviced concurrently (Internet of Things). The key direction for achieving these requirements is to heavily extend the use of the spatial degrees of freedom, especially in the multi-user scenarios. Multi-User Massive MIMO (MU-MIMO) is one of the key technologies...
In this work, we propose a beam selection scheme that exploits the geometric sparsity of the multi-user (MU) massive multiple input and multiple output (MIMO) channel, using its beamspace representation. Assuming knowledge of the beamspace channel, the beamspace precoder consists in selecting and weighting the beams steered to the users, in order to maximize the signal-to-interference-and-noise ratio...
This paper presents two algorithms for optimizing the transmit and receive antenna selection matrices in Multiple Input Multiple Output (MIMO) Device-to-Device (D2D) communications. MIMO antenna selection technique is well-suited for D2D communications since it is relevant to low-cost devices with less Radio Frequency (RF) chains than antennas, and requires low feedback. The proposed algorithms determine...
Noncoherent multi-user detection schemes in combination with subspace projection were shown to be an attractive approach in multi-user massive MIMO systems. Up to now, the subspace projection has been performed via a singular value decomposition (SVD) of the receive matrix and nulling the non-signal dimensions. In this paper, we employ an alternative approach to the subspace estimation step, namely...
We consider wireless information and power transfer in a multi-user massive multiple-input multiple-output (MU-Massive-MIMO) system, where several distributed antenna sets, also denoted as remote radio heads (RRHs), are deployed, while the users can simultaneously perform information detection and energy harvesting. Assuming a large number of antennas and autonomous power allocation for the information...
In this paper, minimum MSE based interference alignment (IA) algorithm is developed for the interfering broadcast channel (IBC), which models the multi-cell downlink system, underlying cognitive radio, device-to-device and other scenarios. The IA precoders and decoders are computed to minimize the MSE. Cascade design is used for IA precoder design, where the first component precoder is obtained by...
With the growth of mobile data application and the ultimate expectations of 5G technology, the need to expand the capacity of the wireless networks is inevitable. Massive MIMO technique is currently taking a major part of the ongoing research, and expected to be the key player in the new cellular technologies. This papers presents an overview of the major aspects related to massive MIMO design including,...
The new networking paradigm of opportunistic spectrum sharing is a promising technology for mitigating the scarcity of spectrum, which has resulted from the exponential increase in the number of wireless devices and ubiquitous services. In light of the new concept of Authorized/Licensed Shared Access (ASA/LSA), in this work, we consider the coexistence and spectrum sharing between a collocated multiple-input-multiple-output...
This paper addresses the spatial-average analysis of uplink signal to interference ratio (SIR) and throughput in massive MIMO networks with maximum ratio combining (MRC). The analysis incorporates the effects of fractional power control (FPC) and other cells interference (ICI) due to estimation error in channel state information (CSI). Based on an asymptotic approach, tractable expressions are presented...
In this paper, energy efficient transmit antenna selection in underlay cognitive radio (CR) multiple-input multiple-output (MIMO) systems from a cross layer perspective, is investigated. Conventional energy efficient antenna selection optimizes an energy efficiency (EE) metric defined in terms of the system capacity and energy consumption, making it a physical layer criterion. In this work, we propose...
In many practical cases, one-tap equalizers achieve a close to optimum performance in filter bank multi-carrier modulation systems. However, if the channel is highly doubly-selective, that is, time-selective and frequency-selective, enhanced equalization methods might be necessary. In this paper, we generalize the n-tap Minimum Mean Squared Error (MMSE) equalization, proposed in literature, by also...
In this paper, we consider the energy efficiency maximization problem in downlink multi-input multi-output (MIMO) multi-cell systems, where all users suffer from inter-cell interference. To solve this optimization problem with a nonconcave objective function and a complex-valued matrix variable, we extend the recently developed successive pseudo-convex approximation framework and propose a novel iterative...
In this paper, we present the design of optimal precoders and receive filters for a full-duplex (FD) two-way amplify-and-forward (AF) multiple- input multiple-output (MIMO) relaying system in a cognitive radio network. The secondary user (SU) or cognitive nodes share the spectrum with the licensed primary user (PU) nodes while keeping the interference to PU nodes below a threshold. The cognitive transceivers...
Sparse code multiple access system with multiple antennas offers unprecedented massive connectivity and capacity. To reduce the interference in a downlink multiple user SCMA (MU-SCMA) system, we propose a layer-aware interference mitigation scheme (L-AIMS). Firstly, preprocess the codewords of paired users to mitigate the intra-layer interference. Secondly, adopt the generalized singular value decomposition...
In this paper, we investigate wireless information and power transfer in full-duplex (FD) two-way massive MIMO amplify-and-forward (AF) relaying network. In the considered network, the relay is an energy demander and applies time switching scheme to harvest energy from the users for amplifying and forwarding the users'' signals. Different from prior studies, MIMO users and antenna correlation are...
The existing cellular networks are being modified under the umbrella of fifth generation (5G) networks to provide high data rates with optimum coverage. Current cellular systems operating in ultra high frequency (UHF) bands suffer from severe bandwidth congestion hence 5G enabling technologies such as millimeter wave (mmWave) networks focus on significantly higher data rates. In this paper, we explore...
Regular zero-forcing (RZF) precoding algorithm is well- known as its low complexity and high performance in massive MIMO systems. However, when the number of transmitting antennas increases, the matrix inversion in RZF leads to high algorithmic complexity. In this paper, we propose an improved Newton iteration to estimate the matrix inversion in RZF precoding. Compared with the traditional Newton...
In this paper, a multi-cell joint optimization scheme based on pilot allocation is proposed in order to mitigate pilot contamination for multi- cell massive MIMO systems. This method measures interference of each pilot sequence caused by users multiplexing from adjacent cells exploiting the massive MIMO characteristics of fading channels. The scheme takes jointly optimizing a plurality of cells into...
In this paper, we analyze the performance of the fractional pilot reuse (FPR) scheme with vertical sectorization in massive multiple-input multiple-output (MIMO) system. In this scheme, users are classified into the cell-center ones in inner vertical sector and the cell-edge ones in outer vertical sector according to their signal-to-interference-plus- noise ratios (SINRs) at the receiver side. Then,...
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