Exploiting statistical and outdated CSI in multiuser downlink transmission

In this paper, we propose a multiuser downlink transmission scheme, which exploits both the statistical and outdated channel state information (CSI) at the transmitter. The proposed scheme extends the outdated CSI-aided scheme, first introduced by Maddah-Ali and Tse in [1] (denoted as MAT), by sending symbols demanded by a user along its statistical eigenmodes, instead of directly sending the symbols through separate antennas, and we refer to it as statistical eigenmode-MAT (SE-MAT). Considering zero-forcing receiver, we explicitly prove that the proposed SE-MAT scheme can achieve a higher ergodic sum-rate compared to the original MAT scheme, under different correlation conditions. Moreover, a user selection method which selects statistically orthogonal users for the SE-MAT transmission is proposed to further improve the system performance

LTE-Advanced radio access enhancements: A survey

Long Term Evolution Advanced (LTE-Advanced) is the next step in LTE evolution and allows operators to improve network performance and service capabilities through smooth deployment of new techniques and technologies. LTE-Advanced uses some new features on top of the existing LTE standards to provide better user experience and higher throughputs. Some of the most significant features introduced in LTE-Advanced are carrier aggregation, enhancements in heterogeneous networks, coordinated multipoint transmission and reception, enhanced multiple input multiple output usage and deployment of relay nodes in the radio network. Mentioned features are mainly aimed to enhance the radio access part of the cellular networks. This survey article presents an overview of the key radio access features and functionalities of the LTE-Advanced radio access network, supported by the simulation results. We also provide a detailed review of the literature together with a very rich list of the references for each of the features. An LTE-Advanced roadmap and the latest updates and trends in LTE markets are also presented

A Novel SAGE Algorithm for Estimating Parameters of Wideband Spatial Nonstationary Wireless Channels with Antenna Polarization

In this article, a novel space-alternating generalized expectation-maximization (SAGE) algorithm is proposed for parameter estimations of wideband spatial nonstationary wireless channels with antenna polarization (SAGE-WSNSAP). Compared with the traditional SAGE algorithm, the proposed SAGE-WSNSAP algorithm adds spatial nonstationarity by introducing birth-death coefficients at both transmitter (Tx) and receiver (Rx) sides into the parametric model. To reduce the complexity of the SAGE-WSNSAP algorithm, a coarse-to-fine search method is adopted in the initialization step. In addition, multiple-input multiple-output (MIMO) channel measurements are conducted to validate the proposed algorithm. The measurement results of the angle-delay power spectral density (PSD) and average delay PSD are compared with those estimated by the far-field SAGE algorithm, the near-field SAGE algorithm, and the proposed algorithm. It is found that the estimation results using the proposed SAGE-WSNSAP algorithm show higher similarity to measurement results than using the other two SAGE algorithms. In comparison to the far-field and near-field SAGE algorithms, the SAGE-WSNSAP algorithm can extract more effective multipath components (MPCs) and improve the power extraction ratios.</p

Outage probability analysis of a space-time block coding Physical-Layer Network Coding

Conference Name:2012 International Conference on Wireless Communications and Signal Processing, WCSP 2012. Conference Address: Huangshan, China. Time:October 25, 2012 - October 27, 2012.IEEE Communications Society Nanjing Chapter; IEEE Signal Processing Society Nanjing Chapter; University of Science and Technology of China; Huawei Technologies Co., Ltd.In this paper, we derive an exact closed-form outage probability expression for a bidirectional relay system using Space-Time Block Coding (STBC) aided with Physical-Layer Network Coding (PNC) protocol based on decode-and-forward relaying. By simulation experiments, one can observe that the Numerical results just go to testify the validity of our theoretical analysis. 漏 2012 IEEE

Impact of imperfect angle estimation on spatial and directional modulation

In this paper, we investigate the impact of imperfect angle estimation (IAE) on spatial and directional modulation (SDM) systems, assuming that the signal experiences line of sight (LoS) propagation. In SDM systems with IAE, the variation is analyzed in detail, when there is a mismatch between the beamforming and precise channel matrices. Based on the union bound and statistics theory, the average bit error probabilities (ABEPs) for both the legitimate user and eavesdropper are derived. In addition, the ergodic rate is also quantified with IAE. Simulation results are presented to show that the achieved theoretical ABEPs are useful in quantifying the potential performance penalty. We also show that the mismatch between the beamforming and precise channel matrices will become greater with the increase in direction measurement error (DME), which affects the detection for both the legitimate user and eavesdropper. On the other hand, due to the effect of IAE, the SDM requires more signal-to-noise ratio (SNR) gain to achieve a stable ergodic secrecy rate

Hedonic Games and Monte Carlo Simulation

Hedonic games have applications in economics and multi-agent systems where the grouping preferences of an individual is important. Hedonic games look at coalition formation, amongst the players, where players have a preference relation over all the coalition. Hedonic games are also known as coalition formation games, and they are a form of a cooperative game with a non-transferrable utility game. Some examples of hedonic games are stable marriage, stable roommate, and hospital/residence problem. The study of hedonic games is driven by understanding what coalition structures will be stable, i.e., given a coalition structure, no players have an incentive to deviate to or form another coalition. Different solution concepts exist for solving hedonic games; the one that we use in our study is core stability. From the computational perspective, finding any stable coalition structure of a hedonic game is challenging. In this research, we use Monte Carlo methods to find the solution of millions of hedonic with the hope of finding some empirical points of interest. We aim to explore the distribution of the number of stable coalition structures for a given randomly generated hedonic game and to analyze that distribution using Cullen and Frey graph approach

Улучшение точности пеленгатора беспилотного вертолета за счет использования виртуальной антенной решетки

This work is devoted to studying the possibility of applying the theory of "virtual" antenna arrays (VAR) to reduce the direction finder error. The case under consideration refers to the direction finder, which is mounted on an unmanned helicopter (UAV). The analysis is performed in the most problematic resonance region of wave scattering on the analyzed electrodynamic object. Based on the data obtained, conclusions are drawn about the prospects of using the VAR apparatus to improve direction finding accuracy.Данная работа посвящена изучению возможности применения аппарата теории «виртуальных» антенных решеток (ВАР) для уменьшения погрешности пеленгования. Рассматриваемый случай относится к пеленгатору, который установлен на беспилотном вертолете (БПЛА). Анализ производится в наиболее проблемной резонансной области рассеяния волн на анализируемом электродинамическом объекте. По полученным данным сделаны выводы о перспективности применения аппарата ВАР для повышения точности пеленгования.Исследование выполнено за счет гранта Российского научного фонда (проект №19-79-10109)

Energy-efficient hardware implementation of LR-aided K-Best MIMO decoder for 5G networks

Energy efficiency is a primary design goal for future green wireless communication technologies. Multiple-input multiple-output (MIMO) schemes have been proposed in literature to improve the throughput of communication systems, they are expected to play a prominent role in the upcoming 5th generation (5G) standard. This paper presents a novel high efficiency MIMO decoder based on the K-Best algorithm with lattice reduction. We have designed a novel hardware architecture for this decoder, which was implemented using 32nm standard CMOS technology. Our results show that the proposed decoder can achieve on average a four-fold reduction in the power costs compared to recently published designs for 5G networks. The throughput of the design is 506 Mbits/sec, which is comparable to existing designs

Modelling and Analysis of Nonstationary Vehicle-to-Infrastructure Channels with Time-Variant Angles of Arrival

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Modelling and Analysis of Nonstationary Vehicle-to-Infrastructure Channels with Time-Variant Angles of Arrival

In mobile radio channel modelling, it is generally assumed that the angles of arrival (AOAs) are independent of time. This assumption does not in general agree with real-world channels in which the AOAs vary with the position of a moving receiver. In this paper, we first present a mathematical model for the time-variant AOAs. This model serves as the basis for the development of two nonstationary multipath fading channels models for vehicle-to-infrastructure communications. The statistical properties of both channel models are analysed with emphasis on the time-dependent autocorrelation function (ACF), time-dependent mean Doppler shift, time-dependent Doppler spread, and the Wigner-Ville spectrum. It is shown that these characteristic quantities are greatly influenced by time-variant AOAs. The presented analytical framework provides a new view on the channel characteristics that goes well beyond ultra-short observation intervals over which the channel can be considered as wide-sense stationary