Achievable Sum Rate Analysis of ZF Receivers in 3D MIMO Systems

( Xingwang Li ),( Lihua Li ),( Ling Xie ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.4

Three-dimensional multiple-input multiple-output (3D MIMO) and large-scale MIMO are two promising technologies for upcoming high data rate wireless communications, since the inter-user interference can be reduced by exploiting antenna vertical gain and degree of freedom, respectively. In this paper, we derive the achievable sum rate of 3D MIMO systems employing zero-forcing (ZF) receivers, accounting for log-normal shadowing fading, path-loss and antenna gain. In particular, we consider the prevalent log-normal model and propose a novel closed-form lower bound on the achievable sum rate exploiting elevation features. Using the lower bound as a starting point, we pursue the "large-system" analysis and derive a closed-form expression when the number of antennas grows large for fixed average transmit power and fixed total transmit power schemes. We further model a high-building with several floors. Due to the floor height, different floors correspond to different elevation angles. Therefore, the asymptotic achievable sum rate performances for each floor and the whole building considering the elevation features are analyzed and the effects of tilt angle and user distribution for both horizontal and vertical dimensions are discussed. Finally, the relationship between the achievable sum rate and the number of users is investigated and the optimal number of users to maximize the sum rate performance is determined.

Capacity Bounds on the Ergodic Capacity of Distributed MIMO Systems over K Fading Channels

( Xingwang Li ),( Junfeng Wang ),( Lihua Li ),( Charles C. Cavalcante ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.7

The performance of D-MIMO systems is not only affected by multipath fading but also from shadowing fading, as well as path loss. In this paper, we investigate the ergodic capacity of D-MIMO systems operating in non-correlated fading (Rayleigh/Gamma) channels. With the aid of majorization and Minkowski theory, we derive analytical closed-form expressions of the upper and lower bounds on the ergodic capacity for D-MIMO systems over non-correlated K fading channels, which are quite general and applicable for arbitrary signal-to-noise ratio (SNR) and the number of transceiver antennas. To intuitively reveal the impacts of system and fading parameters on the ergodic capacity, we deduce asymptotic approximations in the high and low SNR regimes. Finally, we pursue the massive MIMO systems analysis for the lower bound and derive closed-form expressions when the number of antennas at BS grows large, and when the number of antennas at transceivers becomes large with a fixed and finite ratio. It is demonstrated that the proposed expressions on the ergodic capacity accurately match with the theoretical analysis.

Facilely tuning the surface wettability of Cu mesh for multi-functional applications

Xingwang Zhao,Fei Mao,Jiayue Wu,Jinglei Lei,Lingjie Li 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.116 No.-

The Cu meshes with reversible super-wettability have multifunctions of self-cleaning, oil–water separation,floating-oil collection and underwater oil lossless-transportation. However, the facile method totune the surface wettability and prepare reversibly super-wetting Cu meshes remains a great challenge. In this work, one-step chemical-etching method was used to construct the hierarchically-structured CuOof nano-sheets and micro-clusters on Cu meshes to provide suitable surface roughness essential forsuper-wettability. The surface wettability of Cu mesh was then facilely tuned by controlling the adsorptionand desorption of C-containing species at the Cu mesh surface through C-rich ambience storage andIR irradiation for short duration. The super-wetting transition of Cu meshes betweensuperhydrophobicity/superoleophilicity and superhydrophilicity/underwater-superoleophobicity couldrepeat for many cycles. Moreover, the super-wetting Cu meshes demonstrated excellent mechanical,physical and chemical stabilities. The switchable super-wettability endowed the Cu meshes with integratedmulti-functions, which demonstrated remarkable performance of self-cleaning, oil–water separation,floating-oil collection and underwater oil lossless-transportation. This study suggests that utilizingC-rich ambience storage and IR irradiation to control the content of C-containing species at the Cu meshsurface is a facile and effective way to tune the surface wettability of Cu meshes, which can be easilyextended to realize super-wettability transition of various materials.

Probabilistic Constrained Approach for Distributed Robust Beamforming Design in Cognitive Two-way Relay Networks

( Xueyan Chen ),( Li Guo ),( Chao Dong ),( Jiaru Lin ),( Xingwang Li ),( Charles C. Cavalcante ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.1

In this paper, we propose the distributed robust beamforming design scheme in cognitive two-way amplify-and-forward (AF) relay networks with imperfect channel state information (CSI). Assuming the CSI errors follow a complex Gaussian distribution, the objective of this paper is to design the robust beamformer which minimizes the total transmit power of the collaborative relays. This design will guarantee the outage probability of signal-to- interference-plus-noise ratio (SINR) beyond a target level at each secondary user (SU), and satisfies the outage probability of interference generated on the primary user (PU) above the predetermined maximum tolerable interference power. Due to the multiple CSI uncertainties in the two-way transmission, the probabilistic constrained optimization problem is intractable and difficult to obtain a closed-form solution. To deal with this, we reformulate the problem to the standard form through a series of matrix transformations. We then accomplish the problem by using the probabilistic approach based on two sorts of Bernstein-type inequalities and the worst-case approach based on S-Procedure. The simulation results indicate that the robust beamforming designs based on the probabilistic method and the worst-case method are both robust to the CSI errors. Meanwhile, the probabilistic method can provide higher feasibility rate and consumes less power.

Performance Analysis of Two-Way Relay NOMA Systems with Hardware Impair-ments and Channel Estimation Errors

( Xinji Tian ),( Qianqian Li ),( Xingwang Li ),( Hui Zhang ),( Khaled Rabie ),( Charles Casimiro Cavalcante ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.11

In this paper, we consider a two-way relay non-orthogonal multiple access (TWR-NOMA) system with residual hardware impairments (RHIs) and channel estimation errors (CEEs), where two group users exchange their information via the decode-and-forward (DF) relay by using NOMA protocol. To evaluate the performance of the considered system, exact analytical expressions for the outage probability of the two groups users are derived in closed-form. Moreover, the asymptotic outage behavior in the high signal-to-noise ratio (SNR) regime is examined and the diversity order is derived and discussed. Numerical simulation results verify the accuracy of theoretical analyses, and show that: i) RHIs and CEEs have a deleterious effects on the outage probabilities; ii) CEEs have significant effects on the performance of the near user; iii) Due to the RHIs, CEEs, inter-group interference and intra-group interference, there exists error floors for the outage probability.

Security performance analysis of SIMO relay systems over Composite Fading Channels

( Jiangfeng Sun ),( Hongxia Bie ),( Xingwang Li ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.6

In this paper, we analyze the secrecy performance of single-input multiple-output (SIMO) relay systems over κ-μ shadowed fading channels. Based on considering relay model employing decode-and-forward (DF) protocol, two security evaluation metrics, namely, secure outage probability (SOP) and probability of strictly positive secrecy capacity (SPSC) are studied, for which closed-form analytical expressions are derived. In addition, Monte Carlo results prove the validity of the theoretical derivation. The simulation results confirm that the factors that enhance the security include large ratio of (μ_D,μ_E), (m_D,m_E), (L_D,L_E) and small ratio of (k_D,k_E) under the high signal-to-noise ratio regime.

Low-Overhead Feedback Topology Design for the K-User MIMO Interference Alignment

( Jin Jin ),( Xiang-chuan Gao ),( Xingwang Li ),( Charles C. Cavalcante ),( Lihua Li ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.11

Since designing a feedback topology is a practical way to implement interference alignment at reduced cost of channel state information (CSI) feedback, six feedback topologies have been presented in prior works for a K-user multiple-input multiple-output interference channel. To fully reveal the potential benefits of the feedback topology in terms of the saving of CSI overhead, we propose a new feedback topology in this paper. By efficiently performing dimensionality-decreasing at the transmitter side and aligning interference signals at a subset of receivers, we show that the proposed feedback topology obtains substantial reduction of feedback cost over the existing six feedback designs under the same antenna configuration.

Efficient removal of pentachlorophenol from wastewater by novel hydrophobically modified thermo-sensitive hydrogels

Bin Yang,Dan Xu,Xiaolin Wu,Zhongjian Li,Lecheng Lei,Xingwang Zhang 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.25 No.-

Poly (N-isopropyl acrylamide-co-butyl acrylate) (PNIPAM-BA) hydrogels were synthesized by copolymerization of N-isopropyl acrylamide (NIPAM) with butyl acrylate (BA), which have been proposed as adsorbents for the efficient removal of hydrophobic organic pollutants, e.g. pentachlorophenol (PCP). Adsorption experiments showed high removal efficiencies of PCP. The isotherm experimental data of PCP fitted Langmuir model, and the adsorption capacity of PNIPAM-11% BA hydrogel was greater than that of the original PNIPAM hydrogel. It is possibly due to the enhanced interaction between the hydrophobically modified hydrogels and PCP. Moreover, the PNIPAM-BA hydrogels could be easily recycled by the desorption process at 323 K in solution.

Performance Analysis of NOMA-based Relaying Networks with Transceiver Hardware Impairments

( Chao Deng ),( Xiaoya Zhao ),( Di Zhang ),( Xingwang Li ),( Jingjing Li ),( Charles C. Cavalcante ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.9

In this paper, the performance of non-orthogonal multiple access (NOMA) dual-hop (DH) amplify-and-forward (AF) relaying networks is investigated, where Nakagami-m fading channel is considered. In order to cover more details, in our analysis, the transceiver hardware impairments at source, relay and destination nodes are comprehensively considered. To characterize the effects of hardware impairments brought in NOMA DH AF relaying networks, the analytical closed-form expressions for the exact outage probability and approximate ergodic sum rate are derived. In addition, the asymptotic analysis of the outage probability and ergodic sum rate at high signal-to-noise ratio (SNR) regime are carried out in order to further reveal the insights of the parameters for hardware impairments on the network performance. Simulation results indicate the performance of asymptotic ergodic sum rate are limited by levels of distortion noise.

Mining Frequent Sub-hypergraph in an Uncertain Hypergraph for Knowledge Transfer

Xing Wang,Bin-Xing Fang,Hui He,Hong-Li Zhang 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.4

The knowledge transfer learning can generalize across domains where the types of objects and variables are different. Previous studies ignored connectivity and creativity of domain knowledge. Thus, these studies just transfer knowledge from a source domain to a target domain that not effectively use the knowledge from other domains. We proposed a method, called Multi-domain second order knowledge integration (MSKI), for integrating to address this problem. We hybridize and create new knowledge, which is formalized into an uncertain hypergraph. Then, we proposed a method to mine frequent sub-hypergraph from the uncertain hypergraph (MFS-UHG). The frequent sub-hypergraphs are pivot knowledge, which has to be transferred with high priority. We embed the pivot knowledge in the progress of MLN structure learning. The experimental evaluation on four domain datasets shows that the MSKI outperforms state-of-the-art MLN-based transfer learning.