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Beamforming and Power Splitting Designs for AN-Aided Secure Multi-User MIMO SWIPT Systems
Zhengyu Zhu,Zheng Chu,Ning Wang,Sai Huang,Zhongyong Wang,Inkyu Lee IEEE 2017 IEEE transactions on information forensics and sec Vol.12 No.12
<P>In this paper, an energy harvesting scheme for a multi-user multiple-input-multiple-output secrecy channel with artificial noise (AN) transmission is investigated. Joint optimization of the transmit beamforming matrix, the AN covariance matrix, and the power splitting ratio is conducted to minimize the transmit power under the target secrecy rate, the total transmit power, and the harvested energy constraints. The original problem is shown to be non-convex, which is tackled by a two-layer decomposition approach. The inner layer problem is solved through semi-definite relaxation, and the outer problem, on the other hand, is shown to be a single-variable optimization that can be solved by 1-D line search. To reduce computational complexity, a sequential parametric convex approximation method is proposed to find a near-optimal solution. This paper is then extended to the imperfect channel state information case with norm-bounded channel errors. Furthermore, tightness of the relaxation for the proposed schemes is validated by showing that the optimal solution of the relaxed problem is rank-one. Simulation results demonstrate that the proposed SPCA method achieves the same performance as the scheme based on 1-D but with much lower complexity.</P>
( Zhengyu Kong ),( Duanpo Wu ),( Xinyu Jin ),( Shuwei Cen ),( Fang Dong ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.4
Deployment of access point (AP) is a problem that must be considered in network planning. However, this problem is usually a NP-hard problem which is difficult to directly reach optimal solution. Thus, improved AP deployment optimization scheme based on swarm intelligence algorithm is proposed to research on this problem. First, the scheme estimates the number of APs. Second, the multi-objective particle swarm optimization (MOPSO) algorithm is used to optimize the location and transmit power of APs. Finally, the greedy algorithm is used to remove the redundant APs. Comparing with multi-objective whale swarm optimization algorithm (MOWOA), particle swarm optimization (PSO) and grey wolf optimization (GWO), the proposed deployment scheme can reduce AP's transmit power and improves energy efficiency under different numbers of users. From the experimental results, the proposed deployment scheme can reduce transmit power about 2%-7% and increase energy efficiency about 2%-25%, comparing with MOWOA. In addition, the proposed deployment scheme can reduce transmit power at most 50% and increase energy efficiency at most 200%, comparing with PSO and GWO.
Zhengyu Zhu,ZhongyongWang,이경재,Zheng Chu,이인규 한국통신학회 2016 Journal of communications and networks Vol.18 No.2
In this paper, we address a new robust optimization problemin a multiuser multiple-input single-output broadcasting systemwith simultaneous wireless information and power transmission,where a multi-antenna base station (BS) sends energy and informationsimultaneously to multiple users equipped with a singleantenna. Assuming that perfect channel-state information (CSI)for all channels is not available at the BS, the uncertainty of theCSI is modeled by an Euclidean ball-shaped uncertainty set. Tooptimally design transmit beamforming weights and receive powersplitting, an average total transmit power minimization problem isinvestigated subject to the individual harvested power constraintand the received signal-to-interference-plus-noise ratio constraintat each user. Due to the channel uncertainty, the original problembecomes a homogeneous quadratically constrained quadraticproblem, which is NP-hard. The original design problem is reformulatedto a relaxed semidefinite program, and then two differentapproaches based on convex programming are proposed, whichcan be solved efficiently by the interior point algorithm. Numericalresults are provided to validate the robustness of the proposedalgorithms.
Rule-Based Learning via Spherical Classification of Data
Zhengyu Ma,Hong Seo Ryoo 한국경영과학회 2017 한국경영과학회 학술대회논문집 Vol.2017 No.10
In this paper, we develop a rule-based classification machine that partitions data under analysis into spherical patterns. The salient feature of the proposed method is twofold. One, it exploits the efficiency of distance metric-based clustering to fast collect similar data into spherical patterns, each consisting of homogeneous data. The other, owing to its supervised learning nature, it induces a classification rule that accurately generalizes on testing data. Numerical experiments with 15 machine learning datasets prove the utilities of the proposed method well. In comparison with 12 well-established classification methods, the new method proves to be competitively efficient in training while superior in classification of new data.
General Set Covering for Feature Selection in Data Mining
Zhengyu Ma,Hong Seo Ryoo 한국경영과학회 2012 Management Science and Financial Engineering Vol.18 No.2
Set covering has widely been accepted as a staple tool for feature selection in data mining. We present a generalized version of this classical combinatorial optimization model to make it better suited for the purpose and propose a surrogate relaxation-based procedure for its meta-heuristic solution. Mathematically and also numerically with experiments on 25 set covering instances, we demonstrate the utility of the proposed model and the proposed solution method.
Effects of solvent properties on cationic dyeing process of acrylic yarn
Zhengyu Zhang,Chunling Zheng,Ailing Yuan,Haibo Wang,Ling Zhu,Hong Xu 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.4
Cationic dye is a special dye for acrylics, but it is very difficult in dyeing through the core. In practice,the price of a special leveling agent for acrylic fiber is high, and uniform staining is poor. By mixing a number of organicsolvents in the dye bath, we can improve the structure of fibers and their deep-dyeing. We used n-propanol, isopropanoland benzyl alcohol as organic solvents, by adjusting the pH value and the appropriate temperature, and with specialdepth and leveling agent for dyeing soaping fastness contrast, to find economically viable process conditions.
Poly(L-Ala-co-L-Lys) Exhibits Excellent Ice Recrystallization Inhibition Activity
Zhengyu Piao,박진경,백지현,정병문 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
The control of ice recrystallization is very important in cryo-technological fields. Ice recrystallization inhibition (IRI) compounds are therefore designed to limit the growth of ice crystals and control the crystal shape. To improve the IRI activity of cryo-systems, various synthetic polymers such as biomimetic polypeptides from polar fish, facially amphiphilic polymers, polyampholytes, poly(vinyl alcohol) derivatives, and block copolymers with hydrophilic-hydrophobic balance have been developed. Herein, poly(L-alanine-co-L-lysine) (PAK) was shown to exhibit a similar IRI activity to that of PVA. Furthermore, neither poly(L-alanine-co-L-aspartic acid) (PAD) nor poly(ethylene glycol) (PEG) with a similar molecular weight provided any significant IRI activity. These results suggest that PAK is an important compound with superior IRI activity, and that this activity is dependent upon the functional groups and secondary structure of the polypeptides.
Zhengyu Zhang,Ling Qiu 한국통신학회 2012 Journal of communications and networks Vol.14 No.2
This work investigates the progressive linear precoder design for packet retransmissions in multi-input multi-output (MIMO) systems with multiple codewords and automatic repeat request (ARQ) bundling feedback. Assuming perfect channel state information, a novel progressive linear ARQ precoder is proposed in the perspective of minimizing the packet error rate. We devise the ARQ precoder by combining power loading and subchannel pairing between current retransmission and previous transmissions. Furthermore, we extend the design to the case that the channel estimation error exists. Numerical results show that the proposed scheme can improve the performance of MIMO ARQ systems significantly regardless of the channel estimation error.