A Joint Design for Multi-band Heterogeneous Networks when Deploying Reconfigurable Intelligent Surface

Wenyu Jiang,Kaizhi Huang,Yajun Chen,Xiaoli Sun,Jie Yang,Kai Zhao 한국통신학회 2022 Journal of communications and networks Vol.24 No.5

Reconfigurable Intelligent Surface (RIS) technique is effective to improve the capacity and coverage of various networks. However, the practical RIS has dissimilar responses to signals in different frequencies due to its structure. Therefore, directly applying existing schemes to multi-band heterogeneous networks leads to beam misalignment and performance degra- dation issues. This paper considers RIS-assisted multi-band heterogeneous networks where base stations (BSs) use different frequencies. We formulate the problem for maximizing the sum rate of all users (SR) in every frequency band, and aim to jointly design BSs precoding vectors and RIS parameters while taking user choices into account. Based on the closed-form relationship of phase shifts between frequencies, an iterative algo- rithm is proposed to solve the challenging non-convex problems. In particular, we use fractional programming to decouple the problem, and solve the subproblems with Quadratic Transform (QT) and Genetic Algorithm (GA). Simulation results show that the proposed scheme can significantly improve SR among all frequency bands, which could instruct the coexistence of mul- tiple communication systems in future heterogeneous networks. What’s more, results also prove that deploying RISs recklessly will result in a degradation of the network.

Enhancing the Session Security of Zen Cart based on HMAC-SHA256

( Lihui Lin ),( Kaizhi Chen ),( Shangping Zhong ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.1

Zen Cart is an open-source online store management system. It is used all over the world because of its stability and safety. Today, Zen Cart`s session security mechanism is mainly used to verify user agents and check IP addresses. However, the security in verifying the user agent is lower and checking the IP address can affect the user`s experience. This paper, which is based on the idea of session protection as proposed by Ben Adida, takes advantage of the HTML5`s sessionStorage property to store the shared keys that are used in HMAC-SHA256 encryption. Moreover, the request path, current timestamp, and parameter are encrypted by using HMAC-SHA256 in the client. The client then submits the result to the web server as per request. Finally, the web server recalculates the HMAC-SHA256 value to validate the request by comparing it with the submitted value. In this way, the Zen Cart`s open-source system is reinforced. Owing to the security and integrity of the HMAC-SHA256 algorithm, it can effectively protect the session security. Analysis and experimental results show that this mechanism can effectively protect the session security of Zen Cart without affecting the original performance.

CoMP Transmission for Safeguarding Dense Heterogeneous Networks with Imperfect CSI

( Xu Yunjia ),( Huang Kaizhi ),( Hu Xin ),( Zou Yi ),( Chen Yajun ),( Jiang Wenyu ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.1

To ensure reliable and secure communication in heterogeneous cellular network (HCN) with imperfect channel state information (CSI), we proposed a coordinated multipoint (CoMP) transmission scheme based on dual-threshold optimization, in which only base stations (BSs) with good channel conditions are selected for transmission. First, we present a candidate BSs formation policy to increase access efficiency, which provides a candidate region of serving BSs. Then, we design a CoMP networking strategy to select serving BSs from the set of candidate BSs, which degrades the influence of channel estimation errors and guarantees qualities of communication links. Finally, we analyze the performance of the proposed scheme, and present a dual-threshold optimization model to further support the performance. Numerical results are presented to verify our theoretical analysis, which draw a conclusion that the CoMP transmission scheme can ensure reliable and secure communication in dense HCNs with imperfect CSI.

Secure Wireless Communications in The Multi-user MISO Interference Channel Assisted by Multiple Reconfigurable Intelligent Surfaces

Ya Liu,Jie Yang,Kaizhi Huang,Xiaoli Sun,Yi Wang 한국통신학회 2022 Journal of communications and networks Vol.24 No.5

This paper exploits reconfigurable intelligent sur- faces (RIS) to enhance physical layer security (PLS) in a challeng- ing radio environment. By adjusting the reflecting coefficients, RIS can provide a programmable wireless environment so that the electromagnetic wave can propagate in the desired way. Specifically, we consider a scenario where multiple user pairs communicate simultaneously over the same channel in a multi- user MISO interference channel and each pair of transceivers keeps their confidential information secret from other receivers. We investigate the secrecy rate balance of the system aided by multiple RISs and exploit the additional design degrees of freedom provided by the coordinated RISs to increase the secrecy capacity, achieving secrecy transmission. In particular, we adopt cooperative beamforming among the collaborative transmitters to maximize all users’ minimum secrecy rate, achieving the secrecy rate balance. Due to the non-convexity of the formulated opti- mization problem, we propose alternating optimization (AO) to solve it iteratively and optimize active the transmit beamforming at the transmitters and passive phase shifts at the RISs based on positive semi-definite relaxation (SDR) and successive convex approximation (SCA). In each iteration, we solve a semi-definite programming (SDP) problem and finally get the optimal local solution to the optimization problem. Finally, the simulation results validate that the proposed algorithm is effective and the introduced RISs can significantly enhance the system secrecy performance compared to conventional baseline schemes.

Aqueous Extract of Lysimachia christinae Hance Prevents Cholesterol Gallstone in Mice by Affecting the Intestinal Microflora

( Shijia Liu ),( Quji Luorong ),( Kaizhi Hu ),( Weiguo Cao ),( Wei Tao ),( Handeng Liu ),( Dan Zhang ) 한국미생물 · 생명공학회 2021 Journal of microbiology and biotechnology Vol.31 No.9

With changes in human dietary patterns, the proportion of high-fat and high-cholesterol foods in the daily diet has increased. As a result, the incidence rate of cholelithiasis is increasing rapidly. Many studies have reported on the crucial role that the intestinal microflora plays in the progression of gallstones. Although the whole herb of Lysimachia christinae, a traditional Chinese medicine, has long been extensively used as a remedy for cholelithiasis in China, its effects on the intestinal microflora remain unknown. Hence, in this study, we investigated the ability of the aqueous extract of L. christinae (LAE) to prevent cholesterol gallstones (CGSs) in model animals by affecting the intestinal microflora. The effects of LAE on body weight, serum lipid profile, visceral organ indexes, and histomorphology were studied in male C57BL/6J mice, which were induced by a lithogenic diet. After the 8-week study, CGSs formation was greatly reduced after LAE treatment. LAE also reduced body weight gain and hyperlipidemia and restored the histomorphological changes. Moreover, the intestinal microflora exhibited significant variation. In the model group fed the lithogenic diet, the abundances of the genera unclassified Porphyromonadaceae, Lactobacillus and Alloprevotella decreased, but in contrast, Akkermansia dramatically increased compared with the control check group, which was fed a normal diet; the administration of LAE reversed these changes. These results imply that L. christinae can be considered an efficient therapy for eliminating CGSs induced by a high-fat and high-cholesterol diet, which may be achieved by influencing the intestinal microflora.

Convergence rate of extremes for the generalized short-tailed symmetric distribution

Fuming Lin,Zuoxiang Peng,Kaizhi Yu 대한수학회 2016 대한수학회보 Vol.53 No.5

Denote $M_{n}$ the maximum of $n$ independent and identically distributed variables from the generalized short-tailed symmetric distribution. This paper shows the pointwise convergence rate of the distribution of $M_{n}$ to $\exp(-e^{-x})$ and the supremum-metric-based convergence rate as well.

Secrecy Spectrum and Secrecy Energy Efficiency in Massive MIMO Enabled HetNets

( Zhihao Zhong ),( Jianhua Peng ),( Kaizhi Huang ),( Lu Xia ),( Xiaohui Qi ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.2

Security and resource-saving are both demands of the fifth generation (5G) wireless networks. In this paper, we study the secrecy spectrum efficiency (SSE) and secrecy energy efficiency (SEE) of a K-tier massive multiple-input multiple-output (MIMO) enabled heterogeneous cellular network (HetNet), in which artificial noise (AN) are employed for secrecy enhancement. Assuming (i) independent Poisson point process model for the locations of base stations (BSs) of each tier as well as that of eavesdroppers, (ii) zero-forcing precoding at the macrocell BSs (MBSs), and (iii) maximum average received power-based cell selection, the tractable lower bound expressions for SSE and SEE of massive MIMO enabled HetNets are derived. Then, the influences on secrecy oriented spectrum and energy efficiency performance caused by the power allocation for AN, transmit antenna number, number of users served by each MBS, and eavesdropper density are analyzed respectively. Moreover, the analysis accuracy is verified by Monte Carlo simulations.

AKA-PLA: Enhanced AKA Based on Physical Layer Authentication

( Jing Yang ),( Xinsheng Ji ),( Kaizhi Huang ),( Ming Yi ),( Yajun Chen ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.7

Existing authentication mechanisms in cellular mobile communication networks are realized in the upper layer by employing cryptographic techniques. Authentication data are broadcasted over the air in plaintext, enabling attackers to completely eavesdrop on the authentication and get some information about the shared secret key between legitimate nodes. Therefore, reusing the same secret key to authenticate several times results in the secret key`s information leakage and high attacking rate. In this paper, we consider the most representative authentication mechanism, Authentication and Key Agreement (AKA), in cellular communication networks and propose an enhanced AKA scheme based on Physical Layer Authentication (AKA-PLA). Authentication responses generated by AKA are no longer transmitted in plaintext but masked by wireless channel characteristics, which are not available to adversaries, to generate physical layer authentication responses by a fault-tolerant hash method. The authenticator sets the threshold according to the authentication requirement and channel condition, further verifies the identity of the requester based on the matching result of the physical layer authentication responses. The performance analyses show that the proposed scheme can achieve lower false alarm rate and missing rate, which are a pair of contradictions, than traditional AKA. Besides, it is well compatible with AKA.

CONVERGENCE RATE OF EXTREMES FOR THE GENERALIZED SHORT-TAILED SYMMETRIC DISTRIBUTION

Lin, Fuming,Peng, Zuoxiang,Yu, Kaizhi Korean Mathematical Society 2016 대한수학회보 Vol.53 No.5

Denote $M_n$ the maximum of n independent and identically distributed variables from the generalized short-tailed symmetric distribution. This paper shows the pointwise convergence rate of the distribution of $M_n$ to exp($\exp(-e^{-x})$) and the supremum-metric-based convergence rate as well.

Secure Transmission Scheme Based on the Artificial Noise in D2D-Enabled Full-Duplex Cellular Networks

( Chen Yajun ),( Yi Ming ),( Zhong Zhou ),( Ma Keming ),( Huang Kaizhi ),( Ji Xinsheng ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.10

In this paper, a secure transmission scheme based on the artificial noise is proposed for D2D communications underlaying the full-duplex cellular network, and a secure power allocation scheme to maximize the overall secrecy rate of both the cellular user and D2D transmitter node is presented. Firstly, the full-duplex base station transmits the artificial noise to guarantee the secure communications when it receives signals of cellular uplinks. Under this secure framework, it is found that improving the transmission power of the cellular user or the D2D transmitter node will degrade the secrecy rate of the other, although will improve itself secrecy rate obviously. Hence, a secure power allocation scheme to maximize the overall secrecy rate is presented subject to the security requirement of the cellular user. However, the original power optimization problem is non-convex. To efficiently solve it, we recast the original problem into a convex program problem by utilizing the proper relaxation and the successive convex approximation algorithm. Simulation results evaluate the effectiveness of the proposed scheme.