Hybrid Lifi And Wifi Communication System

A system and method are proposed that may transfer information between devices using both LiFi and the WiFi technologies. The hybrid system may use LiFi for downlink traffic and WiFi for uplink traffic. The system may include a LiFi receiver/transmitter and also a WiFi receiver/transmitter in the devices. When a device tries to communicate with a network, the data is uploaded from the device to the router connected to the network through WiFi. The device receives response from the network via the router through LiFi. The disclosed hybrid system incorporates the high download speed of LiFi (up to 4 Gbps), while maintaining the reliability of WiFi (upload speed up to 0.443 Gbps)

Privacy-Preserving Community Detection for Locally Distributed Multiple Networks

Modern multi-layer networks are commonly stored and analyzed in a local and distributed fashion because of the privacy, ownership, and communication costs. The literature on the model-based statistical methods for community detection based on these data is still limited. This paper proposes a new method for consensus community detection and estimation in a multi-layer stochastic block model using locally stored and computed network data with privacy protection. A novel algorithm named privacy-preserving Distributed Spectral Clustering (ppDSC) is developed. To preserve the edges' privacy, we adopt the randomized response (RR) mechanism to perturb the network edges, which satisfies the strong notion of differential privacy. The ppDSC algorithm is performed on the squared RR-perturbed adjacency matrices to prevent possible cancellation of communities among different layers. To remove the bias incurred by RR and the squared network matrices, we develop a two-step bias-adjustment procedure. Then we perform eigen-decomposition on the debiased matrices, aggregation of the local eigenvectors using an orthogonal Procrustes transformation, and k-means clustering. We provide theoretical analysis on the statistical errors of ppDSC in terms of eigen-vector estimation. In addition, the blessings and curses of network heterogeneity are well-explained by our bounds

Precheck Sequence Based False Base Station Detection During Handover: A Physical Layer Based Security Scheme

False Base Station (FBS) attack has been a severe security problem for the cellular network since 2G era. During handover, the user equipment (UE) periodically receives state information from surrounding base stations (BSs) and uploads it to the source BS. The source BS compares the uploaded signal power and shifts UE to another BS that can provide the strongest signal. An FBS can transmit signal with the proper power and attract UE to connect to it. In this paper, based on the 3GPP standard, a Precheck Sequence-based Detection (PSD) Scheme is proposed to secure the transition of legal base station (LBS) for UE. This scheme first analyzes the structure of received signals in blocks and symbols. Several additional symbols are added to the current signal sequence for verification. By designing a long table of symbol sequence, every UE which needs handover will be allocated a specific sequence from this table. The simulation results show that the performance of this PSD Scheme is better than that of any existing ones, even when a specific transmit power is designed for FBS

Step-by-step unbalanced force iteration method for cable-strut structure with irregular shape

In the design process of a cable-strut structure, the desired shape is first defined and the prestress can be obtained if the geometry is feasible; otherwise, the geometry must be modified. Thus, the initial step for prestress calculation is to estimate the feasibility of the geometry. In this paper, a method called Unbalanced Force Iteration (UFI) is proposed to remove the unbalanced forces using the equilibrium and stiffness equations. Feasibility of the geometry can be judged by the convergence property of UFI. Self-stress modes can be directly obtained easily through UFI method, if initial geometry is feasible. For structures with infeasible initial geometry, the Step-by-Step UFI, which combines finite element analysis and UFI, is proposed to gradually move the nodes to feasible locations. Three examples of cable domes with feasible geometry and three examples of cable domes with irregular and infeasible initial geometry are presented to verify the ability of UFI and Step-by-Step UFI for designing new irregular and asymmetric cable-strut structures

Multi-objective optimization for prestress design of cable-strut structures

Load bearing capacity of a cable-strut structure is dependent on the level and distribution of prestress. Although a higher prestress level enhances overall stiffness of the structure, this condition may demand larger member sectional areas and material cost. The effect of fabrication and installation error should also be incorporated in the prestress design. This paper presents a new optimization method for prestress design of cable-strut structures. A multi-objective optimization problem is formulated and solved to obtain preferred coefficient vectors of prestress modes with the following four objective functions: (1) minimize average area of members; (2) maximize minimum eigenvalue of stiffness matrix; (3) minimize prestress variance of cables; and (4) minimize maximum eigenvalue of error sensitivity matrix. Pareto optimal solutions are obtained by NSGA-II. Among the Pareto optimal solutions, the most preferred solution is selected using PROMETHEE-II. Two examples are presented to illustrate the proposed process. The results are compared with those by existing methods of optimization with a single objective function. Significance of each objective function is also evaluated by the number of remaining Pareto optimal solutions after removal of the objective function