Penn State College of Communications

About: Penn State College of Communications is a based out in . It is known for research contribution in the topics: Relay & Cognitive radio. The organization has 2106 authors who have published 2119 publications receiving 24693 citations.

The Security of Cognitive Multiuser Networks Over Space-and-Time Correlated Channels

Abstract: In this paper, we investigate the secrecy performance of cognitive multi-input multi-output multiuser (MIMO-MU) wiretap networks over space-and-time correlated fading channels. Specifically, we propose a joint transmit antenna selection (TAS) and multiuser scheduling scheme to improve the security of the considered system. To thoroughly analyze the impact of the joint TAS and multiuser scheduling scheme and the channel correlation on the physical layer security, the new exact and asymptotic closed-form expressions for the secrecy outage probability of cognitive MIMO-MU wiretap networks are derived in two distinct scenarios, i.e., space-and-time correlated fading channels and independent-and-perfect fading channels. From the theoretical and simulation results, several important remarks are concluded as follows. 1) The channel space correlation does not affect the achievable secrecy diversity order in a high main-to-eavesdropper ratio (MER) regime. While it produces different impacts on the secrecy performance with different values of the MER in a low MER regime. 2) The channel time correlation on the main channel can reduce the achievable secrecy diversity order from $N_{\rm A}N_{\rm B}$ to 1. 3) The joint TAS and multiuser scheduling scheme can achieve better performance than the traditional random scheduling scheme over space-and-time correlated fading channels.

Microstrip-line-slot fed EDPA elements and array with ELP

Abstract: Equally divided patch antenna (EDPA) element and array designs with electrically large property (ELP) are proposed in this study. ELP is realized by dividing the square radiating patch into n × n (n = 1, 2, 3, 4, 5, 6, …) elements gradually with the same overall size but higher resonant frequencies. The dispersion diagrams of the divided unit cells are extracted from the S-parameters and the field characteristics of dominant modes are described to confirm the ELP. Then 4 × 4 EDPA is taken as an example for detail analysis. By optimizing the geometry of the microstrip-line-slot feeding structure, different resonant modes can be merged and broad bandwidth is achieved. Furthermore, 1 × 2 array of the 4 × 4 EDPA is designed. Both the element and array antennas were fabricated for verification and good agreement between the measured and simulated results was obtained. The element and array owns −10 dB impedance bandwidth of 51.4 and 34.9% and maximum gain of 10.6 and 13.5 dBi, respectively. The proposed EDPA method can be used to design antenna element and array with ELP in higher-frequency band of microwave and millimetre-wave band for their easy fabrication, wide bandwidth, and considerable gain property.

Geolocation database based resource sharing among multiple device-to-device links in TV white space

Abstract: The open access of TV white space (TVWS) has aroused many attentions, but there are still some technical challenges with respect to the protection of incumbent TV services and secondary coexistence. Fortunately, the emerging trends of spectrum access through geolocation databases have relaxed the regulatory constraints on Cognitive Radios (CRs). Device-to-device (D2D) communication is a promising technology component that has been proposed in the LTE-Advanced networks to improve spectrum utilization, and it can also show its superiorities in TVWS. In this paper, we study the resource sharing problem for large numbers of D2D communications underlaying TVWS based on geolocation database. Firstly, we introduce the system model. Then the resource allocation with admission control scheme is proposed, which consists of two stages: spectrum assignment with interference minimization as well as power control and admission control. The objective is to maximize the accessed number of D2D links by appropriately allocating available channels and coordinating power levels. Moreover, both the Quality of Service (QoS) requirements for D2D users and interference protection for victim TV receivers can be guaranteed. Finally, simulation results show the well performance of proposed schemes.

A Joint Game-Theoretic Interference Coordination Approach in Uplink Multi-Cell OFDMA Networks

Abstract: In this paper, we present a joint game-theoretic approach to perform inter-cell interference coordination in uplink multi-cell orthogonal frequency division multiple access networks. The coordinated user scheduling and power allocation are considered simultaneously. We prove the existence of the joint-strategy Nash equilibrium (NE) in which both the user scheduling and power allocation strategy reach NE. Then, we design a distributed joint-strategy iterative algorithm to perform interference-aware resource allocation where only partial information exchange is involved. Simulation results demonstrate the effectiveness of the proposed algorithm.

Toughening epoxy resins by modification with in situ polymerized acrylate copolymer composed of butyl acrylate and glycidyl methacrylate

Abstract: Poly(butyl acrylate–glycidyl methacrylate) (PBG) was prepared by in situ polymerization of butyl acrylate (BA) and glycidyl methacrylate (GMA) and further used as a modifier to improve the comprehensive properties of the epoxy resin curing system The modified resin system was based on diglycidyl ether of bisphenol, methyl tetrahydrophthalic anhydride, and tris(dimethylaminomethyl)phenol The influence of copolymer composition on the mechanical properties, thermal performance, and phase behavior of the system was carefully examined Results showed that the addition of PBG greatly improved the impact strength of the modified epoxy resin When 15 wt% of the BA/GMA with a weight ratio composition of 75/75 was added to the epoxy, high-performance-modified epoxy resin was obtained