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Outage Analysis of Multihop Wireless Backhaul Using Millimeter Wave under Blockage Effects
Jung, Haejoon,Lee, In-Ho Hindawi Limited 2017 International journal of antennas and propagation Vol.2017 No.-
<P>We consider multihop millimeter-wave (mm-Wave) wireless backhaul communications, by which small cell base station (SBS) clusters can connect to a macrocell base station (MBS). Assuming the mm-Wave wireless backhaul links suffer from outage caused by obstacles that block the line-of-sight (LoS) paths, we derive the statistics of a perhop distance based on the blockage model using stochastic geometry and random shape theory and analyze the multihop outage probability using the statistics of a perhop distance. We also provide an optimal number of hops to minimize the end-to-end outage performance between the MBS and the destination SBS cluster when the end-to-end distance is given.</P>
Jung, Haejoon,Lee, In-Ho Institute of Electrical and Electronics Engineers 2018 IEEE transactions on antennas and propagation Vol.66 No.10
<P>Buchanan and Huff <xref ref-type='bibr' rid='ref1'>[1]</xref> analyzed the characteristics of spherically bound random arrays and presented a closed-form expression for the expected beam pattern, which is one of the key array characteristics, where <TEX>$N$</TEX> radiators are assumed to be randomly distributed within a spherical volume of radius <TEX>$A$</TEX>. The location of array element <TEX>$n$</TEX> is denoted as radial distance <TEX>$r_{n} \in [0,A]$</TEX>, elevation angle <TEX>$\theta _{n} \in [0,\pi ]$</TEX>, and azimuth angle <TEX>$\phi _{n} \in [0,2\pi )$</TEX> in the spherical coordinates.</P>
Performance Analysis of Three-Dimensional Clustered Device-to-Device Networks for Internet of Things
Jung, Haejoon,Lee, In-Ho Hindawi Limited 2017 WIRELESS COMMUNICATIONS AND MOBILE COMPUTING Vol.2017 No.-
<P>Internet of things (IoT) is a smart technology that connects anything anywhere at any time. Intelligent device-to-device (D2D) communication, in which devices will communicate with each other autonomously without any centralized control, is an integral part of the Internet of Things (IoT) ecosystem. Thus, for D2D applications such as local file sharing or swarm sensing, we study communications between devices in proximity in ultra-dense urban environments, where devices are stacked vertically and dispersed in the horizontal plane. To reflect the spatiotemporal correlation inherently embedded in the D2D communications, we model and analyze clustered D2D networks in three-dimensional (3D) space based on Thomas cluster process (TCP), where the locations of clusters follow Poisson point process, and cluster members (devices) are normally distributed around their cluster centers. We assume that multiple device pairs in the network can share the same frequency band simultaneously. Thus, in the presence of cochannel interference from both the same cluster and the other clusters, we investigate the coverage probability and the area spectral efficiency of the clustered D2D networks in 3D space.</P>
Jung, Haejoon,Lee, In-Ho IEEE 2019 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.18 No.3
<P>A wireless sensor network (WSN) refers to a network of sensor nodes that collaboratively work to sense, monitor, and control their surrounding environments. As WSNs are integrated into the Internet of Things, it is crucial to protect the network against malicious security attacks considering its wide applicability, such as military monitoring, healthcare, and civilian applications. Thus, in this paper, we consider a physical-layer security technique exploiting analog cooperative beamforming (ACB), where multiple sensor nodes create a virtual antenna array (VAA) and locally adapt their phases. As WSNs inherently have clustered topology, we model the VAA elements’ locations by Gaussian distributions. The secrecy capacity of the ACB with the Gaussian-distributed elements is derived in a closed-form expression. The theoretical and numerical results indicate that the ACB-based schemes provide a better secrecy rate compared to the conventional co-located antenna array-based schemes. In addition, the ACB with Gaussian-distributed elements can better suppress side-lobe, which causes undesired information leakage to certain directions, compared to the ACB with uniformly distributed elements. Furthermore, we investigate the impacts of fading channel and phase estimation error in the ACB.</P>
랜덤 스위치 안테나 배열의 수학적으로 정확한 보안 전송률
서정곤(Jung-gon Seo),유병하(Byungha You),정해준(Haejoon Jung) 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.6
본 논문은 물리계층 보안 (PLS: Physical-layer security)에 기반한 Antenna Subset Modulation (ASM) 기법에 대한 정확한 수학적 분석을 제공한다. ASM 기법 중 하나인 switched array 에 대한 기존의 근사적 이론 결과는 시뮬레이션 결과와는 다른 결과를 보였다. 이에 착안하여, 본 논문에서는 array factor 와 보안 전송률 (secrecy rate)에 대해 근사치 없이 수학적으로 분석하여 이들의 closed-form 표현을 제공한다. 또한, 높은 수치의 보안 전송률을 갖는 최적의 부분집합의 크기 (subset size)가 있음을 시뮬레이션 결과를 통해 보인다.
Texture map generation for 3D reconstructed scenes
Jeon, Junho,Jung, Yeongyu,Kim, Haejoon,Lee, Seungyong Springer-Verlag 2016 The Visual computer Vol.32 No.6
<P>We present a novel method for generating texture maps for 3D geometric models reconstructed using consumer RGB-D sensors. Our method generates a texture map for a simplified 3D mesh of the reconstructed scene using spatially and temporally sub-sampled key frames of the input RGB stream. We acquire an accurate texture map by optimizing the texture coordinates of the 3D model to maximize the photometric consistency among multiple key frames. We show that the optimization can be performed efficiently using GPU by exploiting the locality of texture coordinate manipulation. Experimental results demonstrate that our method can generate a texture map in a few tens of seconds for a large 3D model, such as a whole room.</P>