Sunghwan Kim's research while affiliated with University of Ulsan and other places

Publications (131)

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Recently, atmospheric-turbulence-induced fading in free-space optical (FSO) communication with pointing error impairment was modeled and studied using the Fisher–Snedecor F distribution with a good fit to experimental data. In this letter, we investigate the end-to-end performance of dual-hop FSO fixed-gain relaying systems operating over F turbule...
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The problems of finding accurate limits of integration in symbolic form are non-trivial when analyzing the secrecy outage probability (SOP) over complicated communication schemes. To identify these limits, we formulate an existential quantifier elimination (QE) problem based on the description of the secrecy outage events. After that, the resulting...
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In this paper, we propose short-packet communications (SPCs) with non-orthogonal multiple access (NOMA) for coordinated and direct relay transmission (CDRT) Internet-of-Things (IoT) networks to enhance spectrum utilization and system performance. In this system, a source transmits its packets to a near IoT user via direct transmission and a far IoT...
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This paper studies the performance of intelligent reflecting surface (IRS)-aided short-packet non-orthogonal multiple access (NOMA) systems under perfect and imperfect successive interference cancellation. Closed-form expressions for the average block error rate (BLER) with random and optimal phase shifts are derived. To gain some useful insights,...
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This article investigates the outage performance of a wireless powered cooperative nonorthogonal multiple access-based coordinated direct and relay transmission (CDRT) Internet-of-Things (IoT) network with simultaneous wireless information and power transfer capable IoT master node. A method to remedy the high outage situation of a near user by exp...
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This paper investigates reconfigurable intelligent surface (RIS)-aided cognitive non-orthogonal multiple access (NOMA) systems, where an RIS is deployed to serve two users under multi-primary users’ constraints. Our analysis assumes imperfect channel state information and successive interference cancellation under scenarios with and without line-of...
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This paper analyzes the performance of an uplink/downlink reconfigurable intelligent surface (RIS)-based wireless system with a multiple-antenna base station (B), where the RIS selection strategy is considered to alleviate the overhead and resources. With the goal of enhancing system performance, we consider maximal-ratio-combining (MRC) and select...
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Due to the properties of DNA data storage, the errors that occur in DNA strands make error correction an important and challenging task. In this paper, a new code design of quaternary code suitable for DNA storage is proposed to correct at most two consecutive deletion or insertion errors. The decoding algorithms of the proposed codes are also pres...
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In this paper, we study wireless-powered cognitive non-orthogonal multiple access (NOMA) Internet-of-Things (IoT) networks with short-packet communications to improve spectrum utilization and sustainability, as well as reduce the latency under imperfect channel state information (CSI) and successive interference cancellation (SIC). For performance...
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Due to the advantages of high information densities and longevity, DNA storage systems have begun to attract a lot of attention. However, common obstacles to DNA storage are caused by insertion, deletion, and substitution errors occurring in DNA synthesis and sequencing. In this paper, we first explain a method to convert binary data into general m...
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In this paper, we investigate an underlay cognitive non-orthogonal multiple access (NOMA)-based coordinated direct and relay transmission network with imperfect successive interference cancellation, imperfect channel state information, and co-channel interference caused by a multi-antenna primary transmitter. In the secondary network, a source comm...
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In this paper, we study novel wireless powered cognitive non-orthogonal multiple access (NOMA)-based Internet-of-Things (IoT) relay networks to improve the performance of a cell-edge user under perfect and imperfect successive interference cancellation (SIC). In the secondary networks, a source node communicates with a cell-center user via direct-l...
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In this paper, we propose a cooperative non-orthogonal multiple access (NOMA)-enabled simultaneous wireless information and power transfer (SWIPT) Internet-of-Things (IoT) networks, where one information source harvests energy from a multi-antennas power beacon (PB) to serve two IoT users via the help of multiple energy-limited relay nodes. To impr...
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In this paper, we study a mixed cooperative communication system consisting of power line communication (PLC) and free-space optical communication (FSO) links, where the PLC link suffers from log-normal fading and is affected by both impulsive and background noises. Meanwhile, the FSO link undergoes Gamma-Gamma fading with both atmospheric turbulen...
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In this letter, we present the first attempt of active light-emitting diode (LED) indexes estimating for the generalized LED index modulation optical orthogonal frequency-division multiplexing (GLIM-OFDM) in visible light communication (VLC) system by using deep learning (DL). Instead of directly estimating the transmitted binary bit sequence with...
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Motivation: In DNA storage systems, there are tradeoffs between writing and reading costs. Increasing the code rate of error-correcting codes may save writing cost, but it will need more sequence reads for data retrieval. There is potentially a way to improve sequencing and decoding processes in such a way that the reading cost induced by this tra...
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In this paper, we investigate power beacon-assisted wireless powered non-orthogonal multiple access (NOMA) Internet-of-Things (IoT)-based systems, where all transmitters harvest energy from a power beacon (PB) to transmit their signals to a destination by employing a time-splitting mechanism. In order to utilize spectral efficiency and enhance the...
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Future networks communication scenarios by the 2030s will include notable applications are three-dimensional (3D) calls, haptics communications, unmanned mobility, tele-operated driving, bio-internet of things, and the Nanointernet of things. Unlike the current scenario in which megahertz bandwidth are sufficient to drive the audio and video compon...
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Superposed constellation for spatial multiplexing visible light communication (VLC) systems has recently attracted significant attention as a promising method to alleviate the effect of nonlinearity on light-emitting diodes (LEDs) that has achieved significant performance improvements in VLC systems. A large minimum Euclidean distance (ED) value of...
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In this paper, a low cost, highly efficient and low profile monopole antenna for ultra-wideband (UWB) applications is presented. A new inverted triangular shape structure possessing meander lines is designed to achieve a wide-band response and high efficiency. To design the proposed structure, three steps are utilized to achieve an UWB response. Th...
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Recently, distributed massive multiple-input multiple-output (MIMO) systems have gained a lot of attention, in which many access points (APs) are deployed in a wide area to simultaneously serve users. This paper investigates a combination of two problems in distributed massive MIMO systems: user-AP selection and power allocation. We derive a closed...
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Mobile Edge Computing (MEC) has emerged as an alternative to cloud computing to meet the latency and Quality-of-Service (QoS) requirements of mobile devices. In this paper, we address the problem of server resource allocation in MEC. Due to the dynamic load conditions on MEC servers, their resources need to be used intelligently to meet the QoS req...
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Intentional jammers (IJs) can be used by the attackers for launching of distributed denial of service attacks in 5G cellular networks. These adversaries are assumed to have adequate information about the network specifications, such as duration, transmit power and positions. With these assumptions, the IJs gain the ability to disrupt the legitimate...
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With the rapid increase in the development of a cellular communication system, remote health monitoring and smart health care are improving and getting through a swift transformation. Currently, we are utilizing the advance long term evolution (A-LTE) network to support the modern health care. Nevertheless, smart hospital/health concern is not full...
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This paper presents an isolation enhancement of two closely packed multiple-input multiple-output (MIMO) antenna system using a modified U-shaped resonator. The modified U-shaped resonator is placed between two closely packed radiating elements resonating at 5.4 GHz with an edge to edge separation distance of 5.82 mm (λ∘/10). Through careful adjust...
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The deployment of low power small base stations (SBSs) in high density user areas enhances the performance of heterogeneous cellular networks (HCNets). Such user-centric SBS deployment (UCSD) is more appropriate as compared with the conventional uniformly deployed user equipment (UE) based HCNets, because it captures the correlation between UEs and...
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Due to rapid growth in wireless communication technology, higher bandwidth requirement for advance telecommunication systems, capable of operating on two or higher bands with higher channel capacities and minimum distortion losses is desired. In this paper, a compact Ultra-Wideband (UWB) V-shaped monopole antenna is presented. UWB response is achie...
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In multiple-input multiple-output (MIMO) visible light communication (VLC) systems, collaborative constellation design (CC) is effective in improving performance while significantly reducing the total optical power. This letter presents the first attempt to exploit deep learning (DL) in the signal design for MIMO VLC systems using CC, namely CCNet....
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With the emergence of power electronic technology and advancements in highly efficient electric power converters, DC-DC converters play a significant role in DC networks and DC distribution systems. Not being fully understood, nevertheless, the stability, protection and safety of DC systems present an open challenge for the research community. In t...
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In this paper, we propose a multiple user-type massive multiple-input-multiple-output (MIMO) system and present power allocation solutions for this proposed network. Unlike conventional massive MIMO systems in which all users are treated equally, the proposed system consists of two types of users: quality-of-service (QoS) users, who are guaranteed...
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Metamaterial surfaces play a vital role to achieve the surface waves suppression and in-phase reflection, in order to improve the antenna performance. In this paper, the performance comparison of a fifth generation (5G) antenna design is analyzed and compared with a metamaterial-based antenna for 5G communication system applications. Metamaterial s...
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In this paper, we investigate the selection problem of access points (APs) in cell-free massive multiple-input multiple-output (MIMO) systems, where APs equipped with a large number of antennas are geographically distributed over a wide area with no cell border. These APs simultaneously serve many users, which are randomly distributed all over the...
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In fifth generation (5G) networks, the densification of small base stations in the coverage region of macro base station (MBS) leads to significant inter-cell interference (ICI). Similarly, drones (a.k.a. unmanned aerial vehicles) have a diverse scope in multifarious 5G assisted applications and, therefore, cause considerable drones interference (D...
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IPv6 over Low Power Wireless Personal Area Networks (6LoWPAN) has an ample share in the Internet of Things. Sensor nodes in 6LoWPAN collect vital information from the environment and transmit to a central server through the public Internet. Therefore, it is inevitable to secure communications and allow legitimate sensor nodes to access network res...
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Named Data Networking (NDN) is a revolutionary approach to cater for the modern 1 and future Internet usage trends. The advancements in web services, social networks and cloud computing have shifted the Internet utilization towards information delivery. Information-centric networking (ICN) enables content-awareness in the network layer and adopts n...
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The standardization activities of the fifth generation communications are clearly over and deployment has commenced globally. To sustain the competitive edge of wireless networks, industrial and academia synergy have begun to conceptualize the next generation of wireless communication systems (namely, sixth generation, (6G)) aimed at laying the fou...
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In this paper, we propose an orientation-induced link-blocked receiver (OLBR) to simultaneously reduce the correlation of the multiple-input multiple-output (MIMO) channels and avoid disruptive transmission in visible light communication (VLC) system. The idea of this paper is to combine the adjustable normal vector ideology of an angle diversity r...
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In this paper, a novel quantum transmission protocol which are based on the quantum no-key protocol is proposed. First, the quantum no-key protocol is discussed to show its important and its non-efficient on data transmission over quantum channel. Then, we improve it to carry many data bits via transmission. In addition, the error correction code i...
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Massive multiple-input multiple-output (M-MIMO) is a substantial pillar in fifth generation (5G) mobile communication systems. Although the maximum likelihood (ML) detector attains the optimum performance, it has an exponential complexity. Linear detectors are one of the substitutions and they are comparatively simple to implement. Unfortunately, t...
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This paper proposed a “Probabilistic and Deterministic Tree-based Routing for WSNs (PDTR)”. The PDTR builds a tree from the leaves to the head (sink), according to the best elements in the initial probabilistic routing table, measured by the product of hops-count distribution, and transmission distance distribution, to select the best tree-paths. E...
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Chronic Kidney Disease (CKD) implies that the human kidneys are harmed and unable to blood filter in the manner which they should. The disease is designated "chronic" in light of the fact that harm to human kidneys happen gradually over a significant time. This harm can make wastes to build up in your body. Many techniques and models have been deve...
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Multi-focus image fusion is a very essential method of obtaining on all focus image from multiple source images. The fused image eliminates the out of focus regions and the resultant image contains sharp and focused regions. A novel multiscale image fusion system based on contrast enhancement, spatial gradient information, and multiscale image mat...
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Multi-focus image fusion is a very essential method of obtaining an all focus image from multiple source images. The fused image eliminates the out of focus regions, and the resultant image contains sharp and focused regions. A novel multiscale image fusion system based on contrast enhancement, spatial gradient information and multiscale image matt...
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Abstract About 20% of energy in manufacturing is connected to refrigeration, heating water, the purpose of this research is to save environment by conserving water losses and these has to be replenished. Monitor rate of evaporation make up and blow down water superiority to authorize that the up-gradated structure is acting as predicted. Increas...
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In homogeneous cellular networks, fractional power control (FPC) is employed to partially compensate the path-loss and, hence, improve uplink (UL) signal-to-interference ratio (SIR). However, this scheme is less effective in heterogeneous cellular networks (HetNets) because: (i) except the typical user, all other users with variable UL transmit pow...
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Fifth-generation (5G) communications system is commercially introduced by several mobile operators where sub-6 GHz bands are the backbone of the 5G networks. A large-scale multiple-input multiple-output (MIMO), or massive MIMO (mMIMO), technology has a major impact to secure high data rate, high spectral efficiency, and quality of service (QoS). It...
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Fiber optic communication systems (FOCSs) have attained a lot of attention by revolutionizing the telecommunication industry and offering new possibilities with the technical advancements in state-ofthe-art high speed digital electronics. Advanced modulation formats make use of the phase, amplitude and polarization of the optical signals at the sam...
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Multilevel-thresholding is an efficient method used in image segmentation. This paper presents a hybrid meta-heuristic approach for multi-level thresholding image segmentation by integrating both the artificial bee colony (ABC) algorithm and the sine-cosine algorithm (SCA). The proposed algorithm, called ABCSCA, is applied to segment images and it...
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Accomplishing high recognition performance is considered one of the most important tasks for handwritten Arabic character recognition systems. In general, Optical Character Recognition (OCR) systems are constructed from four phases: pre-processing, feature extraction, feature selection, and classification. Recent literature focused on the selection...
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This paper presents a miniaturized circularly polarized multiple-input multiple-output (MIMO) antenna for wearable biotelemetric devices. The proposed MIMO antenna consists of four elements, which are placed orthogonally to the adjacent elements. The proposed antenna has a wideband response 10-dB bandwidth of 2210 MHz (fractional bandwidth (FBW) =...
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This paper presents a wideband, low-profile and semi-flexible antenna for wearable biomedical telemetry applications. The antenna is designed on a semi-flexible material of RT/duroid 5880 (r = 2.2, tanδ = 0.0004) with an overall dimensions of 17 mm × 25 mm × 0.787 mm (0.2λ∘×0.29λ∘×0.009λ∘). A conventional rectangular patch is modified by adding rec...
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In massive multiple-input multiple-output (M-MIMO) systems, a detector based on maximum likelihood (ML) algorithm attains optimum performance, but it exhaustively searches all possible solutions, hence, it has a very high complexity and realization is denied. Linear detectors are an alternative solution because of low complexity and simplicity in i...
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Due to the advantages of high storage densities and longevity, DNA storage has become one of the attractive technologies for future data storage systems. However, the writing/reading cost is still high and more efficient techniques for DNA storage are required. In this paper, we propose improved log-likelihood ratio (LLR) processing schemes based o...
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Any realistic indoor multiple-input multiple-output (MIMO) visible light communication (VLC) system, besides providing reliable high rate transmission, should also support flicker-free, dimming capable, and uniform illumination. In this article, we propose a multi-level multi-pulse modulation for a MIMO VLC system to provide a high data rate with f...
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In heterogeneous cellular networks (HetNets), small base stations (SBSs) are overlaid in the coverage region of a macro base station (MBS) to improve coverage and spectral efficiency. However, the performance of HetNets is significantly degraded by inter-cell interference (ICI) due to aggressive frequency reuse and multi-tier deployment. Besides IC...
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In heterogeneous cellular networks (HetNets), densification of small base stations (SBSs) in the macro base station (MBS) coverage region leads to improved network coverage and capacity. However, this improvement is at the cost of inter-cell interference (ICI) due to the high MBS transmit power. The situation deteriorates further when uniformly dep...
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In this paper, we propose a receiver designing principle for the multiple-input multiple-output (MIMO) visible light communication (VLC) systems with quadrichromatic light emitting diodes (QLEDs). To simultaneously transmit multiple data streams, the system consists of multiple QLEDs and multiple receivers; each includes four photodiodes (PDs). We...
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Optical communication networks (OCNs) provide promising and cost-effective support for the ultra-fast broadband solutions, thus enabling them to address the ever-growing demands of telecommunication industry such as high capacity and end users' data rate. OCNs are used in both wired and wireless access networks as they offer many advantages over co...