• Electronics and Telecommunications Trends
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• v.33 no.5
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• pp.24-32
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• 2018

With the advent of new convergence services, the requirements of 5G mobile communication systems are being newly derived. The 5G mobile communication system has been evolving to solve requirements that cannot be satisfied with existing 4G mobile communication systems, such as a high user experience transmission rate, short transmission delay, and high connection density. The evolution of a 5G mobile communication system to meet the new requirements is expected to be dominated by the UDN environment in which a number of small cells are concentrated. The 5G wireless backhaul system, which has advantages in terms of initial installation and operation cost, is expected to be an indispensable choice for connecting many small cells and core networks. This paper therefore looks at the frequency band characteristics and requirements applicable to 5G wireless backhaul systems that can accommodate new situations, and introduces key related technologies that can satisfy the 5G wireless backhaul requirements.. In addition, we describe the research and development trends of a 5G wireless backhaul system that is currently under development.

• Journal of Communications and Networks
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• v.14 no.1
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• pp.15-20
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• 2012

As Internet protocol and wireless communications have developed, the number of different types of mobile services has increased gradually. Existing priority-computing schemes cannot satisfy the dynamic requirements of supporting multiple services in future wireless communication systems, because the currently used factors, mainly user priority, are relatively simple and lack relevancy. To solve this problem and provide the desired complexity, dynamic behavior, and fairness features of 3G and beyond 3G mobile communication systems, this paper proposes a novel cross-layer dynamic integrated priority-computing scheme that computes the priority based on a variety of factors, including quality of service requirements, subscriber call types, waiting time, movement mode, and traffic load from the corresponding layers. It is observed from simulation results that the proposed dynamic integrated priority scheme provides enhanced performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.4
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• pp.839-847
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• 2014

A recent major development in computer technology is the advent of the wearable computer system that is based on human-centric interface technology trends and ubiquitous computing environments. Wearable computer systems can use the wireless universal serial bus (WUSB) that refers to USB technology that is merged with WiMedia PHY/MAC technical specifications. In this paper, we focus on an integrated system of the wireless USB over the wireless body area networks (WBAN) for wireless wearable computer systems supporting U-health services. To construct the WUSB over WBAN communication systems, we propose a WBAN beaconing structure to assign WUSB communication periods. In the proposed structure, WUSB uses private periods of WBAN. In our performance evaluations, we compare theoretical results and simulation results about throughputs of WUSB under various WBAN channel occupations to evaluate the effectiveness of proposed structure in WUSB over WBAN communications.

• Smart Structures and Systems
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• v.3 no.3
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• pp.321-340
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• 2007

Structural control technologies have attracted great interest from the earthquake engineering community over the last few decades as an effective method of reducing undesired structural responses. Traditional structural control systems employ large quantities of cables to connect structural sensors, actuators, and controllers into one integrated system. To reduce the high-costs associated with labor-intensive installations, wireless communication can serve as an alternative real-time communication link between the nodes of a control system. A prototype wireless structural sensing and control system has been physically implemented and its performance verified in large-scale shake table tests. This paper introduces the design of this prototype system and investigates the feasibility of employing decentralized and partially decentralized control strategies to mitigate the challenge of communication latencies associated with wireless sensor networks. Closed-loop feedback control algorithms are embedded within the wireless sensor prototypes allowing them to serve as controllers in the control system. To validate the embedment of control algorithms, a 3-story half-scale steel structure is employed with magnetorheological (MR) dampers installed on each floor. Both numerical simulation and experimental results show that decentralized control solutions can be very effective in attaining the optimal performance of the wireless control system.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.1
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• pp.176-185
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• 2017

This paper describes a design of the WAVE antenna system in V2X wireless communication systems for Intelligent Transport Systems. The WAVE standard protocols defined 5.825~5.9GHz frequency range for wireless communications with V2X. In a recent, A study of WAVE communication system it has been studied mainly the base station and the OBU technology in order to improve the communication performance of the communication distance. In this paper, the proposed vehicular WAVE antenna using the EBG structure is to improve performance. The proposed WAVE antenna with EBG shows improvement of return loss and radiation beam pattern. The performance of WAVE communication systems for intelligent transport systems is dependent on the performance of antenna. The proposed vehicular antenna for WAVE communication systems shows improvement of return loss for performance.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.2
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• pp.102-106
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• 2013

A cooperative navigation method for cooperative flight of UAVs is proposed. The commonly used navigation method for UAVs is based on GNSS measurements. However, when it is not available by jamming or other causes, an alternative method is needed. In this paper, it is shown that UAVs equipped with inertial sensors, passive sensor and wireless communication link can perform accurate navigation through sharing information with each other. Firstly, the appropriate roles for sensors and wireless communication link are assigned. Secondly, a filter to perform navigation cooperative is constructed. Finally, the boundedness of estimation error of the filter under small initial estimation error is analyzed. The simulation results show that the proposed method can reduce navigation errors effectively.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.11a
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• pp.231-234
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• 2000

In this paper, we formed a transmitter and receiver by using three identical Chuas circuits and then formed wire and wireless transmission line from the channel which was between those three circuits. We proposed a secure communication method in which the desired information signal was synthesized with the chaos signal created in a Chuas circuit and sent to the transmitter through channel. Then the signal was demodulated receiver of Chuas circuit. The method we used to accomplish the secure communication was synthesizing the desired information with the chaos circuit by parallel connection in a wireless transmission line. After transmitting the synthesized signal to the wire and wireless transmission line, we confirmed the actuality of the secure communication by separating the information signal and the chaos signal in the receiver.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.107-111
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• 2011

In World War II, the solar eruption (solar flare) was revealed to make a significant effect to radar systems. The radio disturbance in February 28, 1942 was due to increased cosmic ray during solar maximum. Since such phenomena had been disclosed, many studies were accomplished on solar flare and solar particle event. Now various researches about the effects of solar flare on the spacecrafts, the airplanes flying across the pole, the radar systems, and wireless communication systems are studied. In this paper we analyzed the relationship between the harmful effect on the wireless communication by the solar eruption and the period of solar activity from the sunspot number data and the solar radio burst data for last 40 years.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.14-23
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• 2023

The cooperative communication systems using MIMO(multiple input multiple-output) relay are known as one of the most promising techniques to improve the performance and coverage of wireless communication systems. In this paper, we propose the cooperative communication systems using the relay with multi-antennas and DSTC(distributed space time coding) for decode-and-forward protocol. As using DSTC for DF(decode-and-forward), we can minimize the risk of error propagation at the wireless system using relay system. Also, the MIMO channel cab be formed by multi-antenna and DSTC at the MS(mobile station)-RS(relay station) and at the RS-BS(base station).Therefore, obtaining truly constructive the MIMO diversity and cooperative diversity gain from the proposed approach, the performance of system can be more improved than one of conventional system (relay with single antenna, no relay). The improvement in bit error rate is investigated through numerical analysis of the cooperative communication system with the proposed approach.

• Journal of Advanced Information Technology and Convergence
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• v.9 no.1
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• pp.25-37
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• 2019

Power-line communication (PLC) has influenced smart grid development. In addition, PLC has also been instrumental in current research on internet-of-things (IoT). Due to the implementation of PLC in smart grid and IoT environments, strides have been made in PLC and its combination with the wireless system to form a hybrid communication system. Also, PLC has evolved from a single-input-single-output (SISO) configuration to multiple-input-multiple-output (MIMO) configuration system, and from a point-to-point communication system to cooperative communication systems. In this work, we extend a MIMO wireless two-way amplify-and-forward (AF) cooperative communication system to a hybrid PLC and wireless (PLC/W) system configuration. We then maximize the weighted sum-rate for the hybrid PLC/W by optimizing the precoders at each node within the hybrid PLC/W system. The sum-rate problem was found to be non-convex, therefore, an iterative algorithm is used to find the optimal precoders that locally maximize the system sum-rate. For our simulation results, we compare our proposed hybrid PLC/W configuration to a PLC only and wireless only configuration at each node. Due to an improvement in system diversity, the hybrid PLC/W configuration outperformed the PLC only and wireless only system configurations in all simulation results presented in this paper.