• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.6
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• pp.35-41
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• 2010

The ubiquitous-transportation sensor network (u-TSN) system is a next generation transportation system that provides traffic information through analysis and processing periodic information from vehicles. In this paper, we propose the adequate transmission scheme from vehicles for collecting vehicular information. The conventional scheme is transmitting each vehicle information every 0.1s. A variable transmission period scheme is proposed in this paper according to vehicle speed. The proposed and conventional schemes are compared with computer simulations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.12
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• pp.6243-6259
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• 2019

As a foundation of next-generation air transportation systems, automatic dependent surveillance-broadcast (ADS-B) helps pilots and air traffic controllers create a safer and more efficient national airspace system. Owing to the open communication environment, it is easy to insert fake aircraft into the system via spoofing or the insertion of false messages. Efforts have thus been made in academic research and practice in the aviation industry to ensure the security of transmission of messages of the ADS-B system. An identity-based batch verification (IBV) scheme was recently proposed to enhance the security and efficiency of the ADS-B system, but current IBV schemes are often too resource intensive because of the application of complex hash-to-point operations or bilinear pairing operations. In this paper, we propose a lightweight IBV signature scheme for the ADS-B system that is robust against adaptive chosen message attacks in the random oracle model, and ensures the security of batch message verification and against the replaying attack. The proposed IBV scheme needs only a small and constant number of point multiplication and point addition computations instead of hash-to-point or pairing operations. Detailed performance analyses were conducted to show that the proposed IBV scheme has clear advantages over prevalent schemes in terms of computational cost and transmission overhead.

• ETRI Journal
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• v.41 no.3
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• pp.348-357
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• 2019

Fog radio access network (F-RAN) architectures provide markedly improved performance compared to conventional approaches. In this paper, an efficient genetic algorithm-based content distribution scheme is proposed that improves the throughput and reduces the transmission delay of a F-RAN. First, an F-RAN system model is presented that includes a certain number of randomly distributed fog access points (F-APs) that cache popular content from cloud and other sources. Second, the problem of efficient content distribution in F-RANs is described. Third, the details of the proposed optimal genetic algorithm-based content distribution scheme are presented. Finally, simulation results are presented that show the performance of the proposed algorithm rapidly approaches the optimal throughput. When compared with the performance of existing random and exhaustive algorithms, that of the proposed method is demonstrably superior.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.473-493
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• 2019

5G vehicular communication is one of key enablers in next generation intelligent transportation system (ITS), that require ultra-reliable and low latency communication (URLLC). To meet this requirement, a new hybrid vehicular network structure which supports both centralized network structure and distributed structure is proposed in this paper. Based on the proposed network structure, a new vehicular network utility model considering the latency and reliability in vehicular networks is developed based on Euclidean norm theory. Building on the Pareto improvement theory in economics, a vehicular network uplink optimization algorithm is proposed to optimize the uplink utility of vehicles on the roads. Simulation results show that the proposed scheme can significantly improve the uplink vehicular network utility in vehicular networks to meet the URLLC requirements.

• Journal of Information Technology Applications and Management
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• v.19 no.4
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• pp.19-39
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• 2012

Korean core banking system has been redeveloped twice in the last 30 years with big-bang method, but still needs innovation to meet everlasting business changes. The objective of this study is to identify which decision criteria lead to replacement decision of core baning system in spite of its huge investment and accompanying business risk. For the study, we conducted a survey to 64 decision makers working in banks and IT service companies, and analysed the data using factor analysis and multi-regression analysis method of SPSS. As a result, we extracted statistically valid decision model with 4 major decision criteria, which are IT external, IT internal, IT ecology and Executive's will factor. Among them, we concluded only IT internal and IT ecology criteria give significant influence over the replacement decision of existing core banking system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1364-1373
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• 2016

Ultra High Definition Television (UHDTV) has attracted much attention as one of next generation broadcasting services. For the commercialization of UHD broadcasting service, standardization groups including the DVB (Digital Video Broadcasting) and the ATSC (Advanced Television Systems Committee) have decided to adopt the Orthogonal Frequency Division Multiplexing (OFDM) for signal transmission. However, when the carrier frequency is not properly synchronized at the receiver, inter-symbol interference (ISI) and inter-carrier interference (ICI) may occur. In order to avoid performance degradation resulting from ISI or ICI, receivers should synchronize the carrier frequency by using preambles and pilot symbols. However, there only few published literature dealing with the frequency offset estimation methods regarding the next generation terrestrial broadcasting. In this respect, this paper proposes a method to estimate timing and fractional frequency offset for the ATSC 3.0 system by using a preamble bootstrap symbol. The proposed detector can detect the fractional frequency offset by adding a complex conjugate product on the conventional estimator where only timing offset can be estimated.

• Journal of Internet Computing and Services
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• v.24 no.1
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• pp.1-7
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• 2023

Recently, the technology of device-to-device(D2D) communication has been receiving big attention to improve the system performance since the amount of high quality/large capacity data traffic from smart phones and various devices of Internet of Things increase rapidly in 5G/6G based next generation cellular networks. However, even though the system performance of macro cells increase by reusing the frequency, the performance of macro user equipments(MUEs) decrease because of the strong interference from D2D user equipments(DUEs). Therefore, this paper proposes a dynamic channel management(DCM) scheme for DUEs to guarantee the performance of MUEs as the number of DUEs increases in next generation downlink cellular networks. In the proposed D2D DCM scheme, macro base stations dynamically assign subchannels to DUEs based on the interference information and signal to interference and noise ratio(SINR) of MUEs. Simulation results show that the proposed D2D DCM scheme outperforms other schemes in terms of the mean MUE capacity as the threshold of the SINR of MUEs incareases.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.109-114
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• 2012

Intelligent Transportation Systems (ITS) is aimed to implement IT(Information Technology) to develop the next-generation transportation system in order to improve traffic conditions. In order to provide traffic information, the methods that provide available traffic informations to the public are needed. In this paper, analysis of the transportation applications in smart-phone and currently available methods of traffic information's sharing and providing were discussed. Finally, OPEN API was discussed and shows its effectiveness for transportation information area especially in smart phone.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.2
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• pp.135-144
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• 2003

Traffic performance in a microcellular system is much more affected by cell dwell time and channel holding time in each cell. Cell dwell time of a call is characterized by its mobility pattern, i.e., stochastic changes of moving speed and direction. Cell dwell time provides important information for other analyses on traffic performance such as channel holding time, handover rate, and the average number of handovers per call. In the next generation mobile communication system, the cell size is expected to be much smaller than that of current one to accommodate the increase of user demand and to achieve high bandwidth utilization. As the cell size gets small, traffic performance is much more affected by variable mobility of users, especially by that of pedestrians. In previous work, analytical models are based on simple probability models. They provide sufficient accuracy in a simple second-generation cellular system. However, the role of them is becoming invalid in a picocellular environment where there are rapid change of network traffic conditions and highly random mobility of pedestrians. Unlike in previous work, we propose an improved probability model evolved from so-called Random walk model in order to mathematically formulate variable mobility of pedestrians and analyze the traffic performance. With our model, we can figure out variable characteristics of pedestrian mobility with stochastic correlation. The above-mentioned traffic performance measures are analyzed using our model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.535-538
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• 2012

Recently active research for ITS(Intelligent Transportation System) helps to build for next generation traffic information system at information society. Build the system for sensing a vehicle speed and traffic information on the road. Provide collected data to driver, flow of overall traffic impacts have a good influence. In this study, research for building the platform and development algorithm that provided from other source processing real-time traffic data provides a more reliable real-time traffic data.