• Journal of Satellite, Information and Communications
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• v.5 no.1
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• pp.27-31
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• 2010

Recently, spectrum requirements are rapidly increasing in accordance with wireless communication development. For this reason, FCC(Federal communications commission) is considering cognitive radio system to increase spectral efficiency. In this paper, we present the performance analysis of signal detection by using RS(Reference signal) for LTE environments. Especially, we analyze the performance of detection probability in case of downlink LTE system. In the simulation, we generate OFDMA signal format which is specified in the LTE system. We assume additive white Gausssian noise channel environment. We estimate the performance by setting the threshold value of 5 % and 10 % based on CFAR(Constant false alarm rate) and false alarm rate, respectively. Finally, we discuss a future study plan on the applicability of CR to the LTE system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.864-867
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• 2016

In high speed railway system, LTE(Long Term Evolution) based LTE-R(LTE-Railray) mobile technology is used to supply various control signal required for safty operation of train. In this paper, railway communication technology be used in railway communication system based on LTE-R is investigated in focused on application services. Standardization trends for LTE-R technology are also considered. Results of this study can be used as basic data for research and development of LTE-R and railway mobile communication.

• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.20-30
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• 2017

Due to the evolution of wireless communications technology, Long Term Evolution (LTE), which is a $4^{th}$ generation mobile communications system, has been adopted as a railway communications system. This LTE Railway (LTE-R) system is composed of various elemental functions, which are largely categorized into public safety and wireless communications for train control. Research on the public safety functions of railway communications have their roots in TRS based national public safety communication systems, and research on wireless communications functions for train control have their roots GSM-R, which is utilized by the ETCS in Europe. Based on these circumstances, this paper first analyzes the requirements for developing public safety technology in LTE-R, and compares those requirements with the functions of public safety LTE (PS-LTE), which is being deployed for the first time in the world by the South Korean government. Based on an analysis of the common and specific functions of LTE-R and PS-LTE, we conclude that there is little problem in integrating LTE-R and PS-LTE from the perspective of functionality. Second, this paper provides a comparison of the LTE-R requirements for the Quality of Service (QoS) with those of GSM-R utilized by the ETCS. This offers a guideline to allow LTE-R to be applied to a 500km/h train control system.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.2
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• pp.219-226
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• 2015

As a representative system of the 4th generation mobile communication system, LTE provides much higher transmission rate than the former ones. Considering the varying property that a wireless environment shows, the transmission rate is influenced very deeply by the wireless channel conditions. The transmission rate is one of the most important attributes that has a primary effect on user's satisfaction of the service provided through the LTE system. After we have selected a few metrics that indicate the wireless channel quality, therefore, we have conducted a measurement for the metrics over the real commercial LTE system. By analyzing the measured results, we have found that the channel quality affect more on the transmission rate as the channel quality becomes poorer.

• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.115-120
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• 2020

PS-LTE, which is mentioned as a next-generation disaster network technology, is a communication technology that supports communication between terminals and group communication necessary for public safety communication based on LTE technology. Currently, Korea is establishing a PS-LTE network construction plan and installing a PS-LTE system. The world is currently making a lot of efforts to build a disaster network system using PS-LTE. However, due to the characteristics of the closed network that only the related persons can access, it can not be operated like the existing commercial network, so it is necessary to build a new network. And it is expected that many periods and costs will be required. In order to establish a disaster safety communication network efficiently, it is necessary to consider the linkage of PS-LTE network, which is newly constructed by complementing the problems such as security and access priority to existing LTE network rather than unconditional new construction.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.4
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• pp.373-378
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• 2016

Since the KTX starts operation in 2004, Korean railway system has sustained the highest safety and accuracy. In order to keep this achievement, the LTE based wireless communication system has been introduced for mobile communications and signal transmission. railway, and activities for its standardization are on the way. Railway communication system will be used as part of national safety net through interworking with safety network. This paper reviews the contents of standards and technologies in an LTE-based railway communication(LTE-R) system, and the items to be standardized to improve operational efficiency of the railway system by building a national railway radio communication system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.4
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• pp.18-25
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• 2012

As the demand for smart phone user is rapidly increasing in recent years, the development of new mobile communication system which provides more improved quality compared to existing 3G standard is highly requested. In this point, the long-term evolution (LTE) system, which was being developed in mid of 2000's, has attracted a considerable attention. The LTE has been developed continuously to result a release 10 which is called as LTE-Advanced (LTE-A) in 2010. Among various features in LTE-A, the multiuser MIMO (MU-MIMO) design is expected to give better quality for throughput, spectral efficiency, and latency. In this paper, we first review the development process from LTE to LTE-A. We also provide the overview of design challenges and specific solutions for MU-MIMO systems developed in LTE-Advanced standard.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.827-829
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• 2015

This paper presents process of the UE obtains the cell system information in order to achieve communication with the LTE network on the LTE. This paper deals with the process of extracting MIB(Master Information Block) cell system information in LTE. To study the 3GPP LTE standard spec series 36.200 and 36.300, the simulation is implemented to extract the MIB in MATLAB program. The simulation process is divided into three parts. It consisted of a part that extracts the PSS, SSS and MIB. Called a cell search process for detecting the PSS and SSS, the process is to be done in order to extract only the cell system information. The simulation program is verified based on the signal captured from the real Air.

• Journal of Advanced Navigation Technology
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• v.20 no.6
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• pp.595-603
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• 2016

In the Republic of Korea, the LTE-based public safety (PS-LTE) network is being built for the 700 MHz frequency band. However, the same bands are also assigned to the LTE-based high-speed railway (LTE-R) network. Therefore, it is essential to utilize the co-channel interference management schemes for the coexistence of two LTE networks in order to increase the system throughput and to reduce the user outage probability. In this paper, we focus on the downlink (DL) system for the coexistence of PS-LTE and LTE-R networks by considering non radio access network (RAN) sharing and LTE-R RAN sharing by PS-LTE users (UEs) to analyze the UE throughput. Moreover, we also utilize the cooperative communications schemes, such as coordinated multipoint (CoMP) for the coexistence of PS-LTE and LTE-R networks in order to reduce the UE outage probability. We categorize the coexistence of PS-LTE and LTE-R networks into four different scenarios, and evaluate the performance of each scenario by the important performance indexes, such as UE average throughput and UE outage probability.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.1
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• pp.36-43
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• 2013

This paper provides an overview of the security in the System Architecture Evolution (SAE) / Long-Term Evolution (LTE) system. Security is an integral part of SAE/LTE with improvements over the Third Generation (3G) system. This paper reviews the SAE/LTE system architecture, and discusses the security requirements, algorithms, Authentication and Key Agreement (AKA), Security Mode Command (SMC), key hierarchy and security for mobility.