• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.755-762
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• 2017

In railway communication, LTE based railway wireless communication systems have been developed to support high data rate and reliable communication link. In this paper, the testbed of LTE based railway wireless communication systems is introduced. Then, we describe measurement results of communication performance such as radiation strength, communication coverage, call setup time, handover success rate, and data transmission rate in the testbed. We also consider requirements for commercialization based on measurement results.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.1
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• pp.46-52
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• 2011

In the paper, MIMO antenna for LTE 13 band, LTE 7 band wireless communication service is proposed. The proposed antenna is designed where on the top of FR-4(${\epsilon}_r=4.4$, thickness=-.8mm). In proposed structure, two Planar Inverted F Antennas (PIFAs) using meander and folded structure are symmetrically designed for the miniaturization. The isolation between two antennas was also improved by using two slits on the ground plane. The isolation values of the fabricated antenna exhibits -18 dB, -13dB at LTE 13 and LTE 7 band, respectively. The average gain and efficiency are - 4.1 dBi, 41% on LTE 13 band, -1 dBi, 81% on LTE 7 band, respectively. Thus the proposed antenna can be applied to the LTE 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 Auto-vehicle Safety Association
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• v.15 no.4
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• pp.65-70
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• 2023

In the paper, we propose a design method and process of a hybrid V2X communication module that combines WAVE communication, LTE-V2X communication, and legacy LTE communication in evaluating vehicle V2X electromagnetic compatibility. C-ITS is suitable for safety service applications due to its low latency, and legacy LTE is suitable for applications such as traffic information and infotainment due to its high latency and high capacity. In order to evaluate the V2X communication system, the evaluation equipment must have communication performance of the same level or higher. The main design contents presented in this paper will be applied to the implementation of a hybrid V2X communication module for electromagnetic compatibility evaluation.

• Journal of Digital Contents Society
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• v.16 no.1
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• pp.43-51
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• 2015

South Korea decided to use the public safety long term evolution (PS-LTE) method to build a wireless communications network for national disaster. The move will allow all disaster management agencies, including police, firefighters and the military to use multimedia information, including videos, in addition to voice to carry out rescue operations from 2017. The Ministry of Science, ICT and Future Planning said Thursday that it adopted PS-LTE as the technology method for national disaster management system following a national policy coordination meeting last month. PS-LTE is a method integrating group communication, direction communication between terminals and independent base station function with existing LTE technology. Until now, disaster management agencies used technology that only allowed voice communication. However, transmission of multimedia information is possible using PS-LTE.

• The Journal of Korea Robotics Society
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• v.16 no.3
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• pp.232-237
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• 2021

In this research, a real-time tele-operation system for unmanned excavator using the LTE communication system is suggested. The distance between the operator and the excavator is limitless as long as the LTE communication available. The motion and video data of the excavator is synchronized using the Vehicle Control Unit (VCU) and streamed to the operator for immersion feeling. The video is played on the operator's monitor and the motion data is used to regenerate the excavator movement on the developed master platform. In general, a excavator is tele-operated using RF signal and the maximum distance for direct control is limited to within a hundred meter. In this research, the immersion tele-operation system is suggested for excavator operation within an 100ms time delay using the developed master platform, the VCU and LTE communication. A successful test run of the suggested tele-operation system has already been performed between an operator in Songpa (Seoul) and a excavator in Ansan (Gyeonggi-do) which is approximately 35 km apart.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.442-448
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• 2018

In this paper, a microstrip antenna for LTE / LTE-A is designed and fabricated for a broadband mobile communication system. The proposed antenna is designed to have the characteristics of using FR-4 (er = 4.3), size of $40mm{\times}50mm$, and LTE / LTE-A frequency bands of 2.3 GHz and 2.5 GHz. 2014, and the simulation result shows that the gain is 2.391 dBi at 2.3 GHz and 2.566 dBi at 2.5 GHz. The S-parameter also showed a result of less than -10 dB (WSWR 2: 1) in the desired frequency band. The broadband mobile communication antenna has been miniaturized, high performance, and light weight, and an excellent and low cost system is continuously being developed, and a broadband mobile communication system is used by many people. Since LTE / LTE-A technology has been proposed according to the development of system and demand, it is expected that many users will design and manufacture antennas satisfying the above conditions and apply the applied technology.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.771-776
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• 2017

LTE-R mobile communication technology based on LTE is used to supply various signal and exchange information required for safety operation of train on high speed railway communication system. In this paper, transmission performance of application traffic which is transferred on high speed communication based on LTE-R is analyzed. And some suggestions for application traffic transmission of high speed railway communication will be considered. Computer simulation is used to analyze performance of CBR, VBR as application traffic. Throughput, delay and packet loss rate is used as performance measurement and analysis parameters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2405-2410
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• 2012

The 4th generation mobile communication system, LTE, does not support an additional core network to provide voice service, and it is merged into a packet network based on all IP. Although Voice service over LTE can be supported by VoIP, it will be provided by the existing 3G networks because of the discontinuity of LTE coverage. However, it is inevitable to adopt VoIP over LTE to provide high quality voice service. In this paper, we investigate the capacity of VoIP over LTE. Our results indicate that spectral efficiency can be significantly improved as channel bandwidth increases in terms of VoLTE capacity. In addition, we can achieve higher VoLTE capacity without decreasing control channel capacity.

• International journal of advanced smart convergence
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• v.4 no.2
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• pp.29-33
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• 2015

In this paper, we propose the method to improve the performance of the antenna system that contains three bands, such as Lte3G, WLAN and Lte4G. This antenna has an advantage that can cover the three different frequency bands 2.1GHz, 2.4GHz and 2.6GHz through one antenna design. The design and simulations are done using CST Microwave Studio 2014 program. The antenna is designed by using the FR-4 (lossy) substrate with the dielectric constant of er=4.3 and dielectric loss tangent 0.025. The substrate dimensions are the following; Thickness[h] is 1.6mm, Length is 90mm, and Width is 40mm. The ground is designed by using the PEC material with h=0.035mm. The patch is designed by using the copper with h=0.035mm. In the near future, we will fabricate the antenna, which we have designed, and then apply this antenna to the mobile communication system. And we will test this mobile communication system for the diverse environments.