• Journal of Satellite, Information and Communications
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• v.8 no.1
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• pp.31-34
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• 2013

This paper deals with the interfering audio noise caused by LTE(Long Term Evolution) UE(User Equipment) which is 4th generation mobile communications on audio devices. At first, we realized that the interfering signal of the LTE UE is determined by the transmit power of the LTE UE through analysis and measurement. Then, we performed to measure audio noise level according to the variation of transmitting power level and separation distance between the LTE UE and an audio device. As a result, it is required that minimum separation distance should be 25 cm and above in order to protect audio device from the interference noise of the LTE UE with the maximum transmit power level of 22 dBm.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1017-1022
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• 2020

LTE-R(Long Term Evolution-Railway) for high speed railway system operation as an essential technology is based on LTE. Recently, moving speed of high speed train is on going to 600[km/h] level over commercial speed 400[㎞/h]. LTE-R as communication technology for a high speed railway system can be able to provide seamless communication to support moving speed for high speed railway system. In this study, a handover method based on prediction is suggested and performance of the suggested method is evaluated. Computer simulation based on NS(Network Simulator)-3 is used for this study.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.2
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• pp.171-178
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• 2015

3GPP long-term evolution(LTE) band 2.3~2.4 GHz is adjacent to 2.4~2.5 GHz band for WLAN, and therefore compatibility study of the two systems is desirable. We propose a dynamic system simulation methodology to investigate the effect of WLAN interference on LTE systems. As capturing space/time/frequency changes in system parameters, the dynamic system simulation can exactly predict real system performance. Using the proposed methodology, we obtain LTE downlink throughput loss for the frequency separation between the two systems. Throughput loss under 1 % is obtained from guard band over 11 MHz(single channel allocation) or 10 MHz(three channel allocation).

• Broadcasting and Media Magazine
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• v.19 no.1
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• pp.48-55
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• 2014

One of the recent noticeable evolutions in mobile communication systems is that wideband-codec is deployed rapidly in VoLTE (Voice over Long Term Evolution) service or HD voice. This paper is concerned with next generation HD voice or VoLTE service that is coined to describe high quality communication with super-wideband voice codec. 3GPP EVS (Enhanced Voice Service) Codec is being standardized to develop the super-wideband voice codec. This paper deals with the codec design constraints, performance requirements, the status of standardization, and finally perspective on VoLTE service in future.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.353-359
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• 2014

Recently, the use of mobile devices has increased, and mobile traffic is growing rapidly. In order to deal with such massive traffic, cognitive radio (CR) is applied to efficiently use limited-spectrum resources. However, there can be multiple communication systems trying to access the white space (unused spectrum), and inevitable interference may occur to cause mutual performance degradation. Therefore, understanding the effects of interference in CR-based systems is crucial to meaningful operations of these systems. In this paper, we consider a long-term evolution (LTE) system using additional spectra by accessing the TV white space, where low-power devices (LPDs) are licensed primary users, in addition to TV broadcasting service providers. We model such a heterogeneous system to analyze the co-existence problem and evaluate the interference effects of LPDs on LTE user equipment (UE) throughput. We then present methods to mitigate the interference effects of LPDs by 'de-selecting' some of the UEs to effectively increase the overall sector throughput of the CR-based LTE system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.6
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• pp.1-7
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• 2012

Due to the increasing demand of network convergence, in future, hybrid/integrated satellite and terrestrial systems will play an important role. In that case, compatibilities between the satellite and terrestrial systems are very important for efficiency of the systems. 3GPP Long Term Evolution (LTE) is one of the 4G system. Therefore, in this paper, we introduce the design of interleaver for mobile satellite system based 3GPP LTE specification. The 4G system including the LTE specification adopted adaptive modulation and coding (AMC) schemes for efficient usage of resources, and the updating interval of resource allocation is an order of msec. However, because of the long round trip delay of satellite systems, we cannot employ the same AMC scheme specified for the terrestrial system, and thus it cannot effectively counteract to short term fadings. Therefore, in order to overcome these problems, we propose an interleaver scheme combined with AMC. We present the interleaver design results considering mobile satellite system based on the LTE and analyze the simulation results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.358-365
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• 2017

In order for developing countries to design and deploy Long Term Evolution (LTE) network in a cost-efficient manner, the differentiated way of technological design and deployment methods are necessary as compared to those for advanced countries. This paper focused on Radio Access Network (RAN) design methodology for developing countries that consists of major part of the network cost. To verify the effectiveness of the suggested design methodology, a Korean telecom company A's actual design experience in an African developing country was examined.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1223-1228
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• 2018

LTE-R(Long Term Evolution - Railway), as a mobile communication technology to support safety operation of train on high speed railway system, have to be equipped appropriately by hand-over method for high moving environment of train. In this paper, hand-over performance of LTE-R network, which is used in railway communication system, is analyzed and hand-over implementation condition is suggested with this analysis. The performance analysis of this study is carried out with computer simulation with NS(Network Simulator)-3. SINR(Signal to Interference and Noise Ratio) and RSRP(Reference Signal Received Power), and Data Rate is used for hand-over performance parameter.

• International Journal of Computer Science & Network Security
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• v.23 no.7
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• pp.16-22
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• 2023

Enhanced radio access technologies (RAT) are deployed in Next Generation Convergence Networks by the service providers so as to satisfy the basic requirements of end-users for e.g. QoS. Whenever the available resources are being shared simultaneously and dynamically by multiple users or distribution of allocated channels randomly, the deficiency of spectral resources and dynamic behavior of Network traffic in real time Networking, we may have problem. In order to evaluate the performance of our proposed algorithm, computer simulation has been performed on NS-2 simulator and a comparison with the existing algorithms has been made.

• ETRI Journal
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• v.45 no.6
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• pp.939-951
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• 2023

It is critical to estimate the location using only Long-Term Evolution (LTE) and Wi-Fi information gathered by the user's smartphone and deployable for emergency rescue, regardless of whether the Global Positioning System is received. In this research, we used a vehicle to gather LTE and Wi-Fi wireless signals over a large area for an extended period of time. After that, we used the learning technique to create a positioning database that included both collection and noncollection points. We presented a two-step positioning algorithm that utilizes coarse localization to discover a rough location in a wide area rapidly and fine localization to estimate a particular location based on the coarse position. We confirmed our technology utilizing different sorts of devices in four regional types that are generally encountered: dense urban, urban, suburban, and rural. Results presented that our algorithm can satisfactorily achieve the target accuracy necessary in emergency rescue circumstances.