• 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.

• 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.

• 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.

• Electronics and Telecommunications Trends
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• v.21 no.3 s.99
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• pp.36-47
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• 2006

이동통신 시스템은 점차 고품질 및 고속의 멀티미디어 서비스를 제공하는 방향으로 가고 있다. 3GPP에서는 기존의 WCDMA 기반의 3세대 이동통신 시스템의 기술적 한계를 극복하기 위해 2004년 말에 3rd Generation Long Term Evolution(3G LTE) Plan을 발표하고, 2006년 6월까지 Technical Report 규격을 작성완료하고 2007년 6월까지 Technical Standard 작성완료를 목표로 2005년 초부터 규격 작업을 수행하고 있다. 본 고에서는 3G LTE 물리계층 및 MAC 계층의 기술 표준화 동향을 살펴본다.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.9
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• pp.1027-1034
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• 2014

We present the Low Power Broadband Low noise amplifier(LNA) that can be applied a whole bandwidth from 3G to 4G LTE. This multi input LNA was designed to steadily amplify through a multi input method regardless the size of the input signal and operate on a wide range of frequency band from a standard 3G CDMA band 1.2GHz to LTE band 2.5GHz. The designed LNA consumes an average of 6mA on a 1.2V power supply and this was affirmed using computer simulation tests. The amplification which was corresponded to the lowest input signal is at a maximum of 20dB and was able to obtain the minimum value of the gain of -10dB. The Noise figure is less than 3dB at a High-gain mode and is less than 15dB at a Low-gain mode.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.8
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• pp.712-723
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• 2013

Recent exploration of smart-phone user is fueling the deployment of long term evolution (LTE) service that offers higher data rates service over 3G HSPA networks. In particular, Korea, mobile powerhouse, recently launched the service of LTE-Advanced (LTE-A) which is the latest release in LTE standard. Multiple-input-multiple-output (MIMO) technology is the one of key enablers for LTE and LTE-A for achieving high data rate. MIMO technology has received much attention since it is possible to achieve channel capacity in proportion to the number of antennas without increasing frequency and power. In this paper, we overview of the theoretical background of MIMO technology regarding from single-user MIMO, multiuser MIMO, and massive MIMO and design considerations to implement the communication system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8A
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• pp.787-793
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• 2008

3GPP evolved packet system (EPS) is an all-IP based system that supports various access networks such LTE, HSPA/HSPA+, and non-3GPP networks. Recently, the support of IP flows with packet level QoS profiles was added to the requirements of the EPS. This paper proposes an adaptive modulation and coding (AMC) scheme that supports the QoS of such IP flows in the 3G LTE access network of the EPS. Defining the retransmission as a critical factor for QoS, the proposed scheme applies different maximum packet error probability $P_{max}$ to each packet when selecting the AMC transmission mode. In determining $P_{max}$, the QoS constraints and NACK-to-ACK error as well as channel condition are considered, balancing two objectives: the satisfaction of the QoS and the maximization of spectral efficiency. The simulation results show that it is able to reduce both delay violation and status report by 10%, while improving the throughput 10% in comparison with an existing scheme.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.601-606
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• 2020

In this paper, we designed a microstrip patch antenna that can be applied to the Wimax/LTE 5G system among wireless media usable in coastal ships. The substrate of the proposed antenna is FR-4 (er=4.3), the size is 22 mm × 30 mm, and it can be used in the 3.5 GHz and 5.8 GHz bands of Wimax/LTE 5G by constructing a simple structure using a microstrip patch antenna. CST Microwave Studio 2014 was used for simulation, and the gain of the simulation result is 2.41dB at 2.4 GHz and 3.96 dB at 3.5 GHz. S-Parameter also showed a result of less than -10 dB (VSWR 2:1) in the desired frequency band, and designed a small variable and a miniaturized antenna so that the antenna can be used in mobile phones or electronic devices.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.6
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• pp.71-76
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• 2012

Recently, the huge growth of mobile data traffic has driven the earlier commercialization of LTE network and the evolution of LTE-Adv has been accelerated because of this trend of mobile traffic surges. Thus it has enabled the global connectivity and roaming capability due to continual standardization activities. The 3rd generation mobile communication system has been improved through incorporating technologies of HSDPA, MBMS and HSUPA etc continuously. Also, OFDMA/SC-FDMA-based LTE standardization has been under way. In this paper, the architectures of LTE network and protocol have been introduced and their inherent operation mechanisms have also been explored in order to give some insights about the LTE/LTE-Adv networks while their architectures are considered as most prominent candidate for worldwide standard by ITU-R and mobile operators for international communication networks.

• Journal of the Korea Society of Computer and Information
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• v.24 no.2
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• pp.49-56
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• 2019

In this paper, we propose an efficient congestion control scheme for interworking between 5GS(5G system) and LTE(Long-Term Evolution), called ECC(Efficient Congestion Control). The proposed congestion control scheme (ECC) is considered for coexistence of 5GS and legacy LTE systems and provides a prompt service connectivity based on overriding method while the backoff timer is running in the UE. Also, we briefly introduce Rel-15 5GS from a congestion control perspective and the proposed ECC and simulation results for the existing legacy congestion control mechanism and ECC in the 5GS-LTE coexisting environment are presented. Lastly, the improvement direction is considered in future 3GPP 5GS phase 2 standard in this paper.