• KIPS Transactions on Software and Data Engineering
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• v.3 no.11
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• pp.487-494
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• 2014

This paper focuses on an advanced congestion control scheme for M2M(Machine-to-Machine) communications in 3GPP LTE-A standard. A large number of MTC(Machine-type-Communication) devices try to access to LTE-A networks and send data to the networks all at once. In this characteristics, M2M communications will bring the serious network congestion problems into LTE-A cellular networks. To solve this critical problem, a congestion control mechanism will be required and it has been studied since Rel-10 LTE-A systems based on backoff mechanism for mobility management and session management. In this paper, we briefly introduce the main concept and operation about the congestion control scheme in 3GPP LTE-A standard. Also, simulation results for the basic congestion control and advanced congestion control scheme in MTC communication environment are provided and the improvement direction is considered in future 3GPP LTE-A standard.

• Informatization Policy
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• v.18 no.1
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• pp.45-54
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• 2011

The purpose of this study is to analyze the selection behavior decision model of telecommunications service under the telecommunication environments with joining the WiBro and 3GPP LTE-Advanced service at the sam time. The research results are as follows. First, mobile telecommunication service selection behavior is correlated with each other between WiBro and 3GPP LTE-Advanced service. Second, in the bivariate probit model estimates such as age, income, expenditure and income variable are important decision variables of WiBro and 3GPP LTE-Advanced service selection behavior. Gender and service using years, however, are not an important variables. The single and bivariate probit estimate results show the same estimation results. Finally, the two service selecting predictions by using the bivariate probit estimated results, 28.6% of WiBro and 25.3% of 3GPP LTE-Advanced were expected. Also, chance to join the two telecommunications services simultaneously is 19.3%. Therefore, WiBro selection probability is a little higher than 3GPP LTE-Advanced. The implications of these results, the future telecommunications service selection will be determined by economic factors such as income and expenditure. Thus, to enable the WiBro, policy means for reducing the excessive telecommunications expenditure are needed in the future.

• 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 Information Processing Systems
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• v.4 no.4
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• pp.145-152
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• 2008

The specification of the Home Evolved NodeB (Home-eNB), which is a small base station designed for use in residential or small business environment, is currently ongoing in 3GPP LTE (Long Term Evolution) systems. One of the key requirements for its feasibility in the LTE system is the mobility management in the deployment of the numerous Home-eNBs and other 3GPP network. In this paper, we overview the characteristic of Home-eNB and also describe the mobility management issues and the related approaches in 3GPP LTE based Home-eNB systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9A
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• pp.656-663
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• 2009

In 3GPP LTE system downlink, PSS (primary synchronization signal) and SSS (secondary synchronization signal) sequences are used for initial cell search and synchronization. UE (user equipment) detects slot timing, frequency offset, and cell ID by using PSS. After that it should detect frame timing, cell group ID, and CP length by using SSS. But in 3GPP LTE, there are two kinds of CP length, so we should operate FFT twice. In this paper, to minimize SSS detection complexity in cell searcher, we propose a CP length pre-decision algorithm that reduces the arithmetical complexity by half at most, with negligible performance degradation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1C
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• pp.103-112
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• 2010

In this paper, we propose a coarse and fine frequency synchronization method which is suitable for the 3GPP(3rd Generation Partnership Project) LTE(Long Term Evolution) FDD(Frequency Division Duplexing) / TDD(Time Division Duplexing) dual mode system. In general, PSS(Primary Synchronization Signal) correlation based estimation method and CP(Cyclic Prefix) correlation based tracking loop are applied for coarse and fine frequency synchronization in 3GPP LTE OFDMA(Orthogonal Frequency Division Multiple Access) system, respectively. However, the conventional coarse frequency synchronization method has performance degradation caused by fading channel and squaring loss. Also, the conventional fine frequency synchronization method cannot guarantee stable operation in TDD mode because of signal power difference between uplink and downlink subframe. Therefore, in this paper, we propose enhanced coarse and fine frequency synchronization methods which can estimate more accurately in multi-path fading channel and high speed channel environments and has stable operation for TDD frame structure, respectively. By computer simulation, we show that the proposed methods outperform the conventional methods, and verify that the proposed frequency synchronization method can guarantee stable operation in 3GPP LTE FDD/TDD dual mode downlink receiver.

• Information and Communications Magazine
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• v.33 no.4
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• pp.86-91
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• 2016

커버리지를 확대하고 다이버시티 이득의 극대화를 통해 전송 신뢰도를 높이는데 효과적인 무선 중계기술은 많은 연구자의 높은 관심을 받아왔으며 그동안의 주요 연구결과를 바탕으로 3GPP Release 10에 LTE/LTE-A를 위한 중계기술로 표준화되기에 이르렀다. 본고에서는 LTE/LTE-A를 위한 중계기술이 표준기술로 포함된 Release 10을 중심으로 중계 시스템의 전반적인 구조를 소개하고 중계 절차 및 주요 네트워크 프로토콜을 살펴본다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12A
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• pp.941-948
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• 2009

In the 3GPP LTE systems, SC-FDMA is adopted for the uplink owing to its good PAPR efficiency. In the frequency domain, however, the performance of SC-FDMA is degraded due to frequency selective fading. As a compromise, a Hybrid OFDMA/SC-FDMA was proposed in the LTE-Advanced systems. Hybrid scheme uses SC-FDMA in the edge of cell area, while it uses OFDMA nearby the base-station. In this paper, uplink relays based on hybrid scheme is proposed to increase the performance of the 3GPP LTE systems. With different positions of mobile and relay, the proposed scheme can adaptively select SC-FDMA or OFDMA to improve the link performance. Our simulation results show that the proposed scheme achieves a better performance in terms of end-to-end BER and power consumption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3A
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• pp.217-224
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• 2010

In this paper, we propose a hard handover algorithm for a base station's self-optimization, one of the automatic operational technologies for the 3GPP LTE systems. The proposed algorithm simultaneously considers a mixed target sell selection method for optimal selection and a multiple parameter based active hysteresis method with the received signal strength from adjacent cells and the cell load information of the candidate target cells from information exchanges between eNBs through X2 interface. The active hysteresis method chooses optimal handover hysteresis value considering the costs of the various environmental parameters effect to handover performance. The algorithm works on the optimal target cell and the hysteresis value selections for a base station's automatic operational optimization of the LTE system with the gathered informaton effects to the handover performance. The simulation results show distinguished handover performances in terms of the most important performance indexes of handover, handover failure rate and load balancing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3B
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• pp.158-164
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• 2012

Heterogeneous Network and CSG cell are hot issues in the 3GPP LTE/LTE-Advanced system. In this paper, we analyze the system information measurement methods which are essential for handover to CSG cell. Since there have been no sufficient discussion about this problem, we present and analyze five possible solutions. Moreover, we propose a novel solution to reduce system information measurement delay. In the proposed Autonomous Measurement with Parallel Small Gap(AMPSG) method, the UE measures system information of neighbor cells in a parallel manner. As a result, the proposed method shows better delay performance. Therefore, the proposed AMPSG method can reduce handover delay since the UE have to measure the system information of neighbor cells before CSG handover decision.