Advanced Communications Research Laboratory

Daejeon, South Korea

Advanced Communications Research Laboratory

Daejeon, South Korea
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Chang B.-Y.,Ajou University | Hai P.H.,National Center for Socio economics Information and Forecast | Seo D.-W.,Kyung Hee University | Lee J.-H.,Korea Institute of Science and Technology | Yoon S.H.,Advanced Communications Research Laboratory
2013 International Conference on Computing, Management and Telecommunications, ComManTel 2013 | Year: 2013

Cloud computing can bring many advantages for companies such as cost efficiency, reducing time to access to the market, ease to use, flexibility and adaptability to change to different condition, etc. However, the adoption rate in Vietnam is still in the beginning stage with not many adopters. As a result, this study focuses on the adoption of cloud computing among Vietnamese companies. Eight factors were identified as determinants of cloud computing adoption by combining the two widely applied IT theories i.e. Diffusion on Innovation and Technology-Organization-Environment framework. In the future with eight factors we will conduct survey, factor analysis and logistic regression to determine factors affecting cloud computing adoption. © 2013 IEEE.


Kim K.,Advanced Communications Research Laboratory | Lee J.,Advanced Communications Research Laboratory | Lee S.,Advanced Communications Research Laboratory | Jang Y.,Chungnam National University
ETRI Journal | Year: 2012

This paper proposes a low-cost, low-power, and highcapacity optical-electrical-optical-type reach extender that can provide 3R frame regeneration and remote management to increase the reach and split ratio with no change to a legacy time division multiple access passive optical network. To provide remote management, the extender gathers information regarding optical transceivers and link status per port and then transmits to a service provider using a simple network management protocol agent. The extender can also apply to an Ethernet passive optical network (E-PON) or a gigabit-capable PON (G-PON) by remote control. In a G-PON, in particular, it can provide burst mode signal retiming and burst-to-continuous mode conversion at the upstream path through a G-PON transmission convergence frame adaptor. Our proposed reach extender is based on the quad-port architecture for cost-effective design and can accommodate both the physical reach of 60 km and the 512 split ratios in a G-PON and the physical reach of 80 km and the 256 split ratios in an E-PON. © 2012 ETRI.


Kim K.,Advanced Communications Research Laboratory | Lee S.,Advanced Communications Research Laboratory | Lee J.,Advanced Communications Research Laboratory | Jang Y.,Chungnam National University
ETRI Journal | Year: 2012

This paper proposes a cost-effective hybrid-type power budget extender (PBEx) that can provide a high power budget of over 45 dB in an asymmetric 10-Gb/s Ethernet passive optical network (10/1G-EPON). The hybrid-type 10/1G-EPON PBEx comprises a central office terminal (COT) and remote terminal (RT) module supporting four channels and uses a coarse wavelength division multiplexing (CWDM) technology between the COT and RT for a reduction of fiber cost and efficient access network design. The proposed 10/1G-EPON PBEx can provide over a 40-km reach and 128-way split per CWDM wavelength with no modification of a legacy 10/1G-EPON system and can satisfy the error-free service in 1010 packet transmission. © 2012 ETRI.


Yu H.,Yeungnam University | Lee S.-K.,Advanced Communications Research Laboratory
ETRI Journal | Year: 2012

A beam design method based on signal-to-leakage-plus-noise ratio (SLNR) has been recently proposed as an effective scheme for multiuser multiple-input multiple-output downlink channels. It is shown that its solution, which maximizes the SLNR at a transmitter, can be simply obtained by the generalized eigenvectors corresponding to the dominant generalized eigenvalues of a pair of covariance matrices of a desired signal and interference leakage plus noise. Under time-varying channels, however, generalized eigendecomposition is required at each time step to design the optimal beam, and its level of complexity is too high to implement in practical systems. To overcome this problem, a predictive beam design method updating the beams according to channel variation is proposed. To this end, the perturbed generalized eigenvectors, which can be obtained by a perturbation theory without any iteration, are used. The performance of the method in terms of SLNR is analyzed and verified using numerical results. © 2012 ETRI.


Kang T.-S.,LG Corp | Seo B.,Advanced Communications Research Laboratory
ETRI Journal | Year: 2012

When the number of users is finite, the performance improvement of the orthogonal random beamforming (ORBF) scheme is limited in high signal-to-noise ratio regions. In this paper, to improve the performance of the ORBF scheme, the user set and transmit power allocation are jointly determined to maximize sum rate under the total transmit power constraint. First, the transmit power allocation problem is expressed as a function of a given user set. Based on this expression, the optimal user set with the maximum sum rate is determined. The suboptimal procedure is also presented to reduce the computational complexity, which separates the user set selection procedure and transmit power allocation procedure. © 2012 ETRI.


Ryu N.,Advanced Communications Research Laboratory | Jung J.-H.,Advanced Communications Research Laboratory | Jeong Y.,Chonbuk National University
ETRI Journal | Year: 2012

This paper proposes a high-efficiency power amplifier (PA) with uneven bias. The proposed amplifier consists of a driver amplifier, power stages of the main amplifier with class AB bias, and an auxiliary amplifier with class C bias. Unlike other CMOS PAs, the amplifier adopts a current-mode transformer-based combiner to reduce the output stage loss and size. As a result, the amplifier can improve the efficiency and reduce the quiescent current. The fully integrated CMOS PA is implemented using the commercial Taiwan Semiconductor Manufacturing Company 0.18-μm RF-CMOS process with a supply voltage of 3.3 V. The measured gain, P1dB, and efficiency at P1dB are 29 dB, 28.1 dBm, and 37.9%, respectively. When the PA is tested with 54 Mbps of an 802.11g WLAN orthogonal frequency division multiplexing signal, a 25-dB error vector magnitude compliant output power of 22 dBm and a 21.5% efficiency can be obtained. © 2012 ETRI.


Lee K.-K.,Korea Advanced Institute of Science and Technology | Ryoo J.-D.,Advanced Communications Research Laboratory | Ryoo J.-D.,Korean University of Science and Technology | Kim S.H.,Korea Advanced Institute of Science and Technology | Kim D.,Korea Advanced Institute of Science and Technology
IEEE Communications Letters | Year: 2012

Ethernet ring protection (ERP), defined in ITU-T recommendation G.8032, is a promising technology to realize the SONET/SDH-grade resilience in carrier Ethernet infrastructures. With its own loop prevention technique to block a link called ring-protection-link (RPL) in an ERP ring, the ERP introduces a new optimization problem named RPL positioning whose objective is to find the optimal RPL location to minimize the required ring capacity for given traffic demands. In this paper, we derive the optimal RPL positioning as an integer linear programming (ILP) problem and additionally propose an optimal RPL positioning algorithm for more effective ring loading. By evaluations, we demonstrate that our proposed algorithm is indeed capable of finding the optimal RPL equal to the results by an exhaustive search emerged in prior works or the formulated ILP model. But, it is more efficient in computing time than the exhaustive search and the ILP model. © 2012 IEEE.


Choi Y.,Stanford University | Lee Y.,Korea Advanced Institute of Science and Technology | Chang K.,Advanced Communications Research Laboratory | Chang K.,Simon Fraser University
ETRI Journal | Year: 2012

Carrier aggregation is an essential feature in the Long Term Evolution-Advanced (LTE-A) system, which allows the scalable expansion of the effective bandwidth to be delivered to user equipment (UE) through the concurrent use of radio resources across multiple component carriers (CCs). This system's optimal radio-resource use has received much attention under simultaneous access (SA) scenarios for multiple CCs (m-CCs). This letter establishes how many CCs a UE should simultaneously connect to maintain maximum uplink capacity. Under the m-CC LTE-A system, the spectral efficiency of the m-CC SA scheme (m≥2) is compared with that of CC selection (CCS). Numerical results reveal that the 2-CC SA scheme outperforms CCS and performs almost equally to the m-CC SA scheme (m≥3). © 2012 ETRI.


Kim J.-H.,Advanced Communications Research Laboratory | Yu H.,Advanced Communications Research Laboratory | Lee S.-K.,Advanced Communications Research Laboratory
ETRI Journal | Year: 2012

IEEE 802.11n standards introduced a mixed-mode format frame structure to achieve higher throughput with multiple antennas while providing backward compatibility with legacy systems. Although multi-input multi-output channel estimation was possible only with high-throughput long training fields (HT-LTFs), the proposed scheme utilizes a legacy LTF as well as HT-LTFs in a decision feedback manner to improve the accuracy of the estimates. It was verified through theoretical analysis and simulations that the proposed scheme effectively enhances the mean square error performance. © 2012 ETRI.


Chung H.S.,BigData Software Research Laboratory | Chang S.H.,Advanced Communications Research Laboratory | Lee J.,Advanced Communications Research Laboratory | Kim K.,Advanced Communications Research Laboratory
ETRI Journal | Year: 2012

Transmission performances of direct detection-based 100-Gb/s modulation formats are investigated and compared for metro area optical networks. The effects of optical signal-to-noise ratio sensitivity, chromatic dispersion, cross-channel nonlinearity, and transmission distance on the performance of differential 8-ary phase-shift keying (D8PSK), differential phase-shift keying plus three-level amplitude-shift keying (DPSK+3ASK), and dual-carrier differential quaternary phase-shift keying (DC-DQPSK) are evaluated. The performance of coherent dual-polarization quadrature phase-shift keying (DP-QPSK) with block phase estimation and coherent DP-QPSK with digital differential detection are also presented for reference. According to our analysis, all three direct detection modulation formats could transmit a 100-Gb/s signal over several hundred kilometers of a single-mode fiber link. The results also show that DC-DQPSK outperforms D8PSK and DPSK+3ASK, and the performance of DC-DQPSK is comparable to that of coherent DP-QPSK with digital differential detection. The maximum transmission distance of DC-DQPSK is over 1,000 km, which is enough distance for metro applications. © 2012 ETRI.

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