• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.2062-2064
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• 2015

In this paper, we propose indoor positioning algorithm performed at the image sensor equipped in mobile station, which receives the light signal from LED panels. To evaluate the performance of positioning algorithm, we consider the ambient noise existing indoor environment, and it is found that the proposed algorithm estimates the position of mobile station with high accuracy regardless of existence of ambient noise.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5C
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• pp.276-285
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• 2011

In this paper, we propose new cooperative precoder selection technique for interference limited MIMO networks. Our proposed method gives weighting to precoders in the codebook according to each precoder's performance priority. By applying our proposed method to precoder selection sequence, performance of entire system can be improved in terms of sumrate, stability, and feedback rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4C
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• pp.290-296
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• 2012

In this paper, we propose a practical authentication system based on Wireless Body Area Networks(WBAN) for U-healthcare medical information environments. The proposed authentication system is based on symmetric cryptosystem such as AES and is designed to not only provide security such as data secrecy, data authentication, data integrity, but also prevent replay attack by adopting timestamp technique and perform secure authentication between sensor node, master node, base-station, and medical server.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5B
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• pp.395-404
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• 2012

In this paper, we analyze and develop standard protocols for WAVE Networking Services described by IEEE 1609.3 which is one of standards for Intelligent Transportation Systems. In particular, we develop 'WAVE Management Entity(WME)' and 'WAVE Short Message Protocol(WSMP)'. For verification of development, we also develop Traffic Management System and RSU Manager, then we present results of verification by Traffic Management System in the car accident scenario.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6A
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• pp.426-437
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• 2012

This paper proposes an array antenna assisted Doppler spread compensator with dummy elements which are placed on either end of a monopole array for a digital terrestrial television broadcasting (DTTB) receiver. An array antenna assisted Doppler spread compensator, proposed previously, has a major drawback in performance degradation owing to mutual coupling effect among array elements. In order to solve the mutual coupling problem, dummy elements, placed on both sides of the monopole array mitigate performance degradation of a Doppler spread compensator arising from the mutual coupling among monopole array elements. Computer simulation results show that the dummy elements can reduce this performance degradation as well as expand the operating bandwidth of a Doppler spread compensator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.10B
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• pp.1143-1149
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• 2011

A multi-OLT PON architecture is proposed to accommodate several types of services or multiple service providers economically in a single PON. The operation protocol and a dynamic bandwidth allocation scheme appropriate for two-OLT structure are proposed. Performance analysis shows that the proposed system is very efficient and can be used in the upcoming higher speed PON system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.6
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• pp.497-502
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• 2013

In this paper, we aim to evaluate the performance of the digital signal processing (DSP) algorithm used in [8] in order to improve the resolution of spectrometers with fixed number of low-cost, non-ideal filters. In such spectrometers, the resolution is limited by the number of filters. We aim to demonstrate via new experiments that the resolution improvement by six times over the conventional limit is possible by using the DSP algorithm as claimed by [8].

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.2
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• pp.208-212
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• 2013

Due to the singularity of the within-class scatter, linear discriminant analysis (LDA) becomes ill-posed for small sample size (SSS) problems. An extension of LDA, the null space-based LDA (NLDA) provides good discriminant performances for SSS problems. In this paper, by applying the Lagrange technique, the procedure of transforming the problem of finding the feature extractor of NLDA into a linear equation problem is derived.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.106-113
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• 2014

This work proposes an analytic framework to estimate the capacity of the link in an M2M gateway that multiplexes a massive number of machine type communication devices. First, we specify the network architecture for M2M communications. Next, we summarize the characteristics of M2M traffic, from which we extract an area about the problem that has to be resolved in the dimensioning of the link capacity. After that we propose a new method to determine the capacity of the link in an M2M gateway. Via numerical experiment reflecting the realistic environment of M2M traffic, we illustrate the validity of the proposed model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.9
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• pp.870-879
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• 2014

In this paper, we propose an initial timing acquisition algorithm for terrestrial cloud transmission (CTxn) systems. By combining auto-correlations of several repetition patterns within preamble symbols, the proposed scheme can improve the reliability of the timing metric for CTxn system with co-channel interferences. Simulation results show that the proposed scheme improves the reliability of the timing metric for terrestrial CTxn systems.