• ETRI Journal
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• 제26권6호
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• pp.565-574
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• 2004

Differential unitary space-time modulation (DUSTM) has emerged as a promising technique to obtain spatial diversity without intractable channel estimation. This paper presents a study of the application of DUSTM on multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems with frequency-selective fading channels. From the view of a correlation analysis between subcarriers of OFDM, we obtain the maximum achievable diversity of DUSTM on MIMO-OFDM systems. Moreover, an efficient implementation strategy based on subcarrier reconstruction is proposed, which transmits all the signals of one signal matrix in one OFDM transmission and performs differential processing between two adjacent OFDM blocks. The proposed method is capable of obtaining both spatial and multipath diversity while reducing the effect of time variation of channels to a minimum. The performance improvement is confirmed by simulation results.

• Journal of information and communication convergence engineering
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• 제7권2호
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• pp.182-184
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• 2009

In this letter, we derive a tight closed-form formula for an ergodic capacity of a multiple-input multiple-output (MIMO) for the application of wireless communications. The derived expression is a simple closed-form formula to determine the ergodic capacity of MIMO systems. Assuming the channels are independent and identically distributed (i.i.d.) Rayleigh flat-fading between antenna pairs, the ergodic capacity can be expressed in a closed form as the finite sum of exponential integrals.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 추계종합학술대회 B
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• pp.49-52
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• 2008

In this letter, we derive a tight closed form formula for an ergodic rapacity of a multiple-input multiple-output (MIMO) for the application of wireless communications. The derived expression is a simple close-form formula to determine the ergodic capacity of MIMO systems. Assuming the channels are independent and identically distributed (i.i.d.) Rayleigh flat-fading between antenna pairs, the ergodic capacity can be expressed in a closed form as the finite sum of exponential integrals.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권7호
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• pp.2879-2890
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• 2020

In this paper, we study the estimation of angle, range and polarization parameters of a bistatic polarization sensitive frequency diverse array multiple-input multiple-output (PSFDA-MIMO) radar system. The application of polarization sensitive array in receiver is explored. A signal model of bistatic PSFDA-MIMO radar system is established. In order to utilize the multi-dimensional structure of array signals, the matched filtering radar data can be represented by a third-order tensor model. A joint estimation of the direction-of-departure (DOD), direction-of-arrival (DOA), range and polarization parameters based on parallel factor (PARAFAC) algorithm is proposed. The proposed algorithm does not need to search spectral peaks and singular value decomposition, and can obtain automatic pairing estimation. The method was compared with the existing methods, and the results show that the performance of the method is better. Therefore, the accuracy of the parameter estimation is further improved.

• 한국인터넷방송통신학회논문지
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• 제17권4호
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• pp.83-93
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• 2017

일상생활에서 신용카드 가로세로의 비가 1:1.56이고, A4 프린터 용지도 1:1.414 등 비교적 균형 잡힌 황금비로 되어 있다. 본 논문은 인식하기에 가장 균형적이고 이상적으로 보이는 비율인 황금비를 바탕으로 피보나치 Golden 비를 다항식으로 표현했고 오일러와 대칭 자켓 다항식의 응용을 BPSK, QPSK 성상도의 관계됨을 보였다. 증명방법으로 피보나치 Golden과 Galois 필드 요소 다항식을 유도했다. 이어서 수학적으로 직교 속성을 가진 적합한 코드를 생성하는데 사용될 수 있고 단순히 역 계산으로 사용할 수 있는 Golden 자켓코드를 새롭게 유도했고 MIMO 이동통신채널에서 Block Jacket 행렬을 이용 채널상관관계의 변화에 따른 채널용량을 구했다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.313-316
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• 1997

Two different issues, design of reduced-order robust model predictive control and input signal design for identification of a MIMO system, are addressed and design techniques based on singular value decomposition(SVD) of the pulse response circulant matrix(PRCM) are proposed. For this, we investigate the properties of the PRCM, which is a periodic approximation of a linear discrete-time system, and show its SVD represents the directional as well as the frequency decomposition of the system. Usefulness of the PRCM and effectiveness of the proposed design techniques are demonstrated through numerical examples.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권3호
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• pp.1373-1392
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• 2017

WiFi Direct (WD) is a state of the art technology for a Device-to-Device (D2D) communication in 802.11 networks. The performance of the WD system can be significantly affected by some key factors such as the type of application, specifications of MAC and PHY layer parameters, and surrounding environment etc. It is, therefore, important to develop a system model that takes these factors into account. In this paper, we focus on investigating the design parameters of the PHY layer that could maximize the efficiency of the WD 802.11 system. For this purpose, a basic theoretical model is formulated for a WD network under a 2x2 Multiple In Multiple Out (MIMO) TGn channel B model. The design level parameters such as input symbol rate and antenna spacing, as well as the effects of the environment, are thoroughly examined in terms of path gain, spectral density, outage probability and Packet Error Rate (PER). Thereafter, a novel adaptive algorithm is proposed to choose optimal parameters in accordance with the Quality of Experience (QoE) for a targeted application. The simulation results show that the proposed method outperforms the standard method thereby achieving an optimal performance in an adaptive manner.

• Journal of Information Processing Systems
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• 제16권4호
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• pp.774-783
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• 2020

For the issue of subsurface target localization by reverse projection, a new approach of target localization with different distances based on symmetric sub-array multiple-input multiple-output (MIMO) radar is proposed in this paper. By utilizing the particularity of structure of the two symmetric sub-arrays, the received signals are jointly reconstructed to eliminate the distance information from the steering vectors. The distance-independent direction of arrival (DOA) estimates are acquired, and the localizations of subsurface targets with different distances are realized by reverse projection. According to the localization mechanism and application characteristics of the proposed algorithm, the grid zooming method based on spatial segmentation is used to optimize the locaiton efficiency. Simulation results demonstrate the effectiveness of the proposed localization method and optimization scheme.

• 한국전자파학회논문지
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• 제26권4호
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• pp.357-364
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• 2015

본 논문에서는 6중 이동통신 대역을 만족하는 단말기용 PIFA(Planar Inverted F Antenna) + IFA(Inverted F Antenna) 하이브리드 MIMO(Multi Input Multi Output) 안테나를 설계하고, 이를 구현하였다. 커플링 급전구조를 이용하여 PIFA와 IFA가 동시에 동작하도록 함으로써 접지 면이 많은 현재의 스마트폰에 효과적으로 적용될 수 있도록 시도하였다. 후면이 접지인 부분에는 PIFA를 설계하였고, 접지가 없는 휴대폰 상단 작은 공간에는 IFA를 설계하였다. 안테나는 폰과 동일한 크기로 carrier가 없는 PCB embedded로 대각선 급전 MIMO 안테나로 구현하였다. 베어보드에 구현된 안테나는 CDMA, GSM900, DCS, KPCS, USPCS, WCDMA의 6중 이동통신 서비스 대역에서 VSWR 3 : 1 이하의 특성을 만족하였다. 평균이득과 효율은 CDMA, GSM900대역에서 -5.19~-3.16 dBi 및 30.27~48.26 %를 보였다. 또한, DCS, KPCS, USPCS, WCDMA 대역에서는 -9.50~-5.19 dBi의 평균이득과 11.23~30.28 %의 효율특성을 가짐으로써 휴대폰 안테나로 적용될 수 있음을 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권10호
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• pp.4214-4230
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• 2020

This paper introduces a pilot allocation scheme for massive MIMO systems based on deep convolutional neural network (CNN) learning. This work is an extension of a prior work on the basic deep learning framework of the pilot assignment problem, the application of which to a high-user density nature is difficult owing to the factorial increase in both input features and output layers. To solve this problem, by adopting the advantages of CNN in learning image data, we design input features that represent users' locations in all the cells as image data with a two-dimensional fixed-size matrix. Furthermore, using a sorting mechanism for applying proper rule, we construct output layers with a linear space complexity according to the number of users. We also develop a theoretical framework for the network capacity model of the massive MIMO systems and apply it to the training process. Finally, we implement the proposed deep CNN-based pilot assignment scheme using a commercial vanilla CNN, which takes into account shift invariant characteristics. Through extensive simulation, we demonstrate that the proposed work realizes about a 98% theoretical upper-bound performance and an elapsed time of 0.842 ms with low complexity in the case of a high-user-density condition.