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Distribution of Eigenvalues for 2x2 MIMO Channel Capacity Based on Indoor Measurements
Wonsop Kim,Hyuckjae Lee,Myung-Don Kim,Hyun Kyu Chung IEEE 2012 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.11 No.4
<P>Based on the non line-of-sight (NLOS) indoor measurements performed in the corridors on the third floor of the Electronics and Telecommunications Research Institute (ETRI) building in Daejeon city, Republic of Korea, we investigated the distribution of the eigenvalues of HH*, where H denotes a 2×2 multiple-input multiple-output (MIMO) channel matrix. Using the observation that the distribution of the measured eigenvalues matches well with the Gamma distribution, we propose a model of eigenvalues as Gamma distributed random variables that prominently feature both transmitting and receiving correlations. Using the model with positive integer k_i, i=1, 2, which is the shape parameter of a Gamma distribution, we derive the closed-form ergodic capacity of the 2×2 MIMO channel. Validation results show that the proposed model enables the evaluation of the outage and ergodic capacities of the correlated 2×2 MIMO channel in the NLOS indoor corridor environment.</P>
Time-Division Multiplexing Based MIMO Channel Sounder Using Loosely Synchronous Codes
Wonsop Kim,Jae Joon Park,Myung-Don Kim,Hyun Kyu Chung IEEE 2007 2007 IEEE Vehicular Technology Conference Vol.2007 No.9
<P>In this paper, we propose the time-division multiplexing (TDM) based MIMO channel sounding technique using loosely synchronous (LS) codes for real time measurement of MIMO radio channel. Since LS codes have perfect autocorrelation and cross-correlation functions within certain vicinity of the zero shifts, the proposed technique can substantially reduce multipath channel interference. When cumulative distribution functions (CDFs) of absolute root mean square (RMS) delay spread error are considered, simulation results show that the proposed technique outperforms the conventional TDM based MIMO channel sounding technique. Moreover, in the MIMO channel environment where a mobile station moves with various speeds, the proposed technique is more efficient than the conventional TDM based MIMO channel sounding technique, because the proposed technique obtains about twice the measurement data of the conventional TDM based MIMO channel sounding technique at given time slots.</P>
Wonsop Kim,Kyungnam Lee,Myung-Don Kim,Jae Joon Park,Hyun Kyu Chung,Hyuckjae Lee IEEE 2012 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.11 No.10
<P>The performance of MIMO-OFDM beamforming systems with maximal ratio combining receivers is considered based on the extensive wideband 2 × 8 (i.e., 2 transmitting and 8 receiving antennas) MIMO channel measurement data in non line-of-sight urban macrocell environments. Using the experimental observation that the probability density function (PDF) of the measured maximum eigenvalue for H† <SUB>m</SUB>H<SUB>m</SUB>, where H<SUB>m</SUB> and superscript † denote a MIMO channel frequency response matrix and conjugation and transposition, respectively, matches the Gamma distribution well, we propose the maximum eigenvalue model as Gamma distributed random variables whose parameters are both transmitting and receiving correlations and the number of receiving antennas. Using the model, the performances of MIMO-OFDM beamforming systems, such as the PDF of the output signal-to-noise ratio, outage probability, symbol error rate, and achievable diversity order, are analyzed to demonstrate the effect of spatial correlation in the realistic 2 × n (downlink) and n × 2 (uplink) MIMO channels.</P>
송신 상관된 레일리 채널에서 프리코더를 갖는 MIMO MMSE 수신기의 성능 분석
김원섭(Wonsop Kim) 한국통신학회 2013 韓國通信學會論文誌 Vol.38 No.7C
이 논문에서는 송신 상관된 레일리 페이딩 채널에서 프리코더를 갖는 다중 입출력 안테나 시스템이 고려된다. 특히 최소평균제곱오차 수신기를 적용한 다중 입출력 안테나 시스템을 대상으로 한다. 임의 행렬 이론에 기초하여, 신호 대 간섭 및 잡음비의 확률 밀도 함수를 유도하기 위한 정확하고 일반화된 식을 유도한다. 그리하여 적은 수의 송신 및 수신 안테나에 대하여 정확한 폐쇄형 신호 대 간섭 및 잡음비의 확률 밀도 함수 식을 제안한다. 또한, 신호 대 간섭 및 잡음비의 확률 밀도 함수 식에 기초하여 폐쇄형 심볼 오류율 근사식을 제안한다. 제안하는 심볼오류율 분석결과는 오류 확률을 정확하게 예측하거나, 시스템 디자인을 위한 유용한 툴로서 사용될 수 있을 것으로 예상된다. In this paper, the multiple-input multiple-output (MIMO) system with a precoder is considered in the transmit-correlated Rayleigh channels. We specifically target the MIMO system employing the minimum mean square error receivers. Based on random matrix theory, we first present a direct and generalized formulation for deriving a probability density function (PDF) of the signal-to-interference-plus-noise ratio (SINR). Then, we derive the accurate closed-form SINR PDFs for a small number of transmit and receive antennas. Based on the SINR PDFs, tight closed-form approximations of the symbol error rate (SER) are derived. Our analysis suggests that the SER approximations can be used to accurately estimate the error probabilities or as a useful tool for the system design.
효율적인 행렬 곱 알고리즘 및 이를 활용한 고성능 임베디드 시스템 개발
김원섭(Wonsop Kim),전원보(Wonbo Jeon),공민식(Minsik Gong) 한국항공우주학회 2019 韓國航空宇宙學會誌 Vol.47 No.1
최근 항공우주 및 방위산업 분야에서 다양한 임베디드 시스템들의 소형화 및 저가화 개발이 많이 요구되고 있다. 본 논문에서는 고속 DSP를 이용하여 임베디드 시스템을 개발한다. 또한 비행 조종과 같은 고정밀 알고리즘의 연산시간을 줄이기 위해 행렬 곱을 위한 두 가지 알고리즘을 제안하고 구현한다. 개발한 임베디드 시스템을 이용하여 성능을 검증한 결과, 2×2 단위 계산방법을 이용한 기존 방법과 성능을 비교했을 때 첫 번째 제안방법은 행렬의 사이즈가 작을때 성능이 개선된다. 두 번째 제안방법은 2×2 단위 계산방법보다 전체적으로 성능이 우세하다. In the recent aerospace and defence industries, it is required to develop small and low cost embedded systems. Based on a high speed digital signal processor (DSP), this paper first presents the development of an embedded system. To reduce the computation time of the high precision algorithm such as flight control, we also propose two algorithms for matrix multiplication. Validation results show that, compared to the performance using the 2×2 unit method, the performance of the proposed method 1 is improved, when the size of matrices is small. The proposed method 2 generally outperforms the 2×2 unit method.