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MMSE-Based Throughput Control Algorithm for Generalized PF Scheduling
Heejin Joung,Cheol Mun,Jong-Gwan Yook IEEE 2012 IEEE communications letters Vol.16 No.10
<P>In this paper, we propose a minimum mean square error (MMSE)-based throughput control algorithm for generalized proportional fair (PF) scheduling. The algorithm determines mobile users' scheduling parameters so that the mean square error between expected throughputs and demanded throughputs is minimized. To do this, we simplify a function that predicts users' throughput, formulate a quadratically constrained quadratic problem, and find scheduling parameters that satisfy the first order necessary conditions of the problem.</P>
Capacity Loss Due to Polarization-Mismatch and Space-Correlation on MISO Channel
Heejin Joung,Han-Shin Jo,Cheol Mun,Jong-Gwan Yook IEEE 2014 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.13 No.4
<P>This paper analyzes the effects of polarization-mismatch and space-correlation to a multiple-input and single-output (MISO) channel which is observable in the near future cellular communications environments such as large-scale antenna arrays and small cells. The analysis is based on a polarization-mismatched and space-correlated MISO channel which is modeled from the conventional dual-polarized channel. In the MISO channel, polarization-mismatch is described by the polarization-mismatch angle which is uniformly distributed from 0 to the maximum polarization-mismatch angle and space-correlation is described by the exponential correlation model. Assuming high SNR, approximate expressions of the ergodic capacity are derived as a function of the transmit power, number of transmit antennas, maximum polarization-mismatch angle, and space-correlation coefficient in four representative environments: narrowly or widely spread polarization-mismatch angles and slightly or highly correlated channels. Further, the capacity loss introduced by polarization-mismatch and space-correlation is derived with respect to the maximum polarization-mismatch angle and space-correlation coefficient. It is shown that the capacity loss introduced by polarization-mismatch is upper bounded by 2 bit/s/Hz. Whereas, the capacity loss introduced by space-correlation increase with the number of transmit antennas and is upper bounded by 0.832 bit/s/Hz. Required resources to compensate for the capacity loss is derived as well.</P>
Space-Polarization Division Multiple Access System with Limited Feedback
( Heejin Joung ),( Han-shin Jo ),( Cheol Mun ),( Jong-gwan Yook ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.4
This paper proposes a space-polarization division multiple access (SPDMA) system that has limited feedback channels. The system simultaneously serves data streams to multiple mobile users through dual-polarized antenna arrays, by using pre-determined sets of precoding vectors that are orthogonal in both space and polarization domains. To this end, a codebook whose elements are sets of the precoding vectors is systematically designed based on the discrete Fourier transform (DFT) matrix and considering the power imbalance of polarized channels. Throughput of the SPDMA system is evaluated and compared to that of space division multiple access (SDMA) system, according to the various parameters including cross polarization discrimination (XPD). The results show that the throughput of SPDMA system outperforms that of SDMA in the environments of high XPD with many mobile users.
무선이동 네트워크에서 일반화된 PF 스케줄링을 위한 실시간 링크 용량 관리 알고리즘
정희진 ( Heejin Joung ),문철 ( Cheol Mun ),육종관 ( Jong-gwan Yook ) 한국인터넷정보학회 2011 인터넷정보학회논문지 Vol.12 No.5
일반화된 PF 스케줄링을 사용하는 무선이동 네트워크는 스케줄링 변수를 조정하여 동적인 무선 자원 할당을 가능케 한다. 기존의 확률론적 접근 방법으로는 일반적인 환경에서 네트워크의 용량을 예측하는 데에는 한계가 있다. 더욱이 그 한계는 요구되는 네트워크 용량을 얻도록 하는 스케줄링 변수를 효율적으로 찾을 수 없게 한다. 본 논문은 결정론적 접근 방법을 사용하여 네트워크의 용량을 예측하는 알고리즘을 유도한다. 얻어진 용량 예측 알고리즘을 이용하여 요구되는 용량에 따른 스케줄링 변수 설정을 효과적으로 할 수 있는 용량 조정 알고리즘과 용량 교환 알고리즘 제안한다. IEEE 802.16m 시스템 기반의 시스템 레벨 시뮬레이션을 통해 제안된 용량 예측 알고리즘과 용량 교환 알고리즘의 성능을 확인한다. Wireless mobile networks that exploit generalized PF scheduling can dynamically allocate network resources by using scheduling parameters. There are limitations to predict throughputs by the conventional stochastic approach in general. Moreover the limitations make it difficult to find appropriate scheduling parameters for achieving the demanded throughputs. This paper derives a prediction algorithm that predicts throughputs of the networks by using deterministic approach. A throughput adjust algorithm and a throughput switching algorithm are derived from the prediction algorithm. The performance of the throughput prediction/switching algorithms is evaluated by a simulator based on IEEE 802.16m system.
정희진(Heejin Joung),육종관(Jong-Gwan Yook) 한국정보기술학회 2014 한국정보기술학회논문지 Vol.12 No.6
Densification (by increasing the number of antennas or base stations per unit area) of wireless networks has changed its channel characteristics highly polarized. In this paper, we derive the achievable secrecy rate of polarized channels and find corresponding precoders. To this end, it is supposed that there are a transmitter, receiver, and eavesdropper. The transmitter and receiver (or eavesdropper) are connected with each other by a dual-polarized MISO (multiple-input and single-output) channel. The optimization problem that finds the achievable secrecy rate is formulated and the optimal precoder is found by based on the channel state information known to the transmitter. It is shown by analysis and verified by simulation that the achievable secrecy rate decreases as cross polarization discrimination increases.
심해 장거리 환경에서 시공간 다이버시티를 이용한 수중음향통신성능 향상
박희진,김동현,김재수,한주영,박정수,Park, Heejin,Kim, Donghyeon,Kim, J.S.,Hahn, Joo Young,Park, Joung-Soo 한국음향학회 2019 韓國音響學會誌 Vol.38 No.5
수중음향통신에서 다중경로로 인한 인접 심볼 간 간섭은 통신 성능을 저하시킨다. 인접 심볼 간 간섭의 영향을 최소화하여 수중음향통신 성능을 향상시키기 위해 다이버시티 기법을 사용한다. 본 논문에서는 공간 다이버시티와 시간 다이버시티의 결합을 통해 수중음향통신 성능이 개선됨을 보인다. 시공간 다이버시티를 통해 제한적인 배열에서 수중통신 시스템의 효율성을 증대시켰다. 또한 2018년 10월 한국의 동쪽 해역에서 수행한 BLAC18(Biomimetic Long range Acoustic Communication 18) 실험 데이터와 비교하여 이를 검증하였다. ISI (Inter Symbol Interference) reduces the performance of UAComm (Underwater Acoustic Communication). This paper shows that the performance of UAComm can be improved through the spatiotemporal diversity method that is the combination of spatial diversity and temporal diversity methods. By using spatiotemporal diversity, the array aperture was reduced to increase the efficiency of the UAComm system. It is also verified using the experimental data of BLAC18 (Biomimetic Long range Acoustic Communication 18) conducted in October 2018.
심해에서의 빔 다이버시티를 이용한 수중음향통신 성능 분석
김동현,박희진,김재수,박정수,한주영,Kim, Donghyeon,Park, Heejin,Kim, J. S.,Park, Joung-Soo,Hahn, Joo Young 한국음향학회 2019 韓國音響學會誌 Vol.38 No.6
수중에서는 다중 경로로 인한 인접 심볼 간 간섭의 영향으로 통신 성능이 저하되며, 수동형 시역전 처리는 다중 경로를 완화하기 위한 가장 효율적인 기법이다. 수동형 시역전 처리의 성능을 향상시키기 위해 다이버시티 결합기법이 이용되고 있으며, 본 논문에서는 여러 각도로의 빔 조향을 통해 획득한 신호들을 결합하는 빔 다이버시티 결합기법을 이용하여 통신 성능을 분석하였다. 수직 선 배열 센서에 수신된 탐침 신호로부터 추정한 빔-시간 그래프를 통해 음파의 전달 각도들을 추정하였으며, 추정된 각도 중 결합 개수 및 방식에 따른 통신 성능을 분석하였다. 분석을 위해 2018년 10월 포항 동방 해역에서 수행된 Biomimetic Long range Acoustic Communications 2018(BLAC18) 실험 데이터를 활용하였으며, 통신 성능 지표로써 출력 신호 대 잡음비를 이용하였다. Underwater communication performance is degraded by the influence of Inter-Symbol Interference (ISI) due to multipath. Passive time reversal processing is the most effective technique for mitigating multipath, and the diversity combining method can be used to improve its performance. This paper analyzed communication performance using the beam diversity combining method, which combines signals obtained through the beam steering to various angles. Directions of arrival were estimated through the beam-time migration, which, in turn, was estimated from probe signals received by a vertical line array. The performance was analyzed based on the number and type of combinations among the estimated angles. In this paper, the data obtained from the Biomimetic Long range Acoustic Communications 2018 (BLAC18) experiment, which was conducted in the East sea, ~50 km east of Pohang, in October 2018, were used for the analysis. The output Signal to Noise Ratio (SNR) was used as communication indicators.