• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.9C
• /
• pp.887-895
• /
• 2009

This paper proposes a cooperative power allocation with the use of partial channel information (e.g., the average signal-to-noise ratio (SNR) and transmit correlation) in multi-cell dual-hop multi-input single-output (MISO) relay systems. In a dual-hop MISO relay channel, it is desirable to allocate the transmit power between dual-hop links to maximize the end-to-end capacity. We consider the maximization of the end-to-end capacity of a dual-hop MISO relay channel under sum-power constraint. The proposed scheme adaptively allocates the transmit power considering the average channel gain of the target relay and the transmit correlation of the desired and inter-relay interference channel from adjacent relays. It is shown by means of upper-bound analysis that the end-to-end capacity can be maximized by making the angle difference of the principal eigenvectors of the desired and inter-relay interference channel orthogonal in highly-correlated channel environments. Finally, the performance of the proposed scheme is verified by computer simulation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.11
• /
• pp.2298-2304
• /
• 2015

In this paper, we provide a new approach which optimizes the vertical tilting angle of the base station for multi-cell multiple-input single-output (MISO) downlink active antenna systems (AAS). Instead of the conventional optimal algorithm which requires an exhaustive search, we propose simple and near optimal algorithms. First, we represent a large system approximation based vertical beamforming algorithm which is applied to the average sum rate by using the random matrix theory. Next, we suggest a signal-to-leakage-and-noise ratio (SLNR) based vertical beamforming algorithm which simplifies the optimization problem considerably. In the simulation results, we demonstrate that the performance of the proposed algorithms is near close to the exhaustive search algorithm with substantially reduced complexity.

• Journal of Oriental Medical Thermology
• /
• v.6 no.1
• /
• pp.32-38
• /
• 2008

Objective: To investigate the changes of facial temperature by Miso Facial Rejuvenation Acupuncture treatment. Methods: One middle-aged women who has no other disease was recruited. The Miso Facial Rejuvenation Acupuncture was performed on only right face. We measured the facial temperature using the Digital Infrared Thermal Imaging (DOREX Inc. Spectrum 9000 MB, USA, D.I.T.I.) before, immediate after and 10 minutes after treatment. And we used the Wilcoxon signed rank test (P<0.05) to compare the difference of facial temperature at each time. Results: Right facial temperature (the area treated by acpuncuture) increased immediately from $30.02{\pm}1.87^{\circ}C$ to $32.24{\pm}1.03^{\circ}C$, the change of temperature is statistically significant. At 10 minutes after treatment, right facial temperature decreased little, but there was no statistical significance. Left facial temperature increased little, but there was no statistical significance. The difference between right and left face increased after Miso facial rejuvenation acupuncture treatment. Conclusion: Miso facial rejuvenation acupuncture could make the facial temperature increase.

• Journal of Acupuncture Research
• /
• v.25 no.1
• /
• pp.89-95
• /
• 2008

Objectives : To investigate changes in facial temperature generated by Miso Facial Rejuvenation Acupuncture treatment. Methods : One middle-aged woman with no diseases was recruited. Miso Facial Rejuvenation Acupuncture was performed on only the right side of her face. We measured her facial temperature using digital infrared thermal imaging(DOREX Inc. Spectrum 9,000MB, USA, D.I.T.I) before, immediately after, and 10 minutes after treatment. We also used the Wilcoxon signed rank test(p<0.05) to compare the differences in facial temperature from one side of the face to the other at each time. Results : Facial temperature on the right side(the area treated by acupuncture) increased immediately from $30.02{\pm}1.87^{\circ}C$ to $32.24{\pm}1.03^{\circ}C$, a statistically significant increase. Ten minutes after treatment, facial temperature on the right side decreased a little bit, but there was no statistical significance. Facial temperature on the left side increased a little, but there was no statistical significance. The difference between the right and left sides of the face increased after the Miso Facial Rejuvenation Acupuncture treatment. Conclusions : Miso Facial Rejuvenation Acupuncture could increase facial temperature.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.11
• /
• pp.1209-1216
• /
• 2009

This paper presents an efficient Quantized Equal Gain Transmission(QEGT) codebook index searching technique for MISO beamforming system in a Rayleigh flat fading channel. The searching time for the optimum weight vector among the codebook vectors increases exponentially when the codebook size increases linearly, although the bit error rate decreases. So, newly defined simple metric is proposed for fast searching, which determines a few candidates. Then the conventional method combined with accurate search algorithm selects the optimal index. This strategy significantly reduces the overall search time, while maintaining almost the same bit error rate performance. Furthermore, as the codebook size increases, the search time is considerably decreased compared to that of the conventional approach.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.7B
• /
• pp.878-885
• /
• 2011

Due to reflect at surface of the water and limit bandwidth, it is difficult to design underwater acoustic communication systems with high-reliability and high transmission rate. Therefore the trends of underwater communication is transformed from single sensor to multiple sensor studies. However, underwater MIMO communication techniques have a high correlation value between multiple sensors on transmitters and receivers in underwater environments, it is difficult to expect space diversity gain on muli-path channels. Therefore, this paper proposed the MISO communications system with two transmit sensors and single receiver sensor, and analyzed its performance using the LDPC codes and channel compensation algorithm.

• Journal of Satellite, Information and Communications
• /
• v.12 no.2
• /
• pp.104-111
• /
• 2017

Pre-Rake CDMA system using multiple transmit antenna provides a good system performance without equipping a complicated RAKE combiner at the mobile receiver. However, the performance of the Pre-Rake systems are significantly affected by channel estimation error so that the effect of the channel estimation error should be considered and analyzed for evaluating the system performance. In this paper, MISO(Multi-Input Multi-output) Pre-Rake CDMA system with channel estimation error is analyzed by numerical analysis and the results are compared with that of the computer simulation. From the numerical results, it is found that the performance of the Pre-Rake system is more affected by the phase error than the amplitude error.

• Journal of Broadcast Engineering
• /
• v.24 no.4
• /
• pp.613-622
• /
• 2019

A differential codebook design method using wireless channel's temporal correlation is proposed over closed loop multiple-input single-output (MISO) system. The single layer codewords in a codebook are selected among a set of phase elements. In the conventional codeword selection rule, codewords are assumed to be on a spherical cap and sine formula was used. In this paper, however, a new method using Pythagoras formula is employed to simplify computational complexity. Also, an adaptive differential codebook selection is adopted to enhance performance. Monte-Carlo simulations demonstrate that the proposed codebook is superior to the conventional ones.

• Proceedings of the IEEK Conference
• /
• 2001.09a
• /
• pp.613-616
• /
• 2001

본 논문에서는 3GPP에 규격으로 채택된 전송 다이버 시티 기법들 중에 이상적인 상황에서 가장 우수한 성능을 갖는 폐쇄루프 전송 다이버시티 (CLTD : Closed Loop Transmit Diverstiy) 기법과 선형 사전필터의 조합을 통해 MISO 시스템에서 보다 우수한 성능의 전송 다이버시티 기법을 제안하고 이에 대한 성능을 분석하였다. 또한 사전필터의 최적의 필터 계수 값을 사용하여 다이버시티이득을 최대화하였고 이에 대한 성능을 분석한 결과 CLTD 기법보다 월등히 우수한 성능을 확인하였다.

• Information and Communications Magazine
• /
• v.29 no.8
• /
• pp.34-41
• /
• 2012

본 고에서는 LTE-Advanced 및 Beyond 4G 이동 통신 시스템에서 셀 경계 지역 간섭 문제 해결 및 전송률 향상을 위해 핵심기술로 간주되는 다중 안테나를 사용한 다중 셀 기지국 협력전송 방법에 대해 살펴본다. 특히, 다중 셀 통신 환경을 다중입력 단일출력(multiple-input single-output. MISO) 및 다중입력 다중출력 (multiple-input multiple-output, MIMO) 무선 간섭 채널로 모델링할 수 있는데, 이러한 MISO 및 MIMO 간섭 채널에서의 협력 및 분산 통신 방법에 관해 진행된 최근의 주요 연구 결과들을 소개한다.