• 한국통신학회논문지
• /
• 제32권2A호
• /
• pp.162-168
• /
• 2007

This paper proposes two detection algorithms for Multi-user Space Time Block Code systems. The first one is linear detection Gaussian Elimination algorithm, and then it combined with Ordered Successive Cancellation to get better performance. The comparisons between receiver and other popular receivers, including linear receivers are provided. It will be shown that the performance of Gaussian Elimination receiver is similar but more simplicity than linear detection algorithms and performance of Gaussian Elimination Ordered Successive Cancellation superior as compared to other linear detection method.

• ETRI Journal
• /
• 제37권2호
• /
• pp.338-347
• /
• 2015

The multi-carrier transmission signal in Multi-Carrier Code Division Multiple Access (MC-CDMA) has a high peak-to-average power ratio (PAPR), which results in nonlinear distortion and deteriorative system performance. An n-tuple selective mapping method is proposed to reduce the PAPR, in this paper. This method generates $2^n$ sequences of an original data sequence by adding n-tuple of n PAPR control bits to it followed by an interleaver and error-control code (ECC) to reduce its PAPR. The convolutional, Golay, and Hamming codes are used as ECCs in the proposed scheme. The proposed method uses different numbers of the n PAPR control bits to accomplish a noteworthy PAPR reduction and also avoids the need for a side-information transmission. The simulation results authenticate the effectiveness of the proposed method.

• 대한전자공학회논문지TC
• /
• 제39권9호
• /
• pp.20-27
• /
• 2002

무선 통신망에서의 멀티미디어 전송에 대한 요구는 빠른 속도로 증가하고 있다. 지금까지 CDMA에서의 시스템 분석은 패킷의 재전송을 위한 버퍼가 없는 음성을 위주로 이루어져 왔으나 본 논문에서는 버퍼링과 재전송을 고려한 다양한 QoS 요구조건을 만족할 수 있는 멀티미디어 접속 프로토콜을 제안하고 분석하였다. 먼저 다양한 전송률을 사용할 수 있는 MC-CDMA(Multi-Code CDMA) 전송방식 위에서 버퍼링의 영향을 살펴 보고 다양한 조건에서의 동적 전송률 제어 방식을 제안하고 시뮬레이션을 통해 제시한 방법의 타당성을 검증하였다.

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 1996년도 학술대회
• /
• pp.33-38
• /
• 1996

A multi-media binary DS/CDMA system with variable processing gain and coherent correlation receivers are considered under additive white Gaussian noise channels. Two types of information sources with different rates and transmitting powers are assumed to be transmitted simultaneously in the same channel. Average signal-to-noise ratios at the correlation receiver outputs for each type of information sources are analytically derived as functions of discrete partial cross-correlations between spreading code sequences. The analysis is expected to provide analytical tools for use in preliminary system design and spreading code selection.

• Nuclear Engineering and Technology
• /
• 제37권5호
• /
• pp.469-478
• /
• 2005

The subchannel analysis capability of MARS, a multi-dimensional thermal-hydraulic system code, has been enhanced. In particular, the turbulent mixing and void drift models for the flow-mixing phenomena in rod bundles were improved. Then, the subchannel analysis feature was combined with the existing coupled system thermal-hydraulics (T/H) and 3D reactor kinetics calculation capability of MARS. These features allow for more realistic simulations of both the hot channel behavior and the global system T/H behavior. Using the coupled features of MARS, a coupled analysis of a main steam line break (MSLB) is carried out for demonstration purposes. The results of the calculations are very reasonable and promising.

• Journal of Astronomy and Space Sciences
• /
• 제15권2호
• /
• pp.341-358
• /
• 1998

천문대 X-선 연구팀에서는 검출기 내부잡음을 줄이기 위해, 반-동시 계수법을 채택하는 다중 셀 비례계수를 개발할 예정이다. 이러한 계수기의 X-선 검출효율 결정을 위해, 몬테카를로 법을 이용하는 수치모의실험 프로그램을 개발하였다. 이 프로그램을 이용하여 Ginga/LAC의 검출효율을 재현할 수 있었고, 그럼으로 해서 수치모의 실험 방법에 대한 검증을 할 수 있었다. 이 논문에서는 천문대에서 고려하고 있는 비례계수기에 대한 수치모의실험 결과들을 보고한다.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제12권1호
• /
• pp.24-33
• /
• 2012

This paper describes a multi-mode LDPC decoder which supports 19 block lengths and 6 code rates of Quasi-Cyclic LDPC code for Mobile WiMAX system. To achieve an efficient implementation of 114 operation modes, some design optimizations are considered including block-serial layered decoding scheme, a memory reduction technique based on the min-sum decoding algorithm and a novel method for generating the cyclic shift values of parity check matrix. From fixed-point simulations, decoding performance and optimal hardware parameters are analyzed. The designed LDPC decoder is verified by FPGA implementation, and synthesized with a $0.18-{\mu}m$ CMOS cell library. It has 380,000 gates and 52,992 bits RAM, and the estimated throughput is about 164 ~ 222 Mbps at 56 MHz@1.8 V.

• 한국정보통신학회논문지
• /
• 제6권2호
• /
• pp.141-150
• /
• 2002

본 논문에서는 주파수 도약 시퀀스를 사용하는 직교 멀티캐리어 FH/CDMA 시스템을 구성해 보고 지연된 다른 사용자 신호들에 의한 충돌 발생 가능성을 사용자 접속 캐리어 슬롯 수에 따라 변화시켜 가면서 성능 저하에 큰 영향을 미치지 않는 최적의 사용자 접속 캐리어 슬롯 수를 찾아보았다. 아울러 시스템의 TCM과 Concatenated code 기법을 적용하여 BER 성능 개선 정도를 컴퓨터 시뮬레이션을 통해 평가하였다.

• 한국통신학회논문지
• /
• 제33권4A호
• /
• pp.426-433
• /
• 2008

In this paper, we present a method to improve the performance of the four transmit antenna quasi-orthogonal space-time block code (STBC) in the coded system. For the four transmit antenna case, the quasi-orthogonal STBC consists of two symbol groups which are orthogonal to each other, but intra group symbols are not. In uncoded system with the matched filter detection, constellation rotation can improve the performance. However, in coded systems, its gain is absorbed by the coding gain especially for lower rate code. We propose an iterative decoding method to improve the performance of quasi-orthogonal codes in coded systems. With conventional quasi-orthogonal STBC detection, the joint ML detection can be improved by iterative processing between the demapper and the decoder. Simulation results shows that the performance improvement is about 2dB at 1% frame error rate.

• 한국전산유체공학회지
• /
• 제18권2호
• /
• pp.99-108
• /
• 2013

The standard drag force and virtual mass force, which exert to the primary flow direction, are generally considered in two-phase analysis computational codes. In this paper, the lift force, wall lubrication force, and turbulent dispersion force including turbulence models, which are essential for a computational multi-fluid dynamics model and play an important role in motion perpendicular to the primary flow direction, were introduced and verified with conceptual problems.