다중사용자 MIMO 하향링크 채널 환경에서 시스템 용량 향상을 위한 프리코딩 기법

김광윤,이종식,구성완,양재수,김진영 한국정보통신설비학회 2008 한국정보통신설비학회 학술대회 Vol.2008 No.1

In this paper, we study precoding techniques for co-channel interference suppression in multiuser MIMO systems. DPC is optimal techniques to achieve the system capacity of multiuser MIMO downlink channels. DPC is not proper in practical wireless systems because complexity is very high. So block diagonal precoding for multiuser MIMO downlink channel is studied. The block diagonal precoding is used to suppress co-channel interference between multiuser. Block diagonal precoding method, whose complexity is reduced by modified null space operation, change multiuser MIMO channel to multiple single-user MIMO channel. We also use V-BLAST decoder in receiver. V-BLAST decoder can achieve increased system capacity in proportion to the number of users. We show improved system performance by using computer simulation.

Differencing Multiuser Detection Using Error Feedback Filter for MIMO DS-UWB System in Nakagami Fading Channel

( Zhengmin Kong ),( Yanjun Fang ),( Yuxuan Zhang ),( Shixin Peng ),( Guangxi Zhu ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.10

A differencing multiuser detection (MUD) method is proposed for multiple-input multiple-output (MIMO) direct sequence (DS) ultra-wideband (UWB) system to cope with the multiple access interference (MAI) and the computational efficiency in Nakagami fading channel. The method, which combines a multiuser-interference-cancellation-based decision feedback equalizer using error feedback filter (MIC DFE-EFF), a coefficient optimization algorithm (COA) and a differencing algorithm (DA), is termed as MIC DFE-EFF (COA) with DA for short. In the paper, the proposed MUD method is illuminated from the rudimental MIC DFE-EFF to the advanced MIC DFE-EFF (COA) with DA step by step. Firstly, the MIC DFE-EFF system performance is analyzed by minimum mean square error criterion. Secondly, the COA is investigated for optimization of each filter coefficient. Finally, the DA is introduced to reduce the computational complexity while sacrificing little performance. Simulations show a significant performance gain can be achieved by using the MIC DFE-EFF (COA) with DA detector. The proposed MIC DFE-EFF (COA) with DA improves both bit error rate performance and computational efficiency relative to DFE, DFE-EFF, parallel interference cancellation (PIC), MIC DFE-EFF and MIC DFE-EFF with DA, though it sacrifices little system performance, compared with MIC DFE-EFF (COA) without DA.

현대 대중예술의 아리랑 수용양상

김동권(Kim, Dong-kwon) 숭실대학교 한국문학과예술연구소 2010 한국문학과 예술 Vol.6 No.-

아리랑이 대중적인 전파성이 있는 영화와 연극의 형태로 본격적으로 대중앞에 나타나기 시작한 것은 1926년 10월에 나운규의 무성영화 〈아리랑〉이후다. 이때부터 본격적으로 아리랑이 상징하는 이미지가 식민지를 살아가는 우리 민족의 정서를 표상하기 시작했고, 나아가 〈아리랑〉이 민요를 기반으로 하여 다양한 장르의 문학예술형태로 형상화되기 시작하였다. 대중 앞에 전파성이 강한 영화와 대중극의 형태로 나타난다. 1920년대 중반이후부터 1930년대 초반에 걸쳐 나타나는 〈아리랑〉이라는 이름을 가진, 영화와 극 양식 작품이 여러 편 있음이 이를 반증한다. 대중적 양식인 연극과 영화, 민요 등 다양한 장르 형태로 일제 식민지치하를 살아가는 민중, 특히 농민의 정서를 대변해 주었던 것이 〈아리랑〉이다. 아리랑은 형식적인 측면에서 보여주는 장르의 다양성뿐만 아니라 내용면에서 볼 때 그 자체가 지니는 상징적인 면모가 있다. 아리랑은 출발이 민요인 아리랑을 매개로 하고 있으면서, 이를 바탕으로 가극과 연극, 영화 등의 형태로 변형되어 문화콘텐츠의 정형을 보여주는 One Source Multiuser일 뿐만 아니라 내용면에서도 일제 식민지하의 핍박받는 민중의 삶을 대변하는 민족적 정서를 담아 적절하게 표출시켜 주고 있다. 이들 작품을 보면 나운규의 〈아리랑〉은 문화콘텐츠의 원류로서 One Source Multiuser임을 실증해 준다. 우리의 전래민요 〈아리랑〉이 영화 〈아리랑〉이 되고, 영화 〈아리랑〉이 성공하여 영화소설〈아리랑〉과 연극소설 〈아리랑〉이 되고, 다시 다양한 형태의 공연물인 연극〈아리랑〉으로 탄생하는 일련의 과정이 바로 문화콘텐츠의 원형인 것이다. 이들 작품을 대상으로 〈아리랑〉 작품 속에 나타나는 다양성과 이들 아리랑 작품이 지니는 상징성이 지니는 의미와 함께 시대적인 위상을 가늠해 볼 수 있다. 민족적인 삶의 정서를 담고 있는 아리랑은 나운규의 〈아리랑〉을 시작으로 시대와 지역적인 환경에 따라 다양한 양식의 장르 형태로 변화하고 발전하여 왔다. 이러한 사항은 해외로 이주한 동포에게도 나타나 연해주와 만주, 하와이 등으로 이주한 동포들에게도 〈아리랑〉은 일제 식민지시대에는 일제에 대한 저항과 함께 삶의 기반을 잃고 떠도는 민족적 정서를 표상하고 있다. 아리랑의 상징성과 의미는 현재까지 이어져서 분단된 상황과 통일에 대한 염원을 내포하는 상징적 매개체로써 다양한 형태와 형식으로 형상화되어 나타나고 있다. It is after Na, Un-kyu’s silent film version in Oct, 1926 that Arirang began to appear in film and theatre as artistic and popular media with strong influence on the public. Since then, the images derived from Arirang began to represent the emotions of the Korean people?especially the peasants?under Japanese occupation, and Arirang evolved into various artistic genres such as film and popular theatre, which were influential to people. From the mid-1920s to the early 1930s, many productions of film and play came out under the title of Arirang. Arirang has significance not only in terms of the variety of form but also in terms of its contents. Started as a folk song, Arirang was transformed into musical, play, and film. It became One Source Multiuser, which shows a model of Cultural Contents. As the case of Na, Un-kyu’s Arirangshowed, the process that the folk song became a film, and the success of the film caused a “cine-novel” Arirang, a “play-novel” Arirang, and other play productions titled Arirang was the very paradigm of Cultural Contents. Since Na, Un-kyu’s film, Arirang, with its national sentiments, has changed and developed into various forms in each different time and local environment. Arirangbecame the resisting spirit against Japan and a way to express feelings about the lives in exile for the Koreans in the foreign territories including Siberia, Manchuria, and Hawaii during Japanese occupation. The meaning of Arirangfor the Korean nation has been handed down until today. It is still a symbol that appears in various forms of media to express the pains from the separation of the nation and the wish for the nation’s reunification.

Multiuser Generalized Detector for Uniformly Quantized Synchronous CDMA Signals in Wireless Sensor Networks with Additive White Gaussian Noise

Vyacheslav Tuzlukov 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

We investigate the multiuser generalized detector, which is constructed based on the generalized approach to signal processing in noise [1]?5], for uniformly quantized synchronous code division multiple access (CDMA) signals in additive white Gaussian noise channels of wireless sensor networks and compare with minimum mean-square error (MMSE) multiuser receiver discussed in [6]. The input/output relationship of the quantizer is represented by the gain plus the additive noise model. Based on this model, we derive the weight vector and the output signal-to-interference ratio (SIR) of the multiuser generalized detector. The effects of quantization and sampling of the multiuser generalized detector performance is characterized in a single parameter named “quivalent noise variance”which is a function of the sum of each active user’ signal-to-noise ratio (SNR), processing gain, and the number of quantization and sampling levels. The optimal quantizer step size, which maximizes the multiuser generalized detector output SNR, is also determined. Simulation results validate the accuracy of our theoretical analysis and confirms a superiority of employment of the multiuser generalized detector over minimum mean-square error multiuser receiver, which is analyzed in [6].

Outage Probability Analysis of Multiuser MISO Systems Exploiting Joint Spatial Diversity and Multiuser Diversity with Outdated Feedback

( Chunjuan Diao ),( Wei Xu ),( Ming Chen ),( Bingyang Wu ) 한국인터넷정보학회 2011 KSII Transactions on Internet and Information Syst Vol.5 No.9

In this paper, the outage performance of multiuser multiple-input single-output (MISO) systems exploiting joint spatial and multiuser diversities is investigated for Rayleigh fading channels with outdated feedback. First, we derive closed-form exact outage probabilities for the joint diversity schemes that combine user scheduling with different spatial diversity techniques, including: 1) transmit maximum-ratio combining (TMRC); 2) transmit antenna selection (TAS); and 3) orthogonal space-time block coding (OSTBC). Then the asymptotic outage probabilities are analyzed to gain more insights into the effect of feedback delay. It is observed that with outdated feedback, the asymptotic diversity order of the multiuser OSTBC (M-OSTBC) scheme is equal to the number of transmit antennas at the base station, while that of the multiuser TMRC (M-TMRC) and the multiuser TAS (M-TAS) schemes reduce to one. Further by comparing the asymptotic outage probabilities, it is found that the M-TMRC scheme outperforms the M-TAS scheme, and the M-OSTBC scheme can perform best in the outage regime of practical interest when the feedback delay is large. Theoretical analysis is verified by simulation results.

Multiuser Generalized Detector for Uniformly Quantized Synchronous CDMA Signals in AWGN Channels

투즐루코프, 비아체스라프 에스케이텔레콤 (주) 2010 Telecommunications Review Vol.20 No.5

We investigate the multiuser Generalized Detector (GD) which is constructed based on the generalized app- roach to signal processing in noise for uniformly quantized synchronous Code Division Multiple Access (CDMA) signals in the Additive White Gaussian Noise (AWGN) channels of wireless communication system and compare it with the wellknown Minimum Mean-Square Error (MMSE) multiuser receiver with optimum quantizer. The input/output relationship of the quantizer is represented by the gain plus the additive noise mo- del. Based on this model, we derive the weight vector and the output Signal-to-Interference Ratio (SIR) of the multiuser GD. The effects of quantization and sampling of the multiuser GD performance is characterized in a single parameter named ''equivalent noise variance''which is a function of the sum of each active user's Sig- nal-to-Noise Ratio (SNR), processing gain, and the number of quantization and sampling levels. The optimal qu- antizer step size, which maximizes the multiuser GD output SNR, is also determined. Simulation results valida- te the accuracy of our theoretical analysis and confirm a superiority of employment of the multiuser GD in co- mparison with the MMSE multiuser receiver with optimum quantizer.

다중 안텐나 다중 사용자 하향 링크 환경에서 Regularized Channel Inversion 기법

이흔철,이인규,이광원 한국통신학회 2010 韓國通信學會論文誌 Vol.35 No.3

Channel inversion is one of the simplest techniques for multiuser downlink systems with single-antenna users. In this paper, we extend the regularized channel inversion technique developed for the single-antenna user case to multiuser multiple-input multiple-output (MIMO) channels with multiple-antenna users. We first employ the multiuser preprocessing to project the multiuser signals near the null space of the unintended users based on the MMSE criterion, and then the single-user preprocessing is applied to the decomposed MIMO interference channels. In order to reduce the complexity, we focus on non-iterative solutions for the multiuser transmit beamforming and use a linear receiver based on an MMSE criterion. Simulation results show that the proposed scheme outperforms existing joint iterative algorithms in most multiuser configurations. Channel inversion 선처리 방식은 하나의 안테나를 가진 다중 사용자 하향 링크 환경에서 사용할 수 있는 간단한 기술 중의 하나이다. 본 논문은 Regularized channel inversion 선처리 방식을 단일 안테나 사용자의 채널 환경에서 여러 안테나를 가진 사용자의 경우인 MIMO 채널로 확장한다. 먼저 다중 사용자의 신호들을 원하지 않는 사용자들의 영공간(null space) 근처에 MMSE 기준으로 투영시키는 다중 사용자 처리 기법을 적용한다. 그리고 난 후 분해 된 MIMO 간섭 채널에 단일 사용자 처리 기법을 처리하는 방식으로 진행 된다. 복잡도를 낮추기 위해 본 논문에서는 다중사용자 전송 빔 형성의 비반복적 해법에 초점을 맞추고, MMSE 기준을 기반으로한 선형 수신 필터를 사용하였다. 실험 결과는 제안한 기법이 기존의 공동 반복적 알고리즘 보다 다양한 환경에서 우수한 성능을 나타냄을 보여준다.

Spatial Multiuser Access for Reverse Link of Multiuser MIMO Systems

Oh-Soon Shin(신오순) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.10A

Spatial multiuser access is investigated for the reverse link of multiuser multiple-input multiple-output (MIMO) systems. In particular, we consider two alternative approaches to spatial multiuser access that adopt the same detection algorithm at the base station: one is a closed-loop approach based on singular value decomposition (SVD) of the channel matrix, whereas the other is an open-loop approach based on space-time block coding (STBC). We develop multiuser detection algorithms for these two spatial multiuser access schemes based on the minimum mean square error (MMSE) criterion. Then, we compare the bit error rate (BER) performance of the two schemes and a single-user MIMO scheme. Interestingly, it is found that the STBC approach can provide much better BER performance than the SVD approach as well as than a single-user MIMO scheme.

Spatial Multiuser Access for Reverse Link of Multiuser MIMO Systems

신오순,Shin, Oh-Soon The Korea Institute of Information and Commucation 2008 韓國通信學會論文誌 Vol.33 No.10A

Spatial multiuser access is investigated for the reverse link of multiuser multiple-input multiple-output (MIMO) systems. In particular, we consider two alternative a aches to spatial multiuser access that adopt the same detection algorithm at the base station: one is a closed-loop approach based on singular value decomposition (SVD) of the channel matrix, whereas the other is an open-loop approach based in space-time block coding (STBC). We develop multiuser detection algorithms for these two spatial multiuser access schemes based on the minimum mean square error (MMSE) criterion. Then, we compare the bit error rate (BER) performance of the two schemes and a single-user MIMO scheme. Interestingly, it is found that the STBC approach can provide much better BER performance than the SVD approach as well as than a single-user MIMO scheme.

Spatial Multiuser Access for Reverse Link of Multiuser MIMO Systems

신오순 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.10

Spatial multiuser access is investigated for the reverse link of multiuser multiple-input multiple-output (MIMO) systems. In particular, we consider two alternative approaches to spatial multiuser access that adopt the same detection algorithm at the base station: one is a closed-loop approach based on singular value decomposition (SVD) of the channel matrix, whereas the other is an open-loop approach based on space-time block coding (STBC). We develop multiuser detection algorithms for these two spatial multiuser access schemes based on the minimum mean square error (MMSE) criterion. Then, we compare the bit error rate (BER) performance of the two schemes and a single-user MIMO scheme. Interestingly, it is found that the STBC approach can provide much better BER performance than the SVD approach as well as than a single-user MIMO scheme.