Lattice reduction with fast convergence algorithm and its application to the detection in temporally and spatially-correlated MIMO channel

안찬호 Graduate School Yonsei University 2008 국내석사

This thesis proposes a modified LLL algorithm, which named fast convergence algorithm (FC), in lattice reduction (LR) aided detection which provides advantage of the convergence time compared to conventional LLL reduction algorithm. Generally, LLL algorithm transforms MIMO channel, regarded as basis vector, into orthogonal-like one by using iterative basis reduction which is mainly classified into three functional processes: a Gram-Schmidt orthogonalization, a size-reduction, and a basis swapping. The proposed FC algorithm uses the swapping condition that the all of size reduced basis vectors are sorted out in the descending order of their basis vectors at once while conventional LLL algorithm swap only adjacent basis vectors per one-iteration. Since the same time complexity per iteration is applied for both two algorithms, the convergence time depends on the number of iteration needed. Therefore the convergence time to terminate the algorithm can be decreased by iteration number differences between two algorithms. Moreover, this proposed FC algorithm also provides the shorter resultant basis vectors. Results for these properties are developed, and illustrated by analytical and numerical analyses.In addition, three different schemes to reduce the complexity of LR in specific condition are proposed in this thesis: One is sorted basis reduction method, second is consecutive lattice reduction (CLR), and third is pre-lattice reduction (PLR). First sorting out basis vectors at the initial point helps LR algorithm (whether LLL or FC) to achieve the reduced basis vectors with reduced number of iterations. Secondly, time-correlated nature of the channel can be used in reducing the iteration complexity of doing LR by taking advantage of the information of LR results in the previous symbol time. Finally, PLR applied in spatially correlated channel reduces the number of iteration of LR by pre-multiplying the channel matrix by transformation matrix which reduces the square root of the transmitter correlation matrix. These schemes may provide a better stating point for the lattice reduction algorithm.Simulation result shows that the proposed FC algorithm has fast convergence time and three different schemes have low computational efforts due to small number of iteration taken, which leads to fast convergence and reduced complexity for specific condition. 차세대 통신 시스템에서 요구되는 멀티미디어 서비스 기술의 급속한 확대와 더불어 고품질의 데이터를 고속으로 전송하기 위한 기술로 MIMO 시스템에 대한 많은 연구가 진행 되고 있다. 그러나 MIMO 시스템은 전송된 신호들 사이의 간섭으로 인해 데이터 검출에 어려움이 있다. 최대우도 (ML) 검출 기법은 최적의 성능을 갖지만, 안테나의 수가 증가하거나 변조 차수 (modulation order) 가 증가할수록 복잡도가 기하급수적으로 증가한다는 문제로 인해 실제 시스템에서의 적용에 한계가 존재한다. 또한 ZF과 MMSE와 같은 선형 검출 기법은 낮은 복잡도를 갖지만, ML 검출로 얻을 수 있는 다이버시티 차수 (diversity order)를 잃게 되어 성능의 저하가 발생한다. 최근 LR (Lattice Reduction)을 이용한 선형 검출 기법이 선형 검출 기법과 유사한 복잡도에 ML과 동일한 다이버시티 차수를 제공하는 것이 기존의 많은 연구에서 알려졌다.기존의 대부분의 연구는 채널이 느리게 변하여 일정 심볼시간 (symbol time) 또는 프레임 동안 채널이 변하지 않는 블록 페이딩 채널 (Block fading channel)만을 고려하였다. 그러나 채널 환경이 시간에 대해 빠르게 변하는 상황이라면, 채널의 변화에 따라 계속적으로 LR을 수행해야 하며 이는 시스템 복잡도의 증가를 가져온다. 또한 이는 선형 검출 기법과 유사한 복잡도를 갖는다는 기존의 가정에도 위배된다. 따라서 이러한 채널 환경에서 LR을 이용한 선형 검출 기법이 효과적이기 위해서는 기존의 복잡도를 줄일 수 있는 방법이 필요하다.본 논문은 새로운 LR 알고리즘을 제안하는 것과 시간과 공간 상관이 있는 채널에서 복잡도를 줄일 수 있는 기법의 두 가지 관점에서 연구를 수행하였다. 첫째 FC (Fast Convergence)라고 명명된 LLL의 변형 알고리즘은 기존의 LR 방법으로 가장 많이 사용되는 LLL (Lenstra, Lenstra, and Lovász) 방법을 변형하여 LR을 고속으로 수행하기 위해 제안되었다. LLL 알고리즘은 기저 벡터의 교환 또는 정렬이 없을 때까지 미리 정의된 형태의 순서대로 LR을 반복적으로 수행한다. FC 알고리즘은 LLL 알고리즘의 기저 벡터 교환 조건을 정렬할 수 있는 조건으로 변형하여 반복횟수 (iteration)를 75% 정도 줄여 LR을 빠르게 수행하고, LR을 수행한 기저 벡터의 길이 (Euclidian norm)도 일정 조건에서 LLL보다 더 짧아지는 것을 보였다. 또한 미리 입력 기저 벡터들을 길이 (Euclidian norm) 순서대로 정렬한 후 LR을 수행하여 80% 정도 반복횟수를 줄이는 결과를 보였다. 여기에 FC 알고리즘의 수렴성 (convergence)과 LR을 수한 기저 벡터들의 특성에 대해 LLL과 비교, 분석하여 보다 길이가 짧고 직교성을 띄는 것을 증명하였다.둘째, 본 논문은 시간 또는 공간 상관이 있는 채널에서 복잡도를 줄일 수 있는 방법에 대해서 제안하였다. 시간 상관이 있는 채널에서는 이전 심볼시간에서 수행한 LR의 unimodular 변형 행렬을 현재의 채널에 곱하여 LR을 수행하는 CLR (consecutive lattice reduction) 기법을 사용하여 복잡도를 줄일 수 있다. CLR 기법은 고속의 상황에서도 LLL과 FC 알고리즘에서 각각 65%, 40%의 복잡도를 줄이는 결과를 보였다. 기존의 LLL과 비교하여 미리 정렬된 CLR을 사용할 경우 90% 가량 복잡도를 줄이는 것을 확인 할 수도 있었다.마지막으로 채널의 공간 상관이 있을 때의 복잡도를 줄일 수 있는 PLR (pre-lattice reduction) 기법을 제안하였다. 공간 상관이 있는 경우 채널이 불량조건 (ill-condition)이 되어 LR의 반복횟수를 증가시키게 된다. 따라서 송신 상관 (transmitter correlation)을 알고 있을 때, 송신 상관에 대해 미리 LR을 수행하고 여기서 얻어지는 unimodular 변형 행렬을 채널에 미리 곱하여 LR의 복잡도를 줄여줄 수 있다. 송신 상관과 수신 상관 (receiver correlation)이 모두 있는 경우LLL은 15%, FC는 10% 정도의 복잡도 감소를 보였고, 송신 상관만 있는 경우 LLL은 30%, FC는 15% 정도의 복잡도 감소를 확인 할 수 있었다.본 연구는 기존의 LLL 알고리즘과 동일한 검출 성능을 가지면서 복잡도를 획기적으로 줄일 수 있는 알고리즘과 기법을 제안하였다. 제안한 알고리즘과 기법은 시간에 대해 빠르게 변하는 채널 환경에서도 LR을 효율적으로 적용할 수 있도록 해준다.

강황추출물이 Diethylnitrosamine과 CCl4로 유발된 흰쥐의 간암과 간 손상에 미치는 영향

정태산 동신대학교 대학원 2013 국내박사

In order to investigate the effect of CLR extract on the Hepatocellular carcinogenesis and acute liver damage induced by DENA and CCl4 in Rats. Experimental groups were subdivided into four; normal group (Nor), acute liver damage and hepatocellular cancer inducing control group (Con), and CLR extract 200㎎/㎏/day (CAA) or 400㎎/㎏/day (CAB) administered groups to Con. Thereafter the changes of the body weight, the liver weight and the weight of liver/100g body weight, Total cholesterol, HDL cholesterol, Triglyceride, the activities of AST, ALT, ALP, LDH, AFP, SOD, Catalase were measured. And we observed by optical and electron microscopy. The results were as follows, 1. The body weight was decreased in Con compared with Nor for 5 weeks, but increased in Con compared with Nor from 6 week to 9 week. During experimental period of total 9 weeks, CAA and CAB were increased compared with Con. 2. The liver weight was increased significantly (p<0.05) in Con compared with Nor. The weight of liver/100g body weight was increased significantly (p<0.05) in Con compared with Nor and decreased significantly (p<0.05) in CAB compared with Con. 3. The level of Total cholesterol was increased in Con and CAA compared with Nor, but there was not statistically significant. The level of Triglyceride was decreased in Con compared with Nor. But increased in CAA and CAB compared with Con. The level of HDL-cholesterol was significantly increased (p<0.05) in CAA and CAB compared with Con. 4. The activities of AST, ALT were increased in Con compared with Nor, but decreased in CAA compared with Con, significantly decreased (p<0.05) in CAB compared with Con. 5. The activities of ALP, LDH were increased in Con compared with Nor, but decreased in CAA and CAB compared with Con. 6. The activities of AFP was increased significantly (p<0.05) in Con compared with Nor, but decreased significantly (p<0.05) in CAA and CAB compared with Con. 7. The activities of SOD were increased in Con, CAA and CAB compared with Nor, but decreased in CAA and CAB compared with Con. The activities of Catalase was more increased in CAA and CAB compared than Con. 8. The results of light microscopical observation, a number of hepatocytes were damaged in Con compared with Nor and CAB. 9. According to the electron microscopical observation, irregular nuclear membrane, condensed nucleoplasm was observed in Con, the experimental group was observed in the nucleus of the well-preserved and evenly developed nucleoplasm. These results suggest that administration of CLR extract suppress or retard on the Hepatocellular carcinogenesis and acute liver damage induced by DENA and CCl4 in rats.

Identification of Adaptive Signatures in the Cattle Genome

테레페 서울대학교 대학원 2018 국내박사

Cattle are one of the most common and numerous domestic ungulates. The genomes of domes¬ticated cattle breeds harbor the history of domestication and breed for¬mation due to the combined effect of natural and artificial selection forces. Deciphering the footprints of these selection forces in the genome of cattle breeds is of great interest from the perspective of evolutionary biology seeking to understand the key adaptive features that have generated enormous morphological and production phenotypic variations currently observed within and between populations. Recently, professionals from molecular popu¬lation and evolu¬tionary genetics have shown growing interest in distinguishing neutral molecular vari¬ations from variations that are subject to selection, particularly positive selection, in the genomes of multiple organisms including cattle. The building of the bovine reference genome and the accumulation of single nucleotide polymorphism (SNP) data from geo¬graphically and biologically diverse cattle breeds – due to the emergence of low cost and high throughput Next Generation Sequencing (NGS) technologies – has created unprecedented opportunities and facilitated efforts to uncover and understand this variation. In this doctoral dissertation, the whole genome NGS SNP data from African, N’Dama, Ankole, Holstein, Hanwoo, and Angus cattle breeds were used to elucidate the footprints of natural and artificial selection forces that have contributed to the major phenotypes of the respective breeds. The cross-population extended haplotype homozygosity (XP-EHH) and cross-population composite likelihood ratio (XP-CLR) statistical methods were used to search for the genes/gene regions affected due to selection. The reference genome of cattle (UMD3.1) was used to annotate genes in outlier regions under selection from these analyses. I used the Database for Annotation, Visualization, and Integrated Discovery (DAVID) gene ontology and annotation tool for gene enrichment analysis to understand the biological functions and pathways of genes iden¬tified under selection. In Chapter 1, I introduced the variations in cattle breeds with special emphasis to African cattle breeds, the principles behind signature of positive selection, and the objectives and methods of identification of signature of positive selection. In addition, previously reported results of studies on selection signatures from genetically diverse cattle breeds were reviewed. In Chapter 2, the genome of African cattle breeds was compared with the genome of Commercial Asian-European taurine cattle breeds to reveal genomic regions under selection in African cattle in relation to tropical environment adaptation traits. African cattle breeds have evolved in a hot tropical climate for millennia, which helped them to develop an inherent superior thermotolerance ability. The study revealed several genes/gene regions under selection that are overrepresented in different biological process (BP) terms and pathways in a gene enrichment analysis. In relation to heat stress response, “angiogenesis” and “regeneration” BP terms were enriched. Moreover, several selected genes were involved in anatomical structures, and physi¬ological and/or molecular functions that are associated with heat tolerance mecha¬nisms. These genes are involved in oxidative stress response, osmotic stress response, heat shock response, hair and skin properties, sweat gland devel¬opment and sweating, feed intake and metabolism, and reproduction functions. Therefore, the genes and BP terms identified here directly and/or indirectly con¬tribute to the superior heat tolerance mechanisms of African cattle populations. The high tropical temperature where these cattle breeds have evolved for millennia could be a selec¬tive pressure for the develop¬ment of these thermotolerance mechanisms. In Chapter 3, the genomes of Holstein, Hanwoo, and N’Dama cattle breeds were explored in order to decipher genomic regions affected due to divergent selection for milk traits, meat production and quality traits, and environ¬mental adaptation traits, respectively. Artificial and natural selection for a particular trait in cattle have signif¬icantly modified the cattle genome. Due to this, several cattle breeds have been developed with a mosaic of morphological, productivity, and environmental adapta¬tion characteristics. Holstein cattle are evolved as dairy cattle and Hanwoo cattle are evolved as beef cattle under artificial selection, whereas N’Dama cattle are evolved as a general-purpose breed – a breed that does not artificially selected for a particular purpose under natural selection. Identifying genomic regions affected due to artificial and natural selection forces in cattle would give an insight into the history of selection for economically important traits and genetic adaptation to specific environments of populations under consideration. From this study, genes/gene regions that are related to milk traits (e.g., CSN3, PAPPA2, and ADIPOQ), meat production and quality traits (e.g., NCOA2, and PITPN3), and environmental adaptation traits (e.g., SLC40A1, STOM, and COMMD1) were found under positive selection from the genomes of Holstein, Hanwoo and N’Dama cattle breeds, respectively. Moreover, significant functional annotation cluster terms including milk protein and thyroid hormone signaling pathway, histone acetyl-trans¬ferase activity, and renin secretion were enriched from gene lists identified under selec¬tion in Holstein, Hanwoo, and N’Dama cattle breeds, respectively. In Chapter 4, the genome of Ankole cattle (African Sanga cattle) was explored in order to identify genes and genomic regions under positive selection in relation to meat quality traits. African Sanga cattle are an intermediate type of cattle resulting from interbreeding between B. taurus and B. indicus sub-species. Recently, experi¬mental evidence on the po¬tential of African Sanga cattle breeds for superior beef quality traits over their indicine coun¬terparts has emerged. In this study, the whole genome SNP data of Ankole (Sanga cattle) was compared with the genome of indicine cattle breeds using XP-EHH and XP-CLR statistical methods. As a result, several genes including those affecting beef quality traits such as tenderness, intramuscular fat (IMF) content, and meat color were found under posi¬tive selection. The genes identified are involved in BP terms and KEGG pathways that affect muscle structure and metabolism, adipose metabolism, and adipogenesis – which in turn affects meat quality traits. This study asserted that Ankole cattle have the potential for higher meat production and quality traits under the prevailing tropical environmental conditions. These results provide a basis for further re-search on the genomic characteristics of Ankole and other Sanga cattle breeds for better quality beef in tropical Africa. In Chapter 5, the genetic blueprint behind the superior beef quality characteristics and other associated phenotypes of Angus cattle were elucidated. Angus cattle have been inten¬sively selected for superior beef quality characteristics for decades. Anno¬tating genomic re¬gions under selection in the genomes of Angus cattle resulted in several genes including those associated with beef quality traits and coat color. In addition, putative genes that po-tentially cause genetic disorders in Angus cattle were identified. The results from this study will help to further improve Angus cattle beef quality, and take a precaution on the associated genetic disorders which ultimately reduce production and productivity. In conclusion, from these studies, a catalog of genes were identified under positive selection from African, N’Dama, Ankole, Holstein, Hanwoo, and Angus cattle breeds in relation to the major economic and adaptation traits of the respective breeds to which they have been selected for. The findings in this dissertation will help us to better understand the adaptive events that have generated the enormous phenotypic variation observed between cattle breeds prevailing today. Molecular markers that contribute to local environmental adaptations (e.g., thermotolerance mechanisms - markers that are difficult to identify with other laboratory experimental methods) were revealed in addition to those affecting production traits such as milk production and quality, beef production and quality, reproduction and other associated traits. The markers identified in these studies help to understand the genetic merit of the breeds and can be used in genomic selection and breeding programs to further improve the respective breeds.

Decreased urinary secretion of belotecan in folic acid-induced acute renal failure rats due to down-regulation of Oat1 and Bcrp

Jin, Qingri 서울大學校 大學院 2009 국내박사