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Lowering Error Floor of LDPC Codes Using an Improved Parallel WBF Algorithm
Kexiang Ma,Yongzhao Li,Caizhi Zhu,Hailin Zhang,Yuming Zhang 한국전자통신연구원 2014 ETRI Journal Vol.36 No.1
In weighted bit-flipping-based algorithms for low-densityparity-check (LDPC) codes, due to the existence ofoverconfident incorrectly received bits, the metric values of thecorresponding bits will always be wrong in the decodingprocess. Since these bits cannot be flipped, decoding failureresults. To solve this problem, an improved parallel weightedbit flipping algorithm is proposed. Specifically, a reliabilitysaturationstrategy is adopted to increase the flippingprobability of the overconfident incorrectly received bits. Simulation results show that the error floor of LDPC codes isgreatly lowered.
On the Performance of Cyclic-Prefixed Single-Carrier Cellular Systems in Cochannel Interference
Kyeong Jin Kim,Yongzhao Li,Tsiftsis, T. A. IEEE 2011 IEEE Transactions on Vehicular Technology VT Vol.60 No.8
<P>In this paper, we study cyclic-prefixed single-carrier cellular systems in the presence of cochannel interference from neighboring cells. Performance analysis for the maximum achievable average rate and outage probability based on approximated distributions for the signal-to-interference-plus-noise ratio (SINR) is presented. An asymptotic diversity gain is also derived. Monte Carlo simulations verify the derived analytical expressions.</P>
Improved Genetic Algorithm based 3-D deployment of UAVs
Xiting Wen,Yuhan Ruan,Yongzhao Li,Hongxing Xia,Rui Zhang,Chao Wang,Wei Liu,Xiaoyu Jiang 한국통신학회 2022 Journal of communications and networks Vol.24 No.2
Unmanned aerial vehicles (UAVs) are widely usedas aerial base stations (BSs) to provide flexible connectivity andcoverage for ground users in various scenarios such as disasterrelief, traffic offloading, and so on. Especially, UAV deployment isan important issue that directly affects the coverage performanceof the UAV network. In this paper, we propose a novel heuristic algorithmbased three-dimensional (3-D) UAV deployment schemewhile guaranteeing the connectivity of the UAV network in bothstatic and dynamic user scenarios. For the static user scenario, weaim to deploy the minimum number of UAVs to provide coveragefor the users from the perspective of deployment cost. To reducethe deployment complexity, we decouple the 3-D UAV deploymentproblem from the vertical and horizontal dimensions. Specifically,we firstly determine the optimal vertical height of UAVs based onthe air-to-ground (A2G) model. Then, to alleviate the prematureconvergence of standard genetic algorithm (SGA), we designan improved genetic algorithm (IGA) to obtain the optimalhorizontal locations of UAVs. On this basis, when the users moveor increase, i.e., the dynamic user scenario, the already deployedUAVs cannot provide effective coverage. For this scenario, wepropose a UAV redeployment scheme to maximize the numberof covered users without increasing the number of UAVs. Tofurther reduce the cost of redeployment, we firstly modify theproposed IGA to obtain a feasible set of two-dimensional (2-D)redeployed locations of the UAVs. Then, we design a backtrackingalgorithm (BA) based UAV movement strategy to minimize thetotal flying distance of the UAVs. The simulation results showthat the effectiveness and convergence of our proposed schemes.
The Nrf2 antioxidant defense system in intervertebral disc degeneration: Molecular insights
Xiang Qian,Zhao Yongzhao,Lin Jialiang,Jiang Shuai,Li Weishi 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-
Intervertebral disc degeneration (IDD) is a common degenerative musculoskeletal disorder and is recognized as a major contributor to discogenic lower back pain. However, the molecular mechanisms underlying IDD remain unclear, and therapeutic strategies for IDD are currently limited. Oxidative stress plays pivotal roles in the pathogenesis and progression of many age-related diseases in humans, including IDD. Nuclear factor E2-related factor 2 (Nrf2) is a master antioxidant transcription factor that protects cells against oxidative stress damage. Nrf2 is negatively modulated by Kelch-like ECH-associated protein 1 (Keap1) and exerts important effects on IDD progression. Accumulating evidence has revealed that Nrf2 can facilitate the transcription of downstream antioxidant genes in disc cells by binding to antioxidant response elements (AREs) in promoter regions, including heme oxygenase-1 (HO-1), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and NADPH quinone dehydrogenase 1 (NQO1). The Nrf2 antioxidant defense system regulates cell apoptosis, senescence, extracellular matrix (ECM) metabolism, the inflammatory response of the nucleus pulposus (NP), and calcification of the cartilaginous endplates (EP) in IDD. In this review, we aim to discuss the current knowledge on the roles of Nrf2 in IDD systematically.
Lin Jialiang,Wang Longjie,Wu Yuhao,Xiang Qian,Zhao Yongzhao,Zheng Xuanqi,Jiang Shuai,Sun Zhuoran,Fan Dongwei,Li Weishi 생화학분자생물학회 2024 Experimental and molecular medicine Vol.56 No.-
Intervertebral disc degeneration (IDD) is an important pathological basis for degenerative spinal diseases and is involved in mitophagy dysfunction. However, the molecular mechanisms underlying mitophagy regulation in IDD remain unclear. This study aimed to clarify the role of DJ-1 in regulating mitophagy during IDD pathogenesis. Here, we showed that the mitochondrial localization of DJ-1 in nucleus pulposus cells (NPCs) first increased and then decreased in response to oxidative stress. Subsequently, loss- and gain-of-function experiments revealed that overexpression of DJ-1 in NPCs inhibited oxidative stress-induced mitochondrial dysfunction and mitochondria-dependent apoptosis, whereas knockdown of DJ-1 had the opposite effect. Mechanistically, mitochondrial translocation of DJ-1 promoted the recruitment of hexokinase 2 (HK2) to damaged mitochondria by activating Akt and subsequently Parkin-dependent mitophagy to inhibit oxidative stress-induced apoptosis in NPCs. However, silencing Parkin, reducing mitochondrial recruitment of HK2, or inhibiting Akt activation suppressed DJ-1-mediated mitophagy. Furthermore, overexpression of DJ-1 ameliorated IDD in rats through HK2-mediated mitophagy. Taken together, these findings indicate that DJ-1 promotes HK2-mediated mitophagy under oxidative stress conditions to inhibit mitochondria-dependent apoptosis in NPCs and could be a therapeutic target for IDD.