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Self-attention reinforcement learning for multi-beam combining in mmW ave 3D-MIMO systems

Science China(Information Sciences) 2023年第6期66卷 204-221页

作者： Yingzhi HUANG Zhaoyang ZHANG Jingze CHE Zhaohui YANG Qianqian YANG kai-kit wong College of Information Science and Electronic Engineering Zhejiang University Department of Electronic and Electrical Engineering University College London

Machine learning(ML)has been empowering all aspects of the wireless communication system design, among which, the reinforcement learning(RL)-based approaches have attracted a lot of research attention since they can interact with the environment directly and learn from the collected experiences efficiently. In this paper, we propose a novel and efficient RL-based multi-beam combining scheme for future millimeter-wave(mmWave)three-dimensional(3D)multi-input multi-output(MIMO)communication systems. The proposed scheme does not require perfect channel state information(CSI)or precise user location information which both are generally difficult to obtain in practice, and well addresses the crucial challenge of computational complexity incurred by the extremely huge state and action spaces associated with multiple users, multiple paths, and multiple 3D beams. In particular, a self-attention deep deterministic policy gradient(DDPG)-based beam selection and combination framework is proposed to learn the 3D beamforming pattern without CSI adaptively. We aim to maximize the sum-rate of the mmWave 3D-MIMO system by optimizing the serving beam set and the corresponding combining weights for each user. To this end, the transformer is incorporated into the DDPG to obtain the global information of the input elements and capture the signal directions precisely, which leads to a near-optimal beamformer design. Simulation results verify the superiority of the proposed self-attention DDPG over conventional ML-based beamforming schemes in terms of sum-rate under various scenarios.

关键词： reinforcement learning (RL) deep deterministic policy gradient (DDPG) self-attention precoding/combining millimeter-wave (mmWave) multi-input multi-output (MIMO)

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Federated Learning for 6G:Applications,Challenges,and Opportunities

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Engineering 2022年第1期8卷 33-41页

作者： Zhaohui Yang Mingzhe Chen kai-kit wong H.Vincent Poor Shuguang Cui Department of Electronic and Electrical Engineering University College LondonLondon WC1E 6BTUK Department of Electrical and Computer Engineering Princeton UniversityPrincetonNJ 08544USA Shenzhen Research Institute of Big Data The Chinese University of Hong KongShenzhen 518172China School of Science and Engineering and Future Network of Intelligence Institute The Chinese University of Hong KongShenzhen 518172China

Standard machine-learning approaches involve the centralization of training data in a data center,where centralized machine-learning algorithms can be applied for data analysis and inference.However,due to privacy restrictions and limited communication resources in wireless networks,it is often undesirable or impractical for the devices to transmit data to parameter sever.One approach to mitigate these problems is federated learning(FL),which enables the devices to train a common machine learning model without data sharing and transmission.This paper provides a comprehensive overview of FL applications for envisioned sixth generation(6G)wireless networks.In particular,the essential requirements for applying FL to wireless communications are first described.Then potential FL applications in wireless communications are detailed.The main problems and challenges associated with such applications are discussed.Finally,a comprehensive FL implementation for wireless communications is described.

关键词： Federated learning 6G Reconfigurable intelligent surface Semantic communication Sensing Communication and computing

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User cooperation for IRS-aided secure MIMO systems

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Intelligent and Converged Networks 2022年第1期3卷 86-102页

作者： Gui Zhou Cunhua Pan Hong Ren Kezhi Wang Kok Keong Chai kai-kit wong School of Electronic Engineering and Computer Science Queen Mary University of LondonLondonE14NSUK. the National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China. Department of Computer and Information Sciences Northumbria UniversityNewcastle upon TyneNE18STUK. Department of Electronic and Electrical Engineering University College LondonLondonWC1E 6BTUK.

An intelligent reflecting surface(IRS)is proposed to enhance the physical layer security in the Rician fading channel wherein the angular direction of the eavesdropper(ED)is aligned with a legitimate user.A two-phase communication system under active attacks and passive eavesdropping is considered in this scenario.The base station avoids direct transmission to the attacked user in the first phase,whereas other users cooperate in forwarding signals to the attacked user in the second phase,with the help of IRS and energy harvesting technology.Under the occurrence of active attacks,an outage-constrained beamforming design problem is investigated under the statistical cascaded channel error model,which is solved by using the Bernstein-type inequality.An average secrecy rate maximization problem for the passive eavesdropping is formulated,which is then addressed by a low-complexity algorithm.The numerical results of this study reveal that the negative effect of the ED’s channel error is larger than that of the legitimate user.

关键词： intelligent reflecting surface(IRS) reconfigurable intelligent surface(RIS) robust design energy harvesting physical layer security

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NOMA-Based UAV-Aided Networks for Emergency Communications

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China Communications 2020年第11期17卷 54-66页

作者： Wanmei Feng Jie Tang Nan Zhao Yuli Fu Xiuyin Zhang Kanapathippillai Cumanan kai-kit wong South China University of Technology Guangzhou 510000China Dalian University of Technology Dalian 116000China University of York York YO105DDU.K University College London London WC1E 6BTU.K

High spectrum efficiency(SE)requirement and massive connections are the main challenges for the fifth generation(5G)and beyond 5G(B5G)wireless networks,especially for the case when Internet of Things(IoT)devices are located in a disaster area.Non-orthogonal multiple access(NOMA)-based unmanned aerial vehicle(UAV)-aided network is emerging as a promising technique to overcome the above challenges.In this paper,an emergency communications framework of NOMA-based UAV-aided networks is established,where the disasters scenarios can be divided into three broad categories that have named emergency areas,wide areas and dense areas.First,a UAV-enabled uplink NOMA system is established to gather information from IoT devices in emergency areas.Then,a joint UAV deployment and resource allocation scheme for a multi-UAV enabled NOMA system is developed to extend the UAV coverage for IoT devices in wide areas.Furthermore,a UAV equipped with an antenna array has been considered to provide wireless service for multiple devices that are densely distributed in disaster areas.Simulation results are provided to validate the effectiveness of the above three schemes.Finally,potential research directions and challenges are also highlighted and discussed.

关键词： emergency communications non-orthogonal multiple access(NOMA) Internet of Things(IoT) trajectory optimization unmanned aerial vehicle(UAV)

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Coverage probability of cellular networks using interference alignment under imperfect CSI

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Digital Communications and Networks 2016年第4期2卷 162-166页

作者： Raoul F. Guiazon kai-kit wong Michael Fitch Department of Electronic and Electrical Engineering University College London WCIE 7JE UK BTMobility Group Martlesham Heath Suffolk IP5 3RE UK

Interference alignment (IA) is well understood to approach the capacity of interference channels, and believed to be crucial in cellular networks in which the ability to control and exploit interference is key. However, the achievable performance of IA in cellular networks depends on the quality of channel state information (CSI) and how effective IA is in practical settings is not known. This paper studies the use of IA to mitigate inter-cell interference of cellular networks under imperfect CSI conditions. Our analysis is based on stochastic geometry where the structure of the base station (BS) locations is considered by a Poisson point process (PPP). Our main contribution is the coverage probability of the network and simulation results confirm the accuracy.

关键词： Interference alignment Beamforming Coverage probability Channel errors Stochastic geometry

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A Forward-Looking Nash Game and Its Application to Achieving Pareto-Efficient Optimization

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Applied Mathematics 2013年第12期4卷 1609-1615页

作者： Jie Ren kai-kit wong Jianjun Hou Department of Electronic and Electrical Engineering University College London Torrington Place London UK School of Electronics and Information Engineering Beijing Jiaotong University Beijing China

Recognizing the fact that a player’s cognition plays a defining role in the resulting equilibrium of a game of competition, this paper provides the foundation for a Nash game with forward-looking players by presenting a formal definition of the Nash game with consideration of the players’ belief. We use a simple two-firm model to demonstrate its fundamental difference from the standard Nash and Stackelberg games. Then we show that the players’ belief functions can be regarded as the optimization parameters for directing the game towards a much more desirable equilibrium.

关键词： Belief Cognition Iterative Algorithm Nash Equilibrium Pareto-Optimality Stackelberg

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Feasibility and safety of minimally invasive multivisceral resection for T4b rectal cancer:A 9-year review

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World Journal of Gastrointestinal Surgery 2024年第3期16卷 777-789页

作者： kai Siang Chan Biquan Liu Ming Ngan Aloysius Tan Kwang Yeong How Kar Yong wong Department of General Surgery Tan Tock Seng HospitalSingapore 308433Singapore

BACKGROUND Colorectal cancer is the third most common cancer and the second highest cause of cancer-related mortality worldwide.About 5%-10%of patients are diagnosed with locally advanced rectal cancer(LARC)on presentation.For LARC invading into other structures(i.e.T4b),multivisceral resection(MVR)and/or pelvic ex-enteration(PE)remains the only potential curative surgical treatment.MVR and/or PE is a major and complex surgery with high post-operative morbidity.Minimally invasive surgery(MIS)has been shown to improve short-term post-operative outcomes in other gastrointestinal malignancies,but there is little evi-dence on its use in MVR,especially so for robotic MVR.This is a single-center retrospective cohort study from 1st January 2015 to 31st March 2023.Inclusion criteria were patients diagnosed with cT4b rectal cancer and underwent MVR,or stage 4 disease with resectable systemic metastases.Pa-tients who underwent curative MVR for locally recurrent rectal cancer,or me-tachronous rectal cancer were also included.Exclusion criteria were patients with systemic metastases with non-resectable disease.All patients planned for elective surgery were enrolled into the standard enhanced recovery after surgery pathway with standard peri-operative management for colorectal surgery.Complex sur-gery was defined based on technical difficulty of surgery(i.***.total PE,bladder-sparing prostatectomy,pelvic lymph node dissection or need for flap creation).Our primary outcomes were the margin status,and complication rates.Cate-gorical values were described as percentages and analysed by the chi-square test.Continuous variables were expressed as median(range)and analysed by Mann-Whitney U test.Cumulative overall survival(OS)and recurrence-free survival(RFS)were analysed using Kaplan-Meier estimates with life table analysis.Log-rank test was performed to determine statistical significance between cumulative estimates.Statistical significance was defined as P<0.05.Meier estimates with life table analysis.Log-rank test was performed to

关键词： Laparoscopy Minimally invasive surgical procedures Multivisceral resection Pelvic Exenteration Rectal neoplasms Robotic surgical procedures

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Tbx 4 and Tbx 5 gene expression associated with appendage development and its relationship with the absence of the pelvic fin in Pampus argenteus

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Journal of Oceanology and Limnology 2024年第2期42卷 580-593页

作者： Shun ZHANG Xiaojing ZHU Lingzhu HU kai LIAO Shanliang XU Danli WANG Chunyang GUO School of Marine Science Ningbo UniversityNingbo 315211China Key Laboratory of Applied Marine Biotechnology Ningbo UniversityChinese Ministry of EducationNingbo 315211China

The Tbx family is first known through the study of their functions in the body and limbs,and its members Tbx4 and Tbx5 genes are important factors in determining the characteristics of the appendages.Pampus argenteus is one of the important economical marine fishes widely distributed in offshore areas.Therefore,it is necessary to study the role of Tbx family genes in the deletion of pelvic fin in P.argenteus.In this study,we cloned Tbx4 and Tbx5 cDNA sequence of P.argenteus(GenBank:MH709128 and MH712458).The Western blot and real time PCR were used to detect the expressions of Tbx4 and Tbx5 in different developmental stages and tissues of P.argenteus.In addition,whole-mount in-situ hybridization was used to study the localization of Tbx4 and Tbx5 genes in different developmental stages of P.argenteus.Results show that the translation of Tbx4 mRNA was inhibited during the critical period of pelvic fin development.Among different tissues,Tbx4 protein levels were the lowest in the abdominal epithelium,and even lower than that in the pectoral fin,suggesting that the protein expression was also inhibited in the abdominal epithelium of adult P.argenteus.Therefore,the results indicated that upstream genes regulation led to the key stage-specific and low expression of Tbx4 during pelvic fin development and in the abdominal epithelium.

关键词： Stromateidae pelvic fin protein translation T-box aquaculture broodstock

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Genomics-driven derivatization of the bioactive fungal sesterterpenoid variecolin:Creation of an unnatural analogue with improved anticancer properties

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Acta Pharmaceutica Sinica B 2024年第1期14卷 421-432页

作者： Dexiu Yan Jemma Arakelyan Teng Wan Ritvik Raina Tsz Ki Chan Dohyun Ahn Vladimir Kushnarev Tsz Kiu Cheung Ho Ching Chan Inseo Choi Pui Yi Ho Feijun Hu Yujeong Kim Hill Lam Lau Ying Lo Law Chi Seng Leung Chun Yin Tong kai Kap wong Wing Lam Yim Nikolay S.Karnaukhov Richard Y.C.Kong Maria V.Babak Yudai Matsuda Department of Chemistry City University of Hong KongHong Kong SARChina iGEM Team“VarieCure” City University of Hong KongHong Kong SARChina Department of Biomedical Engineering City University of Hong KongHong Kong SARChina Moscow Clinical Research Center Named After A.S.Loginov Moscow 111123Russian Federation

A biosynthetic gene cluster for the bioactive fungal sesterterpenoids variecolin(1)and variecolactone(2)was identified in Aspergillus aculeatus ATCC 16872.Heterologous production of 1 and 2 was achieved in Aspergillus oryzae by expressing the sesterterpene synthase VrcA and the cytochrome P450 VrcB.Intriguingly,the replacement of VrcB with homologous P450s from other fungal terpenoid pathways yielded three new variecolin analogues(5-7).Analysis of the compounds’anticancer activity in vitro and in vivo revealed that although 5 and 1 had comparable activities,5 was associated with significantly reduced toxic side effects in cancer-bearing mice,indicating its potentially broader therapeutic window.Our study describes the first tests of variecolin and its analogues in animals and demonstrates the utility of synthetic biology for creating molecules with improved biological activities.

关键词： Animal studies Anticancer properties Biosynthesis Natural products Sesterterpenoids Synthetic biology Terpene synthases Variecolin

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The Nano Research Young Innovators Awards in bio-inspired nanomaterials

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Nano Research 2024年第2期17卷 417-425页

作者： Jun Chen Shuotao Wang Department of Bioengineering University of CaliforniaLos AngelesLos AngelesCA 90095USA Key Laboratory of Bio-inspired Materials and Interfacial Science Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China

Nano Research Young Innovators(NR45)Awards are designed to acknowledge and celebrate the achievements of young researchers under 45 years of age.These individuals have made significant contributions to the field of nanoscience and nanotechnology.Since the inaugural NR45 Awards in 2018,the journal's editorial board has recognized over a hundred innovators specializing in nanobiotechnology,nano energy,two-dimensional materials,and nanocatalysis.The focus of the 2023 NR45 Awards is on bioinspired nanomaterials,acknowledging thirty-three outstanding young innovators for their extraordinary contributions in developing these materials with applications spanning clean energy,human healthcare,monitoring,and disease treatments,as shown in Fig.1.We extend our heartfelt congratulations to all the 33 NR45 Awardees in 2023!

关键词： journal materials contributions

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