Hong-Ning Dai
Hong Kong Baptist University, Computer Science, Faculty Member
- Hong-Ning (Henry) Dai is an associate professor in Faculty of Information Technology at Macau University of Science a... moreHong-Ning (Henry) Dai is an associate professor in Faculty of Information Technology at Macau University of Science and Technology. He obtained the Ph.D. degree in Computer Science and Engineering from Department of Computer Science and Engineering at the Chinese University of Hong Kong. He also received the B.Eng. and M.Eng. degrees in Computer Science and Engineering from South China University of Technology. He also holds visiting positions at Department of Computer Science and Engineering, the Hong Kong University of Science and Technology and School of Electrical Engineering and Telecommunications, the University of New South Wales, respectively.His research interests include wireless networks, mobile computing, and distributed systems. He has published more than 70 peer-reviewed papers in refereed conferences and journals, including IEEE Transactions on Industrial Informatics, IEEE Transactions on Vehicular Technology, IEEE INFOCOM, IEEE ICC, IEEE GLOBECOM, IEEE LCN, IEEE WCNC, IEEE PIMRC, IEEE ISSNIP, ICCS etc. He served as conference staff members of a number of conferences, including IEEE ICCS, IEEE ANT, ACM MobiHoc, IEEE SCC, IEEE GCC and CIAPR etc. He is a professional member of the Association for Computing Machinery (ACM), a senior member of the Institute of Electrical and Electronics Engineers (IEEE) and a member of IEEE Communications Society.edit
Research Interests: Computer Science, Distributed Computing, Smart Antenna, Wireless Communications, Wireless Sensor Networks, and 8 moreWireless MAC protocols, Wireless networks, Beamforming, Computer Network, Throughput, Electrical And Electronic Engineering, Directional MW Antennas, and Wireless Personal Communications
The capacity of wireless networks are mainly affected by two key factors: the interference among concurrent transmissions and the number of simultaneous transmissions on a single interface. Recent studies have found that, using multiple... more
The capacity of wireless networks are mainly affected by two key factors: the interference among concurrent transmissions and the number of simultaneous transmissions on a single interface. Recent studies have found that, using multiple channels can separate concurrent transmissions and significantly improve network throughput. However, those studies only consider wireless nodes that are only equipped with omni-directional antennas, which cause high collisions. On the other hand, some researchers have found that directional antennas bring more benefits such as the reduced interference and the increased spatial reuse compared with omni-directional antennas. But, they only focused on a single-channel network which only allows finite concurrent transmissions. In this thesis, we propose a novel network architecture, in terms of multi-channel networks using multiple directional antennas ( MC-MDA), which integrates the two technologies of multiple channels and directional antennas together and potentially brings more benefits. We study the capacity of MC-MDA networks and explore the benefits of such networks. We have found that using directional antennas in multi-channel networks can greatly increase the network capacity. Furthermore, such networks require fewer channels than multi-channels with omni-directional antennas. More specifically, we study the channel assignment problem of such MC-MDA networks. Our results indicate that using directional antennas in wireless networks can significantly reduce the required number of channels. Directional antennas have a better spectrum reuse than omni-directional antennas. However, applying directional antennas to wireless networks can also cause new collisions, such as the new hidden terminal problem and the deafness problem. We study the challenges in the MAC layer design with directional antennas and present the state of the art of current MAC protocols with directional antennas. Then, we propose a novel collision avoidance scheme in terms of BT-DMAC (Busy-Tone based Directional Medium Access Control) to address the new collisions with directional antennas. Both the analytical and simulation results show that transmitting busy tones on a different channel can effectively reduce the hidden nodes and mitigate the deafness problem. Thus, integrating multiple channels with directional antennas can bring numerous benefits. Furthermore, we also explore some techniques in the MAC layer design with directional antennas. Some useful insights are also given.
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Research Interests: Information Systems, Computer Science, Wireless Communications, Network Security, Computational Modelling, and 9 moreWireless security, Computational Science, Computer Security, Wireless Sensor Network Security, Beamforming, Wireless Network, Wireless Computing, Directional Antenna, and Eavesdropping
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Research Interests: Computer Science, Distributed Computing, Mobile Ad Hoc Networks, Wireless Communications, Graph Theory, and 15 moreWireless networks, Beamforming, Computer Network, Wireless Network, Marketing channels, Sensor networks, Wireless, Directional Antenna, Wireless Ad hoc Networks, Wireless Sensor, Sensor Networks, Path Loss, Wireless Ad Hoc Network, Directional MW Antennas, and Channel Allocation
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The implementation of a new Internet standard such as IPv6 depends on the usefulness of the technology to the adopting organizations and the environment in which they operate. The adoption of IPv6 in Korea is mostly driven by a... more
The implementation of a new Internet standard such as IPv6 depends on the usefulness of the technology to the adopting organizations and the environment in which they operate. The adoption of IPv6 in Korea is mostly driven by a governmental strategy that created high network externalities and developed related technologies. However, the speed of adoption is hindered due to lack
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Research Interests: Computer Science, Smart Antenna, Wireless Communications, Survey Research (Research Methodology), Wireless networks, and 10 moreBeamforming, Computer Network, Wireless Network, Wireless, Directional Antenna, Medium Access Control, MAC Protocol, Wireless Ad Hoc Network, Mobile Communication System, and Omnidirectional antenna
Conventional 802.11 networks perform contention and data transmission serially over the whole channel. This leads to low throughput efficiency. In this paper, we propose a novel CSMA/CQ (carrier sense multiple access/contention queuing)... more
Conventional 802.11 networks perform contention and data transmission serially over the whole channel. This leads to low throughput efficiency. In this paper, we propose a novel CSMA/CQ (carrier sense multiple access/contention queuing) to improve the throughput efficiency. In CSMA/CQ, each node performs contention and data transmission concurrently over two separate subchannels, where a contention queue is introduced to coordinate the concurrency. CSMA/CQ inherits the conventional distributed coordination mechanism on contention, and adopts a centralized control idea on data transmission without requiring strict time synchronization. As a result, CSMA/CQ can achieve far higher throughput than conventional 802.11 networks. Extensive simulations verify that the efficiency of CSMA/CQ.
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ABSTRACT In current WiFi networks, to transmit a 1500 byte packet, as the physical data rate increases to about 1Gbps, the throughput just increases up to 55 Mbps. The reason for this throughput inefficiency stems from the fundamental... more
ABSTRACT In current WiFi networks, to transmit a 1500 byte packet, as the physical data rate increases to about 1Gbps, the throughput just increases up to 55 Mbps. The reason for this throughput inefficiency stems from the fundamental limitations existed in the current WLANs. In this paper, we review two recent MAC enhancements that improve the throughput efficiency: the idle sense scheme and the aggregation with fragment retransmission (AFR) scheme, and discuss their respective advantages and disadvantages.
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Wireless Full-duplex technique can significantly improve system throughput of a wireless network. Most existing full-duplex-supporting wireless MAC schemes only achieve symmetric transmission (i.e., the uplink throughput of a node is... more
Wireless Full-duplex technique can significantly improve system throughput of a wireless network. Most existing full-duplex-supporting wireless MAC schemes only achieve symmetric transmission (i.e., the uplink throughput of a node is equal to its downlink throughput). However, in reality, the uplink and downlink traffic is often asymmetric. In this paper, we propose a novel MAC scheme called AT-MAC to achieve asymmetric transmission. In AT-MAC, upon receiving a packet, a receiver determines whether to execute a reverse transmission to the peer or to initiate a new transmission to a third node, according to the peer’s uplink and downlink requirements. Extensive simulations verify that the proposed design is feasible and efficient.
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Research Interests: Engineering, Computer Science, Wireless Communications, Network Security, Wireless Sensor Network Security, and 12 moreWireless networks, Beamforming, Mobile Ad Hoc Network, Computer Network, Ad Hoc Networks, Directional Antenna, Wireless Ad hoc Networks, Eavesdropping, Wireless Communication Security, Wireless Ad Hoc Network, Directional MW Antennas, and Omnidirectional antenna
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This paper concerns with the local connectivity (i.e., the probability of node isolation) of wireless networks with directional antennas. We propose an analytical framework to study the local connectivity with the consideration of... more
This paper concerns with the local connectivity (i.e., the probability of node isolation) of wireless networks with directional antennas. We propose an analytical framework to study the local connectivity with the consideration of directional antenna models and various channel conditions. With the framework, we construct a novel directional antenna model called Iris. We show that Iris can better approximate realistic directional antennas and can be easily used to analyze the local connectivity compared with existing directional antenna models. Extensive simulations show that the theoretical results are in good agreement with the simulation results verifying the accuracy and the effectiveness of our analytical framework.
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Blockchain is gaining extensive attention due to its provision of secure and decentralized resource sharing manner. However, the incumbent blockchain systems also suffer from a number of challenges in operational maintenance, quality... more
Blockchain is gaining extensive attention due to its provision of secure and decentralized resource sharing manner. However, the incumbent blockchain systems also suffer from a number of challenges in operational maintenance, quality assurance of smart contracts and malicious behaviour detection of blockchain data. The recent advances in artificial intelligence bring the opportunities in overcoming the above challenges. The integration of blockchain with artificial intelligence can be beneficial to enhance current blockchain systems. This article presents an introduction of the convergence of blockchain and artificial intelligence (namely blockchain intelligence). This article also gives a case study to further demonstrate the feasibility of blockchain intelligence and point out the future directions.
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The security and privacy of underwater acoustic sensor networks has received extensive attention recently due to the proliferation of underwater activities. This paper proposes an analytical model to investigate the eavesdropping attacks... more
The security and privacy of underwater acoustic sensor networks has received extensive attention recently due to the proliferation of underwater activities. This paper proposes an analytical model to investigate the eavesdropping attacks in underwater acoustic sensor networks. Our analytical framework considers the impacts of various underwater acoustic channel conditions (such as the acoustic signal frequency, spreading factor and wind speed) and different hydrophones (isotropic hydrophones and array hydrophones) in terms of network nodes and eavesdroppers. We also conduct extensive simulations to evaluate the effectiveness and the accuracy of our proposed model. Empirical results show that our proposed model is quite accurate. In addition, our results also imply that the eavesdropping probability heavily depends on both the underwater acoustic channel conditions and the features of hydrophones
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The site selection of sports facilities is a pivotal link in the construction of city livable environment and the development of sports business in digital-twinning cities. Recent years have witnessed data mining and visualization... more
The site selection of sports facilities is a pivotal link in the construction of city livable environment and the development of sports business in digital-twinning cities. Recent years have witnessed data mining and visualization technologies bringing the convenience as well as opportunities for intelligent site selection. However, the lack of effective and reliable systematic analysis leads to difficulties in developing sports facilities planning schemes and constructing the site-selection system. In this article, we design Sport facility Visual analysis system (SpoVis), an interactive visual analysis system for planning sports facilities as well as site selection. SpoVis provides users with the distribution status and statistical analysis of various sports facilities. Based on a comprehensive consideration of city population distribution, construction cost, existing sports facilities, traffic situation, and development potential, SpoVis provides users with a reasonable site-selection scheme of sports facilities from both macro and microperspectives and recommends results through topology and map. Meanwhile, based on the distribution of existing sports facilities and city influencing factors, a set of visual analysis components are designed to facilitate users to evaluate the status and information of existing sports facilities. We have carried out extensive experiments on a real platform with real-world data. The experimental results show that the proposed site-selection models and algorithms have excellent accuracy and operation efficiency.
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Conventional 802.11 networks perform contention and data transmission serially over the whole channel. This leads to low throughput efficiency. In this paper, we propose a novel CSMA/CQ (carrier sense multiple access/contention queuing)... more
Conventional 802.11 networks perform contention and data transmission serially over the whole channel. This leads to low throughput efficiency. In this paper, we propose a novel CSMA/CQ (carrier sense multiple access/contention queuing) to improve the throughput efficiency. In CSMA/CQ, each node performs contention and data transmission concurrently over two separate subchannels, where a contention queue is introduced to coordinate the concurrency. CSMA/CQ inherits the conventional distributed coordination mechanism on contention, and adopts a centralized control idea on data transmission without requiring strict time synchronization. As a result, CSMA/CQ can achieve far higher throughput than conventional 802.11 networks. Extensive simulations verify that the efficiency of CSMA/CQ.
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Open banking brings both the opportunities and challenges to banks all over the world. Due to the different economic development levels of each country and the gaps among financial environment maturity, all countries have different... more
Open banking brings both the opportunities and challenges to banks all over the world. Due to the different economic development levels of each country and the gaps among financial environment maturity, all countries have different strategies and regulations towards the privacy protection of data in financial scenes, such as the General Data Protection Regulation (GDPR) by European Union (EU). A blockchain as a continuously growing list of records managed by a peer-to-peer network is widely used in various application scenarios, and can protect the privacy of financial data. However, financial blockchain still poses some problems that cannot fully meet the data protection needs. In order to address the existing problems, this paper proposes a new blockchain-based data privacy management framework. The framework consists of three components: a data privacy classification method according to the characteristics of financial data and a new collaborative-filtering-based model and a confirmation data disclosure scheme for customer strategies based on the Nudge Theory. We implement a prototype and propose a set of algorithms for this management framework.
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Unmanned aerial vehicles (UAVs) can be leveraged in mobile crowdsensing (MCS) to conduct sensing tasks at remote or rural areas through computation offloading and data sensing. Nonetheless, both computation offloading and data sensing... more
Unmanned aerial vehicles (UAVs) can be leveraged in mobile crowdsensing (MCS) to conduct sensing tasks at remote or rural areas through computation offloading and data sensing. Nonetheless, both computation offloading and data sensing have been separately investigated in most existing studies. In this paper, we propose a novel cooperative data sensing and computation offloading scheme for the UAV-assisted MCS system with an aim to maximize the overall system utility. First, a multi-objective function is formulated to evaluate the system utility by jointly considering flight direction, flight distance,task offloading proportion, and server offload selection for each UAV. Then, the problem is modeled as a partially observable Markov decision process and a multi-agent actor-critic algorithm framework is proposed to train the strategy network for UAVs. Due to high delay and energy cost caused by communications among multiple agents, we leverage the critic network to model other agents and to seek equilibrium among all UAVs rather than adopting the explicit channel for information exchange. Furthermore, we introduce attention mechanism to enhance the convergence performance in model training phases. Finally, experimental results demonstrate the effectiveness and applicability of our scheme. Compared with baselines, our algorithm shows significant advantages in convergence performance and system utility.