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Search Results: 1 - 10 of 225 matches for " Hyunseung Choo "
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An Efficient Method for Proportional Differentiated Admission Control Implementation
Shakhov Vladimir,Choo Hyunseung
EURASIP Journal on Wireless Communications and Networking , 2011,
Abstract: The admission control mechanism inspired in the framework of proportional differentiated services has been investigated. The mechanism provides a predictable and controllable network service for real-time traffic in terms of blocking probability. Implementation of proportional differentiated admission control is a complicated computational problem. Previously, asymptotic assumptions have been used to simplify the problem, but it is unpractical for real-world applications. We improve previous solutions of the problem and offer an efficient nonasymptotic method for implementation of proportional differentiated admission control.
An Efficient Method for Proportional Differentiated Admission Control Implementation
Vladimir Shakhov,Hyunseung Choo
EURASIP Journal on Wireless Communications and Networking , 2011, DOI: 10.1155/2011/738386
Location-Based Data Dissemination for Spatial Queries in Wireless Broadcast Environments
Kwangjin Park,Hyunseung Choo,
Kwangjin Park
,Hyunseung Choo

计算机科学技术学报 , 2010,
Abstract: Most current research on Location-Based Services(LBSs,for short) assumes point-to-point wireless communication, where the server processes a query and returns the query result to the user via a point-to-point wireless channel. However,LBSs via point-to-point wireless channel suffer from a tremendous amount of traffic and service requests from the user and thereby result in poor performance.In this paper,we present broadcast-based spatial query processing algorithms designed to support k-NN(k-Nearest Neighbo...
Dynamic Control of Adsorption Sensitivity for Photo-EMF-Based Ammonia Gas Sensors Using a Wireless Network
Yuriy Vashpanov,Hyunseung Choo,Dongsoo Stephen Kim
Sensors , 2011, DOI: 10.3390/s111110930
Abstract: This paper proposes an adsorption sensitivity control method that uses a wireless network and illumination light intensity in a photo-electromagnetic field (EMF)-based gas sensor for measurements in real time of a wide range of ammonia concentrations. The minimum measurement error for a range of ammonia concentration from 3 to 800 ppm occurs when the gas concentration magnitude corresponds with the optimal intensity of the illumination light. A simulation with LabView-engineered modules for automatic control of a new intelligent computer system was conducted to improve measurement precision over a wide range of gas concentrations. This gas sensor computer system with wireless network technology could be useful in the chemical industry for automatic detection and measurement of hazardous ammonia gas levels in real time.
Energy-efficient Area Coverage by Sensors with Adjustable Ranges
Vyacheslav Zalyubovskiy,Adil Erzin,Sergey Astrakov,Hyunseung Choo
Sensors , 2009, DOI: 10.3390/s90402446
Abstract: In wireless sensor networks, density control is an important technique for prolonging a network's lifetime. To reduce the overall energy consumption, it is desirable to minimize the overlapping sensing area of the sensor nodes. In this paper, we study the problem of energy-efficient area coverage by the regular placement of sensors with adjustable sensing and communication ranges. We suggest a more accurate method to estimate efficiency than those currently used for coverage by sensors with adjustable ranges, and propose new density control models that considerably improve coverage using sensors with two sensing ranges. Calculations and extensive simulation show that the new models outperform existing ones in terms of various performance metrics.
DRDT: Distributed and Reliable Data Transmission with Cooperative Nodes for LossyWireless Sensor Networks
Jaewan Seo,Moonseong Kim,In Hur,Wook Choi,Hyunseung Choo
Sensors , 2010, DOI: 10.3390/s100402793
Abstract: Recent studies have shown that in realistic wireless sensor network environments links are extremely unreliable. To recover from corrupted packets, most routing schemes with an assumption of ideal radio environments use a retransmission mechanism, which may cause unnecessary retransmissions. Therefore, guaranteeing energy-efficient reliable data transmission is a fundamental routing issue in wireless sensor networks. However, it is not encouraged to propose a new reliable routing scheme in the sense that every existing routing scheme cannot be replaced with the new one. This paper proposes a Distributed and Reliable Data Transmission (DRDT) scheme with a goal to efficiently guarantee reliable data transmission. In particular, this is based on a pluggable modular approach so that it can be extended to existing routing schemes. DRDT offers reliable data transmission using neighbor nodes, i.e., helper nodes. A helper node is selected among the neighbor nodes of the receiver node which overhear the data packet in a distributed manner. DRDT effectively reduces the number of retransmissions by delegating the retransmission task from the sender node to the helper node that has higher link quality to the receiver node when the data packet reception fails due to the low link quality between the sender and the receiver nodes. Comprehensive simulation results show that DRDT improves end-to-end transmission cost by up to about 45% and reduces its delay by about 40% compared to existing schemes.
Sink-oriented Dynamic Location Service Protocol for Mobile Sinks with an Energy Efficient Grid-Based Approach
Hyeonjae Jeon,Kwangjin Park,Dae-Joon Hwang,Hyunseung Choo
Sensors , 2009, DOI: 10.3390/s90301433
Abstract: Sensor nodes transmit the sensed information to the sink through wireless sensor networks (WSNs). They have limited power, computational capacities and memory. Portable wireless devices are increasing in popularity. Mechanisms that allow information to be efficiently obtained through mobile WSNs are of significant interest. However, a mobile sink introduces many challenges to data dissemination in large WSNs. For example, it is important to efficiently identify the locations of mobile sinks and disseminate information from multi-source nodes to the multi-mobile sinks. In particular, a stationary dissemination path may no longer be effective in mobile sink applications, due to sink mobility. In this paper, we propose a Sink-oriented Dynamic Location Service (SDLS) approach to handle sink mobility. In SDLS, we propose an Eight-Direction Anchor (EDA) system that acts as a location service server. EDA prevents intensive energy consumption at the border sensor nodes and thus provides energy balancing to all the sensor nodes. Then we propose a Location-based Shortest Relay (LSR) that efficiently forwards (or relays) data from a source node to a sink with minimal delay path. Our results demonstrate that SDLS not only provides an efficient and scalable location service, but also reduces the average data communication overhead in scenarios with multiple and moving sinks and sources.
An Energy-efficient Multi-candidate Greedy Routing Scheme in Wireless Sensor Networks
Tu Dang Nguyen,Wook Choi,Thiep Minh Ha,Hyunseung Choo
Journal of Networks , 2011, DOI: 10.4304/jnw.6.3.365-377
Abstract: Sleep and wake-up scheduling of sensor nodes is an efficient solution to prolong the network lifetime. However, existing scheduling algorithms may significantly decrease the number of active nodes so that the network may be intermittently-connected. In such networks, traditional geographic routing protocols are inappropriate to obtain low latency routes due to route discovery and data forwarding latency. In this paper, we propose a novel emph{multi-candidate greedy routing} (MGR) scheme that makes the best effort to find minimum latency routes in the sensor networks. In MGR, each source node sends an RREQ to a set of first wake-up forwarder candidates and selects a route with minimum estimated delivery latency based on their replies. Moreover, to cope with the unreliability of wireless links, we introduce an add-on algorithm for MGR, called emph{multilevel of link quality requirement-based packet forwarding} (MLRPF), which helps to increase the energy efficiency of MGR while still guaranteeing a low delivery latency. Simulation results demonstrate that MLRPF increases the routing performance of MGR significantly compared with PRRxDistance cite{7}, DGF cite{3}, and ODML cite{2} in terms of packet delivery latency and energy efficiency.
Dynamic Subchannel Assignment-Based Cross-Layer MAC and Network Protocol for Multihop Ad Hoc Networks
Khanh Nguyen Quang,Van Duc Nguyen,Hyunseung Choo
Journal of Computer Networks and Communications , 2013, DOI: 10.1155/2013/962643
Abstract: The paper presents a dynamic subchannel assignment algorithm based on orthogonal frequency division multiple access technology operating in the time division duplexing and a new cross-layer design based on a proposed routing protocol jointed with the MAC protocol. The proposed dynamic sub-channel assignment algorithm provides a new interference avoidance mechanism which solves several drawbacks of existing radio resource allocation techniques in wireless networks using OFDMA/TDD, such as the hidden node and exposed node problems, mobility, and cochannels interference in frequency (CCI). Besides, in wireless networks, when a route is established, the radio resource allocation problems may decrease the end to end performance proportionally with the length of each route. The contention at MAC layer may cause the routing protocol at network layer to respond by finding new routes and routing table updates. The proposed routing protocol is jointed with the MAC protocol based on dynamic sub-channel assignment to ensure that the quality of service in multihop ad hoc networks is significantly improved. 1. Introduction The cochannel interference (CCI) is one of the major challenges in wireless networks for multihop communications. This interference is introduced when two different radio stations simultaneously use the same frequency. It is mainly caused by the spectrum allocated for the system being reused multiple times in TDMA network. CCI is one of the major limitations in cellular and personal communication services wireless telephone networks since it significantly decreases the carrier-to-interference ratio. In addition, it makes the diminished system capacity, more frequent handoffs, and dropped calls. IEEE 802.11 distributed coordination function operation is based on conventional carrier mechanism (CSMA/CA) in order to prevent channel collisions, CCI, and provide the communication between multiple pairs of independent mobile nodes without access points or base stations such as mobile ad hoc networks [1, 2]. Recently, orthogonal frequency division multiplexing (OFDM) has been intensively investigated for wireless data transmission in broadband cellular and ad hoc networks. The multiple access technique for these networks is OFDMA [3]. The concept of this technique is to assign different users to different sub-channels in order to avoid interference. Dynamic sub-channel assignment algorithm based on orthogonal frequency division multiple access (OFDMA) technology operating in time division duplexing has been studied in [4–7]. However, in most of the
ROAD+: Route Optimization with Additional Destination-Information and Its Mobility Management in Mobile Networks
Moonseong Kim,Matt W Mutka,Jeonghoon Park,Hyunseung Choo,
Moonseong Kim
,Matt W.Mutka,Jeonghoon Park,Hyunseung Choo

计算机科学技术学报 , 2010,
Abstract: In the NEtwork MObility(NEMO) environment,mobile networks can form a nested structure.In nested mobile networks that use the NEMO Basic Support(NBS) protocol,pinball routing problems occur because packets are routed to all the home agents of the mobile routers using nested tunneling.In addition,the nodes in the same mobile networks can communicate with each other regardless of Internet connectivity.However,the nodes in some mobile networks that are based on NBS cannot communicate when the network is disconn...
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