• Title/Summary/Keyword: global node number

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Communication Protocol to Support Mobile Sinks by Multi-hop Clusters in Wireless Sensor Networks (무선 센서 네트워크에서 멀티-홉 클러스터를 통한 이동 싱크 지원 통신 프로토콜)

  • Oh, Seung-Min;Jung, Ju-Hyun;Lee, Jeong-Cheol;Park, Ho-Sung;Yim, Yong-Bin;Kim, Sang-Ha
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.3A
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    • pp.287-295
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    • 2010
  • In wireless sensor networks(WSNs), the studies that support sink mobility without global position information exploit a Backbone-based Virtual Infrastructure (BVI) which considers one-hop clusters and a backbone-based tree. Since the clusters of a sink and a source node are connected via flooding into the infrastructure, it causes high routing cost. Although the network could reduce the number of clusters via multi-level clusters, if the source nodes exist at nearest clusters from the cluster attached by the sink and they are in different branches of the tree, the data should be delivered via detour paths on the tree. Therefore, to reduce the number of clusters, we propose a novel multi-hop cluster based communication protocol supporting sink mobility without global position information. We exploit a rendezvous cluster head for sink location service and data dissemination but the proposed protocol effectively reduces data detour via comparing cluster hops from the source. Simulation shows that the proposed protocol is superior to the existing protocols in terms of the data delivery hop counts.

A Cooperative Spectrum Sensing Method based on Eigenvalue and Superposition for Cognitive Radio Networks (인지무선네트워크를 위한 고유값 및 중첩기반의 협력 스펙트럼 센싱 기법)

  • Miah, Md. Sipon;Koo, Insoo
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.13 no.4
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    • pp.39-46
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    • 2013
  • Cooperative spectrum sensing can improve sensing reliability, compared with single node spectrum sensing. In addition, Eigenvalue-based spectrum sensing has also drawn a great attention due to its performance improvement over the energy detection method in which the more smoothing factor, the better performance is achieved. However, the more smoothing factor in Eignevalue-based spectrum sensing requires the more sensing time. Furthermore, more reporting time in cooperative sensing will be required as the number of nodes increases. Subsequently, we in this paper propose an Eigenvalue and superposition-based spectrum sensing where the reporting time is utilized so as to increase the number of smoothing factors for autocorrelation calculation. Simulation result demonstrates that the proposed scheme has better detection probability in both local as well as global detection while requiring less sensing time as compared with conventional Eigenvalue-based detection scheme.

GPS Accuracy Revision Using RSSI and AoA in Wireless Sensor Network (무선 센서 네트워크에서 RSSI와 AoA를 활용한 GPS 정밀도 향상 방안)

  • Cho, Hae-Min;Kwon, Tae-Wook
    • The Journal of the Korea institute of electronic communication sciences
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    • v.17 no.5
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    • pp.889-896
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    • 2022
  • Data required in a wireless sensor network environment requires more accurate figures as technology advances and its complexity increases. However, in the case of operating a large number of sensor nodes in a large area, the balance between the power consumed and the data quality that can be acquired accordingly should be considered for that purpose. In particular, in complex, densely populated urban areas or military operations with specific goals, location data requires increasingly detailed and high accuracy over a wide range. In this paper, we propose a method of mounting a Global Positioning System(: GPS) only on some of the sensor nodes deployed in the wireless sensor network and improving the error of GPS location data measured on that sensor node through Angle of Arrival(: AoA) and Received Signal Strength Indicator(: RSSI).

Adaptive Partitioning of the Global Key Pool Method using Fuzzy Logic for Resilience in Statistical En-Route Filtering (통계적 여과기법에서 훼손 허용도를 위한 퍼지 로직을 사용한 적응형 전역 키 풀 분할 기법)

  • Kim, Sang-Ryul;Cho, Tae-Ho
    • Journal of the Korea Society for Simulation
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    • v.16 no.4
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    • pp.57-65
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    • 2007
  • In many sensor network applications, sensor nodes are deployed in open environments, and hence are vulnerable to physical attacks, potentially compromising the node's cryptographic keys. False sensing report can be injected through compromised nodes, which can lead to not only false alarms but also the depletion of limited energy resource in battery powered networks. Fan Ye et al. proposed that statistical en-route filtering scheme(SEF) can do verify the false report during the forwarding process. In this scheme, the choice of a partition value represents a trade off between resilience and energy where the partition value is the total number of partitions which global key pool is divided. If every partition are compromised by an adversary, SEF disables the filtering capability. Also, when an adversary has compromised a very small portion of keys in every partition, the remaining uncompromised keys which take a large portion of the total cannot be used to filter false reports. We propose a fuzzy-based adaptive partitioning method in which a global key pool is adaptively divided into multiple partitions by a fuzzy rule-based system. The fuzzy logic determines a partition value by considering the number of compromised partitions, the energy and density of all nodes. The fuzzy based partition value can conserve energy, while it provides sufficient resilience.

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Fast Join Mechanism that considers the switching of the tree in Overlay Multicast (오버레이 멀티캐스팅에서 트리의 스위칭을 고려한 빠른 멤버 가입 방안에 관한 연구)

  • Cho, Sung-Yean;Rho, Kyung-Taeg;Park, Myong-Soon
    • The KIPS Transactions:PartC
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    • v.10C no.5
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    • pp.625-634
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    • 2003
  • More than a decade after its initial proposal, deployment of IP Multicast has been limited due to the problem of traffic control in multicast routing, multicast address allocation in global internet, reliable multicast transport techniques etc. Lately, according to increase of multicast application service such as internet broadcast, real time security information service etc., overlay multicast is developed as a new internet multicast technology. In this paper, we describe an overlay multicast protocol and propose fast join mechanism that considers switching of the tree. To find a potential parent, an existing search algorithm descends the tree from the root by one level at a time, and it causes long joining latency. Also, it is try to select the nearest node as a potential parent. However, it can't select the nearest node by the degree limit of the node. As a result, the generated tree has low efficiency. To reduce long joining latency and improve the efficiency of the tree, we propose searching two levels of the tree at a time. This method forwards joining request message to own children node. So, at ordinary times, there is no overhead to keep the tree. But the joining request came, the increasing number of searching messages will reduce a long joining latency. Also searching more nodes will be helpful to construct more efficient trees. In order to evaluate the performance of our fast join mechanism, we measure the metrics such as the search latency and the number of searched node and the number of switching by the number of members and degree limit. The simulation results show that the performance of our mechanism is superior to that of the existing mechanism.

Efficient Message Scheduling Protocol for Variable-sized Messages in a WDM-based Local Network with Nonzero Tuning Time (WDM 기반의 근거리 망에서 변조시간을 고려한 효율적인 가변 길이 메시지 예약 프로토콜)

    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.8A
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    • pp.1238-1246
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    • 2000
  • In a multi-channel network based on wavelength division multiplexing (WDM), an efficient protocol is needed for transmitter and receiver to be tuned to same wavelength during message transmission time. This paper proposes a message scheduling protocol that can efficiently support variable-sized messages, where tunable transceiver has nonzero tuning time. In this protocol, once a node reserves one data channel, it can persistently use the reserved channel till message transmission is finished. Therefore, overhead due to tuning time of the tunable transceiver can be reduced. Moreover, the protocol does not require any global information. Therefore, it can operate independently of the change of the number of nodes, and any new node can join the network at anytime without requiring network initialization. With this protocol, one can avoid data channel and destination conflicts. The protocol is analyzed with a finite population model and the throughput-delay characteristics are investigated as performance measures.

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An Efficient Broadcast Technique for Vehicular Networks

  • Ho, Ai Hua;Ho, Yao H.;Hua, Kien A.;Villafane, Roy;Chao, Han-Chieh
    • Journal of Information Processing Systems
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    • v.7 no.2
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    • pp.221-240
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    • 2011
  • Vehicular networks are a promising application of mobile ad hoc networks. In this paper, we introduce an efficient broadcast technique, called CB-S (Cell Broadcast for Streets), for vehicular networks with occlusions such as skyscrapers. In this environment, the road network is fragmented into cells such that nodes in a cell can communicate with any node within a two cell distance. Each mobile node is equipped with a GPS (Global Positioning System) unit and a map of the cells. The cell map has information about the cells including their identifier and the coordinates of the upper-right and lower-left corner of each cell. CB-S has the following desirable property. Broadcast of a message is performed by rebroadcasting the message from every other cell in the terrain. This characteristic allows CB-S to achieve an efficient performance. Our simulation results indicate that messages always reach all nodes in the wireless network. This perfect coverage is achieved with minimal overhead. That is, CB-S uses a low number of nodes to disseminate the data packets as quickly as probabilistically possible. This efficiency gives it the advantage of low delay. To show these benefits, we give simulations results to compare CB-S with four other broadcast techniques. In practice, CB-S can be used for information dissemination, or to reduce the high cost of destination discovery in routing protocols. By also specify the radius of affected zone, CB-S is also more efficient when broadcast to a subset of the nodes is desirable.

dMMS: A Novel Distributed Dynamic Mobility Management Scheme for Minimizing Signaling Costs in Proxy Mobile IPv6 Networks (프록시 모바일 IPv6 네트워크에서 시그널링 비용을 최소화하기 위한 분산된 이동성관리 기법)

  • Ko, Hyun-Woo;Jeong, Jong-Pil
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.12 no.4
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    • pp.65-80
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    • 2012
  • Mobile IP is a simple and scalable global mobility solution. However, it may cause excessive signaling traffic and long signaling delay. So MN (Mobile Node) to the home network in order to reduce the number of location update signaling is necessary to reduce the delay. In this paper, the signaling overhead to be distributed evenly on the boundary of the regional network, each MN's dynamic mobility and traffic load is adjusted according to the PMIPv6 (Proxy Mobile IPv6) networks in the proposed dynamic regional mobility management scheme (dMMS). Each user in a distributed network system that offers the least amount of signaling traffic is tailored to the optimized system configuration. Signaling cost function in order to propose a new discrete analytical model is proposed, MN's mobility and packet arrival patterns. Location update and packet delivery costs to calculate the total average, the optimized area to determine the size of the network is proposed. The results of mathematical analysis, the proposed technique dMMS in terms of reducing the cost of the entire signaling were found to be excellent performance.

Fine Needle Aspiration Cytology of Palpable Lymph Nodes -A Single Institutional Experience of 1,346 Cases- (촉지 림프절의 세침흡인 세포검사 - 단일 기관의 1,346예 경험 -)

  • Shin, Dong-Hoon;Kim, Jee-Yeon;Kang, Hyun-Jeong;Kim, Ick-Doo;Sol, Mee-Young;Choi, Kyung-Un
    • The Korean Journal of Cytopathology
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    • v.18 no.2
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    • pp.126-132
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    • 2007
  • The aim of this study was to evaluate the diagnostic value of fine needle aspiration cytology (FNAC) for the assessment of palpable enlarged lymph nodes. The authors reviewed the results of 1,346 FNACs of palpable enlarged lymph nodes performed at Pusan National University Hospital from 1998 to 2004. Of the 1,346 cases, 1,265 (94.0%) were satisfactory and 81 (6.0%) unsatisfactory. Cytologic diagnoses were judged in 488 cases, based on subsequent histologic diagnoses, clinical follow up, or both. Global results for all malignancies (lymphoid and non-lymphoid neoplasms) based on cases with final diagnoses, showed a sensitivity of 87.4% and a specificity of 98.7%. The overall diagnostic accuracy was 93,2%, and the false negative rate reduced from 12,6% to 7,3% when lymphomatous cases were excluded. The annual data for this period showed that the number of diagnostic lymph node biopsies and the rate of inadequately sampled material markedly decreased. Gene rearrangement studies for IgH and TCR ${\gamma}$ were helful in 30 cases. FNAC is a useful initial diagnostic procedure for the evaluation of palpable enlarged lymph nodes. However, the technique should be assisted by the appropriate ancillary studies and by proper interpretation by a cytopathologist.

Design of the Structure for Scaling-Wavelet Neural Network Using Genetic Algorithm (유전 알고리즘을 이용한 스케일링-웨이블릿 복합 신경회로망 구조 설계)

  • 김성주;서재용;연정흠;김성현;전홍태
    • Proceedings of the IEEK Conference
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    • 2001.06c
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    • pp.25-28
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    • 2001
  • RBFN has some problem that because the basis function isn't orthogonal to each others the number of used basis function goes to big. In this reason, the Wavelet Neural Network which uses the orthogonal basis function in the hidden node appears. In this paper, we propose the composition method of the actual function in hidden layer with the scaling function which can represent the region by which the several wavelet can be represented. In this method, we can decrease the size of the network with the pure several wavelet function. In addition to, when we determine the parameters of the scaling function we can process rough approximation and then the network becomes more stable. The other wavelets can be determined by the global solutions which is suitable for the suggested problem using the genetic algorithm and also, we use the back-propagation algorithm in the learning of the weights. In this step, we approximate the target function with fine tuning level. The complex neural network suggested In this paper is a new structure and important simultaneously in the point of handling the determination problem in the wavelet initialization.

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