• Title/Summary/Keyword: communication networks

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Analysis of Wireless Network in Freight Container Terminal and Methods for Service Quality Enhancement (컨테이너 터미널의 무선 네트워크 분석과 서비스 품질 향상 방안)

  • Han, Seung-Ho;Park, Hyun-Sung;Kim, Jong-Deok;Kim, Yong-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.3B
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    • pp.235-246
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    • 2009
  • The number of industry wireless networks based on IEEE 802.11 WLAN technology deployed in large outdoor work sites, such as freight container terminal, is increasing these days. Wider service coverage, frequent movements of stations and high requirement on service reliability are main characteristics of these networks compared to the conventional IEEE 802.11 networks used in home, office and school. While the importance of these networks Bets higher, we can hardly find previous studies including concrete analysis on these networks based on actual experiments. We carried out several field experiments at a freight container terminal to analyze its IEEE 802.11 network and found out some problematic situations, such as over 50% retransmission rates and frequent disruption of communication link while a station is moving. We explain why these problematic situations happen and suggest some solutions, such as application of mesh technology, smart handoff based on location and movement pattern and adjustment of signal strength and channel allocation. Methods and tools used in the experiments are also detailed in the paper which may be helpful for similar future studies.

Cross-layer Design of Joint Routing and Scheduling for Maximizing Network Capacity of IEEE 802.11s based Multi-Channel SmartGrid NAN Networks (IEEE 802.11s 를 사용한 스마트그리드 NAN 네트워크의 최대 전송 성능을 위한 다중 채널 스케쥴링과 라우팅의 결합 설계)

  • Min, Seok Hong;Kim, Bong Gyu;Lee, Jae Yong;Kim, Byung Chul
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.5
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    • pp.25-36
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    • 2016
  • The goal of the SmartGrid is to maximize energy efficiency by exchanging bi-directional real-time power information with the help of ICT(Information and Communication Technology). In this paper, we propose a "JRS-MS" (Joint Routing and Scheduling for Multi-channel SmartGrid) algorithm that uses numerical modeling methods in IEEE 802.11s based STDMA multi-channel SmartGrid NAN networks. The proposed algorithm controls the amount of data transmission adaptively at the link layer and finds a high data-rate path which has the least interference between traffic flows in multi-channel SmartGrid NAN networks. The proposed algorithm improve transmission performance by enhancing network utilization. By comparing the results of performance analysis between the proposed algorithm and the JRS-SG algorithm in the previous paper, we showed that the JRS-MS algorithm can improve transmission performance by maximally utilizing given network resources when the number of flows are increasing in the multi-hop NAN wireless mesh networks.

Content Insertion Method using by Frame Control based on Terrestrial IBB Service (지상파 IBB 서비스 기반 프레임 제어를 활용한 콘텐츠 삽입 방안)

  • Kim, Junsik;Park, Sunghwan;Kim, Doohwan;Joo, Jaehwan;Kim, Sangjin;Kim, Kyuheon
    • Journal of Broadcast Engineering
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    • v.25 no.5
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    • pp.758-769
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    • 2020
  • Hybrid broadcasts utilizing heterogeneous networks can provide not only uniform broadcasting services but also various services using broadcast networks and communication networks. In particular, as content is consumed in various countries and regions, demands for personalized services continue to increase, and research on content insertion technology utilizing heterogeneous networks has been actively conducted. The most important technical challenge when inserting content based on heterogeneous networks is that the start of the inserted content, which replaces the original broadcast content at the time of content insertion, should proceed smoothly, and it must be able to accurately return to the original broadcast content. Currently, UHD broadcasting is converted to digital. However, since there is a system that supports the frame rate used in the analog method, when content insertion occurs in a conventional UHD broadcasting service, there is a problem in decoding the broadcast and inserted content. Since the replacement cost of the broadcasting system is astronomical, this paper proposes a content insertion method using by frame control that can support analog methods without replacing transmission equipment.

Timestamps based sequential Localization for Linear Wireless Sensor Networks (선형 무선 센서 네트워크를 위한 시각소인 기반의 순차적 거리측정 기법)

  • Park, Sangjun;Kang, Jungho;Kim, Yongchul;Kim, Young-Joo
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.21 no.10
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    • pp.1840-1848
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    • 2017
  • Linear wireless sensor networks typically construct a network topology with a high reliability through sequential 1:1 mapping among sensor nodes, so that they are used in various surveillance applications of major national infrastructures. Most existing techniques for identifying sensor nodes in those networks are using GPS, AOA, and RSSI mechanisms. However, GPS or AOA based node identification techniques affect the size or production cost of the nodes so that it is not easy to construct practical sensor networks. RSSI based techniques may have a high deviation regrading location identification according to propagation environments and equipment quality so that complexity of error correction algorithm may increase. We propose a timestamps based sequential localization algorithm that uses transmit and receive timestamps in a message between sensor nodes without using GPS, AOA, and RSSI techniques. The algorithms for distance measurement between each node are expected to measure distance within up to 1 meter in case of an crystal oscillator of 300MHz or more.

Low-power 6LoWPAN Protocol Design (저 전력 6LoWPAN 프로토콜 설계)

  • Kim, Chang-Hoon;Kim, Il-Hyu;Cha, Jung-Woo;Nam, In-Gil;Lee, Chae-Wook
    • Journal of the Institute of Convergence Signal Processing
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    • v.12 no.4
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    • pp.274-280
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    • 2011
  • Due to their rapid growth and new paradigm applications, wireless sensor networks(WSNs) are morphing into low power personal area networks(LoWPANs), which are envisioned to grow radically. The fragmentation and reassembly of IP data packet is one of the most important function in the 6LoWPAN based communication between Internet and wireless sensor network. However, since the 6LoWPAN data unit size is 102 byte for IPv6 MTU size is 1200 byte, it increases the number of fragmentation and reassembly. In order to reduce the number of fragmentation and reassembly, this paper presents a new scheme that can be applicable to 6LoWPAN. When a fragmented packet header is constructed, we can have more space for data. This is because we use 8-bits routing table ill instead of 16-bits or 54-bits MAC address to decide the destination node. Analysis shows that our design has roughly 7% or 22% less transmission number of fragmented packets, depending on MAC address size(16-bits or 54-bits), compared with the previously proposed scheme in RFC4944. The reduced fragmented packet transmission means a low power consumption since the packet transmission is the very high power function in wireless sensor networks. Therefore the presented fragmented transmission scheme is well suited for low-power wireless sensor networks.

Opportunistic Multipath Routing Scheme for Guaranteeing End-to-End Reliability in Large-Scale Wireless Sensor Networks (대규모 무선 센서 망에서 종단 간 신뢰성 보장을 위한 기회적 다중경로 라우팅 방안)

  • Kim, Cheonyong;Jung, Kwansoo;Kim, Sang-Ha
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.10
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    • pp.2026-2034
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    • 2015
  • Wireless sensor networks (WSNs) consist of a lot of sensor nodes having limited transmission range. So multi-hop transmission is used for communication among nodes but the multi-hop transmission degrade the end-to-end reliability. Multipath routing and opportunistic routing are typical approaches for guaranteeing end-to-end reliability in WSNs. The existing protocols improve the reliability effectively in small networks but they suffer from rapid performance degradation in large networks. In this paper, we propose the opportunistic multipath routing protocol for guaranteeing end-to-end reliability in large WSNs. Applying multipath routing and opportunistic routing simultaneously is very hard because their conflicting routing features. The proposed protocol applies these approaches simultaneously by section-based routing thereby enhancing end-to-end reliability. Additionally, the proposed protocol guarantees required reliability by the concept of section reliability. The section reliability over a certain level might satisfy required end-to-end reliability. Our simulation results show that the proposed protocol is more suitable for guaranteeing reliability than existing protocols in large-scale WSNs.

The Control System of Wood Pellet Boiler Based on Home Networks (홈 네트워크 기반의 펠릿 활용 난방 보일러 제어시스템)

  • Lee, Sang-Hoon
    • Journal of the Institute of Convergence Signal Processing
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    • v.15 no.1
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    • pp.15-22
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    • 2014
  • This paper presents the implementation of a control system of pellet boiler using wood pellet as carbon neutral material. The system also has the additional features to provide remote controlling and monitoring based on home networking technology through either public switched telephone networks or mobile communication networks. It consists of three kinds of sub-modules; a main controller provides basic and additional features such as a setting of temperature, a supplying of wood pellet, a controlling of ignition and fire-power, and a removing of soot. The second is temperature controller of individual rooms which is connected to the main controller through RS-485 links. And interface modules with PSTN and mobile networks can support remote controlling and monitoring the functions. The test results under the heating area of $172m^2$ show a thermal efficiency of 93.6%, a heating power of 20,640kcal/hr, and a fuel consumption of 5.54kg/hr. These results are superior to those of the conventional pellet boilers. In order to obtain the such high performance, we newly applied a 3-step ignition flow, a flame detection by $C_dS$ sensor, and a fire-power control by fine controlling of shutter to our pellet boiler.

An Efficient Secure Routing Protocol Based on Token Escrow Tree for Wireless Ad Hoc Networks (무선 애드 혹 네트워크에서 보안성을 고려한 Token Escrow 트리 기반의 효율적인 라우팅 프로토콜)

  • Lee, Jae Sik;Kim, Sung Chun
    • KIPS Transactions on Computer and Communication Systems
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    • v.2 no.4
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    • pp.155-162
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    • 2013
  • Routing protocol in ad hoc mobile networking has been an active research area in recent years. However, the environments of ad hoc network tend to have vulnerable points from attacks, because ad hoc mobile network is a kind of wireless network without centralized authentication or fixed network infrastructure such as base stations. Also, existing routing protocols that are effective in a wired network become inapplicable in ad hoc mobile networks. To address these issues, several secure routing protocols have been proposed: SAODV and SRPTES. Even though our protocols are intensified security of networks than existing protocols, they can not deal fluidly with frequent changing of wireless environment. Moreover, demerits in energy efficiency are detected because they concentrated only safety routing. In this paper, we propose an energy efficient secure routing protocol for various ad hoc mobile environment. First of all, we provide that the nodes distribute security information to reliable nodes for secure routing. The nodes constitute tree-structured with around nodes for token escrow, this action will protect invasion of malicious node through hiding security information. Next, we propose multi-path routing based security level for protection from dropping attack of malicious node, then networks will prevent data from unexpected packet loss. As a result, this algorithm enhances packet delivery ratio in network environment which has some malicious nodes, and a life time of entire network is extended through consuming energy evenly.

A Resilient Key Renewal Scheme in Wireless Sensor Networks (센서 네트워크에서 복원력을 지닌 키갱신 방안)

  • Wang, Gi-Cheol;Cho, Gi-Hwan
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.2
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    • pp.103-112
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    • 2010
  • In sensor networks, because sensors are deployed in an unprotected environment, they are prone to be targets of compromise attack, If the number of compromised nodes increases considerably, the key management in the network is paralyzed. In particular, compromise of Cluster Heads (CHs) in clustered sensor networks is much more threatening than that of normalsensors. Recently, rekeying schemes which update the exposed keys using the keys unknown to the compromised nodes are emerging. However, they cause some security and efficiency problems such as single group key employment in a cluster, passive eviction of compromised nodes, and excessive communication and computation overhead. In this paper, we present a proactive rekeying scheme using renewals of duster organization for clustered sensor networks. In the proposed scheme, each sensor establishes individual keys with neighbors at network boot-up time, and these keys are employed for later transmissions between sensors and their CH. By the periodic cluster reorganization, the compromised nodes are expelled from network and the individual keys employed in a cluster are changed continuously. Besides, newly elected CHs securely agree a key with sink by informing their members to sink, without exchangingany keying materials. The simulation results shows that the proposed scheme remarkably improves the confidentiality and integrity of data in spite of the increase of compromised nodes. Also, they show that the proposed scheme exploits the precious energy resource more efficiently than SHELL.

Artificial Neural Network with Firefly Algorithm-Based Collaborative Spectrum Sensing in Cognitive Radio Networks

  • Velmurugan., S;P. Ezhumalai;E.A. Mary Anita
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.17 no.7
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    • pp.1951-1975
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    • 2023
  • Recent advances in Cognitive Radio Networks (CRN) have elevated them to the status of a critical instrument for overcoming spectrum limits and achieving severe future wireless communication requirements. Collaborative spectrum sensing is presented for efficient channel selection because spectrum sensing is an essential part of CRNs. This study presents an innovative cooperative spectrum sensing (CSS) model that is built on the Firefly Algorithm (FA), as well as machine learning artificial neural networks (ANN). This system makes use of user grouping strategies to improve detection performance dramatically while lowering collaboration costs. Cooperative sensing wasn't used until after cognitive radio users had been correctly identified using energy data samples and an ANN model. Cooperative sensing strategies produce a user base that is either secure, requires less effort, or is faultless. The suggested method's purpose is to choose the best transmission channel. Clustering is utilized by the suggested ANN-FA model to reduce spectrum sensing inaccuracy. The transmission channel that has the highest weight is chosen by employing the method that has been provided for computing channel weight. The proposed ANN-FA model computes channel weight based on three sets of input parameters: PU utilization, CR count, and channel capacity. Using an improved evolutionary algorithm, the key principles of the ANN-FA scheme are optimized to boost the overall efficiency of the CRN channel selection technique. This study proposes the Artificial Neural Network with Firefly Algorithm (ANN-FA) for cognitive radio networks to overcome the obstacles. This proposed work focuses primarily on sensing the optimal secondary user channel and reducing the spectrum handoff delay in wireless networks. Several benchmark functions are utilized We analyze the efficacy of this innovative strategy by evaluating its performance. The performance of ANN-FA is 22.72 percent more robust and effective than that of the other metaheuristic algorithm, according to experimental findings. The proposed ANN-FA model is simulated using the NS2 simulator, The results are evaluated in terms of average interference ratio, spectrum opportunity utilization, three metrics are measured: packet delivery ratio (PDR), end-to-end delay, and end-to-average throughput for a variety of different CRs found in the network.