• Title/Summary/Keyword: Equivalent networks

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Partly Random Multiple Weighting Matrices Selection for Orthogonal Random Beamforming

  • Tan, Li;Li, Zhongcai;Xu, Chao;Wang, Desheng
    • Journal of Communications and Networks
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    • v.18 no.6
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    • pp.892-901
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    • 2016
  • In the multi-user multiple-input multiple-output (MIMO) system, orthogonal random beamforming (ORBF) scheme is proposed to serve multiple users simultaneously in order to achieve the multi-user diversity gain. The opportunistic space-division multiple access system (OSDMA-S) scheme performs multiple weighting matrices during the training phase and chooses the best weighting matrix to be used to broadcast data during the transmitting phase. The OSDMA-S scheme works better than the original ORBF by decreasing the inter-user interference during the transmitting phase. To save more time in the training phase, a partly random multiple weighting matrices selection scheme is proposed in this paper. In our proposed scheme, the Base Station does not need to use several unitary matrices to broadcast pilot symbol. Actually, only one broadcasting operation is needed. Each subscriber generates several virtual equivalent channels with a set of pre-saved unitary matrices and the channel status information gained from the broadcasting operation. The signal-to-interference and noise ratio (SINR) of each beam in each virtual equivalent channel is calculated and fed back to the base station for the weighting matrix selection and multi-user scheduling. According to the theoretical analysis, the proposed scheme relatively expands the transmitting phase and reduces the interactive complexity between the Base Station and subscribers. The asymptotic analysis and the simulation results show that the proposed scheme improves the throughput performance of the multi-user MIMO system.

Logic Implementation of HDB3 Codec (HDB3 Codec의 로직구현)

  • Eom, Joon;Kim, Young-Kil
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.22 no.2
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    • pp.369-374
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    • 2018
  • The Line Code is a code used for data transmission and is a coding method used to prevent loss of data between transmitter and receiver. There are various kinds of line code such as B3ZS, HDB3, B8ZS, and HDB3 code is used in the tactical communication networks of Korea. In this paper, we implement the HDB3 Codec that is used in tactical communication networks in order to eliminate the risk factors for component discontinuance and to shorten development period and ensure reliability. Also it is confirmed that it can be implement by minimizing the amount of logic usage so that it can be used unrestrictedly in systems using FPGA and the implemented HDB3 Codec is simulated to confirm that it is equivalent to the performance of HDB3 Codec IC.

First- and Second-best Pricing in Stable Dynamic Models (안정동력학 모형에서 최선 통행료 및 차선 통행료)

  • Park, Koo-Hyun
    • Journal of the Korean Operations Research and Management Science Society
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    • v.34 no.4
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    • pp.123-138
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    • 2009
  • This study examined the first- and second-best pricing by stable dynamics in congested transportation networks. Stable dynamics, suggested by Nesterov and de Palma (2003), is a new model which describes and provides a stable state of congestion in urban transportation networks. The first-best pricing in user equilibrium models introduces user-equilibrium in the system-equilibrium by tolling the difference between the marginal social cost and the marginal private cost on each link. Nevertheless, the second-best pricing, which levies the toll on some, but not all, links, is relevant from the practical point of view. In comparison with the user equilibrium model, the stable dynamic model provides a solution equivalent to system-equilibrium if it is focused on link flows. Therefore the toll interval on each link, which keeps up the system-equilibrium, is more meaningful than the first-best pricing. In addition, the second-best pricing in stable dynamic models is the same as the first-best pricing since the toll interval is separately given by each link. As an effect of congestion pricing in stable dynamic models, we can remove the inefficiency of the network with inefficient Braess links by levying a toll on the Braess link. We present a numerical example applied to the network with 6 nodes and 9 links, including 2 Braess links.

Dynamic Slot Allocation Algorithm of Wireless ATM (무선 ATM에서의 동적 슬롯 할당 알고리즘)

  • Lee, Ji-Hyun;Yu, So-Young;Seo, Ju-Ha
    • Journal of Industrial Technology
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    • v.21 no.A
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    • pp.189-198
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    • 2001
  • In recent years, the predominant part in telecommunications is mobile communications. The next generation network is extending today's voice-only mobile networks to multi-service networks. ATM Network is possible to carry such multi-media traffic and it will be expect to use wireless ATM for the future mobile access network. One of manly important aspects for the performance of wireless ATM is the Medium Access Control (MAC) protocol. The MAC protocol must be able to satisfyingly handle the different ATM services (CBR, VBR, ABR and UBR) with their radically different performance requirements. Additionally, the MAC protocol must be able to cope with the complex radio environment where fading, multi-path propagation interference and burst-errors further complicate the situation. In this paper, a dynamic slot allocation algorithm in wireless ATM is proposed for an efficient channel sharing/media access at the MAC layer. We use equivalent capacity in the allocation of slots for VBR traffic which is variable along the time. It is simple and effective slot allocation method for VBR service. In particular, we consider the slot allocation of a session consisted of several connections for requirement of multimedia traffic. Simulation shows that the cell loss ratio is reduced by re-allocation of extra slots in Mobile Terminal (MT).

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Fusion of Decisions in Wireless Sensor Networks under Non-Gaussian Noise Channels at Large SNR (비 정규 분포 잡음 채널에서 높은 신호 대 잡음비를 갖는 무선 센서 네트워크의 정보 융합)

  • Park, Jin-Tae;Kim, Gi-Sung;Kim, Ki-Seon
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.5
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    • pp.577-584
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    • 2009
  • Fusion of decisions in wireless sensor networks having flexibility on energy efficiency is studied in this paper. Two representative distributions, the generalized Gaussian and $\alpha$-stable probability density functions, are used to model non-Gaussian noise channels. By incorporating noise channels into the parallel fusion model, the optimal fusion rules are represented and suboptimal fusion rules are derived by using a large signal-to-noise ratio(SNR) approximation. For both distributions, the obtained suboptimal fusion rules are same and have equivalent form to the Chair-Varshney fusion rule(CVR). Thus, the CVR does not depend on the behavior of noise distributions that belong to the generalized Gaussian and $\alpha$-stable probability density functions. The simulation results show the suboptimality of the CVR at large SNRs.

Threshold Based Buffer Management Algorithm for Fairness Improvement between Input Channels in ATM Networks (ATM 망에서 채널간 공평성 향상을 위한 문턱값 기반 버퍼 관리 알고리즘)

  • 고유신;강은성;고성택
    • Journal of the Institute of Convergence Signal Processing
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    • v.5 no.1
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    • pp.79-83
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    • 2004
  • The purpose of ATM traffic management is to protect the network using minimum resources and guarantee the requred QoS and also it is desirable to provide fairness between input channels. In this paper, we propose the TBBM(threshold based buffer management) algorithm to improve fairness between input channels and utilization of ATM networks. TBBM algorithm controls output cell rate dynamically based on threshold. The result shows that the required bandwidth of the TBBM algorithm is 14.3% lower in audio traffic and 41.8% lower in video traffic than that of theoretically calculated equivalent capacity method. and also reveals that the TBBM algorithm provide improved CLR fairness between input channels

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Study of Mechanical Modeling of Oval-shaped Piezoelectric Energy Harvester (타원형 압전 에너지 하베스터의 기계적 모델링 연구)

  • Choi, Jaehoon;Jung, Inki;Kang, Chong-Yun
    • Journal of Sensor Science and Technology
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    • v.28 no.1
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    • pp.36-40
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    • 2019
  • Energy harvesting is an advantageous technology for wireless sensor networks (WSNs) that dispenses with the need for periodic replacement of batteries. WSNs are composed of numerous sensors for the collection of data and communication; hence, they are important in the Internet of Things (IoT). However, due to low power generation and energy conversion efficiency, harvesting technologies have so far been utilized in limited applications. In this study, a piezoelectric energy harvester was modeled in a vibration environment. This harvester has an oval-shaped configuration as compared to the conventional cantilever-type piezoelectric energy harvester. An analytical model based on an equivalent circuit was developed to appraise the advantages of the oval-shaped piezoelectric energy harvester in which several structural parameters were optimized for higher output performance in given vibration environments. As a result, an oval-shaped energy harvester with an average output power of 2.58 mW at 0.5 g and 60 Hz vibration conditions was developed. These technical approaches provided an opportunity to appreciate the significance of autonomous sensor networks.

Strategic Alliance Networks in Korean Construction Industry: Network Structure and Performance of Firms (국내건설기업의 제휴네트워크 : 네트워크 구조와 성과)

  • Kim, Kon-Shik;Shin, Tack-Hyun
    • Korean Journal of Construction Engineering and Management
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    • v.10 no.4
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    • pp.151-164
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    • 2009
  • Strategic alliances developed as formalized inter-organizational relationships are core vehicles to share information, resources and knowledge. The structural characteristics of strategic network constructed by strategic alliances have been important agenda in strategic management discipline. This paper has two folds in analysing the strategic network formulated by project level alliances in Korean construction industry. First, we investigate the strategic network using the tools and methods of social network analysis, such as centrality, cohesion, structural equivalence, and power law. Second, the performance of firms within networks are analysed longitudinally with panel data analysis. We have found that the strategic networks in this industry has scale-free characteristics, where the degree distribution fits the power law, and the vertically equivalent structure is clear. We also present that the performance of firms are continuously affected by the degree centrality of firms in this network for the last 10 years.

Preventing ID Mapping Attacks on DHT Networks through Non-Voluntary Node Locating (비 자율적 노드 위치 결정을 통한 DHT 네트워크 ID 매핑 공격 방지)

  • Lee, Cheolho;Choi, Kyunghee;Chung, Kihyun;Kim, Jongmyung;Yun, Youngtae
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.23 no.4
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    • pp.695-707
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    • 2013
  • DHT(Distributed Hash Table) networks such as Kademlia are vulnerable to the ID mapping attack caused by the voluntary DHT mapping structure where the location of a node is solely determined by itself on the network topology. This causes security problems such as eclipse, DRDoS and botnet C&C on DHT networks. To prevent ID mapping attacks, we propose a non-voluntary DHT mapping scheme and perform analysis on NAT compatibility, attack resistance, and network dynamicity. Analysis results show that our approach may have an equivalent level of attack resistance comparing with other defense mechanisms and overcome their limitations including NAT compatibility and network dynamicity.

Range-free localization algorithm between sensor nodes based on the Radical Line for Sensor Networks (센서 네트워크를 위한 Radical line을 기반으로 한 센서 노드간의 Range-free 지역화 알고리즘)

  • Shin, Bong Hi;Jeon, Hye Kyoung
    • Journal of Digital Convergence
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    • v.14 no.8
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    • pp.261-267
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    • 2016
  • In this paper, we studied the range-free localization algorithm between sensor nodes based on the Radical Line for sensor networks. Routing in wireless sensor networks should reduce the overall energy consumption of the sensor network, or induce equivalent energy consumption of all the sensor nodes. In particular, when the amount of data to send more data, the energy consumption becomes worse. New methods have been proposed to address this. So as to allow evenly control the overall energy consumption. For this, the paper covers designing a localization algorithm that can obtain the location information of the peripheral nodes with fewer operations. For the operation of the algorithm is applicable Radical Line. The experimental environment is windows 7, the Visual C ++ 2010, MSSQL 2008. The experimental results could be localized to perform an error rate of 0.1837.