• Title/Summary/Keyword: Hierarchical Networks

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Performance Analysis of Optimal Tracking Load Balance Scheme in Hierarchical LTE Networks (계층적 LTE 네트워크에서 최적의 트래킹 로드밸런스 기법의 성능분석)

  • Jeon, Minsu;Jeong, Jongpil
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.6
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    • pp.9-21
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    • 2013
  • Tracking is a process which explores user equipment (UE) in the area of tracking in terms of cells. In this paper, two tracking schemes based on macrocell-microcell tiers in hierarchical LTE networks, PMMT and IMMT, are evaluated. In this network, UE can receive a signal from macrocells and overlapping microcells, and can be called from each macrocell or microcell-tier in the PMMT. Also, the UE can be called from the combined macrocell-tier and microcell-tier in the IMMT. Finally, we analyze the optimization of load balance between marcocell-tier and microcell-tier, and an analytical model is developed to evaluate those two arrangements.

Beamforming Strategy Using Adaptive Beam Patterns and Power Control for Common Control Channel in Hierarchical Cell Structure Networks

  • You, Cheol-Woo;Jung, Young-Ho;Cho, Sung-Hyun
    • Journal of Communications and Networks
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    • v.13 no.4
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    • pp.319-326
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    • 2011
  • Beamforming techniques have been successfully utilized for traffic channels in order to solve the interference problem. However, their use for control channels has not been sufficiently investigated. In this paper, a (semi-) centralized beamforming strategy that adaptively changes beam patterns and controls the total transmit power of cells is proposed for the performance enhancement of the common channel in hierarchical cell structure (HCS) networks. In addition, some examples of its practical implementation with low complexity are presented for two-tier HCS networks consisting of macro and pico cells. The performance of the proposed scheme has been evaluated through multi-cell system-level simulations under optimistic and pessimistic interference scenarios. The cumulative distribution function of user geometry or channel quality has been used as a performance metric since in the case of common control channel the number of outage users is more important than the sum rate. Simulation results confirm that the proposed scheme provides a significant gain compared to the random beamforming scheme as well as conventional systems that do not use the proposed algorithm. Finally, the proposed scheme can be applied simultaneously to several adjacent macro and pico cells even if it is designed primarily for the pico cell within macro cells.

Segmentation of Range Images Using Hierachical Structure of Neural Networks (계층적 구조의 신경회로망을 이용한 거리영상의 분할)

  • 정인갑;현기호;이준재;하영호
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.31B no.10
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    • pp.123-129
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    • 1994
  • The segmentation of range image is essential to recognize the three dimensional object. Generally, surface curvature is well-known feature for segmentation and classification of the fange image, but it is sensitive to noies. In this paper, we propose the structure of hierarchical neural network using surface curvature for segmentation of range images. The hierarchical structure of neural networks is robust to noise and the result of segmentaion is better than conventional optimization method of single level.

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Hierarchical Fair Queueing: A Credit-based Approach for Hierarchical Link Sharing

  • Jun, Andrew Do-Sung;Choe, Jin-Woo;Leon-Garcia, Alberto
    • Journal of Communications and Networks
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    • v.4 no.3
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    • pp.209-220
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    • 2002
  • In this paper, we propose a hierarchical packet scheduling technique to closely approximate a hierarchical extension of the generalized processor sharing model, Hierarchical Generalized Processor Sharing (H-GPS). Our approach is to undertake the tasks of service guarantee and hierarchical link sharing in an independent manner so that each task best serves its own objective. The H-GPS model is decomposed into two separate service components: the guaranteed service component to consistently provide performance guarantees over the entire system, and the excess service component to fairly distribute spare bandwidth according to the hierarchical scheduling rule. For tight and harmonized integration of the two service components into a single packet scheduling algorithm, we introduce two novel concepts of distributed virtual time and service credit, and develop a packet version of H-GPS called Hierarchical Fair Queueing (HFQ). We demonstrate the layerindependent performance of the HFQ algorithm through simulation results.

Design and Evaluation of a Fuzzy Hierarchical Location Service for Mobile Ad Hoc Networks

  • Bae, Ihn-Han;Kim, Yoon-Jeong
    • Journal of the Korean Data and Information Science Society
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    • v.18 no.3
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    • pp.757-766
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    • 2007
  • Location services are used in mobile ad hoc and hybrid networks to locate either the geographic position of a given node in the network or a data item. One of the main usages of position location services is presented in location based routing algorithms. In particular, geographic routing protocols can route messages more efficiently to their destinations based on the destination node's geographic position, which is provided by a location service. In this paper, we propose an adaptive location service on the basis of fuzzy logic called FHLS (Fuzzy Hierarchical Location Service) for mobile ad hoc networks. The adaptive location update scheme using the fuzzy logic on the basis of the mobility and the call preference of mobile nodes is used by the FHLS. The performance of the FHLS is to be evaluated by a simulation, and compared with that of existing HLS scheme.

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A Synchronization Scheme for Hierarchical Video Streams over Heterogeneous Networks

  • Sohn, Yejin;Cho, Minju;Seo, Minjae;Paik, Jongho
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.9 no.8
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    • pp.3121-3135
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    • 2015
  • Owing to the increase in consumption of multimedia content and the improvement of device capacity, user demand for high-quality content has increased. However, it is difficult to transport such large amounts of content over the existing broadcasting network with limited bandwidth. To provide high-definition broadcasting, some studies suggest methods of transporting multimedia over heterogeneous networks after encoding content hierarchically. MPEG Media Transport (MMT), standardized by Moving Picture Experts Group (MPEG), is a solution that enables large-volume media transport over heterogeneous networks such as digital broadcasting networks and packet-switched networks. In the case of delivering a scalable encoded video over different networks, synchronization of each stream is an important issue. MMT defines a synchronization scheme, but does not contain sufficient functions to implement it. In this paper, we propose a synchronization scheme for media streams that are encoded hierarchically, divided into layers, and transported over heterogeneous networks. We implement our scheme using MMT and HTTP, and experimented using three encapsulated video streams with different durations. As a result, we show that the proposed scheme can reduce the waiting time to display high-quality video, relative to Dynamic Adaptive Streaming over HTTP-Scalable Video Coding (DASH-SVC) by requesting segments of enhanced layers after calculating the transmission time. Additionally, we find out that the selection of durations have a relation to the characteristics of the video.

Implementation of Service Architecture for Hierarchical UHD Broadcasting over Heterogeneous Networks (이기종망에서 계층 부호화된 UHD 방송을 위한 서비스 아키텍처 구현)

  • Seo, Minjae;Paik, Jong Ho
    • Journal of Satellite, Information and Communications
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    • v.9 no.4
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    • pp.38-41
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    • 2014
  • Due to the diversity of device performances and the possibility of providing multimedia service through many networks, media consumption environment has been changed in various ways. In recent, mobile services and broadcasting services started to provided through IP network. According to this flow changes, there was great demand for various multimedia services through heterogenous networks. To solve this problem, MMT was suggested as a standard of multimedia transport which replaces MPEG-2 TS(Transport Stream) which is used for HD(High Definition) transport. MMT can be provided various broadcasting based on IP through terrestrial, satellite, cable broadcasting networks, and also deliver multimedia through many networks at the same time. MMT was risen as a method of servicing UHD broadcasting. In this paper, we present an implementation of service architecture for hierarchical UHD broadcasting over heterogenous networks using MMT.

Spatiotemporal chlorine residual prediction in water distribution networks using a hierarchical water quality simulation technique (계층적 수질모의기법을 이용한 상수관망시스템의 시공간 잔류염소농도 예측)

  • Jeong, Gimoon;Kang, Doosun;Hwang, Taemun
    • Journal of Korea Water Resources Association
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    • v.54 no.9
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    • pp.643-656
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    • 2021
  • Recently, water supply management technology is highly developed, and a computer simulation model plays a critical role for estimating hydraulics and water quality in water distribution networks (WDNs). However, a simulation of complex large water networks is computationally intensive, especially for the water quality simulations, which require a short simulation time step and a long simulation time period. Thus, it is often prohibitive to analyze the water quality in real-scale water networks. In this study, in order to improve the computational efficiency of water quality simulations in complex water networks, a hierarchical water-quality-simulation technique was proposed. The water network is hierarchically divided into two sub-networks for improvement of computing efficiency while preserving water quality simulation accuracy. The proposed approach was applied to a large-scale real-life water network that is currently operating in South Korea, and demonstrated a spatiotemporal distribution of chlorine concentration under diverse chlorine injection scenarios.

Proposal of Traffic Management Strategy between Hierarchical Mobile-WiMAX/WLAN Networks (계층적 Mobile-WiMAX/WLAN 네트워크에서의 트래픽 관리 전략에 관한 연구연구)

  • Moon, Tae-Wook;Kim, Moon;Cho, Sung-Jun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.1
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    • pp.153-160
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    • 2009
  • A hierarchical network between Mobile-WiMAX and WLAN systems is to make it possible to utilize wireless internet services including time sensitive applications such as VoIP, VOD, visual telephony etc. During the process of vertical handoff decision from Mobile-WiMAX to WLAN hotspot, vertical handoff delay causes user dissatisfaction because it doesn't provide the seamless wireless internet service. We make use of type of service (ToS) parameters in IEEE 802.16e specification as the criterion parameter of vertical handoff decision process in hierarchical Mobile-WiMAX/WLAN networks. In this paper, we propose the process of vertical handoff decision for seamless wireless internet service which is sensitive to time delay. If type of service is time sensitive application, the decision of vertical handoff is withdrawn until the service is terminated. In focus on user satisfaction, if the proposed traffic management strategy in hierarchical Mobile-WiMAX/WLAN networks is used, user will utilize seamless wireless internet services including time sensitive applications.

Adaptive Proportional Fair Scheduling for WWAN/WLAN Two-Hop Wireless Relay Networks (WWAN/WLAN 2-홉 무선 중계 네트워크를 위한 적응형 비례 공정 스케줄링 기법)

  • Koo, Young-Dae;Park, Joon-Sang;Han, Seung-Jae
    • Journal of KIISE:Computing Practices and Letters
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    • v.14 no.7
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    • pp.743-747
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    • 2008
  • Hierarchical overlay of heterogeneous wireless cells is considered as a promising architecture for next-generation wireless networks. This paper considers a special form of such architecture, WWAN/WLAN two-hop wireless relay networks. We first describe an undesirable scheduling phenomenon that the conventional proportional fair algorithm can cause in such networks. We, then, propose an enhanced proportional fair scheduling to remedy this problem. We demonstrate the performance of the proposed scheme via a simulation of UMTS/WLAN networks using NS-2.