• Title/Summary/Keyword: load aware

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Improving Overall WMN Performance in Peak Times Using Load-sharing Aware Gateways

  • Vo, Hung Quoc;Dai, Tran Thanh;Hong, Choong-Seon
    • Annual Conference of KIPS
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    • 2007.05a
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    • pp.855-857
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    • 2007
  • In recent years, Wireless Mesh Network (WMN) is a compelling topic to many network researchers due to its low cost in deployment, ease and simplicity in installation and scalability and robustness in operation. In WMN, Gateway nodes (Access Point-AP) are in charge of steering the traffic from the external network (e.g. Internet...) to client devices or mesh clients. The limited bandwidth of wireless links between Gateways and intermediate mesh routers makes the Gateways becomes the bottleneck of the mesh network in both uplink stream and downlink stream. In this paper, we propose a mechanism to permit Gateways collaboratively work to manipulate the traffic to fit our network. They will move the traffic from congested links to the unused capacity on other links.

Load-Aware Cell Selection Method for Efficient Use of Network Resources (효율적 망 자원 이용을 위한 부하 인지 셀 선택 기법)

  • Park, Jaesung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.12
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    • pp.2443-2449
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    • 2015
  • Downlink (DL) data rate for a MS is influenced by not only the signal to interference and noise ratio (SINR) but also the amount of radio resources allocated to the MS. Therefore, when a MS uses SINR to select a cell to associate with, it cannot receive the fastest DL data rate all the time if it associates with a congested cell. Moreover, the SINR-based cell selection may result in cell loads unbalance, which decreases the efficiency of a network. To address the issue, we propose a novel cell selection method by considering not only SINR but also a cell load which are combined into two cell selection criteria. One is the maximum achievable data rate and the other is the minimum outage probability. The simulation results show that the cell selection based on the maximum achievable data rate is superior to the SINR-based method and the method using the minimum outage probability in terms of the system efficiency and the fairness in cell loads while the cell selection method based on the minimum outage probability is superior to the others in terms of the outage probability of a MS.

QoS-Aware Power Management of Mobile Games with High-Load Threads (CPU 부하가 큰 쓰레드를 가진 모바일 게임에서 QoS를 고려한 전력관리 기법)

  • Kim, Minsung;Kim, Jihong
    • KIISE Transactions on Computing Practices
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    • v.23 no.5
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    • pp.328-333
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    • 2017
  • Mobile game apps, which are popular in various mobile devices, tend to be power-hungry and rapidly drain the device's battery. Since a long battery lifetime is a key design requirement of mobile devices, reducing the power consumption of mobile game apps has become an important research topic. In this paper, we investigate the power consumption characteristics of popular mobile games with multiple threads, focusing on the inter-thread. From our power measurement study of popular mobile game apps, we observed that some of these apps have abnormally high-load threads that barely affect the user's gaming experience, despite the high energy consumption. In order to reduce the wasted power from these abnormal threads, we propose a novel technique that detects such abnormal threads during run time and reduces their power consumption without degrading user experience. Our experimental results on an Android smartphone show that the proposed technique can reduce the energy consumption of mobile game apps by up to 58% without any negative impact on the user's gaming experience.

MVC Architecture-aware Restructuring of Web Apps (MVC 아키텍처 인지하는 웹 앱 재구조화)

  • Oh, Jaewon;Ahn, Woo Hyun;Kim, Taegong
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.21 no.11
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    • pp.2153-2166
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    • 2017
  • Web apps have a problem that they cause same data to be repetitively retrieved, processed, and displayed when web browsers load different web pages. To resolve the problem, this paper presents and evaluates a new method for restructuring of Java web apps. This approach dynamically analyzes Java web apps from the MVC (Model-View-Controller) architecture point of view and identifies redundant data by using the composite view pattern. Then the input apps are restructured in order not to load the redundant data when users make requests for new pages. This restructuring generates new web apps that conform to the MVC architecture and improve the performance of input web apps. The experimental results showed that when compared to legacy web apps, the restructured apps' response time was reduced on desktop PCs and mobile devices by 38% and 55%, respectively. In addition, case studies using open-source web apps showed the applicability of the proposed approach.

Energy/Distance Estimation-based and Distributed Selection/Migration of Cluster Heads in Wireless Sensor Networks (센서 네트워크의 에너지 및 거리 추정 기반 분산 클러스터 헤드 선정과 이주 방법)

  • Kim, Dong-Woo;Park, Jong-Ho;Lee, Tae-Jin
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.3 s.357
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    • pp.18-25
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    • 2007
  • In sensor networks, sensor nodes have limited computational capacity, power and memory. Thus energy efficiency is one of the most important requirements. How to extend the lifetime of wireless sensor networks has been widely discussed in recent years. However, one of the most effective approaches to cope with power conservation, network scalability, and load balancing is clustering technique. The function of a cluster head is to collect and route messages of all the nodes within its cluster. Cluster heads must be changed periodically for low energy consumption and load distribution. In this paper, we propose an energy-aware cluster head selection algorithm and Distance Estimation-based distributed Clustering Algorithm (DECA) in wireless sensor networks, which exchanges cluster heads for less energy consumption by distance estimation. Our simulation result shows that DECA can improve the system lifetime of sensor networks up to three times compared to the conventional scheme.

Study on Squeak Noises in Car AVN Materials under High Load and Low Speed Conditions (고하중 저속 조건에서의 자동차 AVN 소재의 스퀵 소음에 관한 연구)

  • Tae Ho Park;HuiYing Jin;Jin Woo Jang;Jonghwan Suhr
    • Composites Research
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    • v.37 no.5
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    • pp.427-433
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    • 2024
  • As the automotive industry transitions from internal combustion engine vehicles (ICEV) to battery electric vehicles (BEVs), customers are becoming increasingly aware of and demanding solutions to squeak noises, especially from audio, video, and navigation (AVN) components. These noises occur under relatively high load and low speed conditions and cannot be reproduced on commercial friction test equipment. Therefore, a new friction testing machine was developed and evaluated in this study. This machine is a pin-on-disk type tribometer that can set up the squeak noises test conditions for AVN component materials and quantitatively measure acceleration, sound pressure, and displacement due to friction. The developed equipment was evaluated through two types of tests: the noise evaluation of well-known contact pairs, and the comparison test of the friction coefficient repeatability. The test results confirm that the developed test machine can be utilized for the evaluation of the squeak noise. In addition, it was also found that the characteristics of squeak noise in high load and low speed conditions can be defined as groan noise. Moreover, displacement, friction force, acceleration was found to have a relationship with sound amplitude with relation of more than R2 = 0.75. Acceleration can be a key parameter to predict squeak noise, since it has a strong correlation (R2 = 0.94) in high load low speed conditions.

Enhanced MAC Scheme to Support QoS Based on Network Detection over Wired-cum-Wireless Network

  • Kim, Moon;Ye, Hwi-Jin;Cho, Sung-Joon
    • Journal of information and communication convergence engineering
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    • v.4 no.4
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    • pp.141-146
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    • 2006
  • In these days, wireless data services are becoming ubiquitous in our daily life because they offers several fundamental benefits including user mobility, rapid installation, flexibility, and scalability. Moreover, the requests for various multimedia services and the Quality of Service (QoS) support have been one of key issues in wireless data communications. Therefore the research relative to Medium Access Control (MAC) has been progressing rapidly. Especially a number of QoS-aware MAC schemes have been introduced to extend the legacy IEEE 802.11 MAC protocol which has not guaranteed any service differentiation. However, none of those schemes fulfill both QoS features and channel efficiency although these support the service differentiation based on priority. Therefore this paper studies a novel MAC scheme, referred to as Enhanced Distributed Coordination Function with Network Adaptation (EDCF-NA), for enhancements of both QoS and medium efficiency. It uses a smart factor denoted by ACK rate and Network Load Threshold (TH). In this paper, we study how the value of TH has effect on MAC performance and how the use of optimal TH pair improves the overall MAC performance in terms of the QoS, channel utilization, collision rate, and fairness. In addition, we evaluate and compare both the performance of EDCF-NA depending on several pairs of TH and the achievement of various MAC protocols through simulations by using Network Simulator-2 (NS-2).

Adaptive Power Saving Protocol Based on Traffic Estimation for Wi-Fi Direct Networks (Wi-Fi Direct 망을 위한 부하량 예측 기반의 전력 절감 기법)

  • Yoo, Hongseok;Park, Yang-Woo;Lee, Chae-Soo;Yun, Tae-Jin
    • IEMEK Journal of Embedded Systems and Applications
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    • v.10 no.4
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    • pp.207-212
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    • 2015
  • Wi-Fi Direct allows battery powered mobile devices to form a wireless ad hoc network. Since one member of the network called Group Owner (GO) takes the role of managing the network, the network lifetime is mainly affected by the energy efficiency of GO. Hence, Wi-Fi Direct defines power saving schemes that allow GO to save the energy by turning off its radio interface during the periods called absence periods. However, the Wi-Fi Direct specification does not specify how to set parameters (denoted by PS parameters) determining the schedule of the absence periods. In this paper, we therefore propose a novel traffic-aware power saving scheme for Wi-Fi Direct networks. In particular, the proposed scheme estimates the application-level traffic load and adaptively tunes the PS parameters according to the estimated value.

WMPS: A Positioning System for Localizing Legacy 802.11 Devices

  • Gallo, Pierluigi;Garlisi, Domenico;Giuliano, Fabrizio;Gringoli, Francesco;Tinnirello, Ilenia
    • IEIE Transactions on Smart Processing and Computing
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    • v.1 no.2
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    • pp.106-116
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    • 2012
  • The huge success of location-aware applications has called for the rapid development of an alternative positioning system to the global positioning system (GPS) for indoor localization based on existing technologies, such as 802.11 wireless networks. This paper proposes the Wireless MAC Processor Positioning System (WMPS), which is a localization system running on off-the-shelf 802.11 Access Points and based on the time-of-flight ranging of users' standard terminals. This paper proves through extensive experiments that the propagation delays can be measured with the accuracy required by indoor applications despite the different noise components that can affect the result: latencies of the hardware transreceivers, multipath, ACK jitters and timer quantization. Key to this solution is the choice of the Wireless MAC Processor architecture, which enables a straightforward implementation of the ranging subsystem directly inside the commercial cards without affecting the basic DCF channel access algorithm. In addition to the proposed measurement framework, this study developed a simple and effective localization algorithm that can work without requiring any preliminary calibration or device characterization. Finally, the architecture allows the measurement methodology to be adjusted as a function of the network load or propagation environments at the run time, without requiring any firmware update.

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Evaluation of the Effects of a Grouping Algorithm on IEEE 802.15.4 Networks with Hidden Nodes

  • Um, Jin-Yeong;Ahn, Jong-Suk;Lee, Kang-Woo
    • Journal of Communications and Networks
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    • v.16 no.1
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    • pp.81-91
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    • 2014
  • This paper proposes hidden-node aware grouping (HAG) algorithm to enhance the performance of institute of electrical and electronics engineers (IEEE) 802.15.4 networks when they undergo either severe collisions or frequent interferences by hidden nodes. According to the degree of measured collisions and interferences, HAG algorithm dynamically transforms IEEE 802.15.4 protocol between a contention algorithm and a contention-limited one. As a way to reduce the degree of contentions, it organizes nodes into some number of groups and assigns each group an exclusive per-group time slot during which only its member nodes compete to grab the channel. To eliminate harmful disruptions by hidden nodes, especially, it identifies hidden nodes by analyzing the received signal powers that each node reports and then places them into distinct groups. For load balancing, finally it flexibly adapts each per-group time according to the periodic average collision rate of each group. This paper also extends a conventional Markov chain model of IEEE 802.15.4 by including the deferment technique and a traffic source to more accurately evaluate the throughput of HAG algorithm under both saturated and unsaturated environments. This mathematical model and corresponding simulations predict with 6%discrepancy that HAG algorithm can improve the performance of the legacy IEEE 802.15.4 protocol, for example, even by 95% in a network that contains two hidden nodes, resulting in creation of three groups.