• Title/Summary/Keyword: channel configuration

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State-Aware Re-configuration Model for Multi-Radio Wireless Mesh Networks

  • Zakaria, Omar M.;Hashim, Aisha-Hassan Abdalla;Hassan, Wan Haslina;Khalifa, Othman Omran;Azram, Mohammad;Goudarzi, Shidrokh;Jivanadham, Lalitha Bhavani;Zareei, Mahdi
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.1
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    • pp.146-170
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    • 2017
  • Joint channel assignment and routing is a well-known problem in multi-radio wireless mesh networks for which optimal configurations is required to optimize the overall throughput and fairness. However, other objectives need to be considered in order to provide a high quality service to network users when it deployed with high traffic dynamic. In this paper, we propose a re-configuration optimization model that optimizes the network throughput in addition to reducing the disruption to the mesh clients' traffic due to the re-configuration process. In this multi-objective optimization model, four objective functions are proposed to be minimized namely maximum link-channel utilization, network average contention, channel re-assignment cost, and re-routing cost. The latter two objectives focus on reducing the re-configuration overhead. This is to reduce the amount of disrupted traffic due to the channel switching and path re-routing resulted from applying the new configuration. In order to adapt to traffic dynamics in the network which might be caused by many factors i.e. users' mobility, a centralized heuristic re-configuration algorithm called State-Aware Joint Routing and Channel Assignment (SA-JRCA) is proposed in this research based on our re-configuration model. The proposed algorithm re-assigns channels to radios and re-configures flows' routes with aim of achieving a tradeoff between maximizing the network throughput and minimizing the re-configuration overhead. The ns-2 simulator is used as simulation tool and various metrics are evaluated. These metrics include channel-link utilization, channel re-assignment cost, re-routing cost, throughput, and delay. Simulation results show the good performance of SA-JRCA in term of packet delivery ratio, aggregated throughput and re-configuration overhead. It also shows higher stability to the traffic variation in comparison with other compared algorithms which suffer from performance degradation when high traffic dynamics is applied.

A Performance Analysis and Experiments on Plastic Film/Paper Humidifying Elements Consisting of Horizontal Air Channels and Vertical Water Channels (수평 공기 채널과 수직 물 채널로 구성된 플라스틱 필름/종이 가습 소자의 성능)

  • Kim, Nae-Hyun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.1
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    • pp.55-63
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    • 2016
  • New materials and shapes for a humidifying element were developed which outperformed the widely used crisscross glass wool Glasdek media design. The new material consists of 50% cellulose and 50% PET. The parallel channel configuration was devised to reduce excessive pressure loss caused by the reduced height (from 7.0 mm to 5.0 mm) of the crisscross configuration. For the same crisscross configuration, the humidification efficiency of the cellulose/PET element was 26% higher than that of the glass wool element. For the same cellulose/PET material, humidification efficiency of the parallel channel configuration was 14% higher than that of the crisscross configuration. As for the pressure drops, the cellulose/PET element was 2-52% higher than those of the glass wool element. For the same cellulose/PET material, the pressure drop of the parallel channel configuration was 14% higher than that of the crisscross configuration. Data were compared against the predictions from existing correlations and those by the proposed model.

Development of a MIMO-OTA System with Simplified Configuration

  • Karasawa., Yoshio;Gunawan, Yannes;Pasisingi, Sahrul;Nakada, Katsuhiro;Kosako, Akira
    • Journal of electromagnetic engineering and science
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    • v.12 no.1
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    • pp.77-84
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    • 2012
  • This paper introduces our development of a MIMO-OTA system with simplified configuration. The key element of our proposal is the adoption of an antenna branch-controlled configuration for generating multipath delayed waves. The signal processing is carried out on IF band signal with an FPGA in a fading-emulator-type MIMO-OTA measurement system. The proposed scheme is largely different from available system configurations for the fading simulator method of constructing the OTA test environment. We describe the principle of the proposed scheme, channel model incorporated in the system, basic configuration of the developed system, and its performance.

The effect of Inclined angle of Channel with multi heat source on Thermal Stability of Electronic Equipment (다수의 열원을 가진 채널의 경사각이 전자장비의 열적 안정성에 미치는 영향)

  • 방창훈;김정수;예용택
    • Journal of the Korean Society of Safety
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    • v.16 no.3
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    • pp.12-18
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    • 2001
  • The objective of the present work is to examine the effect of inclined angle of channel with multi heat source on thermal stability of electronic equipment. The heat sources are mounted on both sides of channel walls by two kinds of configuration such as the zig-zag md symmetric on. Conductive heat transfer was estimated by using of thermocouples and heat flux sensor. Thus, convective heat transfer and mean Nusselt number could be obtained. With increased inclined angle, the convective heat transfer coefficient was decreased. When inclined angle was smaller than 30 degree, The average Nusselt number of Big-zag configuration was larger than that of symmetric. Furthermore, when protruding ration was 0.082, the temperature was strongly affected by inclined angle. whereas, when protruding ration was 0.25, the temperature was strongly affected by heat source configuration.

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An Efficient Channel Selection and Power Allocation Scheme for TVWS based on Interference Analysis in Smart Metering Infrastructure

  • Huynh, Chuyen Khoa;Lee, Won Cheol
    • Journal of Communications and Networks
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    • v.18 no.1
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    • pp.50-64
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    • 2016
  • Nowadays, smart meter (SM) technology is widely effectively used. In addition, power allocation (PA) and channel selection (CS) are considered problems with many proposed approaches. In this paper, we will suggest a specific scenario for an SM configuration system and show how to solve the optimization problem for transmission between SMs and the data concentrator unit (DCU), the center that collects the data from several SMs, via simulation. An efficient CS with PA scheme is proposed in the TV white space system, which uses the TV band spectrum. On the basic of the optimal configuration requirements, SMs can have a transmission schedule and channel selection to obtain the optimal efficiency of using spectrum resources when transmitting data to the DCU. The optimal goals discussed in this paper are the maximum capacity or maximum channel efficiency and the maximum allowable power of the SMs used to satisfy the quality of service without harm to another wireless system. In addition, minimization of the interference to the digital television system and other SMs is also important and needs to be considered when the solving coexistence scenario. Further, we propose a process that performs an interference analysis scheme by using the spectrum engineering advanced Monte Carlo analysis tool (SEAMCAT), which is an integrated software tool based on a Monte-Carlo simulation method. Briefly, the process is as follows: The optimization process implemented by genetic evolution optimization engines, i.e., a genetic algorithm, will calculate the best configuration for the SM system on the basis of the interference limitation for each SM by SEAMCAT in a specific configuration, which reaches the solution with the best defined optimal goal satisfaction.

The Heat Transfer and Pressure Drop Characteristics on Microchannel PCHE with various Configurations (채널 형상에 따른 마이크로채널 PCHE의 열전달 및 압력강하 특성)

  • Kim, Yoon-Ho;Moon, Jung-Eun;Lee, Kyu-Jung
    • Proceedings of the SAREK Conference
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    • 2008.11a
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    • pp.215-220
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    • 2008
  • A microchannel PCHE is manufactured by the two technologies of micro photo-etching and diffusion bonding. In this paper, heat transfer and pressure drop characteristics by applying various configuration for the flow channel in the microchannel PCHE is experimentally investigated. The flow channel configurations are designed three types such as straight, wavy and offset strip channels. The performance experiment of each configuration is performed for Reynolds numbers in ranges of $100{\sim}700$ under various flow conditions for the hot side and the Reynolds number of cold side is fixed at 350. The inlet temperatures of the hot side and cold side are conducted as $40^{\circ}C$ and $20^{\circ}C$, respectively. The heat transfer performance of wavy channel, which was similar to that of offset strip channel, was much higher than that of straight channel. The effectiveness of wavy channel and offset strip channel was evaluated as about $0.5{\sim}0.9$. The pressure drop of wavy channel was highest among configurations and that of offset strip channel was lower than that of straight channel because the round curved surface of each strip edge was reduced the pressure loss.

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MIMO Channel Capacity and Configuration Selection for Switched Parasitic Antennas

  • Pal, Paramvir Kaur;Sherratt, Robert Simon
    • ETRI Journal
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    • v.40 no.2
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    • pp.197-206
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    • 2018
  • Multiple-input multiple-output (MIMO) systems offer significant enhancements in terms of their data rate and channel capacity compared to traditional systems. However, correlation degrades the system performance and imposes practical limits on the number of antennas that can be incorporated into portable wireless devices. The use of switched parasitic antennas (SPAs) is a possible solution, especially where it is difficult to obtain sufficient signal decorrelation by conventional means. The covariance matrix represents the correlation present in the propagation channel, and has significant impact on the MIMO channel capacity. The results of this work demonstrate a significant improvement in the MIMO channel capacity by using SPA with the knowledge of the covariance matrix for all pattern configurations. By employing the "water-pouring algorithm" to modify the covariance matrix, the channel capacity is significantly improved compared to traditional systems, which spread transmit power uniformly across all the antennas. A condition number is also proposed as a selection metric to select the optimal pattern configuration for MIMO-SPAs.

HIGH RESOLUTION IMAGE ACQUISITION MODE USING PANCHROMATIC REDUNDANT CHANNEL

  • Chang, Young-Jun;Kong, Jong-Pil;Huh, Haeng-Pal;Kim, Young-Sun;Park, Jong-Uk
    • Proceedings of the KSRS Conference
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    • v.2
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    • pp.800-803
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    • 2006
  • The Space-borne electro-optical camera system, like KOMPSAT has panchromatic redundant image channel as well as primary channel in order to increase reliability of satellite system. In most case redundant channel never been used during the whole mission period. Staggered array configuration using redundant image channel and new operation mode proposed which operates primary and redundant channel simultaneously. Without new hardware design, fast electronics and system complexity, we can get 1.414 times more fine GSD image of original system and aliasing effect which corrupt high frequency information of image can be minimized. To get the more efficiency from staggered array configuration, we introduce masked pixel CCD.

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Numerical Study of Heat Transfer Enhancement on Microchannel Plate Heat Exchanger with Channel Shape (채널 형상에 따른 마이크로채널 판형 열교환기 열전달 성능 향상에 관한 수치 연구)

  • Jeon, Seung-Won;Kim, Yoon-Ho;Lee, Kyu-Jung
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.1888-1893
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    • 2007
  • In this study, the microchannel plated heat exchanger were numerically studied for the enhancement of heat transfer in the channel configuration. Unit cold and hot fluid region with the microchannel were modeled and periodic boundary condition at the side wall was applied to continuously repeating geometry. The material of micro-structured plate is STS304 and working fluid is water. Triangular obstacles were placed in micro channel to enhance heat transfer. The performance of microchannel plated heat exchangers were numerically investigated with various obstacle configuration and Reynolds number under the parallel and counter flows. Heat transfer rate has increased about 18% compared with straight channel, but pressure drop also increased about 3.5 times. The main factor of increasing of pressure drop and heat transfer rate is considered that the momentum was lost to collide against obstacles, generation of secondary flow and boundary layer separation, wake and vortex forming phenomena.

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Design and Fabrication of the 1-Channel Monopulse Receiver (단일채널 모노펄스수신기 설계 및 제작)

  • Kwon, Hyuk-Ja;Lee, Young-Jin;Kang, Byoung-Wook
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.12
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    • pp.3-9
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    • 2015
  • In this paper, we propose the operation procedures of the 1-channel monopulse receiver which achieves the new configuration. Also, we analyzed the monopulse ratio and the target angle accuracy of the fabricated receiver by using the monopulse signal generator developed for verifying the proposal equipment. As a result, it is apparent that the monopulse ratio of the proposal receiver is equal to that of the 3-channel monopulse receiver. Also, the fabricated receiver exhibits the target angle accuracy with fewer than 0.1 RMS. The proposal receiver achieves the simple receiver configuration and the simple tracking procedures, as contrasted with the 3-channel monopulse receiver. Also, the proposal receiver has advantages in terms of size, weight, cost and power. Because the proposal monopulse receiver requires 1-channel receiver and needs not the signal processor in comparison with 3-channel monopulse receiver which requires 3-channel receiver and need the signal processor.