• Title/Summary/Keyword: Avoidance ratio

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Dynamic Carrier Sensing Threshold Scheme based on SINR for Throughput Improvement in MANET (MANET에서 처리율 향상을 위한 SINR 기반 동적 캐리어 감지 임계값 방법)

  • Lee, Hyun-No;Kim, Dong-Hoi
    • Journal of Digital Contents Society
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    • v.15 no.3
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    • pp.319-326
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    • 2014
  • IEEE 802.11 WLAN uses CSMA/CA(Carrier Sense Multiple Access/Collision Avoidance) method in MAC(Media Access Control) protocol, and through the carrier sense checks whether other users use the channel during the data transmission to avoid the data collision. Currently, IEEE 802.11 standard recommends the use of a fixed threshold which gives an impact on carrier sensing range. However, the existing scheme using the fixed threshold causes the operation of network to be inefficiency owing to the mobility in MANET(Mobile Ad hoc NETwork). In this paper, we found the better network throughput to be obtained by applying the proposed scheme, which chooses properly the carrier sensing threshold and transmission rate considering SINR(Signal to Interference-plus-Noise Ratio), to the MANET.

A Study on the CSMA/CA Performance Improvement based IEEE 802.15.6 (IEEE 802.15.6 기반 CSMA/CA 성능 향상에 관한 연구)

  • Lee, Jung-Jae;Kim, Ihn-Hwan
    • The Journal of the Korea institute of electronic communication sciences
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    • v.10 no.11
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    • pp.1225-1230
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    • 2015
  • MAC protocol for WBAN performs CSMA/CA(:Carrier Sense Multiple Access with Collision Avoidance)algorithm that handles traffic which occurs in emergency with top priority in order to deal with variable data of sensor node for medicine. Emergency message that node sends undergoes collision and delay of transmission by retransmission of emergency message and waste of energy by retransmission. This paper suggests algorithm that minimizes loss of frame caused by collision and applies different backoff parameters by setting order of priority between MAC instruction frame and data frame in CSMA/CA algorithm case which applies order of priority queuing to improve aforementioned problem. According to performance evaluation, it has been found that using suggested MAC protocol showed lower collision probability, higher packet transmission processing ratio and lower packet loss compared with using IEEE 802.15.6.

A Study of Localization Algorithm of HRI System based on 3D Depth Sensor through Capstone Design (캡스톤 디자인을 통한 3D Depth 센서 기반 HRI 시스템의 위치추정 알고리즘 연구)

  • Lee, Dong Myung
    • Journal of Engineering Education Research
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    • v.19 no.6
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    • pp.49-56
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    • 2016
  • The Human Robot Interface (HRI) based on 3D depth sensor on the docent robot is developed and the localization algorithm based on extended Kalman Filter (EKFLA) are proposed through the capstone design by graduate students in this paper. In addition to this, the performance of the proposed EKFLA is also analyzed. The developed HRI system consists of the route generation and localization algorithm, the user behavior pattern awareness algorithm, the map data generation and building algorithm, the obstacle detection and avoidance algorithm on the robot control modules that control the entire behaviors of the robot. It is confirmed that the improvement ratio of the localization error in EKFLA on the scenarios 1-3 is increased compared with the localization algorithm based on Kalman Filter (KFLA) as 21.96%, 25.81% and 15.03%, respectively.

The Optimal Parameter Design of the stone surface equipment Using the Taguchi Method (다구찌 방법을 이용한 석재표면처리장치의 최적표면가공조건 선정에 관한 연구)

  • 김득주;서장훈;박명규
    • Journal of the Korea Safety Management & Science
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    • v.6 no.2
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    • pp.251-262
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    • 2004
  • There is boner process of stone manufacturing to become quality down of stone to consolidated micro crack appearance of stone surface and biotite by fire that is to be route process in stone surface by flame of LPG. And then, it is develop that stone surface process equipment by automation for the work method of boner process can be substitute work method by shotball blasting. To developement of equipment, There is to be down noise and dust. Acording to remove calamity growth hazardous substance in the work environment, there is to solve workplace avoidance factor. We have taken Taguchi's parameter design approch, specifically orthogonal array, and determined the optimal levels of stone surface through analysis of the experimental results using SIN ratio.

Dynamic Contention Window based Congestion Control and Fair Event Detection in Wireless Sensor Network

  • Mamun-Or-Rashid, Md.;Hong, Choong-Seon
    • Proceedings of the Korea Information Processing Society Conference
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    • 2007.05a
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    • pp.1288-1290
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    • 2007
  • Congestion in WSN increases energy dissipation rates of sensor nodes as well as loss of packets and thereby hinders fair and reliable event detections. We find that one of the key reasons of congestion in WSN is allowing sensing nodes to transfer as many packets as possible. This is due to the use of CSMA/CA that gives opportunistic media access control. In this paper, we propose an energy efficient congestion avoidance protocol that includes source count based hierarchical and load adaptive medium access control. Our proposed mechanism ensures load adaptive media access to the nodes and thus achieves fairness in event detection. The results of simulation show our scheme exhibits more than 90% delivery ratio with retry limit 1, even under bursty traffic condition which is good enough for reliable event perception.

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Buffer and Rate Control Based Congestion Avoidance in Wireless Sensor Networks

  • Alam, Muhammad Mahbub;Hong, Choong-Seon
    • Proceedings of the Korea Information Processing Society Conference
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    • 2007.05a
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    • pp.1291-1293
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    • 2007
  • Due to dense deployment and innumerable amount of traffic flow in wireless sensor networks (WSNs), congestion becomes more common phenomenon from simple periodic traffic to unpredictable bursts of messages triggered by external events. Even for simple network topology and periodic traffic, congestion is a likely event due to dynamically time varying wireless channel condition and contention caused due to interference by concurrent transmissions. In this paper, we have proposed three mechanisms: upstream source count and buffer based rate control and snoop based MAC level ACK scheme to avoid congestion. The simulation results show that our proposed mechanism achieves around 80% delivery ratio even under bursty traffic condition

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Estimation of Tire-Road Friction Coefficient using Observers (관측기를 이용한 노면과 타이어 간의 마찰계수 추정)

  • 정태영;이경수;송철기
    • Journal of Institute of Control, Robotics and Systems
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    • v.4 no.6
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    • pp.722-728
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    • 1998
  • In this paper real-time estimation methods for identifying the tire-road friction coefficient are presented. Taking advantage of the Magic Formula Tire Model, the similarity technique and the specific model for the vehicle dynamics, a reduced order observer/filtered-regressor-based method is proposed. The Proposed method is evaluated on simulations of a full-vehicle model with an eight state nonlinear vehicle/transmission model and nonlinear suspension model. It has been shown through simulations that it is possible to estimate the tire-road friction from measurements of engine rpm, transmission output speed and wheel speeds using the proposed identification method. The proposed method can be used as a useful option as a part of vehicle collision warning/avoidance systems and will be useful in the implementation of a warning algorithm since the tire-road friction can be estimated only using RPM sensors.

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Void Less Geo-Routing for Wireless Sensor Networks

  • Joshi, Gyanendra Prasad;Lee, Chae-Woo
    • Proceedings of the KIEE Conference
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    • 2007.04a
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    • pp.433-435
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    • 2007
  • Geographic wireless sensor networks use position information for Greedy routing. Greedy routing works well in dense network where as in sparse network it may fail and require the use of recovery algorithms. Recovery algorithms help the packet to get out of the communication void. However, these algorithms are generally costlier for resource constrained position based wireless sensor type networks. In the present work, we propose a Void Avoidance Algorithm (VAA); a novel idea based on virtual distance upgrading that allows wireless sensor nodes to remove all stuck nodes by transforming the routing graph and forward packet using greedy routing only without recovery algorithm. In VAA, the stuck node upgrades distance unless it finds next hop node which is closer to the destination than itself. VAA guarantees the packet delivery if there is a topologically valid path exists. NS-2 is used to evaluate the performance and correctness of VAA and compared the performance with GPSR. Simulation results show that our proposed algorithm achieves higher delivery ratio, lower energy consumption and efficient path.

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Tree-based Multi-channel Communication with Interference Avoidance using Dynamic Channel Switching in Wireless Sensor Network

  • Mohd, Noor Islam;Choi, Sun-Woong;Jang, Yeong-Min
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.12B
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    • pp.1498-1505
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    • 2009
  • In centralized control sensor network, tree-based multi-channel communication overcomes the recurrent channel switching and makes possible to transfer data simultaneously from different sources. In our paper, we propose a greedy algorithm named as NIT (Non-Intersecting Tree) that the trees can avoid inter-tree interference. We also propose channel switching technique by which trees can avoid link failure or area blocking due to external interference locally without rerunningthe algorithm and without interrupting the whole network. At first we applied our algorithm for a random topology and then we evaluate the performance of the network using NS-2 simulator. The results show that with the increasing of channel the throughputand delivery ratio are increased significantly. We got better performance than a using a recent proposed Tree-based Multi-Channel Protocol (TMCP).

Growth and Flowering Responses of Petunia to Various Artificial Light Sources with Different Light Qualities

  • Park, In Sook;Cho, Kyung Jin;Kim, Jiseon;Cho, Ji Yoon;Lim, Tae Jo;Oh, Wook
    • Horticultural Science & Technology
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    • v.34 no.1
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    • pp.55-66
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    • 2016
  • This study was carried out to investigate the effect of artificial light sources with different light qualities on the growth and flowering characteristics of a herbaceous long-day plant, Petunia ${\times}$ hybrida Hort. Seedlings of petunia cultivar 'Madness Rose' were potted, acclimated for one week, and grown in a phytotron equipped with tube- and bulb-type fluorescent lamps (FL tube and bulb), tube-type white light-emitting diodes (LED tube), halogen lamps (HL), metal halide lamps (MH), and high pressure sodium lamps (HPS) for 10 weeks. The temperature, photoperiod, and photosynthetic photon flux density (PPFD) in the phytotron were $22{\pm}2^{\circ}C$, 16 h, and $25{\pm}2{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, respectively. Light sources combined with HL promoted stem elongation, and plant height and internode length decreased with increasing red to far-red (R:FR) ratio. FL tube + LED tube, HPS, and FL tube promoted branching, whereas plants grown under light sources combined with HL did not have any branches. Days to flowering (from longest to shortest) occurred as follows: FL tube + HL > FL tube + HL > MH > HPS = FL tube + FL bulb > FL tube + LED tube > LED tube > FL tube, indicating that reducing the R:FR ratio of the light sources promoted flowering. Only 20% of plants grown under an FL tube flowered, whereas under all other treatments, 100% of plants flowered. At 10 weeks after treatment, plants grown under HPS and MH had (cumulatively) 12 open flowers, and those grown under FL tube + FL bulb, LED tube, FL tube + LED tube, and HPS treatment had approximately seven flower buds. These results suggest that light sources with low R:FR ratios promote flowering and stem elongation in petunia, but they reduce its ornamental value due to overgrowth and poor branching.