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RISS 인기검색어
- 검색키워드
- 저자 : Masaki Hanada (검색결과 4 건)
- 무료
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- 유료
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Asymmetric RTS/CTS for Exposed Node Reduction in IEEE 802.11 Ad Hoc Networks
Matoba, Akihisa,Hanada, Masaki,Kanemitsu, Hidehiro,Kim, Moo Wan Korean Institute of Information Scientists and Eng 2014 Journal of Computing Science and Engineering Vol.8 No.2
One interesting problem regarding wireless local area network (WLAN) ad-hoc networks is the effective mitigation of hidden nodes. The WLAN standard IEEE 802.11 provides request to send/clear to send (RTS/CTS) as mitigation for the hidden node problem; however, this causes the exposed node problem. The first 802.11 standard provided only two transmission rates, 1 and 2 Mbps, and control frames, such as RTS/CTS assumed to be sent at 1 Mbps. The 802.11 standard has been enhanced several times since then and now it supports multi-rate transmission up to 65 Mbps in the currently popular 802.11n (20 MHz channel, single stream with long guard interval). As a result, the difference in transmission rates and coverages between the data frame and control frame can be very large. However adjusting the RTS/CTS transmission rate to optimize network throughput has not been well investigated. In this paper, we propose a method to decrease the number of exposed nodes by increasing the RTS transmission rate to decrease RTS coverage. Our proposed method, Asymmetric Range by Multi-Rate Control (ARMRC), can decrease or even completely eliminate exposed nodes and improve the entire network throughput. Experimental results by simulation show that the network throughput in the proposed method is higher by 20% to 50% under certain conditions, and the proposed method is found to be effective in equalizing dispersion of throughput among nodes.
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Asymmetric RTS/CTS for Exposed Node Reduction in IEEE 802.11 Ad Hoc Networks
Akihisa Matoba,Masaki Hanada,Hidehiro Kanemitsu,Moo Wan Kim 한국정보과학회 2014 Journal of Computing Science and Engineering Vol.8 No.2
One interesting problem regarding wireless local area network (WLAN) ad-hoc networks is the effective mitigation of hidden nodes. The WLAN standard IEEE 802.11 provides request to send/clear to send (RTS/CTS) as mitigation for the hidden node problem; however, this causes the exposed node problem. The first 802.11 standard provided only two transmission rates, 1 and 2 Mbps, and control frames, such as RTS/CTS assumed to be sent at 1 Mbps. The 802.11 standard has been enhanced several times since then and now it supports multi-rate transmission up to 65 Mbps in the currently popular 802.11n (20 MHz channel, single stream with long guard interval). As a result, the difference in transmission rates and coverages between the data frame and control frame can be very large. However adjusting the RTS/CTS transmission rate to optimize network throughput has not been well investigated. In this paper, we propose a method to decrease the number of exposed nodes by increasing the RTS transmission rate to decrease RTS coverage. Our proposed method, Asymmetric Range by Multi-Rate Control (ARMRC), can decrease or even completely eliminate exposed nodes and improve the entire network throughput. Experimental results by simulation show that the network throughput in the proposed method is higher by 20% to 50% under certain conditions, and the proposed method is found to be effective in equalizing dispersion of throughput among nodes.
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Evaluation of Asymmetric RTS/CTS Method with Mobility
Emilia Weyulu(에미리아),Masaki Hanada(하나다),Hidehiro Kanemitsu(가네미쯔),Moowan Kim(김무완) 한국정보과학회 2019 정보과학회 컴퓨팅의 실제 논문지 Vol.25 No.2
무선노드의 이동은 송신노두와 수신노두간의 경로정보를 동적으로 변경하기 때문에 exposed 노두 문제를 악화시킨다. 본 논문에서는 IEEE 802.11 W-LAN의 표준 RTS/CTS 방식을 확장하여 제안한 비대칭 RTS/CTS 방식의 이동을 고려한 평가결과를 제시한다. RWP(Random Waypoint) 이동모델을 적용하면서, 비대칭 RTS/CTS 방식은 전파 도달거리를 적응적으로 제어하여 exposed 노두 문제에 대응하고 있다. NS-2를 사용한 시뮬레이션 결과, 비대칭 RTS/CTS 방식은 최대 30%이상 표준 RTS/CTS 방식에 비해 성능 향상을 보였다. 또 향후의 연구 방향과 연구 과제를 제시한다. The mobility of wireless nodes exacerbates the problem of exposed nodes as routes between the source and the target of information change because of movement. This paper presents the evaluation result of the proposed asymmetric RTS/CTS method in IEEE 802.11 W-LANs by considering mobility. Based on RWP (Random Waypoint) model, the proposed method considers the constantly changing transmission ranges and utilizes asymmetric transmission ranges for RTS and CTS control frames to solve the problem of exposed nodes problem. The simulation results obtained through NS-2 show that the proposed RTS/CTS method improves network performance. With mobility, the throughput gain of asymmetric RTS/CTS method is significantly more, with up to 30% increase over the standard RTS/CTS method.
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오호경,신진호,Manabu Ato,Xiao Ma,David Williams,한기원,김양진,강형구,정기경,Kentaro Hanada,Masaki Ochiai,Pham Van Hung,박상미,안치영 질병관리본부 2017 Osong Public Health and Research Persptectives Vol.8 No.1
The first meeting of the National Control Laboratories for Vaccines and Biologicals in the Western Pacific Region was held on September 1–2, 2016 in Seoul, the Republic of Korea. The meeting objectives were to share results of current research and to promote collaboration between the National Control Laboratories. To this end, we first discussed each country’s current status of research on quality control of biologicals. Next, we reviewed quality control of snake venom and antivenom production and the progress of a collaborative study on the Korean reference standard candidate for snake venom. We also discussed the establishment of the second regional reference standard antivenom and the characterization of the Vero cell genome landscape and its application to quality control. Moreover, we also reflected on the importance of collaboration among interested parties participating in this meeting. In conclusion, the meeting initiated networking between the national control laboratories in the Western Pacific region and paved the way to continue collaboration, which will eventually improve the region’s capacity for quality control of biologicals.
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