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COMIC: Intelligent Contention Window Control for Distributed Medium Access
Pudasaini, Subodh,Moonsoo Kang,Seokjoo Shin,Copeland, John A IEEE 2010 IEEE communications letters Vol.14 No.7
<P>In this letter, a scheme for Collision Mitigation with Intelligent Contention Window Control (COMIC) is proposed for backoff based collision resolution algorithm. COMIC intelligently mitigates collisions by probabilistically maximizing the selection likelihood of relatively less collision-probable contention slots over the backoffed contention window. A unified Markovian model for the Distribution Coordination Function (DCF) that incorporates COMIC, DCF<SUB>comic</SUB>, is formulated for the performance analysis. The performance results show that DCF<SUB>comic</SUB> outperforms the conventional DCF in both throughput and average packet delay due to the significant reduction in packet collisions.</P>
Pudasaini, Subodh,Kyung Sup Kwak,Seokjoo Shin IET 2015 IET COMMUNICATIONS Vol.9 No.5
<P>Maximising the tag reading rate of a reader is one of the most important design objectives in radio frequency identification (RFID) systems as it is inversely proportional to the time required to completely read all the tags within the reader's radio field. To this end, numerous techniques have been independently suggested so far and they can be broadly categorised into pure advancements in the link-layer tag anti-collision protocols and pure advancements in the physical-layer RF signal reception model. This study shows by rigorous mathematical analysis and Monte-Carlo simulations that how those two independent approaches can be coupled to maximise the tag reading efficiency in an RFID system, considering a slotted Aloha-based dynamic link-layer anti-collision protocol at tags and a multi-packet reception capable RF reception model at the reader.</P>
Indigenous Knowledge and Practices of Beekeeping with Apis cerana in Nepal
Rameshwor Pudasaini 한국양봉학회 2018 韓國養蜂學會誌 Vol.33 No.2
Economically five important honeybees’ species namely Apis cerana F., A. mellifera L., A. laboriosa S., A. dorsata F., and A. florae F. are recorded in Nepal. To understand the farmers’ indigenous knowledges and practices on beekeeping, a survey was conducted in Nepal in 2015/016. Farmers searched honeybee colonies in hollow tree around the forest and domesticated them bykeeping twothree bee hives made of traditional wood log bee hives of A. cerana in a house with least management practices. Majority of the farmers (74%) harvested honey two times in a year, between March to May and second September to November. The techniques of beekeeping had been handed down from generation to generation since immemorial time.Indigenous knowledge and practices could be an important basis for the development of beekeeping and maintenance of beekeeping in rural areas of Nepal.
Subodh Pudasaini,신석주 한국차세대컴퓨팅학회 2013 한국차세대컴퓨팅학회 논문지 Vol.9 No.3
전통적인 회선교환 방식에서 패킷 교환 방식으로 네트워크가 진화함에 따라 분산된 클럭의 동기화를 위한 패킷 기반 동기화 방식은 큰 주목을 받고 있다. 특히 네트워크의 혼잡이 심각한 경우 패킷교환 네트워크의 특성에 기인하는 패킷 지연 변화 (PDV)는 IEEE1588 PTP (Precision Time Protocol)를 기반으로 하는 패킷 기반의 동기화 시스템에서 클럭 잡음의 주요 원인으로 작용한다. 본 논문에서는 IEEE1588 PTP의 동기화 성능을 개선하기 위해 이러한 클럭 잡음을 완화시킬 수 있는 비선형 SMoPF (Sample Mode Packet Filtering) 메커니즘을 제안하였다. 제안된 SMoPF 기법의 성능평가를 얻기 위하여 임의의 혼잡도를 갖는 패킷 교환 네트워크에서의 IEEE1588 PTP 동기화 프로토콜을 고려하였으며OMNET++ 툴 기반의 컴퓨터 시뮬레이션을 수행하였다. 또한, 제안된 기법의 성능은 기존의 샘플 최소 필터링, 평균 필터링, 최대 필터링 기법들과 비교 분석 되었다.
A Novel Dynamic Contention Window Control in IEEE 802.11 DCF
Subodh Pudasaini,Anup Thapa,Seokjoo Shin 한국통신학회 2009 한국통신학회 학술대회논문집 Vol.2009 No.6
The primary Medium Access Control (MAC) technique of IEEE 802.11 is Distributed Coordination Function (DCF). DCF is a contention based access mechanism with Carrier Sense Multiple Access which incorporates Collision Avoidance (CSMA/CA) scheme with Binary Exponential Backoff (BEB) retransmission rules. Collision resolution using BEB is simple and effective when the network is lightly loaded, however, its performance starts worsening with increase in the network load. In this paper, we proposed a novel contention window control scheme on top of BEB with a minor modification. The proposed modification dynamically controls the randomness of deferring time by changing the distribution of the deferring time adaptively after each unsuccessful/colllided access attempt. The proposed protocol is expected to leverage the performance in terms of both average delay and average throughput in the whole range of offered load maintaining fairness among the competing stations meanwhile. More importantly, this protocol can be ported even to the already existing 802.11 network interface card (NIC) drivers only with a simple software upgrade.