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A decentralized approach for topology discovery in home netwo
Euiyul Ko,Ikjun Yeom IEEE 2006 IEEE TRANSACTIONS ON CONSUMER ELECTRONICS - Vol.52 No.3
<P>As electronic home appliances become smart, there have been many attempts to connect these appliances with a network. Accordingly, a concept of home networks has been emerged. Since most home network users do not have experiences or knowledge of network management, home networks have to be easily managed with minimal efforts of users. This paper presents a novel system for topology discovery and management in home networks. This system is fully distributed and automatically discovers topology information with minimal user configuration. It considers heterogeneous network media such as Ethernet, WLAN, and IEEE 1394. It also provides QoS information by measuring available bandwidth. We have implemented this system on Linux and present experiment results to show the effectiveness of the system</P>
Retransmission scheduling for multimedia delivery over wireless home networks
Sungwon Han,Ikjun Yeom IEEE 2006 IEEE transactions on consumer electronics Vol.52 No.3
<P>The key technique for wireless TVs is to deliver multimedia streams stably over an unstable wireless link. In wireless LANs, a link level retransmission mechanism is used to deal with packet losses due to unstable wireless links. While the retransmission mechanism is effective to hide link level losses to users, if may causes additional delay to other packets which is fatal for real time multimedia traffic such as TV streams. In this paper, we propose a retransmission scheduling scheme to remove the impact of packets to unstable links. In the proposed scheme, when a link to a node observes bad state, packets to the node are exclusively scheduled from others. Through extensive simulations, we show that the proposed scheme effectively removes unnecessary delay caused by retransmitted packets</P>
Avoiding collision with hidden nodes in IEEE 802.11 wireless networks
Jinkyu Lee,Ikjun Yeom IEEE 2009 IEEE COMMUNICATIONS LETTERS Vol.13 No.10
<P>In wireless networks, collision is a major factor of performance degradation. In this letter, we propose a scheme for reducing collision in IEEE 802.11 networks. Each node can avoid collision by maintaining a disjoint set of time slots for transmission. Through simulation, we show that the proposed scheme is effective to reduce collision even in the presence of hidden nodes.</P>
Distributed Fair Scheduling for Wireless Mesh Networks Using IEEE 802.11
Janghwan Lee,Hyunsoo Yoon,Ikjun Yeom IEEE 2010 IEEE Transactions on Vehicular Technology VT Vol.59 No.9
<P>In IEEE-802.11-based wireless mesh networks (WMNs), unfair bandwidth sharing may arise, because the carrier sense multiple access with collision avoidance protocol is designed to provide per-station fairness only in one hop. As the hop count from a mobile client to the gateway node increases, the throughput of the node drastically decreases. In this paper, we propose a fair bandwidth allocation scheme for multiradio multichannel WMNs. This scheme provides fair bandwidth sharing among the nodes in a WMN, regardless of their hop distance from the gateway node. To achieve fairness, we first estimate the number of active nodes attached to each router and calculate the effective weights of routers based on the estimation. Then, we differentiate their contention window using their weights. For this method, we derive a multihop packet collision model. The proposed scheme is fully distributed and does not require any global information. Through an extensive simulation study, we show that our scheme ensures per-node fairness without loss of the total aggregate throughput.</P>
Cardinality estimation using collective interference for large-scale RFID systems
Park, Jonghoon,Moon, Cheoleun,Yeom, Ikjun,Kim, Yusung Elsevier 2017 JOURNAL OF NETWORK AND COMPUTER APPLICATIONS - Vol.83 No.-
<P><B>Abstract</B></P> <P>Estimating the number (cardinality) of Radio Frequency Identification (RFID) tags is a principal problem for large-scale RFID systems. This paper proposes a novel protocol for RFID cardinality estimation using synchronized response signals. For every estimation round, we need a single time-slot to parse multi-bit information from the synchronized signals that are concurrently transmitted from tags. Our protocol guarantees satisfaction of an arbitrary accuracy requirement within the smallest number of time-slots compared to existing estimation protocols. The efficiency of our protocol is based on two components: tags' synchronization and random number generation from a geometric distribution. We design these components to be feasible without heavy computation or memory overhead, and our protocol can be applied to low-cost and resource-constrained passive RFID tags. We have implemented a proof of concept prototype using software defined radio and programmable RFID tags. By conducting large-scale simulations, we have shown that our protocol outperforms the existing cardinality estimation protocols.</P>
Modeling and Performance Analysis of Address Allocation Schemes for Mobile <i>Ad Hoc</i> Networks
Sehoon Kim,Jinkyu Lee,Ikjun Yeom IEEE 2008 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY Vol.57 No.1
<P>Address allocation is an essential part in maintaining a mobile ad hoc network (MANET) effectively, and several address allocation schemes have been proposed. In this paper, we present a set of analytical models to evaluate the efficiency of address allocation schemes. The derived models quantitatively characterize the efficiency of four popular address allocation schemes in terms of latency and communication overhead. Through the analysis, we achieve numerical results that show the impact of network parameters on the efficiency of these schemes. We also conduct simulations and compare with analytical results to validate our models. The analytical model developed in this paper is able to more accurately predict the performance of address allocation schemes over a various range of loss rates and would be useful in providing more insights for the study of an efficient address allocation scheme in MANETs. To our understanding, this is the first attempt in mathematically investigating the performance of addressing schemes in ad hoc networks.</P>
Diffserv를 이용한 다자간 통화 서비스의 QoS 제공방안
연정익(JengIck Yeon),염익준(Ikjun Yeom) 한국정보과학회 2001 한국정보과학회 학술발표논문집 Vol.28 No.1A
세계적인 인터넷을 통하여 인터넷 텔레포니는 폭발적으로 성장하고 있으며 무한한 성장가능성이 있다. 이에 따라 인터넷 텔레포니에 대한 표준안은 IETF(Internet Engineering Task Force)와 ITU(International Telecommunications Union)등에서 제시하고 있다. 또한 인터넷 텔레포니에 이동성과 멀티캐스트 지원방안에 대한 방법을 제시하고 있고, 지금까지 제시된 방법을 기반으로 인터넷 텔레포니에서 Diffserv의 에지에서 멀티케스트용 패킷을 제한하는 방법으로 QoS(Qoality of Service)제공 서비스를 하여 다자간 통화 즉, QoS를 제공하는 다자간 통화 서비스를 할 수 있도록 본 논문은 제안한다.