• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.418-423
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• 2008

802.11 에서 유니캐스트 통신을 할 때 수신 호스트는 ACK 프레임을 전송하여 데이터의 수신을 확인한다. 그러나 프레임 오류율이 낮은 상황에서 ACK 프레임을 전송하는 것은 에너지 측면에서 낭비가 될 수 있다. 본 논문에서는 상위 계층의 유비캐스트 통신을 상위 계층에는 투명하게 ACK가 없는 802.11 멀티 캐스팅을 이용하여 통신을 하는 기법을 제안하고 실제 환경에서 이를 구현 및 실험하였다. 실험결과, TCP와 같이 상위 계층에서 오류제어를 하는 경우 정상적인 통신이 항상 가능하며, 무선 전송 오류가 낮 은 경우는 에너지는 물론 처리량도 증가하는 것을 확인하였다.

• Journal of Computing Science and Engineering
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• v.5 no.1
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• pp.19-31
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• 2011

In this paper, we propose two new routing schemes for double-layered peer-to-peer systems; a shorter-lower mobility routing scheme and a reverse path routing scheme. The shorter-lower mobility routing scheme first chooses shortest routing paths among possible routing paths and selects the path associated with the relay peer who has lower mobility to improve the reliability of the system. The reverse path routing scheme carries out unicasting (instead of multicasting) based on the reverse path information that can be obtained during the initial file search to further reduce network traffic. The experimental results showed that a double-layered peer-topeer system with the proposed hybrid scheme improved the reliability of the system about 1.5% over the hop count scheme and reduced network traffic by about 0.5% compared to the hop count scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3B
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• pp.493-503
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• 2000

Multicast routing algorithms such PIM, CBT, BGMP use shared multicast routing trees and the location of the multicast tree has great impact on the packet delay. In this pater we propose three new center location algorithms and analyze their performance through simulation studies. these three algorithms consider as candidates for the center not only multicast group members but also a few non-members nodes. To select these non-member nodes, we first find all the shortest paths among every couple of members and consider either nodes which are most frequently visited during the process of finding shortest paths or nodes which lie at the center of a shortest path and are most frequently visited during the same process. There the proposed algorithms are able to find the better center than not only algorithms which consider only member nodes but also other algorithms which consider selected non-member nodes in addition ot member nodes. The proposed algorithms either incur too much overhead nor depend upon unicasting algorithms.

• The KIPS Transactions:PartA
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• v.10A no.4
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• pp.313-320
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• 2003

This paper design and implements a synchronized agent mechanism that be able to synchronize SFT (Slow Frequency Transaction) data among e-business processes in distributed environment. This synchronized agent system is adopted to use mobile agent to guarantee the interoperability of the distributed processes and to solve some problems at the client/server architecture and proposes a policy to synchronize data of e-business processes on the any platforms of distributed heterogeneous systems. The proposed synchronization policy is based on the time-stamp transaction with the system priority on the unicasting transportation.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.12
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• pp.1359-1364
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• 2014

IEEE 802.11p is a representative PHY/MAC layer standard in vehicular communications. The performance of IEEE 802.11p based communication systems has been measured in various criterions such as link setup time, error rate, and throughput for the case of one-to-one. In this paper, we measure the performance of IEEE 802.11p based communication systems in large capacity transmission. The performance of large capacity transmission is measured by considering the maximum 32 simultaneous transmission including one-to-one transmission. We consider two transmission schemes, i.e., broadcasting and unicasting, and the performance is represented as the receiving rate and throughput.

• Journal of Communications and Networks
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• v.11 no.1
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• pp.84-93
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• 2009

This paper focuses on message complexity performance analysis of mobile ad hoc network (MANET) address autoconfiguration protocols (AAPs) in reference to link errors generated by mobile wireless nodes. An enhancement was made using a proposed retransmission limit, S, to be computed for error recovery (based on the link error probability), to measure message complexity of AAPs in reference to the link error probability, $P_e$. The control procedures for the retransmission limit have been included for each of the AAPs. Retransmission limit control is critical for efficient energy consumption of MANET nodes operating on limited portable energy. O-notation has been applied to analyze the upper bound of the number of messages generated by a MANET group of nodes. The AAPs investigated in this paper are strong duplicate address detection (DAD), weak DAD with proactive routing protocol (WDP), weak DAD with on-demand routing protocol (WDO), and MANETConf. Each AAP reacts different to link errors, as each AAP has different operational procedures. The required number of broadcasting, unicasting, relaying, and received messages of the nodes participating in a single-node joining procedure is investigated to asymptotically calculate the message complexity of each AAP. Computer simulation was conducted and the results have been analyzed to verify the theoretical message complexity bounds derived. The message complexity of WDP was lowest, closely followed byWDO, based on the simulation results and analysis of the message complexity under nominal situations. The message complexity of MANETConf was higher than WDO, and strong DAD resulted to be most complex among the four AAPs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.2 no.1
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• pp.23-35
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• 2008

Mobile IP (MIP) is the solution supporting the mobility of Mobile Nodes (MNs), however, it is known to lack the support for NEtwork MObility (NEMO). NEMO manages situations when an entire network, composed of one or more subnets, dynamically changes its point of attachment to the Internet. NEMO Basic Support (NBS) protocol ensures session continuity for all the nodes in a mobile network, however, there exists a serious pinball routing problem. To overcome this weakness, there are many Route Optimization (RO) solutions such as Bi-directional Tunneling (BT) mechanism, Aggregation and Surrogate (A&S) mechanism, Recursive Approach, etc. The A&S RO mechanism is known to outperform the other RO mechanisms, except for the Binding Update (BU) cost. Although Improved Prefix Delegation (IPD) reduces the cost problem of Prefix Delegation (PD), a well-known A&S protocol, the BU cost problem still presents, especially when a large number of Mobile Routers (MRs) and MNs exist in the environment such as train, bus, ship, or aircraft. In this paper, a solution to reduce the cost of delivering the BU messages is proposed using a multicast mechanism instead of unicasting such as the traditional BU of the RO. The performance of the proposed multicast-based BU scheme is examined with an analytical model which shows that the BU cost enhancement is up to 32.9% over IPDbased, hence, it is feasible to predict that the proposed scheme could benefit in other NEMO RO protocols.

• Journal of Internet Computing and Services
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• v.7 no.6
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• pp.63-77
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• 2006

Nowadays as many Grid communities appear, the requirement of singlepoint-to-multipoint data transfer in Grid environment is growing. In a typical LAN or a special purpose network environment, a multicasting technology was used in such a data dissemination transfer case. However, compared with unicasting fouler performance transfer performance the multicating transfer is worse, and the obligation of a special hardware setting makes it difficult to implement in common Grid environment. Therefore, in this paper we propose on effective data dissemination mechanism for Grid environment named DDMG(Data Dissemination Mechanism for Grid), DDMG uses P2P(Peer-to-Peer) mechanism and Globus XIO library to improve the performance in a data dissemination process and to support heterogeneous protocols in Grid environment. We also evaluate the performance of DDMG mechanism in LAN and WAN environment by comparing with unicast transfer.

• The Journal of Korean Institute of Next Generation Computing
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• v.14 no.6
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• pp.75-86
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• 2018

The DDS (Data Distribution Service) specification defines a discovery method for finding participants and endpoints in a DDS network. The standard discovery mechanism uses the multicast protocol and finds all the endpoints in the network. Because of using multicasting, discovery may fail in a network with different segments. Other problems include that memory space wastes due to storing information of all the endpoints. The Topic Name Service (TNS) solves these problems by unicasting only the endpoints, which are required for communication. However, an extra delay time is inevitable in components of TNS, i.e, a front-end server, topic name servers, and a terminal server. In this paper, we analyze the performance of TNS. Delay times in the servers of TNS and time required to receive endpoint information are measured. Time to finish discovery and number of receiving endpoints compare with the standard discovery method.

• Journal of KIISE:Information Networking
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• v.31 no.5
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• pp.532-543
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• 2004

Mobile Ad hoc NETworks (MANET) consist of mobile nodes which are usually powered by battery Approaches for minimizing power consumption have been proposed for all network layers and devices. IEEE 802.11 DCF (Distributed Coordination Function), a well-known medium access control protocol for MANETS, also defines a power save mode operation. The nodes in power save mode periodically repeat the awake state and the doze state in synchronized fashion. When all nodes are in the awake state, the exchange the announcements for the subsequent message transmission with neighbors. The nodes that send or receive the announcements stay awake for data transmission, and others go into the dole state. The previous works for enhancing the power save mode operation have focused on shortening the duration of the awake state. We observed that the longer sleeping period results in seriously long delivery latency and the consequent unnecessary power consumption as well, because the packets can move forward only one hop for a fixed interval. In this paper, we propose an improved protocol for the power save mode of IEEE 802.11 DCF, which allows the flooding packets to be forwarded several hops in a transmission period. Our approach does not reduce the duration of compulsory awake period, but maximizes its utilization. Each node propagates the announcements for next flooding to nodes of several hops away, thus the packets can travel multiple hops during one interval. Simulation results of comparison between our scheme and the standard show a reduction in flooding delay maximum 80%, and the unicasting latency with accompanying flooding flows near 50%, with slight increase of energy consumption.