• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.4
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• pp.200-206
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• 2014

Accountable Internet Protocol (AIP) is one of the future Internet architectures to provide accountability concept by using the self-certifying address that is derived by the public key of the host. In AIP, when a host sends a packet, a domain that is located between the source and the destination hosts discards the packet in order to verify the source IP address. Therefore, performance degradation can occur due to packet discard especially when there is asymmetric route. In this paper, we propose the improved AIP mechanism to verify the source IP address without discarding the packet by including the timestamp, public key value and the signature for protecting from forfeiting the source address. Security safety of the proposed mechanism is evaluated and the proposed mechanism can provide the more robust security as well as reducing the latency due to discarding packets.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.121-126
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• 2018

IEEE 802.1 TSN TG is developing standards for end-to-end delay bounds and zero packet loss based on Ethernet technology. We focus on packet forwarding techniques. TSN packet forwarding techniques can be classified into Synchronous and Asynchronous framework. Synchronous approach allocates fixed time period for a class, yet is complex for large networks. Asynchronous approach provides delay guarantee by regulator-scheduler pair, yet is unnecessarily complex, too. We propose network components for TSN Asynchronous architecture, which remove the complexity of maintaining flow state for regulation decisions. Despite such a simplicity, the proposed architecture satisfies the TSN's delay requirements provided the limited high priority traffic's maximum packet length.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.433-438
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• 2020

Nodes on a data communication path in a wireless network emit electro-magnetic waves whenever they transmit packets; thus, the path can be exposed and identified with capturing and analyzing a sequence of the signals emitted there. One of countermeasures against a malicious eavesdropper is to let certain nodes mimic the nodes on the data path in sending dummy packets. In this paper we propose a packet transfer protocol which establishes the shortest path between source-destination pair a time and restricts heavy generation of dummy packets. We verify the location-privacy of a node on the communication paths through simulation.

• Journal of information and communication convergence engineering
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• v.12 no.3
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• pp.135-139
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• 2014

Opportunistic routing was originally introduced in various multihop network environments to reduce the number of hops in such a way that, among the relays that decode the transmitted packet for the current hop, the one that is closest to the destination becomes the transmitter for the next hop. Unlike the conventional opportunistic routing case where there is a single active S-D pair, for an ad hoc network in the presence of fading, we investigate the performance of parallel opportunistic multihop routing that is simultaneously performed by many source-destination (S-D) pairs to maximize the opportunistic gain, thereby enabling us to obtain a logarithmic gain. We first analyze a cut-set upper bound on the throughput scaling law of the network. Second, computer simulations are performed to verify the performance of the existing opportunistic routing for finite network conditions and to show trends consistent with the analytical predictions in the scaling law. More specifically, we evaluate both power and delay with respect to the number of active S-D pairs and then, numerically show a net improvement in terms of the power-delay trade-off over the conventional multihop routing that does not consider the randomness of fading.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3B
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• pp.161-167
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• 2007

In this paper, we evaluate the capacity of voice over internet protocol (VoIP) services over high-speed downlink packet access (HSDPA), in which frame-bundling (FB) is incorporated to reduce the effect of relatively large headers in the IP/UDP/RTP layers. Also, a modified proportional pair (PF) packet scheduler design supporting for VoIP service is provided. The main focus of this work is the effect of FB on system outage based on delay budget in radio access networks. Simulation results show that VoIP system performance with FB scheme is highly sensitive to delay budget. We also conclude that HSDPA is attractive for transmission of VoIP if compared to the circuit switched (CS) voice that is used in WCDMA (Release'99).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.31-34
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• 2012

In MANET, frequent movement of nodes causes the dynamic network topology changes. Therefore the routing protocol, which is very stable to effectively respond the changes of the network changes, is required. Moreover, the existing cluster-based routing protocol, that is the hybrid approach, has routing delay due to the re-electing of the cluster header. In addition, the routing table of CBRP has all only one hop distant neighbor nodes. PCBRP, proposed in this paper, ties two clusters in one pair of clusters to make longer radius. Then the pair of the cluster headers manages and operates corresponding member nodes. When they route nodes in the paired cluster internally, PCBRP reduces the delay by requesting a route. Therefore PCBRP shows improved total delay of the network and improved performance of packet transmitting rate.

• Journal of Internet Computing and Services
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• v.6 no.4
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• pp.141-147
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• 2005

Ding and Bhuyan, however, has shown that the performance of multistage interconnection networks(MIN's) can be significantly improved if the packet movements are confined within each pair of adjacent stages using small clock cycles. In this paper, an effective model for estimating the performance of multibuffered MIN's employing the approach is proposed. the relative effectiveness of the proposed model is identified compared to the traditional design.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.272-275
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• 2008

종단에서 네트워크 용량에 대한 정보는 사용자뿐 아니라 전송 계층 프로토콜 상에서 전송량 등을 조절하기 위한 중요한 용도로 활용된다. 이러한 네트워크 용량(또는 대역폭)을 종단에서 측정하기 위해 활용되는 방법 중 하나가 바로 패킷 페어 기법이다. 패킷 페어 기법은 계산이 간단하고 빠른 측정이 가능하다는 장점이 있으나, 각 프로빙 패킷에 대한 즉각적인 응답 패킷을 필요로 하기 때문에 지연 ACK 방식이 존재하는 TCP 상에서는 적용하기 어렵다는 단점이 있다. 본 논문에서는 이러한 지연 ACK의 효과를 그대로 유지하면서 네트워크 용량의 추정이 가능한 지연 패킷 페어 기법을 제안한다. 시뮬레이션 결과를 통해 제안된 지연 패킷 페어 기법이 기존 방식의 정확성, 빠른 측정 시간 등의 장점을 보존하면서 지연 ACK의 사용 여부에 관계없이 정확히 동작할 수 있음을 보였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.6
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• pp.779-792
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• 1997

Flow characteristics are numerically investigated when a packet of waves consisting of a Tollmien-Schlichting wave and a pair of Squire waves evolves in a flat-plate laminar boundary layer using a large eddy simulation with a dynamic subgrid-scale model. Characteristics of early stage transitional boundary layer flow such as the .LAMBDA. vortex, variation of the skin friction and backscatter are predicted. Smagorinsky constants and the eddy viscosity obtained from the dynamic subgrid-scale model significantly change as the flow evolves. Far Field noise radiated from the transitional boundary layer shows the dipole and quadrupole characteristics owing to the wall shear stress and the Reynolds stresses, respectively.

• Journal of Communications and Networks
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• v.18 no.2
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• pp.238-245
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• 2016

A sequence number checking technique is proposed to improve the performance of TCP connections in mobile ad hoc networks. While a TCP connection is initialized, a routing protocol takes the responsibility for checking the hop count between a source and destination pair. If the hop count is greater than a predefined value, the routing protocol decides to use a proxy node. The responsibility of a proxy node is to check the correctness of data packets and inform the missing packets by sending an acknowledgement from a proxy node to the source node. By doing so, the source node is able to retransmit any missing packet in advance without waiting until an end-to-end acknowledgement is received from the destination. Simulation results show that the proposed mechanism is able to increase throughput up to 55% in static network and decrease routing overhead up to 95%in mobile network.