• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1194-1201
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• 2003

Measurements of network traffic have shown that self-similarity is a ubiquitous phenomenon spanning across diverse network environments. We have advance the framework of multiple time scale congestion control and show its effectiveness at enhancing performance for fast TCP prototype control. In this paper, we extend the fast TCP prototype control framework to window-based congestion control, in particular, TCP. This is performed by interfacing TCP with a large time scale control module which adjusts the aggressiveness of bandwidth consumption behavior exhibited by TCP as a function of "large time scale" network state. i.e., conformation that exceeds the horizon of the feedback loop as determined by RTT. Performance evaluation of fast TCP prototype is facilitated by a simulation bench-mark environment which is based on physical modeling of self-similar traffic. We explicate out methodology for discerning and evaluating the impact of changes in transport protocols in the protocol stack under self-similar traffic conditions. We discuss issues arising in comparative performance evaluation under heavy-tailed workload. workload.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2553-2562
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• 2013

It is difficult for TCP congestion control algorithm to ensure the bandwidth and delay bound required for media streaming services in broadband wireless network environments. In this paper, we propose the COIN TCP (COncave INcrease TCP) scheme for providing a high-quality media streaming services. The COIN TCP concavely increases the congestion window size by adjusting the increment rate of congestion window, that is inversely proportional to the amount of data accumulated in the router queue. As a result, our scheme can quickly occupy the available bandwidth and prevent the heavy congestion. It also improves the link utilization by adjusting the decrement rate of congestion window according to the packet loss rate with the random loss. Through the simulation results, we prove that our scheme improves the total throughput in broadband wireless network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4B
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• pp.411-423
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• 2004

This paper defines test methodologies and performance indices for SIP server system, and describes elements that can have influence on the test of SIP network equipments. Moreover, we implement a tester to evaluate the performance of SIP Servers such as Registrar and Proxy server. The performance indices for testing SIP servers are message processing rate, transaction delay, and call success probability. The parameters that can have an effect on the performance of SIP servers are user population, transport protocol, method of database access, method of DNS, call creation pattern, definition of transactions, and size of packets. We tested several SIP servers that act as Registrar, Proxy, and Redirect server using the implemented SIP tester, and, as a result, verified functions of the tester and performance indices and input parameters defined in this paper. Performance indices and methodologies presented in this paper can be used to evaluate SIP servers in NGN

• Journal of IKEEE
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• v.11 no.4
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• pp.165-170
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• 2007

The main goal of research concerning clustering protocols is to minimize the energy consumption of each node and maximize the network lifetime of wireless sensor networks. However, most existing clustering protocols mainly focused on the design and formation of clusters, leaving the consideration of communication between the cluster head and the sink behind. In this paper, we propose efficient multi path routing algorithm by using MAC-NET Cross-layering. multi path needed only one tiny packet from sink to setup. In addition proposed algorithm can be used for any cluster-based hierarchical inter-clustering routing algorithm. The simulation results demonstrate that proposed algorithm extended the overall survival time of the network by reducing the load of cluster heads. The performance of proposed algorithm is less affected by the extension of sensing field than other inter-clustering operation.

• Journal of Korea Multimedia Society
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• v.8 no.2
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• pp.258-268
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• 2005

The efficient provision of multicast service to moving hosts in mobile computing environments is not so easy task. Bi-directional tunneling scheme causes overhead about encapsulation and triangular routing. On the other hand, remote subscription scheme need freDuent tree reconstruction, which is inefficient for rapid moving hosts. In this paper we propose Mobility Based Mobile Multicast(MBMOM) scheme which is based on host's mobility information. Ultimately MBMOM try to find the strong points of remote subscription scheme and hi-directional tunneling scheme. If host's mobility speed is considered to be high, multicast packets are forwarded using hi-directional tunneling scheme from home agent continuously. If host's mobility speed is considered to be slow, remote subscription scheme is applied for foreign agent and it try to join multicast tree. We developed analytical models to analyze the performance of proposed scheme and simulated our scheme compared with MOM(Mobile Multicast), RBMOM(Range Based MOM), and TBMOM(Timer Based MOM) schemes. Simulation results show that our scheme has shorter transmission delay than above 3 schemes in the aspect of host's mobility speed and multicast group size.

• Journal of KIISE:Information Networking
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• v.31 no.2
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• pp.233-241
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• 2004

In this paper, we propose a packet-lossless fast rerouting scheme at a link/node fault in MPLS (Multiprotocol Label Switching) network with minimized accumulated buffer delay problem at ingress node. The proposed scheme uses a predefined, alternative LSP (Label Switched Path) In order to restore user traffic. We propose two restoration approaches. In the first approach, an alternative LSP is initially allocated with more bandwidth than the protected working LSP during the failure recovery phase. After the failure recovery, the excessively allocated bandwidth of the alternative LSP is readjusted to the bandwidth of the working LSP. In the second approach, we reduce the length of protected working LSP by using segment-based restoration. The proposed approaches have merits of (ⅰ) no buffer delay problem after failure recovery at ingress node, and (ⅱ) the smaller required buffer size at the ingress node than the previous approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1613-1621
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• 2015

This paper analyzes the rate adaptation scheme and suggests applicable strategy of the MCS(Modulation and Coding Scheme) for improving DCF throughput in the IEEE 802.11ad and 802.11ad wireless LAN. IEEE 802.11ac and 802.11ad wireless LAN provide MCS technique that dynamically adjusts modulation level and code rate to the time-varying channel conditions in order to obtain considerably high data rates. But these standards did not provide rate adaptation algorithm, so this paper surveyes rate adaptation algorithm and suggests MCS scheme applied to IEEE 802.11ac and 802.11ad wireless LAN. Specially A MAC(Medium Access Control) layer throughput is evaluated over error-prone channel in the IEEE 802.11ac-based wireless LAN. In this evaluation, DCF (Distributed Coordination Function) protocol and A-MPDU (MAC Protocol Data Unit Aggregation) scheme are used. Using theoretical analysis method, the MAC saturation throughput is evaluated with the PER (Packet Error Rate) on the condition that the number of station, transmission probability, the number of parallel beams and the number of frames in each A-MPDU are variables.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11B
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• pp.1234-1244
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• 2009

Nowadays, the traffic type and behavior are extremely diverse due to the appearance of various services and applications on Internet, which makes the need of application-level traffic classification important for the efficient management and control of network resources. Although lots of methods for traffic classification have been introduced in literature, they have some limitations to achieve an acceptable level of performance in terms of accuracy and completeness. In this paper we propose an application traffic classification method using statistic signatures, defined as a directional sequence of packet size in a flow, which is unique for each application. The statistic signatures of each application are collected by our automatic grouping and extracting mechanism which is mainly described in this paper. By matching to the statistic signatures we can easily and quickly identify the application name of traffic flows with high accuracy, which is also shown by comprehensive excrement with our campus traffic data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.1
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• pp.159-169
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• 1994

A multichannel optical slotted ring network is designed using a wavelength division multiplexing(WDM) technique and photonic packet switching devices. The electronics speed bottleneck is removed out of the ring, which allows utilization of the full bandwidth for the optical fiber transmission medium. The ring channel adopts a slotted ring concept with a destination cell remove strategy for the eing access mechanism. The slot size in the ring is selected as the same as that of ATM based cell in order to be used as B-ISDN Access Networks. In this paper, we devised a mathematical method to measure the average transfer delay characteristics of the network. The analytical method turned out to yield accurate results over a broad range of parameters in comparison to simulation results. From the study, we observed the average transfer delay of the network as the network parameters vary.

• Journal of Internet Computing and Services
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• v.9 no.4
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• pp.61-68
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• 2008

Ethernet passive optical network (EPON) is the next-generation technology mitigating the bottleneck between high-capacity local area networks (LANs) and a backbone network. The bottleneck is aggrevated depending on burstiness and long range dependence (LRD) of traffic characteristics as well as amount of outgoing traffic from the high-capacity LANs. The proposed scheme decreases average packet delay for data upstreaming by considering such traffic characteristics to dynamically allocate bandwidth to multiple optical network units (ONUs). In addition, it can appropriately support delay-sensitive traffic such as constant bit ratio (CBR) traffic by making maximum cycle time fix regardless of the number of ONUs. The comprehensive simulation results indicate that the proposed scheme acheives up to 77% and 82% lower than previous schemes in terms of average packet delay and average queue size while it limits the maximum cycle time to twice of the basic cycle time.