• Journal of Korea Multimedia Society
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• v.9 no.1
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• pp.73-88
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• 2006

With the development of Next Generation convergence Network, the current Internet needs a new network architecture and new session establishment methods, which can support various applications requiring differentiated traffic processing and high quality of service instead of the conventional best-effort service. It is expected that, in next generation network based on All-IP. SIP will play an important role in the session establishment between the end to end user terminals. In this paper, we propose a new network architecture that can provide quality of service based on SIP using the QoS enabled SIP servers and policy servers, and we also propose a new session establishment method that apply the user's demands participating the session establishment when setting up the session using the SIP. Through simulations under various environments, we show the parameter ranges in terms of server capacity and the number of users in access networks to achieve reasonable delay bounds.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.4
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• pp.829-836
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• 2013

Wireless mesh networks(WMNs) are wireless backbone networks technology consisting of a multi-hop routers. Location management is essential to provide a service to the terminal in WMNs. IEEE 802.11s standards have two basic location management scheme for location management - the proxy registration procedure and the associated station discovery protocol. These basic schemes, however, suffer from serious drawbacks including redundancy control message, ineffective location information maintenance, additional delay time. This paper propose an on-demand station location management scheme using 6-address structure of IEEE 802.11s. Through analysis and experimental evaluation on simulation, we show that proposal scheme reduce control message and forwarding delay time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6B
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• pp.443-452
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• 2012

In Mobile Ad-hoc Networks, previous routing protocols classified into proactive and reactive approach respectively have pros and cons under the use of applications and environment. Moreover, to integrate their advantages in case by case, hybrid approach is consistently researched, and Zone Routing Protocol (ZRP) was motivating many recent hybrid protocols. ZRP uses proactive routing to the node located within the zone defined by the specific number of hops, while it uses reactive routing to other nodes. However, in ZRP, because proactive routing is applied only within the zone defined by the number of hops, the zone is formed regardless of whether real data communication occurred frequently or not. In this paper, we propose a new hybrid routing scheme which employs the zone method but forms customized zone considering traffic load and number of hops, by a new decision method named Dynamic Zone Decision (DZD). Additionally, we analyze the performance of the proposed scheme, comparing with the previous proactive, reactive, and hybrid routings.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11B
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• pp.1142-1150
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• 2009

In this paper, we propose an novel bandwidth scheduling algorithm for the MAC protocol employed by the Data Over Cable Service Interface Specifications (DOCSIS) 3.0 compliant cable networks. The proposed algorithm statistically improves the chances of request piggybacking to minimize the access delay. It utilizes the piggyback request feature of the segment packets that has been newly specified in DCOSIS 3.0. In DOCSIS 3.0, a bandwidth request can be granted to several upstream channels within an upstream bonding group. The grant on each individual channel is treated as a segment packet. We find the optimal segment placement to minimize the access delay in the proposed algorithm. We also use a self-similar traffic model for simulation and analysis to evaluate the performance of the proposed algorithm.

• Journal of KIISE
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• v.44 no.11
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• pp.1219-1230
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• 2017

Real-time streaming services over the Internet have increased with the explosive growth of the various mobile platforms, with a focus on smart phones, and the demand for them is growing. In addition, the bandwidth occupied by the streaming services over the Internet had already surpassed 50% in 2010. Because of the shortage of network bandwidth for multimedia services traffic, restrictions on quality and capacity will become more and more serious. CCN is a future Internet architecture that improves how existing host-based Internet architecture handles content-oriented structure, but it is designed for the transmission of general contents and is not suitable for transmitting real-time streaming contents. In this paper, we focus on the inefficient aspects of CCN and propose a hierarchical grade-based scheme for real-time service for a more efficient environment in real-time streaming services. Experiments have shown better performance in terms of bandwidth, network load, and reliability.

• Journal of Internet Computing and Services
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• v.9 no.6
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• pp.37-48
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• 2008

VoIP service is a transmission of voice data using SIP protocol on IP based network, The SIP protocol has many advantages such as providing IP based voice communication and multimedia service with cheap communication cost and so on. Therefore the SIP protocol spread out very quickly. But, SIP protocol exposes new forms of vulnerabilities on malicious attacks such as Message Flooding attack and protocol parsing attack. And it also suffers threats from many existing vulnerabilities like on IP based protocol. In this paper, we propose a new Virtual Proxy Server system in front of the existed Proxy Server for anomaly detection of SIP attack and stateful management of SIP session with enhanced security. Based on stateful virtual proxy server, out solution shows promising SIP Message Flooding attack verification and detection performance with minimized latency on SIP packet transmission.

• Journal of Internet Computing and Services
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• v.8 no.4
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• pp.93-103
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• 2007

Networking environments are exposed to outside attacks and privacy threats. Due to broadcast nature of radio transmissions, wireless devices experience more vulnerable situations than those of wired network devices. This paper assumes that a wireless device has two network interfaces, one for accessing internet using 3G services, and the other for constructing an ad hoc network. To deal with privacy threats, this paper introduces an approach in which wireless devices form a special ad hoc network in order to exchange data using anonymous communications. One or more intermediate peers should be involved in the construction of an anonymous path. The proposed anonymous communication mechanism discourages traffic analysis and improves user privacy. According to simulation results, the anonymous connection in an ad hoc network prefers the intermediate peer(s) which is located near the source and/or the destination peer, rather than randomly-selected peers.

• 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 Communications and Information Sciences
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• v.27 no.12C
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• pp.1197-1206
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• 2002

Recently, the research on the construction of optical Internet backbone networks using WDM has been actively progressed. In this paper, we propose the offset based service-differentiation scheme in optical burst switching (OBS) networks. We classify the services into two classes; high class and low class. The proposed scheme decides the offset time of high class so as to satisfy the required burst loss rate (BLR) of services according to the service-differentiation ratio (SDR). The SDR may be set depending on the environment of OBS network and user's requirements, our scheme decides the BLR of high class by using the required SDR and conservation law. Finally, we use the offset time decision (OTD) algorithm to determine the offset time of high class. The proposed scheme is evaluated through simulation. The result of simulation is compared with that of analysis to verify the proposed scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.122-131
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• 2000

In this paper, we propose a cell scheduling algorithm for input queueing ATM switch. The input queueing architecture is attractive for building an ultra-high speed ATM (Asynchronous Transfer Mode) switch. We proposea WMUCS (Weighted Matrix Unit Cell Scheduler) based on the MUCS which resolves HOL blocking and outputport contention. The MUCS algorithm selects an optimal set of entries as winning cells from traffic matrix (weightmatrix). Our WMUCS differs from the MUCS in generating weight matrices. This change solves the starvationproblem and it reduces the cell loss variance. The performance of the proposed algorithm is evaluated by thesimulation program written in C++. The simulation results show that the maximum throughput, the average celldelay, and the cell loss rate are significantly improved. We can see that the performance of WMUCS is excellentand the cost-effective implementation of the ATM switch using proposed cell scheduling algorithm.