• Journal of Internet Computing and Services
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• v.2 no.3
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• pp.9-17
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• 2001

Ad-Hoc networks consist of a set of mobile hosts that communicate using wireless links, without the use of other communicate support facilities (such as base stations). The topology of an Ad-Hoc network changes due to the movement of mobile host. which may lead to sudden packet loss. Recently, a large amount of research has focused on the routing protocols needed in such an environment. but researches about Internet traffic performance analysis were unexhausted. Accordingly, we have simulated Ad-Hoc mobile network that using AODV routing protocol and Ad-Hoc mobile network topology size and node speed as simulation estimation-factor to analysis traffic performance. As the result of the simulation, we identify that TCP /Reno was more sensitive than TCP/Sack about node speed and a number of the node.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10B
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• pp.904-910
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• 2008

In this paper, we consider the military requirement, study the military network services and their related traffic parameters, evaluate the performance the experimental army network and then suggest the design guideline of applying VoIP to the whole military. We evaluate the performance of the delay and loss in the viewpoint of packet and call levels for the several scenarios. First, the performances of separate network service were considered and the satisfaction of the requirement was obtained. Secondly, the delays and losses of the integrated network services were calculated as the amount of the background traffic increases. Finally, based on the simulation results, we presented the design guideline which classified network configurations for applying VoIP equipment and helped estimate the number of VoIP terminals in the existing link.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.1
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• pp.105-112
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• 2014

The utilization of Wireless Ad Hoc Network which can build easily network using wireless device in difficult situation to build network is very good. However, it has security threat element because it transfers data by only forwarding of wireless devices. The measures against this should be prepared because damage by especially routing attack can affect the entire network. It is hard to distinguish malicious node and normal node among nodes composing network and it is not easy also to detect routing attack and respond to this. In this paper, we propose new method which detect routing attack and can respond to this. The amount of traffic in all nodes is measured periodically to judge the presence or absence of attack node on the path set. The technique that hides inspection packet to suspected node and transmits is used in order to detect accurately attack node in the path occurred attack. The experiment is performed by comparing SRAODA and SEAODV technique to evaluate performance of the proposed technique and the excellent performance can be confirmed.

• ETRI Journal
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• v.27 no.6
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• pp.759-767
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• 2005

This research is to substantially analyze the economic value of portable Internet (WiBro), WCDMA High Speed Downlink Packet Access (HSDPA), WiBro+VoIP, and WiBro+DMB regarded as the next generation of broadcasting. Based on the empirical analysis of economic values, we provide the optimal paths of converged communications and broadcasting services related to WiBro. 1,000 Internet users in the Seoul and Gyeonggi areas were surveyed in their homes. The collected survey was calculated as an accurate economic value distribution for relevant services, and the average and mean were taken using a parametric logit model, semi-parametric Spike model, and nonparametric Turnbull and Kernel estimations in order to analyze the contingent economic value of the amount offered to the subjects of the analysis. The contingent value analysis results varied slightly according to the different methodologies; however, all showed the following common features. The economic value of WiBro, Internet-based WCDMA, VoIP, and DMB with WiBro appeared to be similar. Therefore, if WiBro and WCDMA (HSDPA) form a competitive relationship, the types of bundled services offered as portable Internet service and the supply point of such bundled services are expected to emerge in a strategic plan for stimulating service markets and the prior occupation of the market.

• Journal of Korea Game Society
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• v.16 no.1
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• pp.83-92
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• 2016

An online game is a huge distributed system comprised of servers and untrusted clients. In such circumstances, cheaters may employ abnormal behaviors through client modification or network packet tampering. Client-side detection methods have the merit of distributing the burden to clients but can easily be breached. In the other hand, server-side detection methods are trustworthy but consume tremendous amount of resources. Therefore, this paper proposes a security reinforcement method which involves both the client and the server. This method is expected to provide meaningful security fortification while minimizing server-side stress.

• Journal of Communications and Networks
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• v.9 no.3
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• pp.265-273
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• 2007

This paper expands an analytical performance model of 802.11 to accurately estimate throughput and energy demand of 802.11-based wireless sensor network (WSN) when sensor nodes employ Reed-Solomon (RS) codes, one of block forward error correction (FEC) techniques. This model evaluates these two metrics as a function of the channel bit error rate (BER) and the RS symbol size. Since the basic recovery unit of RS codes is a symbol not a bit, the symbol size affects the WSN performance even if each packet carries the same amount of FEC check bits. The larger size is more effective to recover long-lasting error bursts although it increases the computational complexity of encoding and decoding RS codes. For applying the extended model to WSNs, this paper collects traffic traces from a WSN consisting of two TIP50CM sensor nodes and measures its energy consumption for processing RS codes. Based on traces, it approximates WSN channels with Gilbert models. The computational analyses confirm that the adoption of RS codes in 802.11 significantly improves its throughput and energy efficiency of WSNs with a high BER. They also predict that the choice of an appropriate RS symbol size causes a lot of difference in throughput and power waste over short-term durations while the symbol size rarely affects the long-term average of these metrics.

• Journal of Korea Multimedia Society
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• v.11 no.7
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• pp.997-1006
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• 2008

SVP-capable router supporting guaranteed services on the internet generally uses a packet scheduler based on the Weighted Fair Queuing(WFQ) algorithm to secure required qualities of traffic flows. In this paper we proposed a RSVP-capable router based on the LOFQ(Latency optimized fair queuing) algorithm that improves the efficiency in bandwidth utilization with keeping the compatibility with the original RSVP procedure. The proposed router reserves the optimal amount of resource for each flow to secure its required quality-of-service with the recently introduced LOFQ scheduler. The results of the simulation applying the proposed router to an evaluation network showed that it may yield the gain of up to 30% compared to that in the original one in terms of the number of admitted flows.

• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.28-37
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• 2006

Recently, transport layer mobility supporting approaches based on SCTP, which is a new standard transport layer protocol, are proposed. In this paper, the handover performance and overheads of these transport layer mobility supporting approaches are compared to those of the traditional network layer mobility supporting approaches. Through the simulation results, it is shown that the handover performance of the transport layer mobility supporting approaches is better or at least similar to that of the plain MIPv6, which is the representative network layer mobility supporting approach. With respect to the amount of control packet, the transport layer approaches impose less overhead than any of the network layer approaches.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.10
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• pp.529-538
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• 2007

Fair Queueing algorithms based on Generalized Processor Sharing (GPS) not only guarantee sessions with service rate and delay, but also provide sessions with instantaneous fair sharing. This fair sharing distributes server capacity to currently backlogged sessions in proportion to their weights without regard to the amount of service that the sessions received in the past. From a long-term perspective, the instantaneous fair sharing leads to a different quality of service in terms of delay and bandwidth to sessions with the same weight depending on their traffic pattern. To minimize such long-term unfairness, we propose a delay-bandwidth normalization model that defines the concept of value of service (VoS) from the aspect of both delay and bandwidth. A model and a packet-by-packet scheduling algorithm are proposed to realize the VoS concept. Performance comparisons between the proposed algorithm and algorithms based on fair queueing and service curve show that the proposed algorithm provides better long-term fairness among sessions and that is more adaptive to dynamic traffic characteristics without compromising its service rate and delay guarantees.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.6 s.348
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• pp.23-29
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• 2006

It is difficult to apply conventional security algorithms to the wireless sensor networks composed of nodes that have resource constraints such as memory, computing, power resources limitation. Generally, shared key based algorithms with low resource consumption and short key length are used for broadcast packets in authentication of base station. But it is not suitable that all the nodes hold the same shared key only for packet authentication. Recently, broadcast authentication algorithm for sensor network is proposed, which uses key chain generation by one-way hash function, Message Authentication Code generation by each keys of the key chains and delayed key disclosure. It provides suitable authentication method for wireless sensor networks but may leads to inefficient consequence with respect to network conditions such as broadcast ratio, key chain level, and so on. In this paper, we propose an improved broadcast authentication algorithm that uses key chain link and periodical key disclosure. We evaluated the performance of proposed algorithm using TOSSIM(TinyOS Simulator) in TinyOS. The results show that the proposed algorithm ensures low authentication delay, uses memory and computing resource of receiving nodes efficiently and reduces the amount of packet transmitting/receiving.