• Journal of KIISE:Information Networking
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• v.32 no.2
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• pp.244-253
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• 2005

In this paper, a performance evaluation model of the switch router with the multiple-buffered crossbar switches is proposed and examined. Buffered switch technique is well known to solve the data collision problem of the crossbar switch. The proposed evaluation model is developed by investigating the transfer patterns of data packets in a switch with output-buffers. The performance of the multiple-buffered crossbar switch is analyzed. Steady state probability concept is used to simplify the analyzing processes. Two important parameters of the network performance, throughput and delay, are then evaluated. To validate the proposed analysis model, the simulation is carried out on a network that uses the multiple buffered crossbar switches. Less than $2\%$ differences between analysis and simulation results are observed. It is also shown that the network performance is significantly improved when the small number of buffer spaces is given. However, the throughput elevation is getting reduced and network delay becomes increasing as more buffer spaces are added in a switch.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.1055-1057
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• 2013

Routers currently used in homes and institutions have a function of multiple computers to connect to the Internet with a single IP address. It is possible only through setting or establishing a separate operation in a used PC or server to function as a web/printer server, web hard, and P2P. In this paper, by utilizing the OpenWRT Linux-based through the construction of the Web server through a router OpenWRT of (Open Wireless Router) base, to build a server simple compact, low power consumption, low cost, to operate by reliability to provide Internet telephony and multimedia services high securely over the server security, which is based on the setting of policy and various firewall at the same time the configuration of the network utilizing OpenWRT router that can be enhanced, to construct a Web server through a router multi functional can receive the provision of services using the program PC and mobile APP.

• The KIPS Transactions:PartC
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• v.13C no.3 s.106
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• pp.345-352
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• 2006

In the integrated wired/wireless network which consists of the Internet and moving networks, multiple wireless links are used to connect a fixed host(FH) in the Internet to a mobile host(MH) in the moving network. For use in such an environment, we propose a scheme to overcome the TCP performance degradation due to the packet losses over the wireless links without losing the end-to-end TCP semantics. The proposed scheme in each mobile router(MR) allows to obtain the information regarding packet losses over the upstream wireless links based on the received packet sequence number and the ACK number. This information is delivered to the upstream router, which enables the upstream access router(AR) or MR to quickly retransmit the lost packets. The proposed scheme has the feature to quickly recover the packet losses incurred over the upstream wireless links and the performance of the proposed scheme is evaluated through simulation. It is shown that the significant performance gain can be obtained using the proposed scheme compared with the snoop mechanism which maintains end-to-end TCP semantics and does not require any additional features at the source and/or destination nodes.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.2 s.3
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• pp.43-54
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• 2003

As the demand for ubiquitous mobile wireless Internet grows, vehicles are receiving a lot of attention as new networking platforms. The demand for 4G all-IP networks encourages vehicle networks to be connected using IPv6. By means of network mobility (NEMO) support, we can connect sensors, controllers, local ,servers as well as passengers' devices of a vehicle to the Internet through a mobile router. The mobile router provides the connectivity to the Internet and mobility transparency for the rest of the mobile nodes of an in-vehicle nv6 network. So, it is .important for the mobile router to assure reliable connection and a sufficient data rate for the group of nodes behind it. To provide reliability, this paper proposes an adaptive multihoming architecture of multiple mobile routers. Proposed architecture makes use of different mobility characteristics of different vehicles. Simulation results with different configurations show that the proposed architecture increases session preservation thus increases reliability and reduces packet loss. We also show that the proposed architecture is adaptive to heterogeneous access environment which provide different access coverage areas and data rates. The result shows that our architecture achieves sufficient data rates as well as session preservation.

• The KIPS Transactions:PartC
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• v.15C no.2
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• pp.111-118
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• 2008

A wireless router is a device which allows several wireless clients to share an internet line using NAT (Network Address Translation). In a school or a small office environment where many clients use multiple wireless routers, a client may select any one of wireless routers so that most clients can be clustered to a small set of the wireless routers. In such a case, there exists load unbalancing problem between clients and wireless routers. One of its result is that clients using the busiest router get poor service. The other is that the resource utilization of the whole wireless routers becomes very low. In order to resolve the problems, we propose a load sharing scheme to maximize network bandwidth utilization based on SSID(Service Set IDentifier) hiding. The proposed scheme keeps checking the available bandwidth of all the possible wireless routers in a time interval and select the most available one. If a new client appears, the most available router is visible to him or her whereas the others are not visible. This is handled by SSID hiding in the proposed scheme. We implemented the proposed scheme with ASUS WL 500G wireless router and performed experiments. Experimental results show the bandwidth utilization improvement compared to the existing method.

• The KIPS Transactions:PartA
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• v.8A no.2
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• pp.147-156
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• 2001

A high performance routing switch is an essential device to either the high performance parallel processing or communication networks that handle multimedia transfer systems such as VOD. The high performance routing chip called STC104 is a typical example in the technical aspect which has 32 bidirectional links of 100Mbps transfer sped. It has exploited new technologies, such as wormhole routing, interval labeling, and adaptive routing method. The high speed router has been applied into some parallel processing system as a single chip. However, its performance over the various interconnection networks with multiple routing chips has not been studied. In this paper, the strucrtures and characteristics of the STC104 have been investigated in order to evaluate the high speed router. Various topology of the STC104, such as meshes, torus, and N-cube are defined and constructed. Algorithms of packet transmission have been proposed based on the interval labeling and the group adaptive routing method implemented in the interconnected network. Multicast algorithms, which are often requited to the processor networks and broadcasting systems, modified from U-mesh and U-torus algorithms have also been proposed overcoming the problems of point-to-point communication.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5A
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• pp.359-369
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• 2005

For large capacity optical CDMA networks, we propose a shared-type encoder/decoders based on an tunable wavelength converter(TWC) and an arrayed waveguide grating (AWG) router. The proposed encoder/decoder treats codewords of wavelength/time 2-D code simultaneously using the dynamic code allocation property of the TWC and the cyclic property of the AWG router, and multiple subscribers can share the encoder/decoder in networks. Feasibility of the structure of the proposed encoder/decoder for dynamic code allocation is tested through simulations using two wavelength/time 2-D codes, which are the generalized multi-wavelength prime code(GMWPC) and the generalized multi-wavelength Reed-Solomon code(GMWRSC). Test results show that the proposed encoder/decoder can increase the channel efficiency not only by increasing the number of simultaneous users without any multiple-access interference but by using a relatively short length CDMA codes.

• The Journal of the Korea Contents Association
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• v.10 no.9
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• pp.79-87
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• 2010

This paper proposes a L3 handover method to minimize packet loss for supporting service continuity to IMS Terminal which has a single WLAN interface. The existing IMS based handover solution is able to support handover between different access networks in case that a terminal has multiple interfaces. That is, WLAN terminals need multiple interfaces to connect with one or more access networks. This proposed method configures IP address for the terminal in target WLAN previously by using Candidate Access Router Discovery(CARD) mechanism. Also, in the proposed method, service continuity server performs L3 connection establishment in target WLAN and registration to IMS server instead of the terminal. And then session control mechanism based on SIP is performed to support service continuity. We analyzed handover latency and signaling cost in the proposed method and existing method to show the improved performance by the proposed method.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.6
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• pp.445-453
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• 2016

Fixed robust routing is attracting attention as routing that achieves high robustness against changes in traffic patterns without conducting traffic measurement and performing dynamic route changes. Fixed robust routing minimizes the worst-case maximum link load by distributing traffic of every source-destination (s-d) router pair onto multiple candidate paths (multipath routing). Multipath routing, however, can result in performance degradation of Transmission Control Protocol (TCP) because of frequent out-of-order packet arrivals. In this paper, we first investigate the influence of multipath routing on TCP performance under fixed robust routing with a simulation using ns-2. The simulation results clarify that TCP throughput greatly degrades with multipath routing. We next propose a candidate path selection method to improve TCP throughput while suppressing the worst-case maximum link load to less than the allowed level under fixed robust routing. The method selects a single candidate path for each of a predetermined ratio of s-d router pairs in order to avoid TCP performance degradation, and it selects multiple candidate paths for each of the other router pairs in order to suppress the worst-case maximum link load. Numerical examples show that, provided the worst-case maximum link load is less than 1.0, our proposed method achieves about six times the TCP throughput as the original fixed robust routing.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.177-182
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• 2011

These days as there are growing the number of vessel sailing, diverse aquaculture industries, fishing works, and leisure activities in coastal area, the diverse communication services have been required for secure voyage information. This paper addresses the scheme for costal area service using mobile IP router with multiple interfaces. For this, this system has the wireless interfaces, such as WiBro, HSDPA, and WLAN that can provides vessels with divers communication services, and can provide the vessels with the diverse information communication services in real-time through wireless communication network installed in costal area. So this can provide the infrastructure that supplies the authorized seamless information communication services.