• The Journal of Information Technology
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• v.4 no.3
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• pp.87-100
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• 2001

IETF has proposed integrated services model(Int-Serv) and differentiated service(Diff-Serv) to supply IP QoS in Internet[1][2]. Int-Serv model uses state information of each IP flow, so satisfies QoS according to traffic characteristics, but increases the amount of flow state information with increasing flow number. Diff-Serv uses PHP(Per Hop Behaviour) and there are well-defined classes to provide differentiated traffics with different services according to delay and loss sensitivity. Diff-Serv model can provide diverse services in Internet because of having no the state and signal information of each flow. As MPLS uses the packet forwarding technology based on label, it implements the forwarding engine of high performance easily. The MPLS can set up the path having different and variable bandwidth and assign each path to particular CoS (Class of Service). Therefore it is possible to support the Diff-Serv model of well- defined classes that can provide the differentiated traffic with different services according to delay and loss sensitivity in IP QoS models of IETF. In this paper we propose a scheme that can accommodate Diff-Serv model to provide QoS. The system performance has been estimated by scheduling plan according to traffic classes.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.1
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• pp.84-91
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• 2011

To develop the new network, the future network architecture is studied. Since the mobile devices are also advanced, they need for the mobility protocols. The one of the protocols, Fast handovers for proxy MIPv6(PFMIPv6) has studied by the Internet Engineering Task Force(IETF). Since PFMIPv6 adopts the entities and the concepts of fast handovers for MIPv6(FMIPv6) in proxy MIPv6(PMIPv6), it reduces the packet loss. Although the conventional scheme has proposed that it cooperated with an Authentication, Authorization and Accounting (AAA) infrastructure for authentication of a mobile node in PFMIPv6, it has the drawbacks such as high signaling cost and long handover latency. To reduce the signaling cost and the handover latency, we propose an enhanced authentication scheme in Fast handover for Proxy MIPv6. The proposed scheme reduces the handover latency and the signaling cost because the registration procedure and the authentication procedure are simultaneously performed. We also compare the proposed scheme with the conventional scheme in terms of the signaling cost and the handover latency.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.8 s.350
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• pp.47-58
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• 2006

Due to the movement of nodes, ad-hoc networks suffer from the problems such as the decrease of data delivery ratio, the increase of end-to-end delay, and the increase of routing overhead. The backup routing schemes try to solve these problems by finding the backup routes during the route discovery phase and using them when a route fails. Generally the backup routing schemes outperform the single-path routing schemes in terms of data delivery ratio, end-to-end delay, and routing overhead when the nodes move rapidly. But when the nodes don't move rapidly, the backup routing schemes generate more routing traffics than the single-path routing schemes because they need to exchange packets to find the backup route. In addition, when the backup route fails earlier than the main route, it can not use the backup route because in many backup route algorithms, the backup route is found only at the initial route discovery phase. RBR(Reactive Backup Routing Algorithm) proposed in this paper is an algorithm that provides more stable data delivery than the previous backup routing schemes through the selective maintenance of backup route and the backup route rediscovery. To do that RBR prioritize the backup routes, and maintain and use them selectively Thus it can also decrease the routing overheads. Also, RBR can increase data delivery ratio and decrease delay because it reestablishes the backup route when the network topology changes. For the performance evaluation, OPNET simulator is used to compare RBR with the single-path routing scheme and some of the well known backup routing schemes.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.1
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• pp.1-12
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• 2004

In this paper, we take advantage of the characteristics of optical burst switching (OBS) to support service-differentiation in optical networks. With the offset time between control packet and burst data, the proposed scheme uses different offset time of each service class. As contrasted with the Previous method, in which the high Priority service use only long offset time, it derives the burst loss rate as a QoS parameter in consideration of conservation law and given service-differential ratios and decides a reasonable offset time for this QoS finally Firstly proposed method classifies services into one of high or low class and is an algorithm deciding the offset time for supporting the required QoS of high class. In order to consider the multi-classes environment, we expand the analysis method of first algorithm and propose the second algorithm. It divides services into one of high or low group according to their burst loss rate and decides the offset time for high group, and lastly cumulates the offset time of each class. The proposed algorithms are evaluated through simulation. The result of simulation is compared with that of analysis to verify the proposed scheme.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.9
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• pp.26-37
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• 2016

The core technologies of the current transport network are OAM and protection switching to meet the sub-50ms protection switching time via a path redundancy when a link or node failure occurs. The transport networks owned by public network operators, central/local governments, and major enterprises are individually configured and managed with service resiliency in each own protected sub-network. When such networks are cascaded, it is also important to provide a node resiliency between two protected sub-networks. However, the linear protection switching in packet transport networks, such as MPLS-TP and Carrier Ethernet, does not define a solution of dual node interconnection. Although Ethernet ring protection switching covers the dual node interconnection scheme, a large amount of duplicated data frames may be flooded when a failure occurs on an adjacent (sub) ring. In this paper, we suggest a dual node interconnection scheme with linear protection switching technology in multiple protected sub-networks. And we investigate how various protected sub-network combinations with a proposed linear or ring protection process impact the service resiliency of multiple protected sub-networks through extensive experiments on link and interconnected node failures.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.12
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• pp.17-27
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• 2011

Most of the previous mobility management protocols such as IETF MIPv4/6 and its variants standardized by the IETF do not support global seamless handover because they require partially changes of the existing network infrastructure. In this article, we propose a simple mobility management protocol (SMMP) which can support global seamless handover between homogeneous or heterogeneous wireless networks. To do this, the SMMP employs separate location management function as DMMS to support global user and service mobility and the bidirectional tunnels are dynamically constructed to support seamless IP mobility by using the IEEE MIH extension server, which is extended the IEEE 802.21 MIH standards. The detailed architecture and functions of the SMMP have been designed. Finally, the mathematical analysis and the simulation have been done. The performance results show the proposed SMMP outperforms the existing MIPv6 and HMIPv6 in terms of handover latency, packet loss, pear signal noise ratio (PSNR).

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.227-237
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• 2014

The purpose of this paper is to implement a multiple bio-signal central monitoring system based on textile fabrics flexible platform which can obtain and monitor bio signals(heart rate, body temperature, electrocardiography, electromyogram) of workers in special working environments and additional situational information (3-axis acceleration, temperature, humidity, illumination, surrounding image). This system can prevent various accidents that may occur in the remote work environment and provide fast and efficient response by detecting workers' situations in real-time. For it, the textile fabrics flexible platform was made as innerwear or outerwear so that it does not interfere with workers' performance while collecting bio-signal and situational information, and obtained information is sent to the central monitoring system through wireless communication. The central monitoring system is based on wireless medical telemetry service of WMTS (Wireless Medical Telemetry Service); can monitor from 2 to 32 people simultaneously; and was designed so that it can be expanded. Also, in this study, to verify performance of the WMTS communication model, packet transmission rates were compared according to the distance.

• 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.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.34-42
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• 2012

This paper analyses the energy saving basic power models in core IP networks, and proposes the adaptive buffer and burst scheme which is a possible energy saving method, and its implementation algorithm in core IP networks. Especially this paper describes the adaptive buffer and burst scheme dynamically varying the buffering interval B according to the input traffic volume of ingress router, and explains the operation principle of proposed scheme. This method is to adjust the buffering interval B according to input traffic volume of ingress router, that is increasing the interval B when input traffic volume is low, and decreasing the interval B when input traffic volume is high between some given interval regions. This method can gets the high energy saving effect as decreasing the transition number of idle/active in networks when input traffic volume is low, and decreasing the transition number of idle/active by the continuous of burst packets in transit router when input traffic volume is high. This paper shows the increasing of asleep rate for the energy saving of core IP networks and confirms the energy saving of core IP networks by the computer simulation. We confirmed that proposed method can be save the energy of IP networks by properly trade off network performances.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.4
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• pp.436-444
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• 2018

Currently, the new substation automation uses the international standard IEC 61850 communication protocol. KEPCO is also constructing a new substation based on IEC 61850 from 2013 through the pilot application and research and development starting from 2007. However, there are few cases where existing substations(Transformer, T/L GIS, D/L GIS, etc.) have been used, and RTU based substations operating systems have been changed to SA substations based on IEC 61850. Therefore, the introduction of IEC 61850 in existing substation facilities has the advantage of enhancing the substantiality of the substation by reusing existing facilities, improving the interoperability with the latest substations introduced, and converting existing substations into systems suitable for unmanned operation. In this paper, we introduce a case of changing the existing RTU based substation operation system to digital substation using IEC 61850 field information processor, Ethernet switch and SA operation system. Also, IEC 61850 client authentication program and Wireshark, which is a packet analysis tool, verify IEC 61850 conformance and its feasibility.