• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.49-56
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• 2011

One of the most important VANET applications is providing active safety by broadcasting emergency messages. In order to prevent broadcast storm of flooding-based broadcasting scheme in which any node receiving message will rebroadcast, the existing protocols use the different methods to limit the number of relay nodes. Nevertheless, the existing protocols have low delivery ratio with high traffic density and cause message overhead. Currently, the dramatic increase in the number of vehicles equipped with Global Positioning System (GPS) and onboard radar created new application scenarios that were not feasible before. Consequently, we proposed a broadcasting protocol that selects relay node by using GPS-based position information and detecting neighboring vehicles with the help of onboard radar to. Simulation results show that our proposed protocol has better performance than the existing schemes.

• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.637-646
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• 2001

The multicasting telecommunication is an important research as an applicable technique in the development of adaptable technique for modern mobile computing and mobile IP, because that is supposed to be a solution for transferring the large-size information on the mobile and wireless network with the narrow bandwidth. This paper will suggest one solution for the bidirectional tunneling and the local re-registration problems to support transferring mobile multicasting datagram by the partitioned network. The bidirectional tunneling technique is in use for mobile host moving around in a region and the local re-registration technique for crossing regions to reduce traffic load caused by transferring datagram along a long distance, and we compare those models with our suggested model by simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.61-64
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• 2007

MPLS networks architectures have been prevailed as scalable approach to provide quality of service in the Internet. Many researches have been mainly focused on scalability and multi-path calculation scheme for failure restoration. However, the MPLS network have an scalability problem about traffic, and the existing failure restoration methods are wasted resources, and it has the problem that loss of a packet by a lot of delay occurs in too. Therefore in this paper, we propose a H-MPLS (Hierachical-Multiprotocol Label Switching)network for rapidly failure restorations and effective management of network extended. The proposed H-MPLS Network apply LSP multi-path routing algorithm and consists of several MPLS. After comparing the performance among the existing failure restoration methods with various network models, we use NS simulator in order to analyze the performance. Finally, we present an improvement scheme of the efficiency and scalability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.12
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• pp.1338-1345
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• 2014

Recently, wireless technology gains attention for industrial networks due to low cost, flexibility, relatively easy installation and most importantly, solving the rouring issue. ISA100.11a is one of promising standard for wireless industrial networks (WINs). Data traffic in industrial networks are known to be periodic and must satisfy the real-time property namely deadline. Therefore, in this paper, we proposed to apply deadline monotonic scheduling to periodic tasks in ISA100.11a networks and to evaluate the performance of ISA100.11a by checking the schedulability and beacon frame overhead. Simulation results showns, that our proposed scheme can reduces the network overhead while maintaining schedulability as compared to the previous algorithm. In addition, by reducing the network overhead, our proposed scheme can send more data without degrading the overall performance of WINs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1A
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• pp.23-29
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• 2006

In wireless sensor networks(WSNs), it is crucial to maintain network connectivity as long as possible since nodes are battery-powered and unchange-able. We propose a new routing protocol called Energy Aware Source Routing(EASR) which can be efficient in respect of network lifetime and long-term connectivity. Our protocol is multipath source routing, only one path will be selected at the same time and each path has probability to be selected like as Energy Aware Routing(EAR) protocol. The route discovery procedure of EASR protocol is reformed from the route discovery procedure of Split Multipath Routing(SMR) protocol. However, there is the difference between SMR and EASR. In EASR, we define an overhearing ratio in order to reduce energy waste due to overhearing effect among each selected path. Thus, we can establish energy efficient multiple paths by making use of overhearing ratio. The simulation results are also demonstrated that our scheme increases in network lifetimes, and achieves reasonable packet latency time.

• The KIPS Transactions:PartD
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• v.11D no.4
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• pp.975-982
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• 2004

In current P2P concept, pure P2P and Hybrid P2P structures are used commonly. Gnutella and Ktella are forms of pure P2P. and forms of Hybrid P2P are innumerable. File searching models exist in these models. These models provide group management for file sharing, searching and indexing. The general file sharing model is good at maintaining connectivity. However, it is defective in group management. Therefore, this study approaches hierarchical structure in file sharing models through routing technique and backup system. This system was designed so that the user was able to maintain group efficiency and connection reliability in large-scale network.

• The KIPS Transactions:PartC
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• v.11C no.5
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• pp.683-688
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• 2004

NAT is a very useful IP address translation technique that allows two connected networks using different and incompatible IP address schemes. But it is impractical to use NAT for an application which uses the encrypted IP packet, embedding IP addresses inside of data payloads, to guarantee End-to-End Security such as IPSec. In addition to rewriting the source/destination IP addresses in the packet, NAT must modify IP checksum every time, which could lead to considerable performance decrease of the overall system in the process of the address translation. RSIP is an alternative to solve these disadvantages of NAT and the address shortage problems. Both NAT and RSIP divide networks into inside and outside addressing realms. NAT translates addresses between internal network and external network, but RSIP uses a borrowed external address for outside communications. RSIP server assigns a routable public address to a RSIP client temporarily to communicate with public net-work outside of the private network. In this paper, RSIP gateway for intranet environment is designed and its performance is evaluated. From the results of performance evaluation, we knew that RSIP is operated less sensitive to the data traffic. Also, the experiment shows that RSIP performs better than NAT when the transmission data grows larger.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11B
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• pp.707-721
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• 2005

Recently, there has been a dramatic increase in data traffic, driven primarily by the explosive growth of the Internet. Optical networking is believed as a key solution to keep up with the growth, thus, the most pressing issue is how to manage and control large optical networks. Currently, provisioning end-to-end connections across the transport network has involved the network operator, leading to long provisioning times in an era when customers are demanding shorter provisioning time. To address this critical issue, new control intelligence is being studied for use within optical networks to shorten provisioning time. Both the IETF and the ITU-T have been aggressively defining many aspects of a control plane for the next generation convergence transport network. Basically, they are based on the distributed control scheme. In this Paper, we suey the applicability of the centralized control scheme for the provisioning control of optical transport network to utilize its inherent advantages over the distributed control scheme. We discuss new central control architecture, and control procedure. Also, we examine the applicability of the existing IETF routing and signaling protocols to the new control concepts, and then, we propose the additional routing and signaling information elements.

• 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.15-24
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• 2006

We design and implement explicit mobile multicast, named XMIP, by enhancing explicit multicast for a great number of small group multicast communications. XMIP is a straightforward multicast mechanism without maintaining multicast states due to the inheritance from the explicit multicast based on a unicast routing. This research modifies and extends the functionality of each mobility agent of IETF Mobile IP for interworking XMIP XMIP Packets captured by an extended home agent are forwarded to each extended foreign agent through nested tunnels, named X-in-X tunnels, made by the binding table of the extended home agent. X-in-X tunneling mechanism can effectively solve the serious traffic concentration problems of Mobile IP multicast specifications. Finally heterogeneous mobile networks as an XMIP testbed including CDMA2000 1X EV-DO and WLAN are actually established, and a multi-user instant messenger system for small group communications is developed for verifying the feasibility of the proposed protocols.

• The Journal of the Korea Contents Association
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• v.6 no.2
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• pp.84-92
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• 2006

In this paper, we propose an efficient multicasting algorithm in multistage interconnection networks (MIN's) employing the region encoding scheme. The proposed algorithm uses the recursive scheme to recycle a multicast message at most two times through MIN, in order to send it to its desired destinations. It is composed of two recycling phases which are the copying phase and the routing phase of the multicast message. In the first phase, a source sends the message to a region that contains the largest number of destination regions, and destinations in these regions receive and store the message in this phase. The remaining destinations can finally receive the message in the second phase. This method of the algorithm can improve its performance by reducing the delay of message and the volume of traffic. Moreover, we evaluate the performance of our algorithm in terms of the average number of recycling and the number of internal links used per destination, comparing with the previously proposed algorithm.