• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.11
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• pp.934-936
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• 2013

A routing scheme for a group of mobile users for wireless ad-hoc networks is presented. The proposed scheme mines social activity patterns from wireless traces, and exploits social user group for efficient data routing among users based on a data publish approach. Simulation results based on real-world wireless traces show that our routing scheme reduces routing cost for a large mobile user group with a factor of 1.8 compared to a baseline counterpart.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.1060-1073
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• 2013

In this paper, we present a cluster-based routing scheme for efficiently delivering data to group mobile users by extracting and clustering mobile user group simply from beacon message information in wireless ad-hoc networks. First, we propose an online-clustering mechanism that uses a local neighbor table on each node by recursively transmitting to neighbor nodes, and forms a group table where a set of listed nodes are classified as group members, without incurring much overhead. A node that appears the most frequently from neighbor tables throughout the network is selected as the cluster-head node, serving as a data gateway for the intra-cluster. Second, we design an inter-cluster routing that delivers data from stationary data sources to the selected cluster-head node, and a intra-cluster routing to deliver from the cluster-head node to users. Simulation results based on ns-2 in the ad-hoc networks consisting of 518 stationary nodes and 20 mobile nodes show that our proposed clustering mechanism achieves high clustering accuracy of 96 % on average. Regarding routing performance, our cluster-based routing scheme outperforms a naive one-to-one routing scheme without any clustering by reducing routing cost up to 1/20. Also, our intra-cluster routing utilizing a selected cluster-head node reduces routing cost in half as opposed to a counterpart of the intra-cluster routing through a randomly-selected internal group member.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1851-1854
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• 2002

The Internet with conventional routing scheme cannot meet user demands driven from drastic growth in the Internet user and various service and traffic type. MPLS(Multi Protocol Label Switching) was introduced to the Internet fur solution to resolve this problem. MPLS is a paradigm to integrate higher layer’s software routing functions including layer-3 routing with layer-2 switching. But, the exponential growth of Internet traffic brings out of label space. One scalable solution to cope with this problem is to introduce flow merge technique, i. e. a group of flows is forwarded using the same label. Specially, IETF(Internet Engineering Task Force) recommends that ATM based MPLS system may include VC merge function, so it is scalable to increase of internet traffic. We implemented the MPLS LER system that includes the look-up and forwarding function in incoming path and VC merging function and limited traffic management function in outgoing path. This paper describes the implementation of the LER’s outgoing parts.

• Journal of the Korea Society of Computer and Information
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• v.6 no.2
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• pp.116-122
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• 2001

A conventional multicast secure protocol. MVMRP, CBT is designed for a large scaled r protocol so the PIM-SM (protect Independent Multicst-Sparse Mode) routing protocol which small number of clients, long distance path among the hosts and shortest path routing chara weak point of require it's own Core tree and re-keying when the traffic is pass through the ro In this study, proposes a architect for a licit information secure of join/leave to all the user or on-service user. With proposed architect, subgroups for multicast secure group mana will be divided by RP (Rendezvous-Point) unit and each RP has a subgroup manager. As a result, the transmitting time is shortened because there is no need to data translation by group key on data sending and the whole architecture size is samller than the other multicast secure architecture.

• The Transactions of the Korea Information Processing Society
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• v.7 no.4
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• pp.1184-1192
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• 2000

Multicast has communication mechanism that is able to transfer voice, video for only the specific user group. As compared to unicast, multicast is more susceptive to attack such as masquerading, malicious replay, denial of service, repudiation and traffic observation, because of the multicast has much more communication links than unicast communication. Multicast-specific security threats can affect not only a group's receivers, but a potentially large proportion of the internet. In this paper, we proposed the multicast security model that is able to secure multi-group communication in CBT(Core Based Tree), which is multicast routing. And designed the multicast key distribution protocol that can offer authentication, user privacy using core (be does as Authentication Server) in the proposed model.

• Journal of the Korea Computer Industry Society
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• v.3 no.9
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• pp.1235-1244
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• 2002

This paper proposes a group key management protocol for a secure of all the multicast user in PIM-SM multicast group communication. With prosed architect, subgroups for multicast secure group management will be divided by RP (Rendezvous-Point) unit and each RP has a subgroup manager. Each subgroup manager gives a secure key to it's own transmitter md the transmitter compress the data with it's own secure key from the subgroup manager. Before the transmitter send the data to receiver, the transmitter prepare to encrypt a user's service by sending a encryption key to the receiver though the secure channel, after choking the user's validity through the secure channel. As the transmitter sending a data after then, the architecture is designed that the receiver will decode the received data with the transmitter's group key. As a result, the transmitting time is shortened because there is no need to data translation by group key on data sending and the data transmition is possible without new key distribution at path change to SPT (Shortest Path Tree) of the router characteristic. Additionally, the whole architecture size is samller than the other multicast secure architecture by using the conventional PIM-SIM routing structure without any additional equipment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.115-120
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• 2013

There are lots of vulnerability and chance to be attacked in wireless sensor networks, which has many applications. Among those attacks, sybil attack is to generate a lot of false node and to inject false information into networks. When a user uses such false information without recognizing the attack, there might be a disaster. Although authentication method can be used to protect such attack, the method is not a good choice in wireless sensor networks, where sensor nodes have a limited battery and low power. In this paper, we propose a novel method to detect sybil attack with a little extra overhead. The proposed method use the characteristics that there is a weak connection between a group of normal nodes and a group of false nodes. In addition, the method uses energy aware routing based on random routing and adds a little information into the routing. Experimental results show that the proposed method detects false node by more than 90% probability with a little energy overhead.

• The KIPS Transactions:PartC
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• v.12C no.2 s.98
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• pp.267-280
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• 2005

In this paper, we implement and verify XMIP integrating IETF Mobile IP and the Explicit Multicast mechanism for a great number of small group multicast communications. U a source node sends Xcast packets explicitly inserting destination nodes into the headers, each Xcast router decides routes and forwards the packets toward each destination node based on unicast routing table without the support of multicast trees. n is a straightforward and simple multicast mechanism just based on a unicast routing table without maintaining multicast states because of the inheritance from the Explicit Multicast mechanism. This research modifies and extends the functionality of IETF Mobile IP's mobility agents, such as HA/FA to HA+/FA+ respectively, considering interworking with Xcast networks. Xcast packets captured by HA+ are forwarded into X-in-X tunnel interfaces for each FA+ referred to the binding table of HA.. This X-in-X tunneling mechanism can effectively solve the traffic concentration problem of IETF Mobile IP multicast services. Finally WLAN-based testbed is built and a multi-user Instant messenger system is developed as a Xcast application for finally verify the feasibility of the implemented XMIP/Xcast protocols.

• 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.

• 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.