• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1807-1824
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• 2015

As the technologies advance, mobile peer-to-peer (MP2P) networks or systems become one of the major ways to share resources and information. On such a system, the information retrieval (IR), including the development of scalable infrastructures for indexing, becomes more complicated due to a huge increase on the amount of information and rapid information change. To keep the systems on MP2P networks more reliable and consistent, the index structures need to be updated frequently. For a semantic IR system, the index structure is even more complicated than a classic IR system and generally has higher update cost. The most well-known indexing technique used in semantic IR systems is Latent Semantic Indexing (LSI), of which the index structure is generated by singular value decomposition (SVD). Although LSI performs well, updating the index structure is not easy and time consuming. In an MP2P environment, which is fully distributed and dynamic, the update becomes more challenging. In this work, we consider how to update the sematic index generated by LSI and keep the index consistent in the whole MP2P network. The proposed Concept Space Update (CSU) protocol, based on distributed 2-Phase locking strategy, can effectively achieve the objectives in terms of two measurements: coverage speed and update cost. Using the proposed effective synchronization mechanism with the efficient updates on the SVD, re-computing the whole index on the P2P overlay can be avoided and the consistency can be achieved. Simulated experiments are also performed to validate our analysis on the proposed CSU protocol. The experimental results indicate that CSU is effective on updating the concept space with LSI/SVD index structure in MP2P semantic IR systems.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.7
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• pp.293-302
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• 2013

Home network providers have many worries about providing home network services with an expandable, reliable, flexible and low-cost structure according to the expanding market environment. The existing client-server system has various problems such as complexity and high costs in providing home network services. In this paper we propose the P2P-SIP structure. P2P communication terminal supporting access of distributed resources provides functions which the existing SIP-based network devices have. Because diverse terminals in a home network access through networks, also, partitioning network domains with home gateways to manage, and applying the network-based PMIPv6(Proxy Mobile IPv6) technology considering mobility of terminals would help to have a more efficient home network structure. Especially, the proposed P2P-SIP structure proves itself as a very efficient structure to have an outstanding expandability among different home networks in a region, and to reduce maintenance costs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4C
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• pp.451-457
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• 2006

A peer-to-peer(P2P) network is inherently vulnerable to malicious attacks from participating peers because of its open, flat, and autonomous nature. This paper addresses the problem of effectively defending from active attacks of malicious peers at bootstrapping phase and at online phase, respectively. We propose a secure membership handling protocol to protect the assignment of ID related things to a newly joining peer with the aid of a trusted entity in the network. The trusted entities are only consulted when new peers are joining and are otherwise uninvolved in the actions of the P2P networks. For the attacks in online phase, we present a novel message structure applied to each message transmitted on the P2P overlay. It facilitates the detection of message alteration, replay attack and a message with wrong information. Taken together, the proposed techniques deter malicious peers from cheating and encourage good peers to obey the protocol of the network. The techniques assume a basic P2P overlay network model, which is generic enough to encompass a large class of well-known P2P networks, either unstructured or not.

• Journal of the Korea Society of Computer and Information
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• v.12 no.2 s.46
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• pp.209-220
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• 2007

Mobile devices become a pak of our daily life due to their versatility, such as the wireless phone calls, the wireless accessibility to Internet, the display of multimedia content, and the communication with nearby mobile devices. Third generation telecommunication service provides an easy access to the Internet for nubile devices. Mobile users pay a fee charged by the telecommunication provider based on the amount of data transferred. This paper introduces a special ad hoc network in which mobile devices cooperate each other to download an interesting content from the Internet in order to reduce the telecommunication cost. The mobile devices, called the peers, in the ad hoc network are assigned a portion of the target file, and are responsible for downloading the portion using their 3G connection. Then, the peers exchange their downloaded portion with other participating peers using their cost-free ad hoc connection in order to reconstruct the whole content. According to the simulation results, large number of participating peers saves the telecommunication cost up to 90% with as few as 10 peers, although it slightly increase the overall content reconstruction time.

• The KIPS Transactions:PartA
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• v.13A no.1 s.98
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• pp.11-18
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• 2006

In the Internet of various networks, it is difficult to reduce real routing time by just minimizing their hop count. We propose an adaptive proximity route selection method in DHT-based peer-to-peer systems, in which nodes select the nぉe with smallest lookup latency among their routing table entries as a next routing node. Using Q-Routing algorithm and exponential recency-weighted average, each node estimates the total latency and establishes a lookup table. Moreover, without additional overhead, nodes exchange their lookup tables to update their routing tables. Several simulations measuring the lookup latencies and hop-to-hop latency show that our method outperforms the original Chord method as well as CFS' server selection method.

• The Journal of the Korea Contents Association
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• v.12 no.8
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• pp.47-58
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• 2012

In this paper, we propose a continuous k-nearest neighborhood query processing method for updating the query results in real-time over mobile peer-to-peer environments. The proposed method disseminates a monitoring region to efficiently monitor the k-nearest neighbor peers. The Monitoring Region is created to assure at least k peers as the result of the query within the time range using the vector of neighbor peers. In the propose method, the monitoring region is valid for a long time because it is calculated by the vector of neighbor peers of the query peer. Therefore, the proposed method decreases the cost of re-processing by monitoring region invalidation. In order to show the superiority of the proposed method, we compare it with the previous schemes through performance evaluation.

• The KIPS Transactions:PartD
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• v.10D no.2
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• pp.327-336
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• 2003

Recently the rapid growth of Internet and the construction of high speed networks make many kinds of multimedia services possible. But most of current multimedia services are designed being by client/server model, which incurs high load of central server. In order to solve this problem, we propose a peer-to-peer network-based discovery mechanism for multimedia services. In the proposed scheme, mobile agents that have autonomy and mobility are used to search the location of resources. Use of mobile agents can solve the loss problem of the search result that occurs when the network is unsettled in pure peer-to-peer network. It also supports interoperability in heterogeneous system environments. In the proposed scheme, each host maintains the location information of resources which are locally requested or recently requested by other hosts. So, the proposed scheme has faster response time than the pre-existing mechanisms in pure peer-to-peer network environments.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.343-346
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• 2002

This paper presents a Prototype system developed for a Bluetooth interfaced VoIP system. The VoIP phone is developed based on tile implementation of a CELP coder on the TI 16bit DSP Processor A PC interfaced with Bluetooth module is used to designing a access point system. Host controller protocol stack is implemented to realize gateway between the wireless and wired line networks. A server application program for user management and call processing, which is based on TCP/IP peer to peer connection, is implemented for tile evaluation of overall interface system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.411-413
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• 2010

Now, smart phone markets are grows quickly. So it is needed research of CDN(Contents Delivery Network) technology for contents transmission in mobile networks. Especially the services of smart phone are focused on open platform model. So P2P(Peer to Peer) protocols will be used for mobile network because it is a distributed network architecture composed of participants that make a portion of their resources directly available to other network participants, without the need for a central server. Current research of P2P protocols for mobile network are not activated. The reason is appropriate in the mobile P2P network simulation environment, since it is not provided. So, in this paper we design a mobile P2P simulation system for CDN based on mobile P2P.

• International Journal of Contents
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• v.5 no.1
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• pp.21-26
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• 2009

Peer to Peer (P2P) utilizes the resources of an offered service without the need for a central server or preexistent server-client, making it a desirable network environment for data exchange based on direct connection between peers. Proposed by Sun Microsystems. JXTA(Juxtapose) is a typical P2P system and distributed computing model that does not require central service resources and is flexible to deal with various network configuration changes. Meanwhile. Mobile Ad-hoc NETwork(MANET) is a typical wireless network configured with mobile nodes and without an infrastructure. where a network is established by direct connection or through other peers in the propagation area. Thus, MANET maintains the latest path information by establishing paths and changing path information for communication between peers in a highly mobile wireless network. Accordingly. this article proposes the JXTAMANET method for wireless networks to enable JXTA to be applied to MANET. NS2 is used to evaluate the performance and the proposed architecture is shown to produce better results than a conventional flooding method.