• Title/Summary/Keyword: communication

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Implementation of Secure E-Mail System based on lava (자바기반의 안전한 전자 메일 시스템 구현)

  • 이원구;김성준;이희규;조한진;이재광
    • Journal of Internet Computing and Services
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    • v.2 no.3
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    • pp.51-62
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    • 2001
  • Recently, as computers and networks become popular, distributing information on the Internet is common In our daily life. also, the explosion of the Internet. of wireless digital communication and data exchange on Internet has rapidly changed the way we connect with other people. The e-mail has been commonly used by users as well recognizing It as the standard of manners among users on the Internet. In the past, e-mail has been the primary choice of exchanging Information, but secure mail is gaining popularity abroad and domestically because of their nature of providing security. That is. it has been used a variety of fields such as general mail and e-mail for advertisement. But, As the data transmitted on network can be easily opened or forged with simple operations. most of existing e-mail system don't have any security on the transmitted information. Thus. security mail system need to provide security including message encryption, content Integrity, message origin authentication, and non-repudiation. In this paper, we design implement secure mail system with non-repudiation service and encryption capability to provide services for certification of delivery and certification of content as well as the basic security services. API.

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Personal Mutual Authentication System for Ubiquitous Wireless Environments (유비쿼터스 무선환경을 위한 개인 상호인증 시스템)

  • Kim Byung-Gi;Hong Sang-Sun;Jouhn Young-Keel
    • Journal of Internet Computing and Services
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    • v.5 no.1
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    • pp.99-111
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    • 2004
  • Two general security measures in computing networks are secure data transmission and user authentication, These problems are still critical in the wireless LAN environments. Thus security becomes most significant issue in personal network environments and ubiquitous networks based on wireless LANs. We purpose a new authentication system for these kind of environments, and coined it UPMA(Ubiquitous Personal Mutual Authen-tication) model. UPMA supports authenticating configurations which provides personal verification for each system. It guarantees secure communications through the session key setup, and provides mutual authentication by verifying each user and his/her station. UPMA solves security problems in ubiquitous networks without accessing authentication server, Instead it performs mutual authentication between terminals or between systems. It is a global authentication system which enables global roaming service through the Internet or other public networks, It can be used to guarantee safe and convenient access to a company Intranet or to a home network.

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Design and Evaluation of a Fault-Tolerant Distributed Location Management Method in Mobile Environments (이동 환경에서 결함 포용 분산 위치 관리 방법의 설계 및 평가)

  • Bae, Ihn-Han;Oh, Sun-Jin
    • Journal of Internet Computing and Services
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    • v.1 no.1
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    • pp.35-46
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    • 2000
  • One of the main chalenges in personal communication services (PCS) is to locate many mobile terminals that may move frequently from place to place. Such a system operation is called location management. Many network signaling traffic, and database queries are required to achieve such a task. Several strategies have been proposed to improve the efficiency of location management. These strategies use location register databases to store the current location on mobile terminals, and are vulnerable to failure of the location registers. In this paper, we propose a fault-tolerant pointer forwarding with distributed home location register (FT-RFDHLR) to tolerate the failure of location registers. The performance of the proposed method is evaluated by an analytical model, and is compared with thew pointer forwarding with the single home location register (PFSHLR), the pointer forwarding with distributed home location register (PFDHLR), Biaz's bypass forwarding strategy (BFS) and two-path forwarding strategy (TPFS).

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A Study on the Design of Switch for High Speed Internet Communication Network (고속 인터넷 통신망을 위한 스위치 설계에 관한 연구)

  • 조삼호
    • Journal of Internet Computing and Services
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    • v.3 no.3
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    • pp.87-93
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    • 2002
  • A complex network and a parallel computer are made up of interconnected switching units. The role of a switching unit is to set up a connection between an input port and an output port, according to the routing information. We proposed our switching network with a remodeled architecture is a newly modified Banyan network with eight input and output ports. We have analysed the maximum throughput of the revised switch. Our analyses have shown that under the uniform random traffic load, the FIFO discipline is limited to 70%, The switching system consists of an input control unit, a switch unit and an output control unit. Therefore the result of the analyses shows that the results of the networking simulation with the new switch are feasible and if we adopt the new architecture of the revised model of the Banyan switch, the hardware complexity can be reduced. The FIFO discipline has increased by about 11% when we compare the switching system with the input buffer system. We have designed and verified the switching system in VHDL using Max+plusII. We also designed our test environment including micro computers, the base station, and the proposed architecture. We proposed a new architecture of the Banyan switch for BISDN networks and parallel computers.

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Mobility-Aware Interference Avoidance Scheme for Vehicular WLANs

  • Park, Lai-Hyuk;Na, Woong-Soo;Lee, Gun-Woo;Lee, Chang-Ha;Park, Chang-Yun;Cho, Yong-Soo;Cho, Sung-Rae
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.5 no.12
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    • pp.2272-2293
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    • 2011
  • Communication technology of future networks is predicted to provide a large variety of services including WiFi service in vehicular network. In this paper, we assume that vehicles are embedded with WiMAX antenna and in-vehicle terminals receive WiMAX traffic through WiFi interface. This assumption will impose severe performance degradation due to interference among mobile BSSs when WiFi access points (APs) are densely located. Existing interference avoidance techniques cannot properly resolve the above problems and do not cope with dynamically moving vehicular scenario since they focus only on the fixed network topology. In this paper, we propose a mobility-aware interference avoidance scheme for WiFi services. The proposed scheme computes the interference duration by exploiting mobility vector and location information of neighboring APs. If the interference duration is not negligible, our scheme searches for another channel in order to avoid interference. However, if the interference duration is negligible, our scheme continues to use the channel to reduce switching overhead. To measure the effectiveness of the proposed scheme against other existing techniques, we evaluated performance by using OPNET simulator. Through the simulation, we obtained about 60% reduction in the maximum interference frequency and about 67% improvement in throughput. Furthermore, our scheme provides fair channel usage.

An Efficient Adaptive Bitmap-based Selective Tuning Scheme for Spatial Queries in Broadcast Environments

  • Song, Doo-Hee;Park, Kwang-Jin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.5 no.10
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    • pp.1862-1878
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    • 2011
  • With the advances in wireless communication technology and the advent of smartphones, research on location-based services (LBSs) is being actively carried out. In particular, several spatial index methods have been proposed to provide efficient LBSs. However, finding an optimal indexing method that balances query performance and index size remains a challenge in the case of wireless environments that have limited channel bandwidths and device resources (computational power, memory, and battery power). Thus, mechanisms that make existing spatial indexing techniques more efficient and highly applicable in resource-limited environments should be studied. Bitmap-based Spatial Indexing (BSI) has been designed to support LBSs, especially in wireless broadcast environments. However, the access latency in BSI is extremely large because of the large size of the bitmap, and this may lead to increases in the search time. In this paper, we introduce a Selective Bitmap-based Spatial Indexing (SBSI) technique. Then, we propose an Adaptive Bitmap-based Spatial Indexing (ABSI) to improve the tuning time in the proposed SBSI scheme. The ABSI is applied to the distribution of geographical objects in a grid by using the Hilbert curve (HC). With the information in the ABSI, grid cells that have no objects placed, (i.e., 0-bit information in the spatial bitmap index) are not tuned during a search. This leads to an improvement in the tuning time on the client side. We have carried out a performance evaluation and demonstrated that our SBSI and ABSI techniques outperform the existing bitmap-based DSI (B DSI) technique.

A Hybrid Multiuser Detection Algorithm for Outer Space DS-UWB Ad-hoc Network with Strong Narrowband Interference

  • Yin, Zhendong;Kuang, Yunsheng;Sun, Hongjian;Wu, Zhilu;Tang, Wenyan
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.6 no.5
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    • pp.1316-1332
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    • 2012
  • Formation flying is an important technology that enables high cost-effective organization of outer space aircrafts. The ad-hoc wireless network based on direct-sequence ultra-wideband (DS-UWB) techniques is seen as an effective means of establishing wireless communication links between aircrafts. In this paper, based on the theory of matched filter and error bits correction, a hybrid detection algorithm is proposed for realizing multiuser detection (MUD) when the DS-UWB technique is used in the ad-hoc wireless network. The matched filter is used to generate a candidate code set which may contain several error bits. The error bits are then recognized and corrected by an novel error-bit corrector, which consists of two steps: code mapping and clustering. In the former step, based on the modified optimum MUD decision function, a novel mapping function is presented that maps the output candidate codes into a feature space for differentiating the right and wrong codes. In the latter step, the codes are clustered into the right and wrong sets by using the K-means clustering approach. Additionally, in order to prevent some right codes being wrongly classified, a sign judgment method is proposed that reduces the bit error rate (BER) of the system. Compared with the traditional detection approaches, e.g., matched filter, minimum mean square error (MMSE) and decorrelation receiver (DEC), the proposed algorithm can considerably improve the BER performance of the system because of its high probability of recognizing wrong codes. Simulation results show that the proposed algorithm can almost achieve the BER performance of the optimum MUD (OMD). Furthermore, compared with OMD, the proposed algorithm has lower computational complexity, and its BER performance is less sensitive to the number of users.

Direction Prediction Based Resource Reservation in Mobile Communication Networks for Telematics (텔레매틱스를 위한 이동통신망에서 이동 방향 추정에 근거한 자원 예약)

  • Lee, Jong-Chan;Park, Ki-Hong;Lee, Yang-Weon
    • Journal of Internet Computing and Services
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    • v.8 no.1
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    • pp.1-14
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    • 2007
  • IF handoff events are occurred during the transmission of multimedia traffic, the efficient resource allocation and handoff procedures are necessary to maintain the same QoS of transmitted multimedia traffic because the QoS may be defected by some delay and information loss, This paper proposes a handoff scheme to accommodate multimedia traffic based on the resource reservation procedure using direction estimation, This scheme uses a novel mobile tracking method based on Fuzzy Multi Criteria Decision Making, in which uncertain parameters such as PSS (Pilot Signal Strength), the distance between the mobile and the base station, the moving direction, and the previous location are used in the decision process using the aggregation function in fuzzy set theory, With the position information, the moving direction is determined, The handoff requests for real time sessions are handled based on the direction prediction and the resource reservation scheme, The resources in the estimated adjacent cells should be reserved and allocated to guarantee the continuity of the real time sessions, Through simulation results, we show that our proposed resource reservation method provides a better performance than that of the conventional method.

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SNS as a Method of Election Campaign: A Case study of the 2015's Special Election in South Korea (정치인들의 선거 캠페인 수단으로서의 SNS 활용: 2015년 4·29 재·보궐선거를 중심으로)

  • Park, SeMi;Hwang, HaSung
    • Journal of Internet Computing and Services
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    • v.17 no.2
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    • pp.87-95
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    • 2016
  • Considerable research over the years has been devoted to ascertaining the impact of social media on political settings.In recent days, Social Network Sites (SNS) such as Facebook allowed users to share their political beliefs, support specific candidates, and interact with others on political issues. This study examines the role of SNS as the means of political campaign. The study tasks the case of the 2015'sspecial election, Seoul Korea. The analysis aims to identify how candidates use Facebook or Twitter to interact with voters by applying functional theory of political campaign discourse developed by Benoit. In this study, we analyzed the candidates' SNS messages in terms of political behavior such as self-expression, informing policy, asking voters to participate in political events. Among them the results indicated that two candidates, Jung, Dong Young and Byun, Hee Jae, both of them used SNS to express themselves the most. The study also found that two candidates used mainly the strategy called 'acclaim' which praises their own strengths. In terms of topics of SNS messages (policy versus character) there was different between two candidates. Jung, sent message in relation to 'character' the most, while Byun contained 'policy' message on SNS the most. Based on these findings implications and directions for future studies are discussed.

Device-to-Device assisted user clustering for Multiple Access in MIMO WLAN

  • Hongyi, Zhao;Weimin, Wu;li, Lu;Yingzhuang, Liu
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.7
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    • pp.2972-2991
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    • 2016
  • WLAN is the best choice in the place where complex network is hard to set up. Intelligent terminals are more and more assembled in some areas now. However, according to IEEE 802.11n/802.11ac, the access-point (AP) can only serve one user at a single frequency channel. The spectrum efficiency urgently needs to be improved. In theory, AP with multi-antenna can serve multiple users if these users do not interfere with each other. In this paper, we propose a user clustering scheme that could achieve multi-user selection through the mutual cooperation among users. We focus on two points, one is to achieve multi-user communication with multiple antennas technique at a single frequency channel, and the other one is to use a way of distributed users' collaboration to determine the multi-user selection for user clustering. Firstly, we use the CSMA/CA protocol to select the first user, and then we set this user as a source node using users' cooperation to search other proper users. With the help of the users' broadcast cooperation, we can search and select other appropriate user (while the number of access users is limited by the number of antennas in AP) to access AP with the first user simultaneously. In the network node searching, we propose a maximum degree energy routing searching algorithm, which uses the shortest time and traverses as many users as possible. We carried out the necessary analysis and simulation to prove the feasibility of the scheme. We hope this work may provide a new idea for the solution of the multiple access problem.