• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11C
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• pp.889-895
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• 2010

MIMO system generally requires more than one antenna at the communication device. However, many wireless devices are limited by size, cost or hardware complexity to one antenna. To overcome such restrictions, we used a new technique, called cooperative communication. We propose a new cooperative transmission strategy system using cross-layer coding method base on H-ARQ for optimal communication. Proposed cooperative H-ARQ system that can improve the above problems and can get the better performance. In proposed cooperative system with H-ARQ method, if the received signal from source node is satisfied by the destination preferentially, the destination transmit ACK message to both relay node and source node, and then recovers the received signal. In addition, if ARQ message indicates NACK message, relay node operates selective retransmission. Based on the simulation results in aspect to BER performance and throughput, the proposed method which combined cooperative system with H-ARQ based on cross-layer coding can improve spectral efficiency reliability of system compared with that of general one by one system.

• Journal of KIISE
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• v.42 no.8
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• pp.979-989
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• 2015

Machine to Machine (M2M) technology has gained attention due to the fast diffusion of Internet of Things (IoT) technologies and smart devices. Most wireless network experts believe that Bluetooth Low Energy (BLE) Communications technology in an iBeacon network has amazing advantages in terms of providing communication services at a low cost in smartphone applications. Specifically, BLE does not require any pairing process during its communication phases, so it is possible to send a message to any node without incurring additional transmissions costs if they are within the BLE communication range. However, BLE does not require any security verification during communication, so it has weak security. Therefore, a security authorization process would be necessary to obtain customer confidence. To provide security functions for iBeacon, we think that the iBeacon Message Encryption process and a Decryption (Authorization) process should be designed and implemented. We therefore propose the BLE message Authorization Mechanism based on a One Time Password Algorithm (BLE-OTP). The effectiveness of our mechanism is evaluated by conducting a performance test on an attendance system based on BLE-OTP.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.5
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• pp.897-905
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• 2007

In this paper, we present a new framework and synchronization mechanism to effectively support developing real-time communication service by using a real-time object model named TMO (Time-Triggered Message-Triggered Object). Also, we describes the application environment as the DHS(distributed high-precision simulation) to guarantee real-time service message with TMO structure in distributed network systems. The TMO scheme is aimed for enabling a great reduction of the designer's effort in guaranteeing timely real-time communication service capabilities of among distributed multi-nodes systems. Our real-time framework provide the consistent construction and configuration of tine-triggered processing components across heterogeneous distributed object environment more easily. It has been formulated from the beginning with the objective of enabling design-time guaranteeing of timely action. In the real time simulation techniques based on TMO object modeling, we have observed several advantages to the TMO structuring scheme. TMO object modeling has a strong traceability between requirement specification and design.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.269-273
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• 2010

Massively Multiplayer Online Game (MMOG) is one of diverse applications where more than hundreds of users enjoy experiencing virtual worlds. Voronoi-based Overlay Network (VON) is proposed to reduce a bandwidth consumption in P2P MMOGs and Vorocast also is made using message forwarding in VON. We propose a dynamic area of interest (AOI) management method that solves problems such as less consistency and high latency due to sending position updates to more neighbor nodes from the message originator in forwarding scheme. Our scheme provides the higher consistency and reduces latency by combining direct connection scheme and Vorocast scheme compared to existing schemes. The proposed model is evaluated through simulations.

• Journal of Digital Convergence
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• v.10 no.8
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• pp.179-184
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• 2012

A car accident on a highway occurs a chain-reaction collision because of a vehicle's fast velocity. In order to prevent it, the accident vehicle should broadcast a safe message to its neighbors. If there are many neighbor nodes, a frame collision probability is high. To solve this, it was proposed for a system as a previous study to send a safe message without frame-collision using separating channels. However, the separation of multiple channels make feasibility low because of increasing hardware's development cost and complexity. In this paper, we proposes a TDMA-based MAC protocol using a single channel. As a result, we show the frame reception success rate of our protocol was almost the same as the previous protocol.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.35-40
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• 2013

The messages on mobile terminal may contain context information such as user's location, time and preference. This paper proposes message forwarding system based on user's context. The server stores the predefined target addresses which may be mobile phone number, web server address and email address. On request for message transmission, the server tries to find a target address matching a user's context. Thus, a sender transmits messages to a representative address without knowing various receiver's addresses and a receiver can retrieve classified messages according to subject/location.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.6
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• pp.2841-2860
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• 2018

Vehicular networks play an important role in current intelligent transportation networks and have gained much attention from academia and industry. Vehicular networks can be enhanced by Long Term Evolution-Vehicle (LTE-V) technology, which has been defined in a series of standards by the 3rd Generation Partnership Project (3GPP). LTE-V technology is a systematic and integrated V2X solution. To guarantee secure LTE-V communication, security and privacy issues must be addressed before the network is deployed. The present study aims to improve the security functionality of vehicular LTE networks by proposing an efficient and secure ID-based message authentication scheme for vehicular networks, named the ESMAV. We demonstrate its ability to simultaneously support both mutual authentication and privacy protection. In addition, the ESMAV exhibit better performance in terms of overhead computation, communication cost, and security functions, which includes privacy preservation and non-frameability.

• The KIPS Transactions:PartA
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• v.12A no.1 s.91
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• pp.23-30
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• 2005

Causal order of message delivery algorithm ensures that every transmitted message is delivered in causal order. It should be noted that control information should be transmitted with each message in order to enforce causal order. Hence, it is important to reduce this communication overhead because the impact of the overhead increases proportionally with the number of related processes. In this paper we propose and evaluate effective a ${\Delta}-causal$ order algorithm for multimedia data which have real-time property. To reduce transmission overhead, proposed algorithm eliminates redundant information as early as possible which is not explicitly required for preserving causal order. Average communication overhead of our algorithm is much smaller than other existing algorithms.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.4
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• pp.43-51
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• 2013

This paper proposes the design of protocol management system for aggregationg messages based on certification between vehicles which not only prevents the messages between vehicles from being forged and altered by Sybil attack by authenticating the them, and but also provides the efficient communication by aggregating the redundant vehicle messages which frequently happens when communicating. For this, the proposed system proposes the SKLC(Session Key Local Certificate) design which is a local certificate based on a session key, and the MAP(Message Aggregation Protocol) design which aggregates the redundant vehicle messages. Therefore, when the proposed system checks the certificate of vehicle, it provides the reliable information securely by verifying the integrity of vehicle with a hash function operation, and improves communication efficiency by reducing the processing time.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.43-49
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• 2012

Personalized message syndication is an important process for maximizing the effect of mobile marketing. This paper proposes an algorithm for determining clients satisfying target conditions in real-time. The proxy server as an intermediate node stores client profiles (gender, age, location, etc) and their respective summaries into a database. When a company syndicates messages at run time, the proxy server maps target conditions expressed by boolean expressions to integer value and determines target clients by comparing target value with profile summary. Thus, this approach provides efficient personalized message syndication in very large systems with millions of clients because it can determine target clients in real-time and work with a traditional database easily.