• Journal of information and communication convergence engineering
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• 제8권1호
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• pp.40-44
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• 2010

opportunistic spectrum access (OSA) allows unlicensed users to share licensed spectrum in space and time with no or little interference to primary users, with bring new research challenges in MAC design. We propose a cognitive MAC protocol using statistical channel information and selecting appropriate idle channel for transmission. The protocol based on the CSMA/CA, exploits statistics of spectrum usage for decision making on channel access. Idle channel availability, spectrum hole sufficiency and available channel condition will be included in algorithm statistical information. The model include the control channel and data channel, the transmitter negotiates with receiver on transmission parameters through control channel, statistical decision results (successful rate of transmission) from exchanged transmission parameters of control channel should pass the threshold and decide the data transmission with spectrum hole on data channel. A dynamical sensing range as a important parameter introduced to maintain the our protocol performance. The proposed protocol's simulation will show that proposed protocol does improve the throughput performance via traditional opportunistic spectrum access MAC protocol.

• 한국정보통신학회논문지
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• 제13권6호
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• pp.1208-1214
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• 2009

센서 네트워크는 무선 네트워크에 비해 데이터 혼잡과 핫 스팟에 취약하다. 이는 이동 싱크 지원 라우팅 프로토콜이 다수의 제어 패킷을 사용하고 단일 노드를 통해 모든 패킷을 전송하기 때문이다. 따라서 패킷의 수를 감소시키고 패킷을 분산시키는 라우팅 프로토콜이 필요하다. 이를 위해서 본 논문에서는 클러스터 노드의 에이전트를 이용한 이동 싱크 지원 라우팅 프로토콜을 제안한다. 이의 프로토콜은 기존 이동 싱크 지원 라우팅 프로토콜보다 패킷의 수를 줄임으로써 통신 오버헤드와 에너지 소비를 감소시킨다.

• 정보과학회 논문지
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• 제45권3호
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• pp.195-199
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• 2018

최근 사물인터넷(IoT)의 규모가 증가함에 따라 다량의 데이터가 발생하고 있고 이런 데이터를 이용한 다양한 서비스가 등장하고 있다. 이에 따라 빅 데이터들을 효율적으로 처리/전송 할 수 있는 사물 인터넷 환경에 적합한 프로토콜이 필요하다. MQTT는 사물인터넷환경을 위한 경량의 메시징 프로토콜이다. 그러나 MQTT 프로토콜은 보안성을 제공하기 위해서는 TLS를 사용할 수 있지만, TLS를 사용할 경우 Handshake 및 패킷 오버헤드가 증가하는 문제점을 갖는다. 따라서 본 논문에서는 MQTT 프로토콜에 경량화 암호화 알고리즘을 활용하여 보다 강한 보안성을 제공하는 Secure_MQTT 프로토콜을 제안한다.

• Journal of Information Processing Systems
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• 제13권3호
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• pp.500-517
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• 2017

In this paper, an improved zone-based routing protocol for heterogeneous wireless sensor networks is proposed. The proposed protocol has fixed the sized zone according to the distance from the base station and used a dynamic clustering technique for advanced nodes to select a cluster head with maximum residual energy to transmit the data. In addition, we select an optimal route with minimum energy consumption for normal nodes and conserve energy by state transition throughout data transmission. Simulation results indicated that the proposed protocol performed better than the other algorithm by reducing energy consumption and providing a longer network lifetime and better throughput of data packets.

• 전자공학회논문지A
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• 제33A권2호
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• pp.50-58
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• 1996

This paper proposes the channel-access protocol suitable to a very high speed photonic WDM network with star configuration, which can provide a high channel utilization and insensitivity to the propagation delay. The proposed protocol employs a control channel and a simple status table to deal with the propagation delay which has been a major limiting factor in the performance of the very high speed optical communication networks. The control channel transmits control information in order to reserve access on data channels, and each node constitutes a status table after the reception of control pckets which holds information about the availbility of destination node and data channel. The proposed protocol is insensitive to the propagation delay time by removing necessity of the retransmission and by allowing parallel transmission of control packet and data packets. It is proved in analysis and discrete event simulation that the proposed protocol is superior in throughput and mean delay, especially at the high load conditions compared to the existing high speed channel-access protocols.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.423-425
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• 2007

In this paper, Medium Access Control(MAC) protocol designed for Wireless Body area Sensor Network(Bio-MAC) is proposed, Because in WBSN, the number of node is limited and each node has different characteristics. Also, reliability in transmitting vital data sensed at each node and periodic transmission should be considered so that general MAC protocol cannot satisfy such requirements of biomedical sensors in WBSN. Bio-MAC aims at optimal MAC protocol in WBSN. For this, Bio-MAC used Pattern -SuperFrame, which modified IEE E 802.15.4-based SuperFrame structurely. Bio-MAC based on TDMA uses Medium Access-priority and Pattern eXchange -Beacon method for dynamic slot allocation by considering critical sensing data or power consumption level of sensor no de etc. Also, because of the least delay time. Bio-MAC is suitable in the periodic transmission of vital signal data. The simulation results demonstrate that a efficient performance in WBSN can be achieved through the proposed Bio-MAC.

• 전자공학회논문지B
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• 제33B권9호
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• pp.70-79
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• 1996

Block data transfer poses a serious problem is a pipelined bus where each data transfer step is pipelined. In this paper, we describe the design and implementation of a variable data block transfer protocol for a pipelined bus of a shared-memory multiprocessor. The proposed method maintains compatibility with the existing protocol for the pipelined bus and ensures fairness and effectiveness by preventing starvation. We present flow charts of requester and responder during a block transfer in the pipelined bus that uses the proposed protocol. The proposed protocol was implemented for the TICOM-III HiPi+Bus.

• 한국컴퓨터정보학회논문지
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• 제21권1호
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• pp.79-84
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• 2016

In this paper, we propose reliable message transmission scheme based on CoAP, considering the constrained feature of IoT device, such as low power, the limited memory size and low computing capacity. Recently, the various kinds of application protocol has been studied to support IoT environments. In particular, CoAP protocol was developed as application protocol for IoT at the IETF core WG. However, because CoAP protocol is deigned to be used in constrained node, this protocol uses UDP at transport layer. Thus, data loss may occur frequently in network congestion environments. The proposed scheme, in this paper, is to overcome the problem of frequent data loss with low overhead. Also it includes the function which is to minimize the data loss in sleep mode of IoT device.

• 전자공학회논문지
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• 제51권7호
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• pp.96-102
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• 2014

본 논문에서는 dual-rail data encoding방식을 적용하여 비동기식시스템을 설계할 때, 신호천이를 줄이고 소비전력을 줄이기 위하여 4-phase handshaking 프로토콜과 2-phase handshaking 프로토콜을 혼합한 dual-rail data encoding방식을 제안한다. 기존의 dual-rail data encoding 4-phase handshaking 프로토콜은 space state가 존재함으로 말미암아 신호 천이가 많이 발생하게 되고 많은 전력소비를 발생한다. 이론적으로 dual-rail data encoding 2-phase handshaking 프로토콜은 dual-rail data encoding 4-phase handshaking 프로토콜보다 빠르고 신호천이도 적지만 표준 라이브러리를 사용하여 설계할 수 없다. 제안하는 혼합형 dual-rail data encoding 방식의 성능을 평가하기 위하여 Adder블록, Multiplier블록, Latch를 포함한 benchmark회로를 설계를 설계하였다. Benchmark회로를 이용하여 시뮬레이션해본 결과, 제안하는 혼합형 dual-rail data encoding방식은 기존의 dual-rail data encoding 4-phase handshaking 프로토콜에 비해 35%이상 전력소비가 감소되는 결과를 얻었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권9호
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• pp.3151-3168
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• 2021

Internet of Things (IoT) connects several objects with embedded sensors and they are capable of exchanging information between devices to create a smart environment. IoT smart devices have limited resources, such as batteries, computing power, and bandwidth, but comprehensive sensing causes severe energy restrictions, lowering data quality. The main objective of the proposal is to build a hybrid protocol which provides high data quality and reduced energy consumption in IoT sensor network. The hybrid protocol gives a flexible and complete solution for sensor selection problem. It selects a subset of active sensor nodes in the network which will increase the data quality and optimize the energy consumption. Since the unused sensor nodes switch off during the sensing phase, the energy consumption is greatly reduced. The hybrid protocol uses Dijkstra's algorithm for determining the shortest path for sensing data and Ant colony inspired variable path selection algorithm for selecting active nodes in the network. The missing data due to inactive sensor nodes is reconstructed using enhanced belief propagation algorithm. The proposed hybrid method is evaluated using real sensor data and the demonstrated results show significant improvement in energy consumption, data utility and data reconstruction rate compared to other existing methods.