• Journal of the Korea Society of Computer and Information
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• v.21 no.1
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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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1215-1223
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• 2014

In multi-hop wireless networks, a message transmission path is set up on demand by a route discovery step, where a shortest path is used in general. The shortest path, however, normally uses the nodes near the center area, which causes a high traffic load in that area and reduces the message transmission reliability. We propose a stable routing protocol considering the remaining energy of nodes. Our protocol uses ETX as a link performance estimator and tries to avoid the nodes with smaller energy. By doing this, we can reduce the route failure probability and packet loss. We have evaluated the performance of the proposed protocol using QualNet and compared with AODV and MRFR protocols. The simulation result shows that our protocol has a similar performance as MRFR in terms of end-to-end message reception ratio, average message delay and delay jitter, but outperforms MRFR in terms of traffic load distribution.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.3
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• pp.251-265
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• 2009

VoIP service is the transmission of voice data using SIP protocol on an IP-based network. The SIP protocol has many advantages, such as providing IP-based voice communication and multimedia service with low communication cost. Therefore, the SIP protocol disseminated quickly. However, SIP protocol exposes new forms of vulnerabilities to malicious attacks, such as message flooding attack. It also incurs threats from many existing vulnerabilities as occurs for IP-based protocol. In this paper, we propose a new virtual proxy to cooperate with the existing Proxy Server to provide state monitoring and detect SIP message flooding attack with IP/MAC authentication. Based on a proposed virtual proxy, the proposed system enhances SIP attack detection performance with minimal latency of SIP packet transmission.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.5
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• pp.21-29
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• 1992

This paper proposes a new MAC propocol for high-speed MAN. The proposed protocol is based on the P$_1$-persistent tranmission scheme and each node calculates the transmission probability periodically by using delay information(DI). A window mechanism for the calculation of message delay in each node is proposed to improve the adaptability of the proposed protocol to traffic changes. The capactiy of the proposed protocol is analyzed. The simulation results show that the proposed protocol gives fair message delay under heavy load conditions and, when the transmission speed or distance is increased, the message delay variation of the proposed protocol is less than that of IEEE 802.6 DQDB.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2198-2202
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• 2003

The data transmission of MVB(Multifunction Vehicle Bus) of TCN(Train Network Communication) is divided into the periodic transmission phase and the sporadic transmission phase. TCN standard defines the event-polling method for the message transfer in the sporadic phase. However, since the event-polling method does not use pre-scheduling to the priority of the messages to be transmitted, it is inefficient for the real-time systems. To schedule message transmission, a master node should know the priority of message to be transmitted by a slave node prior to the scheduling the sporadic phase, but the existing TCN standard does not support any protocol for this. This paper proposes the slave frame bit-stuffing algorithm, with which a master node gets the necessary information for transmission scheduling and includes the simulation results of the event-polling method and the proposed algorithm.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.5
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• pp.859-870
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• 2020

The MQTT-SN (Message Queuing Telemetry Transport-Sensor Network) protocol is a message transmission protocol used in a sensor-based Internet of Things (IoT) environment. This MQTT-SN protocol is a publish-subscribe model with a broker in the middle of message transmission, and each IoT device sends and receives messages through an intermediary when delivering messages. However, the MQTT-SN protocol does not provide security-related functions such as message security, mutual authentication, access control, and broker security. Accordingly, various security problems have recently occurred, and a situation in which security is required has emerged. In this paper, we review the security requirements of MQTT-SN once again, and propose a modified protocol that improves security while satisfying the constraints in the environment where the resource of IoT to which this protocol is applied is limited. Unlike the existing protocol, the security field and authentication server have been added to satisfy the security requirements. In addition, the proposed protocol is actually implemented and tested, and the proposed protocol is evaluated for practical use in terms of energy consumption.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.10
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• pp.720-726
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• 2004

The data transmission over MVB(Multifunction Vehicle Bus) of TCN(Train Communication Network) is divided into the periodic transmission phase and the sporadic transmission phase. TCN standard recommends the event-polling method as the message transfer in the sporadic phase. However, since the event-polling method does not use pre-scheduling to the priority of the messages, it is inefficient for the real-time systems. To schedule message transmission, a master node should know the priority of message to be transmitted by a slave node prior to the sporadic phase, but the existing TCN standard does not support any protocol for this. This paper proposes the slave frame bit-stuffing algorithm, with which a master node gets the necessary information for scheduling and includes the simulation results of the event-polling method and the proposed algorithm.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.231-234
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• 2003

In this paper, we propose the enhanced CSMA/CA MAC protocol fir mobile multi-hop wireless Ad-hoc networks. In the conventional wireless Ad-hoc network such as WLAN using CSMA/CA MAC protocol, communications between terminals that fn connected within multi-hop node may degrade the transmission efficiencies as increasing the multi-hop nodes because of RTS-CTS-DATA-ACK message exchange between terminals. In this raper, we apply the ACK/RTS control message into multi-hop transmission between terminals for wireless ad-hoc networks and improve the data traffic transmission efficiencies compared with conventional CSMA/CA MAC protocol used in WLAN.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.2
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• pp.190-197
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• 2011

In industrial distributed control systems, sensors collect data from the physical environment periodically and transmit them to the actuators, which process the control operations based on the received data. For the effective operation of the control systems, the data transmitted by the sensors has to be delivered to the actuators reliably within the deadline, and if the message reception rate of the actuators becomes lower than a threshold, then the performance of the control systems drops greatly. This paper suggests a message routing protocol to transmit periodic messages reliably in a distributed control system based on wireless sensor networks. For reliable message transmission, the proposed protocol selects a routing path whose end-to-end message reception rate is the highest before transmitting data messages. The proposed protocol has the capability of maintaining a target message reception rate for each flow. To maintain the required target reception rate, each destination monitors the actual message reception rate periodically and transmits a feedback message to the source if it drops below the target reception rate. On receiving the feedback message, the source tries to find a new path which can satisfy the target rate. The performance of the proposed protocol has been evaluated using simulation and compared with other protocols in terms of the message reception rate, the message delay and delay jitter, and so on. The simulation results show that the proposed protocol has a higher message reception rate and comparable message delay and delay jitter to other protocols. The simulation results also show that the proposed protocol has an ability to adapt well to the dynamic network traffic change.

• Journal of Electrical Engineering and Technology
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• v.8 no.3
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• pp.649-657
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• 2013

DTN flooding based routing protocol replicate the message copy to increase the delivery like hood that overloads the network resources. The probabilistic routing protocols reduce replication cost by forwarding the message to a node that holds high predictability value to meet its destination. However, the network traffic converges to high probable nodes and produce congestion that triggers the drop of previously stored messages. In this paper, we have proposed a routing protocol called as Connection frequency Buffer Aware Routing Protocol (CFBARP) that uses an adaptive method to maintain the information about the available buffer space at the receiver before message transmission. Furthermore, a frequency based method has been employed to determine the connection recurrence among nodes. The proposed strategy has performed well in terms of reducing message drop, message relay while increases the delivery probability.