• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.5
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• pp.1208-1220
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• 1996

In this paper, the performance of a Carrier Sense Multiple Access/Collision avoidance (CSMA/CA) protocol using stop-and-Wait automatic Repeat reQuest, which is adapted as a draft standard in IEEE 802.11, is analyzed using a mathematical method based on a renewal theory, and simulation checks are performed, which confirm the goodness of our anlysis. In order to anlayze of CSMA/CA, we model that network is composed of finite populationand channel is slotted. And, we consider the CSMA/CA protocol as a hybrid protocol of 1-persistent CSMA and p-persistent CSMA protocol. As resuls of analysis, we have found that the throughput is degraded and packet delay is increased as the number of stations, Acknowledgement (ACK) length and Distributed coordination function Inter Frame Space (DIFS) length are increased.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.9
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• pp.485-490
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• 2006

According to the computerization of railway signaling systems, the interface link between the signaling systems has been replaced by the digital communication channel. At the same time, the importance of the communication link is more pronounced than before. In this paper, new Network-based protocol between railway signaling and SCADA (Supervisory Control and Data Acquisition system) has designed and the overview of designed protocol is briefly represented. And also this paper addresses analysis of newly designed train control systems. Fame error rates of the data transmissions are calculated and compared for the two cases that the CTC (Centralized Traffic Control)/SCADA has an extra data transmission error control (CRC16) besides the inherent error control of the Ethernet and that the CTC/SCADA has no extra data transmission error control. With simulation results it has been verified that the additional error control code contributes to lowering the frame error rate. It will be expected to increase the safety, reliability and efficiency of maintenance of the signaling systems by using the designed protocol for railway signaling system.

• Journal of Communications and Networks
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• v.5 no.3
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• pp.249-257
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• 2003

Ring networks are very commonly exploited among local area and metropolitan area networks (LAN/MAN), whereas cells or small fixed-size packets are widely used in synchronized ring networks. In this paper, we present an analytical method for evaluating the delay-throughput performance of a MAC protocol with multiple self-tokens in a slotted ring network under uniform traffic. In our analysis, we introduce the stationary probability, which indicates the number of packets in a node. Also, it is assumed that each node has a sufficiently large amount of self-tokens, and a slotted ring has the symmetry. The analytical results with respect to delay-throughput performance have similar values to computer simulated ones. Furthermore, in order to achieve fair access under non-uniform traffic, we propose an adaptive MAC protocol, where the number of self-tokens in a node dynamically varies, based on the number of packets transmitted within a specified period. In the proposed protocol, when the number of packets transmitted by a node within a specified period is larger than a specified threshold, the node decreases the number of self-tokens in a per-node distributed method. That results in creating free slots in the ring, thus all nodes can obtain an equal opportunity to transmit into the ring. Performance results obtained by computer simulation show that our proposed protocol can maintain throughput fairness under non-uniform traffic.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.8
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• pp.3542-3566
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• 2018

In this paper, we investigate a buffer-aided wireless powered cooperative communication network (WPCCN), in which the source and relay harvest the energy from a dedicated power beacon via wireless energy transfer, then the source transmits the data to the destination through the relay. Both the source and relay are equipped with an energy buffer to store the harvested energy in the energy transfer stage. In addition, the relay is equipped with a data buffer and can temporarily store the received information. Considering the buffer-aided WPCCN, we propose two buffer-aided relaying protocols, which named as the buffer-aided harvest-then-transmit (HtT) protocol and the buffer-aided joint mode selection and power allocation (JMSPA) protocol, respectively. For the buffer-aided HtT protocol, the time-averaged achievable rate is obtained in closed form. For the buffer-aided JMSPA protocol, the optimal adaptive mode selection scheme and power allocation scheme, which jointly maximize the time-averaged throughput of system, are obtained by employing the Lyapunov optimization theory. Furthermore, we drive the theoretical bounds on the time-averaged achievable rate and time-averaged delay, then present the throughput-delay tradeoff achieved by the joint JMSPA protocol. Simulation results validate the throughput performance gain of the proposed buffer-aided relaying protocols and verify the theoretical analysis.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.4
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• pp.63-72
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• 2010

This paper proposes a new authentication protocol for the LR-WPAN. In order to guarantee the reliability and safety of a protocol, this protocol uses the hierarchical authentication approach. In addition, in order to reduce the impact of the denial of service attack, the proposed protocol performs the authentication between a parent router and a joiner device prior to the authentication between a trust center and the joiner device. Moreover, this protocol reduces the authentication delay by decreasing the number of message exchanges during authentication procedure. This paper evaluates the safety of the proposed protocol by the security analysis and reliability of the proposed protocol by the GNY analysis. This paper also compares the number of message exchanges of the ZigBee authentication protocol and the proposed protocol when denial of service attack occurs to evaluate the resistance of the proposed protocol against the denial of service attack. We also analyze the delay for authentication of the joiner device through the implementation of both protocols. Those results show that the proposed protocol effectively protects networks from the denial of service attack and reduces the time for authenticating the joiner device up to maximum 30% as the number of hops increases.

• Journal of KIISE:Information Networking
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• v.29 no.5
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• pp.543-552
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• 2002

Wireless Session Protocol(WSP) which was updated and supplemented based on HyperText Transfer Protocol(HTTP) was designed by Wireless Application Protocol(WAP) forum regarding the characteristics of wireless environment. WSP improved the performance in wireless network, and introduced various facilities considering wireless environment. In this paper, we more improve the performance of WSP adding protocol message compression capability; we cail improved WSP protocol as WSP+. And, we analysis the performance of each protocol with WSP and WSP+ implementation. As a result of experiment, the capability which proposed in this paper reduced a response traffic about 45%. In $10^{-4}$ bit error rate, we also found the packet loss rate and time delay per transaction of WSP+ was improved over 40%. Finally, we found that the protocol message compression capability reduces message retransmission count in transaction layer and shorten the delay time per transaction by reducing a message size.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1565-1570
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• 2014

In networking communication, nodes and base station send data to each nodes and destination nodes. In this perspective, it is very important to determine the direction in which data sent to each nodes or destination nodes. Ad-hoc routing protocol is a standard routing protocol that determines how the packets sent to destination. Ad-hoc routing protocol includes protocols such as Ad-hoc On-demand Distance Vector (AODV) and Dynamic Source Routing (DSR). In our efficient proposed protocol based on small end-to-end sequence numbers, route direction can be changed properly with the assistance of helper nodes. In this paper, we focus on the simulation analysis of proposed protocol and comparison with other routing protocol models such as AODV and DSR. We simulated using Network Simulator (NS-2) by parameters such as simulation time, number of nodes and packet size based on our metrics (packet delivery fraction, routing load, data throughput). Our proposed protocol based on small end-to-end sequence numbers shows better performance and superior to other two protocols.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.8
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• pp.165-170
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• 2020

As the IoT (Internet of Things) era is activated, a lot of information including personal information is being transmitted through IoT devices. For information protection, it is important to perform cryptography communication, and it is required to use a lightweight security protocol due to performance limitations. Currently, most of the encryption methods used in the security protocol use RSA and ECC (Elliptic Curve Cryptography). However, if a high performance quantum computer is developed and the Shor algorithm is used, it can no longer be used because it can easily solve the stability problems based on the previous RSA and ECC. Therefore, in this paper, we designed a security protocol that is resistant to the computational power of quantum computers. The code-based crypto ROLLO, which is undergoing the NIST (National Institute of Standards and Technology) post quantum cryptography standardization, was used, and a hash and XOR computation with low computational consumption were used for mutual communication between IoT devices. Finally, a comparative analysis and safety analysis of the proposed protocol and the existing protocol were performed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.1
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• pp.12-18
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• 2013

In 2012, Woosik Bae proposed a DAP3-RS(Design of Authentication Protocol for Privacy Protection in RFID Systems) using the hash function and AES(Advanced Encryption Standard) algorithm to hide Tag's identification and to generates variable data in every session. He argued that the DAP3-RS is safe from spoofing attack, replay attack, traffic analysis and etc. Also, the DAP3-RS resolved problem by fixed metaID of Hash-Lock protocol using AES algorithm. However, unlike his argue, attacker can pass authentication and traffic analysis using by same data and fixed hash value on the wireless. We proposed authentication protocol based on AES algorithm. Also, our protocol is secure and efficient in comparison with the DAP3-RS.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.5
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• pp.955-963
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• 2022

The Internet of Things (IoT), combined with various technologies, is rapidly becoming an integral part of our daily life. While it is rapidly taking root in society, security considerations are relatively insufficient, making it a major target for cyber attacks. Since all devices in the IoT environment are connected to the Internet and are closely used in daily life, the damage caused by cyber attacks is also serious. Therefore, encryption communication using a network security protocol must be considered for a service in a more secure IoT environment. A representative network security protocol includes TLS (Transport Layer Protocol) defined by the IETF. This paper analyzes the performance measurement results for TLS version 1.2 and version 1.3 in an IoT device open platform environment to predict the load of TLS, a representative network security protocol, in IoT devices with limited resource characteristics. In addition, by analyzing the performance of each major cryptographic algorithm in version 1.3, we intend to present a standard for setting appropriate network security protocol properties according to IoT device specifications.