• The KIPS Transactions:PartC
• /
• v.11C no.1
• /
• pp.89-98
• /
• 2004

AQM (Active Queue Management) techniques such as RED (Random Early Detection) which be proposed to solve the congestion of internet perform congestion control effectively for TCP data. However, in the situation where TCP and UDP share the bottleneck link, they can not solve the problems of the unfairness and long queueing delay. In this paper, we proposed an simple queue management algorithm, called PSRED (Protocol Sensitive RED), that improves fairness and decreases queueing delay. PSRED algorithm improves fairness and decreases average queue length by distinguishes each type of flow in using protocol field of packets and applies different drop functions to them respectively.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.7A
• /
• pp.973-986
• /
• 1999

In this paper, we propose MAC protocol that consists of channel access mechanism and transmission mechanism to support effective wireless packet data service. In channel access mechanism, broadcast channel announces status information of random access channel, and mobile station tries random access based on status information. Also, mobile station has access probability to prevent collision increase due to transmission of short message. For effective transmission, mobile station changes transmission rate based on transmission queue status to adapt burst traffic characteristics. In restricted environments of transmission code and bandwidth, proposed protocol shows better performance than cdma2000 system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.7B
• /
• pp.858-867
• /
• 2011

The RFID(Radio-Frequency IDentification) systems have many security problem such as eavesdropping, a replay attack, location tracking and DoS(Denial of Service) attacks. Because RFID systems use radio-frequency. So research are being made to solve the problem of RFID systems, one of which is AES algorithm. This paper presents an authentication protocol using AES and one-time random number to secure other attacks like eavesdropping, a replay attack, location tracking, In addtion, RSMAP uses OTP(One-Time Pad) in order to safely transmit.

• Journal of Communications and Networks
• /
• v.16 no.4
• /
• pp.397-406
• /
• 2014

Radio frequency (RF) jamming is a denial of service attack targeted at wireless networks. In resource-hungry scenarios with constant traffic demand, jamming can create connectivity problems and seriously affect communication. Therefore, the vulnerabilities of wireless networks must be studied. In this study, we investigate a particular type of RF jamming that exploits the semantics of physical (PHY) and medium access control (MAC) layer protocols. This can be extended to any wireless communication network whose protocol characteristics and operating frequencies are known to the attacker. We propose two efficient jamming techniques: A low-data-rate random jamming and a shot-noise based protocol-aware RF jamming. Both techniques use shot-noise pulses to disrupt ongoing transmission ensuring they are energy efficient, and they significantly reduce the detection probability of the jammer. Further, we derived the tight upper bound on the duration and the number of shot-noise pulses for Wi-Fi, GSM, and WiMax networks. The proposed model takes consider the channel access mechanism employed at the MAC layer, data transmission rate, PHY/MAC layer modulation and channel coding schemes. Moreover, we analyze the effect of different packet sizes on the proposed jamming methodologies. The proposed jamming attack models have been experimentally evaluated for 802.11b networks on an actual testbed environment by transmitting data packets of varying sizes. The achieved results clearly demonstrate a considerable increase in the overall jamming efficiency of the proposed protocol-aware jammer in terms of packet delivery ratio, energy expenditure and detection probabilities over contemporary jamming methods provided in the literature.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.4
• /
• pp.1479-1501
• /
• 2020

Dependable functioning of dynamic networks is essential for delivering ubiquitous services. Faults are the root causes of network outages. The comparison diagnosis model, which automates fault's identification, is one of the leading approaches to attain network dependability. Most of the existing research has focused on stationary networks. Nonetheless, the time-free comparison model imposes no time constraints on the system under considerations, and it suits most of the diagnosis requirements of dynamic networks. This paper presents a novel protocol that diagnoses faulty nodes in diagnosable dynamic networks. The proposed protocol comprises two stages, a testing stage, which uses the time-free comparison model to diagnose faulty neighbour nodes, and a disseminating stage, which leverages a Random Linear Network Coding (RLNC) technique to disseminate the partial view of nodes. We analysed and evaluated the performance of the proposed protocol under various scenarios, considering two metrics: communication overhead and diagnosis time. The simulation results revealed that the proposed protocol diagnoses different types of faults in dynamic networks. Compared with most related protocols, our proposed protocol has very low communication overhead and diagnosis time. These results demonstrated that the proposed protocol is energy-efficient, scalable, and robust.

• Journal of Advanced Navigation Technology
• /
• v.13 no.6
• /
• pp.876-883
• /
• 2009

In 2008, Kim-Jun proposed RFID Mutual Authentication Protocol based on One-Time Random Numbers which are strong in Eavesdropping Attack, Spoofing attack and Replay attack. However, In 2009, Yoon-Yoo proved that it was weak in Replay attack and proposed a protocol which can prevent Replay attack. But Yoon-Yoo's protocol has problems that efficiency on communication and Brute-force attack. This paper shows weak points of Yoon-Yoo's protocol and proposes an RFID mutual authentication protocol with security and performance improvements.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.1C
• /
• pp.117-123
• /
• 2008

We propose an improved Diffie-Hellman(DH) key agreement protocol over a radio link in peer-to-peer networks. The proposed protocol ensures a secure establishment of the shared key between two parties through distance bounding(DB). Proposed protocol is much improved in the sense that we now reduce the number of messages exchanged by two, the number of parameters maintained by four, and 2(7682(k/64)-64) of XOR operations, where k is the length of the random sequence used in the protocol. Also, it ensures a secure reusability of DH public parameters. Start after striking space key 2 times.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.21 no.5
• /
• pp.161-168
• /
• 2011

In 2009, Jeon et al proposed the lightweight strong authentication and strong privacy protocol, where the tag requrires only simple bitwise operations and random number generator. JK-RFID authentication protocol provides strong security: eavesdropping, replay, spoofing, Location tracking, DoS attack and forward security. Nevertheless, this paper points out the vulnerability of the forward security and improve the process of key updating. As a result, proposes an enhanced JK-RFID authentication protocol providing forward security and verify its satisfaction. In addition, a security and an efficiency of the proposed scheme analyze. Since partial adjustments of the key updating operation in JK-RFID authentication protocol, our protocol improve the forward security.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1993.04a
• /
• pp.49-56
• /
• 1993

We consider a B/G/1 queueing system with vacations, where the server closes the gate when it begins a vacation. In this system, customers arrive according to a Bernoulli process. The service time and the vacation time follow discrete distributions. We obtain the distribution of the number of customers at a random point in time, and in turn, the distribution of the residence time (queueing time + service time) for a customer. This system finds an application in the performance evaluation of the DQDB protocol which has been adopted as the standard protocol for IEEE 802.6 MAN.

• Proceedings of the IEEK Conference
• /
• summer
• /
• pp.35-38
• /
• 2004

The MAC protocol of HIPERLAN/2 is based on TDMA/TDD and AP (Access Point) can dynamically allocate the number of RCHs (Random CHannels). We propose a dynamic random channel allocation scheme improved by limiting the number of minimum RCHs. On a simulated scenario adopted practical Internet traffic, the proposed scheme is shown to achieve over $19\%$ lower delay than previously studied algorithm. This study will be a first step towards designing scope of RCHs for high-performance wireless packet network