• Journal of Computing Science and Engineering
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• v.8 no.3
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• pp.129-136
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• 2014

This paper presents the equivalent circuit modelling and eigenfrequency analysis of a wideband robust capacitive radio frequency (RF) microelectromechanical system (MEMS) switch that was designed using Poly-Si and Au layer membrane for highly reliable switching operation. The circuit characterization includes the extraction of resistance, inductance, on and off state capacitance, and Q-factor. The first six eigenfrequencies are analyzed using a finite element modeler, and the equivalent modes are demonstrated. The switch is optimized for millimeter wave frequencies, which indicate excellent RF performance with isolation of more than 55 dB and a low insertion loss of 0.1 dB in the V-band. The designed switch actuates at 13.2 V. The R, L, C and Q-factor are simulated using Y-matrix data over a frequency sweep of 20-100 GHz. The proposed switch has various applications in satellite communication networks and can also be used for devices that will incorporate the upcoming IEEE Wi-Fi 802.11ad protocol.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.235-240
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• 2006

Stream Control Transmission Protocol (SCTP) provides the multi-homing feature, which allows each SCTP endpoint to use two or more IP addresses for data transmission. In this paper, the SCTP multi-homing feature is experimented and analyzed in terms of throughput over Linux platforms based on the NISTNET network emulator. We perform the experimental analysis of SCTP throughputs by SCTP multi-homing for the various network conditions: different packet loss rates, network bandwidths, and transmission delays. From the experimental results, it is shown that the SCTP multi-homing gives much better throughout gun over the SCTP single-homing case in the networks with a high packet loss rate. In the meantime, the other factors including network bandwidth and transmission delay do not seem to give a significant impact on the performance of the SCTP multi-homing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6A
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• pp.893-899
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• 2000

WDM technology has been an emerging issue for the efficient use of optical links. WDM uses a number of different wavelengths that are assigned to each channel. The minimal number of optical transcievers and receivers should be used in a node to build an economic WDM transmission system without degrading system performance. Hence, the analysis of performance parameters such as throughput and delay is important to guarantee the WDM system performance. In this paper, the performance of a MAC protocol on a slotted WDM system that has a tunable transmitter(TTX), a tunable receiver(TRX), and a fixed receiver(FRX), respectively, on each node, was statistically analyzed. The computer simulation validates the performance analysis.

• Journal of Internet Computing and Services
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• v.2 no.3
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• pp.9-17
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• 2001

Ad-Hoc networks consist of a set of mobile hosts that communicate using wireless links, without the use of other communicate support facilities (such as base stations). The topology of an Ad-Hoc network changes due to the movement of mobile host. which may lead to sudden packet loss. Recently, a large amount of research has focused on the routing protocols needed in such an environment. but researches about Internet traffic performance analysis were unexhausted. Accordingly, we have simulated Ad-Hoc mobile network that using AODV routing protocol and Ad-Hoc mobile network topology size and node speed as simulation estimation-factor to analysis traffic performance. As the result of the simulation, we identify that TCP /Reno was more sensitive than TCP/Sack about node speed and a number of the node.

• Journal of electromagnetic engineering and science
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• v.11 no.2
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• pp.133-142
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• 2011

Coded cooperation that integrates channel coding in cooperative transmission has gained a great deal of interest in wireless relay networks. The performance analysis of coded cooperation protocol with multiple relays is investigated in this paper. We show that the diversity order achieved by the coded cooperation in a multi-relay wireless network is not only dependent on the number of cooperating relays but is also dependent on the code-rate of the system. We derive the code-rate bound, which is required to achieve the full diversity gain of the order of cooperating nodes. The code-rate required to achieve full diversity is a linearly decreasing function of the number of available relays in the network. We show that the instantaneous channel state information (CSI)-based relay selection can effectively alleviate this code-rate bound. Analysis shows that the coded cooperation with instantaneous CSI-based relay selection can achieve the full diversity, for an arbitrary number of relays, with a fixed code-rate. Finally, we develop tight upper bounds for the bit error rate (BER) and frame error rate (FER) of the relay selection based on coded cooperation under a Rayleigh fading environment. The analytical upper bounds are verified with simulation results.

• ETRI Journal
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• v.43 no.1
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• pp.40-52
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• 2021

DNS (Domain Name System) tunnels almost obscure the true network activities of users, which makes it challenging for the gateway or censorship equipment to identify malicious or unpermitted network behaviors. An efficient way to address this problem is to conduct a temporal-spatial analysis on the tunnel traffic. Nevertheless, current studies on this topic limit the DNS tunnel to those with a single protocol, whereas more than one protocol may be used simultaneously. In this paper, we concentrate on the refined identification of two protocols mixed in a DNS tunnel. A feature set is first derived from DNS query and response flows, which is incorporated with deep neural networks to construct a regression model. We benchmark the proposed method with captured DNS tunnel traffic, the experimental results show that the proposed scheme can achieve identification accuracy of more than 90%. To the best of our knowledge, the proposed scheme is the first to estimate the ratios of two mixed protocols in DNS tunnels.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.1
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• pp.1-9
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• 2022

Global Navigation Satellite System (GNSS) provides location information using signals from multiple satellites. However, a spoofing attack that forges signals or retransmits delayed signals may cause errors in the location information. To prevent such attacks, authentication protocols considering the navigation message structure of each GNSS can be used. In this paper, we analyze the authentication protocols of Global Positioning System (GPS), Galileo, and BeiDou, and compare the performance of Navigation Message Authentication (NMA) of the above systems, using several performance indicators. According to our analysis, authentication protocols are similar in terms of performing NMA and using Elliptic Curve Digital Signature Algorithm (ECDSA). On the other hand, they are different in several ways, for example, whether to perform Spreading Code Authentication (SCA), whether to use digital certificates and whether to use Timed Efficient Stream Loss-tolerant Authentication (TESLA). According to our quantitative analysis, the authentication protocol of Galileo has the shortest time between authentications and time to first authenticated fix. We also show that the larger the sum of the navigation message bits and authentication bits, the more severely affected are the time between authentications and the time to first authenticated fix.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.12
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• pp.1815-1827
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• 1993

In this paper, we evaluate the performance of a Futurebus based multiprocessor system with MESI cache coherence protocol for four bus transaction types. Graphical symbols and compiler of SLAM II are used in modeling and simulation. A steady-state probability of each state for MESI protocol is computed by a Markov chain. The probability of each state is used as an input value for a correct simulation. Processor utilization, memory utilization, bus utilization, and the waiting time for bus arbitration are measured in terms of the number of processors, the hit ratio of cache memory, the probability of internal operation, and bus bandwidth.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.1945-1956
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• 1994

In this paper, a multiaccess network protocol for high-speed communication is proposed, which enables multimedia sevices with integrating the existing networks. We examine the traffic control mechanisms and configurations for the network architecture and compare with various protocols which are suitable to high speed LAN/MAN and propose an adaptive access control mechanism. ATMR has low channel utilization due to window size reset time, and that MetaRing is very sensitive over the change of traffic load. This suggested protocol, however, has quite a good performance for that situation by adding adaptive parameter condition. This mechanism may introduce a model of small-scaled Broadband Integrated Service Network and be used as an internetworking system for the ATM network.

• IEIE Transactions on Smart Processing and Computing
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• v.6 no.3
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• pp.200-209
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• 2017

In this paper, we investigate the tradeoff between security and reliability for a multi-hop protocol in cluster-based underlay cognitive radio networks. In the proposed protocol, a secondary source communicates with a secondary destination via the multi-hop relay method in the presence of a secondary eavesdropper. To enhance system performance under the joint impact of interference constraint required by multiple primary users and hardware impairments, the best relay node is selected at each hop to relay the source data to the destination. Moreover, the destination is equipped with multiple antennas and employs a selection combining (SC) technique to combine the received data. We derive closed-form expressions of the intercept probability (IP) for the eavesdropping links and the outage probability (OP) for the data links over a Rayleigh fading channel. Finally, the correction of our derivations is verified by Monte-Carlo simulations.