• 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.

• Smart Media Journal
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• v.8 no.3
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• pp.9-16
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• 2019

Apple provides its own protocol, the Bonjour protocol, for convenient file transmission and reception between device. Airdrop is a Bonjour-based, representative service that is widely used as a simple data transmission/reception protocol for Apple's desktops, laptops and smartphones. However, it was demonstrated in Black Hat, a hacking security conference in 2016, that it is possible to commence a Man-in-the-Middle attack by exploiting the Bonjour protocol's weak points. In this paper, we explain the Bonjour protocol's such vulnerability for secure file transmission/reception between devices and propose an ECDH (Elliptic Curve Diffie-Hellman) based authentication protocol to enhance the protocol's security. The proposed protocol is described along with detailed operational procedures, demonstrating that it is possible to reduce the possibility of Man-in-the-Middle attack and its masquerade variant.

• The Journal of the Acoustical Society of Korea
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• v.34 no.2
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• pp.91-97
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• 2015

In this paper, wireless communication from a smart phone to a hearing aid using audible frequency band sound was considered. 1kHz single channel carrier frequency was applied for amplitude shift keying (ASK) binary data modulation, and the result of the transmission and reception was tested. The overall system process was precisely explained and experimentally evaluated. The result will be applied for realizing a digital hearing aid with remote control feature by a smart phone.

• Journal of information and communication convergence engineering
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• v.11 no.3
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• pp.167-172
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• 2013

Recently, mobile communication systems are suffering from exponentially increasing data traffic. As a promising solution to the increase in data traffic, a coordinated multi-point transmission and reception (CoMP) scheme has been proposed. Although a great deal of research has been done on this new technology, the performance of mobile communication systems with CoMP has not been evaluated properly in a typical indoor environment. To address this, we have developed a system-level simulator and evaluated the performance of mobile communication systems with CoMP. Unlike previous works, we have used an actual antenna pattern in our simulator and link-level results are properly taken into account through link-level abstraction. By using a system-level simulator, we have evaluated the performance of mobile communication systems with CoMP in an indoor environment and found that unlike an outdoor cellular environment, CoMP may not improve the performance of overall mobile communication systems in an indoor environment.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.5
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• pp.643-653
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• 2014

High-capacity video, control and situation awareness data should be transmitted efficiently to control robots properly in the ground unmanned system, which requires the technology maximizing the communication range and the data transmission throughput. This technology is connected to the OFDMA(Orthogonal Frequency Division Multiple Access)-MIMO(Multiple Input Multiple Output) transmission technology under the limited bandwidth and transmission power. In this paper, we design MIMO communication system for ground unmanned systems, and investigate the data reception performance experimentally, comparing with SISO(Single Input Single Output) system. Experiment results show that the data reception performance of MIMO is significantly improved compared to that of SISO, e.g. 4dB gain of sensitivity and 5dB of SNR at the value MPR = 1, for the mobile stations with $2{\times}2$ STBC diversity.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.3
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• pp.613-621
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• 2016

Since the error control problem is a critical and sensitive issue in the one-way network, we can adopt a forward error correction code method or data retransmission method based on the response of reception result. In this paper, we propose error control method and continuous data transmission protocol in the one-way network which has unidirectional data transmission channel and special channel to receive only the response of reception result. Furthermore we present data encryption and key update mechanism which is based on the pre-shared key distribution scheme and suggest some ASDU(Application Service Data Unit) formats to implement it in the one-way network.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.11-22
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• 1996

We address an issue of channel sharing among users by using a random assignment-transmitter-based (RA-T) spread-spectrum transmission scheme which permits the contention mode only in the transmission of a header while avoiding collision during the data packet transmission. Once the header being successfully received, the data packet is ready for reception by switching to one of programmable matched-filters. But the receoption may be blocked due to limited number of matched-filters so that this effect is taken into account in our analysis. For realistic analysis, we integrate detection performance at the physical level with channel activity at the link level through a markov chain model. We also consider an acknowledgement scheme to notify whether the header is correctly detcted and the data packet can be processed continuously, which aims at reducing the interference caused unwanted data transmission. It is shown that receiver complexity can be greatly reduced by choosing a proper number of RA codes at the cost of only a little throughput degradation.

• Journal of Satellite, Information and Communications
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• v.10 no.1
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• pp.62-66
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• 2015

This paper introduces various applications and contents of digital signage, and analyzes conventional communication techniques to increase communication range. To realize digital signage in long distance, this paper proposes a hybrid modulation scheme and analyzes its performance. To verify its performance in real channel environment, we mapped symbols and experimented data transmission and reception with a visible light communication module with USRP. As a result, we confirmed a data receiving range and power of transmission and reception of the hybrid modulation mode. Also, we showed that the proposed modulation scheme has better performance of communication range and power efficiency than that of the conventional QAM technique.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.9
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• pp.691-698
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• 2006

TCP/IP Offload Engine (TOE) is a technology that processes TCP/IP on a network adapter instead of a host CPU to reduce protocol processing overhead from the host CPU. There have been some approaches to implementing TOE: software TOE based on an embedded processor; hardware TOE based on ASIC implementation; and hybrid TOE in which software and hardware functions are combined. In this paper, we designed software modules and hardware modules for a hybrid TOE on an FPGA that had two processor cores. Software modules are based on the embedded Linux. Hardware modules are for data transmission (TX) and reception (RX). One core controls the TX path and the other controls the RX path of the Linux. This TX/RX path separation mechanism can reduce task switching overheads between processes and overcome poor performance of single embedded processor. Hardware modules deal with creating headers for outgoing packets, processing headers of incoming packets, and fetching or storing data from or to the host memory by DMA. These can make it possible to improve the performance of data transmission and reception. We proved performance of the TOE with separated transmission and reception paths by performing experiments with a TOE network adapter that was equipped with the FPGA having processor cores.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.7
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• pp.500-507
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• 2018

A three-channel radio frequency (RF) monopulse receiver using a data signal with a maximum transmission rate of 274 Mbps was designed. A monopulse receiver using a broadband communication signal was designed to operate in the Ku band, and it consists of a down-conversion module and a signal-processing module. To satisfy the performance of the proposed RF monopulse receiver, a signal-processing function less than the reception sensitivity for each transmission rate according to the adaptive transmission rate is required. To minimize signal reception and mutual frequency interference of various bandwidths, two RF filters were applied. To verify the satisfaction of system requirements, an AWR Corp. simulation tool was used.