• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.11-18
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• 2021

The small radio frequency tracking radar is a tracking system with a radio frequency sensor that identifies a target through all-weather radio frequency signal processing for a target and searches, detects and tracks the target for the major target. In this paper, we describe the development of a board equipped with TMS320C6678 and XILINX FPGA (Field Programmable Gate Array), a high-speed multi-core DSP that acquires target information through all-weather radio frequency and identifies a target through real-time signal processing. We propose DSP-FPGA combination architecture for DSP and FPGA selection and signal processing, and also explain the design of SRIO for high-speed data transmission.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.603-612
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• 2010

Recently, with the advance of computing and networking technique, the high speed internet becomes widespread, however, it is still hard job to do streaming the media which requires high network bandwidth over the internet. Previous VoD system researches for streaming over the internet mainly proposed techniques that controls the QoS(Quality of Service) of the media in proportion to the network status. Though, this could be the solution for the service provider while the service user who wants constant QoS may not satisfy with variable QoS. In the paper, we propose greedy precedent frame transmission technique, GPFT, for guarantee of constant QoS. In GPFT, Streaming VoD server prefetches precedent frames and transmits the frame greedily by increasing the frame transmission rate while the available network bandwidth is high. The GPFT uses the prefetched precedent frames to guarantee the QoS while the available network bandwidth is low. The experiment result shows that the proposed GPFT could guarantee the constant QoS by prefetching the frames adaptively to the network bandwidth with the characteristic of video stream.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.6
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• pp.491-496
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• 2021

In line with the modern era in which the safety of underground facilities and the use of underground information are increasingly emphasized, the state is pushing for more precise and accurate underground spatial information to be secured and utilized. Therefore, we need to pay more attention to subsurface geospatial data. In the future, the Ministry of Land, Infrastructure and Transport will actively utilize the 15 types of Integrated Underground Geospatial Information Map(6 types of underground facilities, 6 types of underground structures, 3 types of ground) that the Ministry of Land, Infrastructure and Transport is building as three-dimensional underground spatial information, and contribute greatly to improving national safety and convenience in underground construction. expected to do However, when a site manager requests an Integrated Underground Geospatial Information Map with a mobile device, if the large-capacity integrated underground space map is not quickly transmitted over the wireless section and is not serviced, it causes inconvenience to the site manager and delays work. In this paper, the goal of this paper is to enable field managers to quickly receive a tiled Integrated Underground Geospatial Information Map with minimal information exchange. Therefore, the tiling system is configured according to the dataset for high-speed Mobile Integrated Underground Geospatial Information Map transmission. In addition, a transmission system for the Mobile Integrated Underground Geospatial Information Map is established, and a TCP/IP (Transmission Control Protocol/Internet Protocol)-based spatial information tiling transmission protocol dedicated to the on-site Integrated Underground Geospatial Information Map is developed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.18-25
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• 2020

With the development of water internet technology, data communication between objects is expanding. Research related to data communication technology between vehicles that incorporates related technologies into vehicles has been actively conducted. For data communication between mobile terminals, data stability, reliability, and real-time performance must be guaranteed. The 5 GHz Wi-Fi band, which is advantageous in bandwidth, communications speed, and wireless saturation of the wireless network, was selected as the data communications network between vehicles. This study analyzes how to design and implement a 5 GHz Wi-Fi network in a vehicle network. Considering the characteristics of the mobile communication terminal device, a continuous variable communications structure is proposed to enable high-speed data switching. We simplify the access point access procedure to reduce the latency between wireless terminals. By limiting the Transmission Control Protocol Internet Protocol (TCP/IP)-based Dynamic Host Configuration Protocol (DHCP) server function and implementing it in a broadcast transmission protocol method, communication delay between terminal devices is improved. Compared to the general commercial Wi-Fi communication method, the connection operation and response speed have been improved by five seconds or more. Utilizing this method can be applied to various types of event data communication between vehicles. It can also be extended to wireless data-based intelligent road networks and systems for autonomous driving.

• Journal of IKEEE
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• v.1 no.1 s.1
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• pp.47-54
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• 1997

Today's communication needs the super high-speed data transmission system to send many data rapidly, correctly, and simultaneously because of the increase of internet use, the demand of multimedia service and so on. Before long, the super high data service will be offered us by a satellite called platform which will be located at stratosphere of 20[km]over earth. It is possible to build the optical wireless communication networks which have the high data-tarrying capacity because this system use a laser. But, there are many problems to overcome because it make use of the atmospheric space as transmission channel. In this paper, therefore, we study up on the relations of data rates, bit error rates, and turbulent effects of atmosphere to present the effects of atmosphere to present the effects of atmospheric turbulence on the optical satcom link.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3B
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• pp.130-137
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• 2005

Wireless communication environment is changing rapidly as we use new wireless communication technology such as WiBro to access high speed Internet. As a result, reliable data transmission using TCP is also expected to increase. Since TCP assumes that it is used in wired network, TCP suffers significant performance degradation over wireless network where packet losses are related to non-congestion loss. Especially RTO imposes a great performance degradation of TCP. In this paper, we analyze the loss recovery probabilities based on previous researches, and use simulation results of our algorithm to show that it prevents performance degradation by quickly detecting and recovery losses without RTO during fast recovery.

• Convergence Security Journal
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• v.16 no.7
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• pp.3-11
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• 2016

With repid development of optical networking technology, Software-Defined Network (SDN) and Network Function Virtualization (NFV), high performance networking service, collaboration platform that enables collaborative research globally, drastically National Research Network (NRN) including Internet Service has changed. Therefore we compared and analyzed several world-class NRNs and took a view of future development strategy of the NRN. Also we suggest high speed security environment in super high bandwidth network with 40Gbps and 100Gbps optical transmission technology, network separation of NRN with Science DMZ to support high performance network transmission for science big data, building security environment for last-mile in campus network that supports programmability of IDS using BRO framework.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4305-4323
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• 2014

In this paper, we investigate the degrees of freedom (DOF) of the Y channel consisting of three single-antenna users and a two-antenna common access relay, where each user intends to exchange independent messages with the other two users with the assistance of the relay. We show that the DOF of this particular scenario is 1.5. In order to prove this result, we firstly derive a DOF upper bound based on cut-set bound by allowing cooperation among users, which shows that the total DOF is upper bounded by 1.5. Then we propose a novel transmission scheme based on asymmetric signal space alignment (ASSA) to demonstrate the achievability of the upper bound. Theoretical evaluation and numerical results confirm that the upper bound can be achieved by utilizing ASSA, which also proves the optimality of the ASSA-based scheme in terms of DOF. Combining the upper bound and achievability, we conclude that the exact DOF is 1.5. Moreover, we present a novel iterative joint beamforming optimization (I-JBO) algorithm to further improve the sum rate. Numerical simulations have been provided to demonstrate the convergence speed and performance advantage of the I-JBO algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.3
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• pp.549-557
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• 2017

ICMP(Internet Control Message Protocol) is a main protocol in TCP/IP protocol stack. ICMP compensates the disadvantages of the IP that does not support error reporting. If any transmission problem occurred, a router or receiving host sends ICMP message containing the error cause to sending host. However, in this process, an attacker sends a fake ICMP messages to the host so that the communication can be terminated abnormally. An attacker host can paralyzes system of victim host by sending a large number of messages to the victim host at a high rate of speed. To solve this problem, we have designed and implemented outbound traffic controller that prevents various ICMP attacks. By preventing the transmission of attack messages in different ways according to each case, various network attacks can be prevented. In addition, unnecessary network traffic can be filtered before transmitted.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.962-977
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• 2019

The human voice is a convenient method of information transfer between different objects such as between men, men and machine, between machines. The development of information and communication technology, the voice has been able to transfer farther than before. The way to communicate, it is to convert the voice to another form, transmit it, and then reconvert it back to sound. In such a communication process, a vocoder is a method of converting and re-converting a voice and sound. The CELP (Code-Excited Linear Prediction) type vocoder, one of the voice codecs, is adapted as a standard codec since it provides high quality sound even though its transmission speed is relatively low. The EVRC (Enhanced Variable Rate CODEC) and QCELP (Qualcomm Code-Excited Linear Prediction), variable bit rate vocoders, are used for mobile phones in 3G environment. For the real-time implementation of a vocoder, the reduction of sound quality is a typical problem. To improve the sound quality, that is important to know the size and shape of noise. In the existing sound quality improvement method, the voice activated is detected or used, or statistical methods are used by the large mount of data. However, there is a disadvantage in that no noise can be detected, when there is a continuous signal or when a change in noise is large.This paper focused on finding a better way to decrease the reduction of sound quality in lower bit transmission environments. Based on simulation results, this study proposed a preprocessor application that estimates the SNR (Signal to Noise Ratio) using the spectral SNR estimation method. The SNR estimation method adopted the IMBE (Improved Multi-Band Excitation) instead of using the SNR, which is a continuous speech signal. Finally, this application improves the quality of the vocoder by enhancing sound quality adaptively.