• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.426-435
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• 2013

In this paper, we propose the MIMO circular polarization feed network to enhance the communication performances from the previous $2{\times}2$ MIMO channel to $4{\times}4$ channel for Land Mobile Satellite communication system. The only possibility to extend the communication channel is to use the additional satellite because of the limitation of satellite spaces to install additional antennas. For overcoming this problems, we propose the MIMO circular polarization feed network to secure the isolation characteristics without the distant antenna space. The port isolation characteristics and each port impedance matching conditions are numerically verified and we suggest the $4{\times}4$ MIMO channel model of the proposed system and the performances are verified. The fabricated circular polarization patch antennas with the proposed feed network are measured in the reverberation chamber and 7~10 dB of diversity gain and 80 % increasement of channel capacity are obtained.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.121-127
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• 2017

In the land mobile satellite (LMS) communication, a hybrid satellite-terrestrial relay networks (HSTRNs) using a maximal ratio combining (MRC) scheme are widely used to enhance the quality of signal from a satellite. In this paper, we derive equations for the TCP throughput and the spectral efficiency in the HSTRN and analyze results of the performance evaluation for TCP in various environments. In the simulation results, it is shown that increasing the number of terrestrial relays can enhance the TCP throughput and spectral efficiency thanks to the MRC scheme. However, the usage of the static number of terrestrial relays considering no channel states would cause the overhead. Furthermore, it has a limitation to enhance the network performance by only MRC scheme in HSTRN because the TCP performance is sensitive to the packet los rate. Therefore, we discuss the possible solutions that can additionally enhance the network performance and reduce the overhead.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3412-3431
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• 2015

This paper considers the effect of co-channel interference on hybrid satellite-terrestrial relay network. In particular, we investigate the problem of amplify-and-forward (AF) relaying in hybrid satellite-terrestrial link, where the relay is interfered by multiple co-channel interferers. The direct link between satellite and terrestrial destination is not available due to masking by surroundings. The destination node can only receive signals from satellite with the assistance of a relay node situated at ground. The satellite-relay link is assumed to follow the shadowed Rice fading, while the channels of interferer-relay and relay-destination links experience Nakagami-m fading. For the considered AF relaying scheme, we first derive the analytical expression for the moment generating function (MGF) of the output signal-to-interference-plus-noise ratio (SINR). Then, we use the obtained MGF to derive the average symbol error rate (SER) of the considered scenario for M-ary phase shift keying (M-PSK) constellation under these generalized fading channels.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6196-6203
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• 2013

This study examined cadastral surveying technology regulated under the "Special Law for the cadastral surveying", and analyzed the related surveying methods currently used. Based on the analysis, this study suggested the efficient application plan future cadastral surveying projects. The new technologies analyzed were GNSS, GPS RTK, Network RTK, GPS Augmentation System, and the mobile and auto sighting TS. As a result of the analysis, this study suggests that if a receiving technology is possible for the integrated receiving of GPS/GLONASS/Galileo systems, both the accuracy of location determination could be enhanced and stable data could be obtained. The Network RTK technology may solve the constraint receiving factors of satellite information in the long term if a GPS Augmentation System is used. Finally, mobile and auto sighting TS technologies can reduce the personnel factors, but can be applied after the offset problem is overcome.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1159-1164
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• 2010

The current maritime data communications mainly depend on radio and satellite which have restrictions on data rate and cost. That leads to needs of novel relatively-high-speed data communication systems at sea just like on land. This paper proposes a routing protocol (MWR) for newly designed model of ship-to-ship communication networks at sea. The MWR protocol finds out an optimal route by selecting an optimal network for each specific application from overlapped networks of available wireless media at sea.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.187-190
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• 2010

Lately, IT has been rapidly in land. as a result, mobile device come into wide use and is very important in everyday life. But in ship are limits network with communication Equipment and service. as a result, be far removed from information age. Currently, ship Is connected with the outside world via satellite on the voyage. but, because high billing, ship is possible data transfer using low speed bandwidth. because ship is not possible using LAN, only limit ship's crew some use internet in limited space. so, ship is required construction of the network. in this paper, because composition of basic IT environment with information need of crew and customer from ship to cruises, there construct LAN in ship and propose network design for network of ship.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.250-253
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• 2014

Due to limited resource, marine communication is severely limited when compared to communications in land. Radio relay facilities, etc. based on a wired network through a long distance communication is possible. In addition, the aircraft is in the air, the ground-based network service based on long-range straight-line distance and elevation (LOS: Line of Sight) communications. On the other hand, the distance in a straight line to the sea, the sea level because communication is limited or through satellite, underwater communications relay equipment installed in the communication scheme has been investigated.. In this paper, using TCP-based real-time joint maritime security communication links were studied. Harsh marine environment, real-time communication that can provide secure communications and propose a LINK joint. In this study, more secure, and convenient communications at sea, a plan was presented to you.