• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.2 s.332
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• pp.1-8
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• 2005

We have implemented a Jini-Agent system which enables resource-limited mobile devices to utilize the Jini connection service. The Jini-Agent system supports Jini connection technologies to mobile devices without additional client program installation in it. It also supports a dynamic service list which helps the mobile devices to search and to utilize the services through web browser in real time. A couple of examples such as a file search service and a print service with mobile devices have been demonstrated by using the Jini-Agent system.

• International Journal of Internet, Broadcasting and Communication
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• v.9 no.4
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• pp.59-66
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• 2017

Cloud computing has evolved into a core computing infrastructure for the internet that encompasses content, as well as communications, applications and commerce. By providing powerful computing and communications capabilities in the palm of the hand everywhere with a variety of smart devices, mobile applications such as virtual reality, sensing and navigation have emerged and radically changed the patterns people live. The data that is generated is getting bigger. Cloud computing, on the other hand, has problems with system load and speed due to the collection, processing and control of remote data. To solve this problem, fog computing has been proposed in which data is collected and processed at an edge. In this paper, we propose a system that dynamically selects a fog server that acts as a cloud in the edge. It serves as a mediator in the cloud, and provides information on the services and systems belonging to the cloud to the mobile device so that the mobile device can act as a fog. When the role of the fog system is complete, we provide it to the cloud to virtualize the fog. The heterogeneous problem of data of mobile nodes can be solved by using mDBaaS (Mobile DataBase as a Service) and we propose a system design method for this.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.4
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• pp.332-337
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• 2010

In this paper, we propose G-Robot framework implemented with the fusion technology called RITS(Robot Technology & Information Technology System) for robot control and remote monitoring using the mobile phone. In our implemented system, the mobile phone mounted on the robot controls the robot and sends the images to the mobile phone of the user. We can monitor surrounding area of the robot with mobile phone and control the movement of the robot by sending the data between mobile-phones. Also, if the predefined situation occurs to the robot, the mobile phone on the robot sends the data to the mobile-phone of the user. From the experimental result, we can conclude that it's possible to control the robot and monitor surrounding area of the robot in real time in the region where the 3G(Generation) communication is possible. In addition, we can control the robot using the bluetooth instead of the mobile phone communication if the robot is in visual range.

• Information and Communications Magazine
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• v.19 no.9
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• pp.77-85
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• 2002

In this paper, we introduce an ADSRC(hdvanced DSRC) OFDM packet communication system which has been developed by ETRI. The ADSRC system is targeted to provide high terminal mobility, high data rate and seamless service in roadside environment for mobile office services. We discuss the requirements of the ADSRC communication system for mobile office services, and the system design specification to meet them with regard to air interface. The ADSRC packet communication systems consist of the MAC processor block, the OFDM packet modem block and the RF block. The MAC processor block handles medium access control and the test. The OFDM packet modem transmits data packets at up to 24Mbps adaptively and recovers the data from RF block. We describe the ADSRC packet communication system architecture and the ADSRC system protocol.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3068-3078
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• 2015

Although the massive MIMO system supports a high throughput, it requires a lot of channel information for channel compensation. For the reduction of overhead, the massive MIMO system generally uses TDD as duplexing scheme. Therefore, the massive MIMO system is sensitive to rapidly changing fast fading in according to time. For the improvement of reduced SINR by fast fading, the adaptive power control is proposed. Unlike the conventional scheme, the proposed scheme considers mobility of device for adaptive power control. The simulation of the proposed scheme is performed with consideration for mobility of device. The result of the simulation shows that the proposed scheme improves SINR. Since SINR is decreased in according to the number of device in the network by unit of cell, each base station can accommodate more devices by the proposed scheme. Also, because the massive MIMO system with high SINR can use high order modulation scheme, it can support higher throughput.

• The Transactions of the Korea Information Processing Society
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• v.6 no.11S
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• pp.3190-3198
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• 1999

Because of the rapid growth of the mobile communication, the need for the mobile internet access has grown up as well. since the current mobile communication network, however, is optimized for a voice communication system, which exclusively occupies a channel for a given time, it is not suitable for variable rate packet data. In order to support the mobile internet access, it is essential do design a reasonable packet switching network which supports the mobility. Since mobile packet network has longer latency, high speed switching and QoS are required to meet the user's requirements. In this paper, we suggest an resonable way to construct a network and its operation procedures utilizing GPRS(General Packet Radio Service) network and MPLS(Multi Protocol Label Switching) to provide a high speed switching and QoS mobile internet access. GPRS is used as a network which supports the mobility and MPLS guarantees the QoS and high speed IP protocol transmission based on the ATM switching technology.

• Journal of the Korea Society for Simulation
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• v.20 no.4
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• pp.91-96
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• 2011

As the user's demand for ultra high-speed wireless internet has increased, the standardization, research and development of future mobile communication systems have been done for several years. IMT-Advanced system which is called fourth generation mobile communication should support the data rate of 1 Gbps for nomadic users and 100 Mbps for mobile users. Also, the system should hold call connection at the mobile speed of 350 km/h. Meanwhile, since Doppler spread is linearly proportional to mobile speed, high mobility leads to the increase of interference between subcarriers and the deterioration of detection performance consequently. In this paper, we evaluate and analyze detection probability with respect to equalization methods in time-varying channels under system parameters complying with IMT-Advanced requirements. According to computer simulation conducted by varying mobile speed and code rate, MMSE based equalization can mitigate performance degradation of IMT-Advanced system considerably in time-varying channels.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3487-3494
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• 2013

Diverse application service such as mobile payment, access control or smart poster have been provided by using smart devices with built-in Near Field Communication technology. Especially, a mobile payment system can provide convenience to its users, but it also can poses including data disclosure while transmitting. There are vulnerabilities while generating session keys used to encrypt data in transaction processes as proposed in KS X 6928, the standard for mobile payment system. Therefore, in this thesis, I analyzed weaknesses of session keys used to encrypt transaction data and proposed a more secure mobile payment system based on NFC to enhance security. The proposed system will provide security functionalities such as key freshness, mutual authentication and key confirmation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.171-179
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• 2011

In these days, various wireless internet services are possible since the advanced wireless networks enable to transfer more data than before and smarter devices have developed to display the multimedia information more efficiently. Therefore, Korean MIPS such as SKT and LGT provide many kinds of advanced services such as wireless on-line shopping, mobile banking system and etc using 2.5 generation wireless network technology and smartcards. In a transportation system, a cellular phone can be used as a useful payment tool since most people always keep it and a mobile payment system has developed as infrastructure for wireless on-line services. In this paper, a mobile transportation payment system is introduced. A driver needs to pay a toll fee when he/she uses the highways. Recently, a high pass system has introduced, in which a vehicle can pass a toll gate without stopping to pay the fee to a counter. The payment is done automatically by an attached payment device. We have developed an advanced mobile system in which a smartcard embedded cellular phone is used as a payment device. The personnel and financial information is stored at a smartcard and the communication between the phone and OBU(On Board Unit) is done by Bluetooth.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.4
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• pp.733-738
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• 2005

The distress communication system in the maritime mobile service had almost depended on the wireless telephony or telegraphy technique. The GMDSS (Global Maritime Distress and Safety System) which was introduced in 1992 brought a lot of changes in the maritime distress communication service such as the automatic transmission of distress signals and implementation of global search and rescue networks. However, there are some deficiencies in the GMDSS distress communication system such as a lack of compatibility in the maritime distress communication between CMDSS ships and Non-GMDSS ships, increasing deceptive or false distress alerts generated by GMDSS installations, lack of understanding about the CMDSS installations for the operators. In this paper, the problems of distress communication system in the maritime mobile service are analyzed and the methods to solve or minimize these problems are suggested.