• IEIE Transactions on Smart Processing and Computing
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• v.3 no.4
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• pp.212-220
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• 2014

The current cellular communications are optimized for low mobility users, meaning that their performance is degraded at high speed. Therefore, passengers in a high-speed train experience very poor radio link quality due to the significantly large number of simultaneous handovers. In addition, wireless data traffic is expanding exponentially in trains, subways and buses due to the widespread use of smartphones and mobile devices. To solve the inherent problem of cellular communication networks and meet the growing traffic demand, this paper proposes the mobile hotspot network of a millimeter-wave communication system as a mobile wireless backhaul. This paper describes the physical layer design of uplink and downlink in the proposed system, and the performances of uplink and downlink are evaluated under Rician fading channel conditions. The implemented baseband prototype of the proposed millimeter-wave communication modem is presented. This system can provide a Gbps data rate service in high-speed trains carrying hundreds of wireless Internet users.

• Journal of Communications and Networks
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• v.2 no.1
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• pp.35-45
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• 2000

this paper presents the concept of "mobile ATM', a proposal for third-generation (3G) mobile communication network infrastructure capable of supporting flexible evolution of radio technologies from today's cellular and data services towards future wireless multimedia services. Mobile ATM provides generic mobility management and QoS-based transport capabilities suitable for integration of multiple radio access technologies including cellular voice. wireless data, and future broadband wireless services. The architecture of a mobile ATM network is outlined in terms of the newly-defined "W-UNI" interface at the radio link and "M-UNI"and "M-UNI" interface which supports unified access for WATM and non-ATM mobile terminals through corresponding interworking functions (IWF) is explained. leading to an understanding of how different radio access technologies are supported by the same ATM-based core network infrastructure. Generic mechanisms for handoff and location management within the core mobile network are discussed. and related protocol extensions over the "W-UNI" and "M-UNI/NNI"interfaces are proposed. the issue of "crossover switch (COS)" selection in mobile ATM is considered, and a unified handoff signaling syntax which supports flexibility in COS selection is described. Typical signaling sequences for call connection and handoff using the proposed protocols are outlined. Experimental results form a proof-of-concept mobile ATM network prototype are presented in conclusion.

• Journal of the Korea Society of Computer and Information
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• v.24 no.5
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• pp.1-9
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• 2019

In this paper, we propose the algorithms which determine 1) the efficient anchor-node visiting route of mobile sink in terms of energy supply and 2) the efficient energy amount to be charged to each anchor node, by using the information of each anchor node and the mobile sink. Wireless sensor networks (WSNs) using mobile sinks can be deployed in more challenging environments such as those that are isolated or dangerous, and can also achieve a balanced energy consumption among sensors which leads to prolong the network lifetime. Most mobile sinks visit only some anchor nodes which store the data collected by the nearby sensor nodes because of their limited energy. The problem of these schemes is that the lifetime of the anchor nodes can be shorten due to the increased energy consumption, which rapidly reduces the overall lifetime of WSN. This study utilizes a mobile sink capable of wireless power transmission to solve this problem, so a mobile sink can gather data from anchor nodes while charging energy to them. Through the performance verification, it is confirmed that the number of blackout nodes and the amount of collected data are greatly improved regardless of the size of the network.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1936-1939
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• 2002

Much recent attention on wireless technologies s put on topology-less wireless network, in which all nodes an be mobile and can communicate over wireless links, due to its ease of deployment, high flexibility and low expenses. One key in topology-less wireless network is mobile base stations (MBSs), which provides access points or mobile terminals (MTs) to wireless backbone network. MBSs can move to anywhere in accordance with changes in geographical distribution of MTs. They serve as dynamic odes. However, in order to utilize network resources and take full advantage of this topology-less network, MBSs must move to suitable position according to the current tate of network use. Moreover, MBSs have to consider the distance among them to avoid the crash and gap area of MBSs. Therefore, this paper proposes MBS movement algorithm by implementing push-pull method to fulfill the corporation of MBSs and considering the center of covered MTs or centroid to satisfy the MT coverage. From the simulation results, the proposed algorithm increases the performance of system when comparing with the centroid-based algoriom〔7〕, such as coverage area, MT coverage and call drops rate.

• Convergence Security Journal
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• v.4 no.2
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• pp.53-60
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• 2004

We describe CHAP authentication for roaming service method of visited ISP subscriber on GPRS network. We also illustrate how visited mobile ISP subscriber can access ISP server and authenticate RADIUS in home network via Gateway GPRS Support Node (GGSN) on GPRS/UMTS network for wireless internet service and roaming. For this we propose the modified CHAP message format, PCO Message format at MT, and interworking message and format between GGSN and RADIUS in home ISP network for wireless internet service of mobile ISP subscriber at GPRS network in this paper. We also show authentication results when visited mobile ISP subscriber via CHAP at GPRS network accesses the RADIUS server in home ISP network.

• Electronics and Telecommunications Trends
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• v.35 no.2
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• pp.38-49
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• 2020

In recent years, the unmanned aerial vehicle (UAV) assisted mobile free space optical (FSO) communication technique has attracted considerable attention regarding its aims to provide improved communication conditions for fixed-to-fixed FSO network and promising fronthaul and backhaul solutions for 5G+ wireless networks. This can be attributed to its outstanding advantages such as fast deployment and flexible network configuration. The UAV-assisted mobile FSO system can be used to provide cost-effective internet services in rural and remote areas and in hotspot areas that are characterized by increased data traffic. Additionally, it can be used to provide secure communication services under emergency circumstances. In this report, we review recent R&D trends in wireless network technology employing the UAV-assisted mobile FSO technique and key technologies for mobile FSO wireless networks. Furthermore, we introduce drone-based mobile FSO terminals and control systems that we have developed.

• Journal of information and communication convergence engineering
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• v.10 no.4
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• pp.337-342
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• 2012

The medical industries are integrated with information technology with mobile devices and wireless communication. The advent of mobile healthcare systems can benefit patients and hospitals, by not only providing better quality of patient care, but also by reducing administrative and medical costs for both patients and hospitals. Security issues present an interesting research topic in wireless and pervasive healthcare networks. As information technology is developed, many organizations such as government agencies, public institutions, and corporations have employed an information system to enhance the efficiency of their work processes. For the past few years, healthcare organizations throughout the world have been adopting health information systems (HIS) based on the wireless network infrastructure. As a part of the wireless network, a mobile agent has been employed at a large scale in hospitals due to its outstanding mobility. Several vulnerabilities and security requirements related to mobile devices should be considered in implementing mobile services in the hospital environment. Secure authentication and protocols with a mobile agent for applying ubiquitous sensor networks in a healthcare system environment is proposed and analyzed in this paper.

• Convergence Security Journal
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• v.16 no.5
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• pp.49-55
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• 2016

Recently mobile service industry has grown very rapidly. In this paper, We investigated the changes in mobile service network as well as security vulnerabilities of network in future 5G mobile service network, too. Recently, there are rapid developement of information and communication and rapid growth of mobile e-business users. Therefore We try to solve security problem on the internet environment which charges from wire internet to wireless internet or wire/wireless internet. Since the wireless mobile environment is limited, researches such as small size, end-to-end and privacy security are performed by many people. In addition, there is a need of internetworking between mobile and IoT services. Wireless Application Protocol has weakness of leaking out information from Gateway which connected wire and wireless communication. As such, We investigate the structure of mobile service network in order to gain security vulnerabilities and insights in this paper.

• Journal of Korea Game Society
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• v.6 no.1
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• pp.21-28
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• 2006

This study focused on design and implementation of Mobile 3D Bluetooth Engine based on OpenGL-ES. In Mobile 3D network game so far, there is a form the mainstream of wireless internet game using WAP and VM. But, VM game are popular because of an excessive communication expense problem for this mobile network game that occur when connect to wireless internet as point out to problem by it, that is, stand-alone game are very popular. This study introduce a mobile 3D Bluetooth Engine which is based on mobile 3D standard using OpenGL-ES to solve a mobile network game generally that occurs when connect to take pleasure a wireless internet from some people into a short distance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.1027-1030
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• 2005

The article introduces developing trends of an adaptive mobile terminal as an interface for use of various network resources, such as public wireless networks and un-licensed wireless networks in ubiquitous sensor network environments, without troublesome settings or operations by users. These adaptive mobile terminals able to provide seamless services that adapt autonomously to the user's movements and changes in the state of wireless resources. Consequently, adaptive mobile terminals should be had respective independent hardware structure of usable wireless networks.