• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.217-219
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• 2003

무선 인터넷 서비스 사용자의 증가 및 초고속 멀티미디어의 출현으로 셀룰러 망(Cellular Network)의 부하가 증가하고 대역폭의 부족 현상을 초래하게 되었다. 셀룰러 망에서 모든 단말기들은 기지국(Base Station)을 통해서만 데이터 전송을 할 수 있어 기지국과 단말들 간에 셀룰러 대역폭 사용의 증가를 초래 할 수 있다. 본 논문에서는 이러한 셀룰러 망의 대역폭 부족 현상을 해결할 수 있는 기법으로 단말기들간의 Peer-to-Peer통신이 가능한 이동 Ad Hoc 망을 셀룰러 망에 통합함으로써, 셀룰러 망의 부하를 줄일 수 있는 방안들을 제안한다 이들 제안된 기법들에서의 공통적인 특징은 특정 데이터를 이미 가지고 있는 단말기가 같은 데이터의 액세스를 원하는 다른 단말기를 위한 가상의 캐쉬로 동작하며, 가능할 때마다 이 가상 캐쉬로부터 원하는 파일을 획득함으로써 셀룰러 망의 부하를 줄일 수 있다는 것이다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.9
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• pp.8-15
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• 2009

Although traditional single-hop cellular networks had been serving well in past years, they are no longer economically feasible in supporting high data-rate, multimedia services of $4^{th}$Generation (4G) communications due to the requirement of high transmission power By contrast, multi-hop cellular networks (MCN) are capable of dramatically saving the transmission power by overlaying the capability of ad hoc networking among mobile terminals on the cellular network infrastructure. To achieve this performance gain as well as enable 4G services, an efficient routing protocol needs to be designed for MCN. In this paper, we propose a reactive route discovery protocol for MCN that uses directional information to the base station in the route discovery process. Our analysis/simulation results have demonstrated that the proposed protocol significantly reduces flooding overheads. In addition, we consider issues for 4G services in MCN and applications of the proposed protocol.

• Journal of KIISE:Information Networking
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• v.34 no.4
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• pp.239-245
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• 2007

New multimedia services over the cellular/WLAN overlay networks require different Quality of Service (QoS). In the cellular/WLAN overlay structure, the main issue of load balancing is to balance the available bandwidth among different networks. In this paper, we propose a new online network management scheme. Our proposed scheme is designed to improve bandwidth utilization by balancing the traffic load between the cellular network and WLANs. Simulation results indicate the superior performance of our proposed framework to strike the appropriate performance balance between contradictory QoS requirements under widely varying diverse traffic loads.

• Journal of KIISE:Information Networking
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• v.31 no.1
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• pp.53-61
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• 2004

In this paper, we investigate a charging mechanism for the system interworking between Wireless Local Area Networks(LANs) and Cellular Networks. Because the charging mechanisms of the two networks are different, a unified charging mechanism is required to correlate the charging informations of the two networks in the system interworking. Therefore, we propose a unified charging mechanism to collect charging information with a combined identifier. Also, we propose a decision method to control the interval of transferring accounting information according to the charging types of users (pre-paid, off-paid, and fixed-rate) and show that the proposed decision method improves the granularity and the communication efficiency of charging informations.

• Journal of KIISE:Information Networking
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• v.29 no.2
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• pp.165-173
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• 2002

In the static channel assignment scheme for cellular mobile computing environment, each cell has a fixed number of channels and supports a service for a user′s request entering to the cell. This scheme has an advantage of simplicity. However, this scheme has a disadvantage that can′t control far hot cell problem. Therefore, to solve this problem, the "channel borrowing" concept is needed. In this paper, we propose a load balancing(channel borrowing, channel reassignment) approach using genetic algorithm. The purposes of using genetic algorithm in this paper are ${\circled1}$ to find early a cell including an available channel and ${\circled2}$ to decrease a number of probings and ${\circled3}$ to migrate to the cell after searching an available channel near upon optimality. To represent effectiveness of the proposed algorithm, we simulated various experiments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.912-919
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• 2005

The Growth in wireless Internet has made Networking possible at anytime and anywhere. So mobile devices like cellular phone and PDA are now used in various fields. In particular, the mobility of mobile devices has a great advantage in remote control. This paper designed and implemented a Mobile VNC system that transmitted the screen image of a remote computer, control the remote computer GU and monitor all by cellular phone. The proposed system consists of a Mobile Viewer un on the cellular phone, VNC Server m on a number of remote computers and a VNC Monitor. For communication between the VNC Server and the Mobile Viewer the MRFB protocol is used. The screen image transmitted to the Mobile Viewer is encoded in the PNG format supported by SK-VM, the Java execution environment of the Cellular phone. According to implementation results, the image is about $2KB\~8KB$. According to the 65 times transmission test, the average frame per second is 4.93fps in the emulator and a real cellular phone takes 0.8fps. Therefore, the proposed system is more efficient than existing systems.

• The Journal of the Korea Contents Association
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• v.5 no.5
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• pp.26-32
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• 2005

Standardization of the home-networking technologies and the home network trial has been tried to activate the home network services and develop the new business models. Home network mobile service using a cellular phone provides the control and monitoring the states of the information appliances and HA(home automation) devices through a home network gateway interworking with a home server. For this purpose, the home network mobile application in a cellular phone can automatically change the configuration of the information appliances and HA devices interworking with a home server. In this paper, we propose the home appliance auto-configuration scheme using XML for home network mobile services. The proposed scheme is implemented on WIPI of the domestic mobile platform standardization.

• Journal of KIISE:Information Networking
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• v.29 no.3
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• pp.216-223
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• 2002

This paper proposes an efficient location management scheme for next-generation cellular mobile networks. In the proposed scheme, the users are classified into two classes according to their mobility patterns; high mobility users (HMU) and low mobility users (LMU). We design the intelligent location management strategy based on theme user mobility classes. The performance of the proposed scheme is compared with that of pure intelligent paging scheme by computer simulation. As a result, it is shown that the proposed scheme provides the better performance than the pure intelligent paging scheme.

• Journal of Communications and Networks
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• v.17 no.5
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• pp.506-516
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• 2015

Wireless sensor networks (WSNs) are generally comprised of densely deployed sensor nodes, which results in highly redundant sensor data transmissions and energy waste. Since the sensor nodes depend on batteries for energy, previous studies have focused on designing energy-efficient medium access control (MAC) protocols to extend the network lifetime. However, the energy-efficient protocols induce an extra end-to-end delay, and therefore recent increase in focus on WSNs has led to timely and reliable communication protocols for mission-critical applications. In this paper, we propose an energy efficient and delay guaranteeing node scheduling scheme inspired by biological systems, which have gained considerable attention as a computing and problem solving technique.With the identification of analogies between cellular signaling systems and WSN systems, we formulate a new mathematical model that considers the networking challenges of WSNs. The proposed bio-inspired algorithm determines the state of the sensor node, as required by each application and as determined by the local environmental conditions and the states of the adjacent nodes. A control analysis shows that the proposed bio-inspired scheme guarantees the system stability by controlling the parameters of each node. Simulation results also indicate that the proposed scheme provides significant energy savings, as well as reliable delay guarantees by controlling the states of the sensor nodes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.1
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• pp.110-132
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• 2019

To ensure reliable and secure communication in heterogeneous cellular network (HCN) with imperfect channel state information (CSI), we proposed a coordinated multipoint (CoMP) transmission scheme based on dual-threshold optimization, in which only base stations (BSs) with good channel conditions are selected for transmission. First, we present a candidate BSs formation policy to increase access efficiency, which provides a candidate region of serving BSs. Then, we design a CoMP networking strategy to select serving BSs from the set of candidate BSs, which degrades the influence of channel estimation errors and guarantees qualities of communication links. Finally, we analyze the performance of the proposed scheme, and present a dual-threshold optimization model to further support the performance. Numerical results are presented to verify our theoretical analysis, which draw a conclusion that the CoMP transmission scheme can ensure reliable and secure communication in dense HCNs with imperfect CSI.