• Journal of KIISE:Information Networking
• /
• v.30 no.6
• /
• pp.755-763
• /
• 2003

To improve performance over noisy wireless channels, mobile wireless networks employ forward error correction(FEC) techniques. The performance of static FEC algorithms, however, degrades by poorly matching the overhead of their correction code to the degree of the fluctuating underlying channel error. This paper proposes an adaptive FEC technique called FECA(FEC-level Adaptation), which dynamically tunes FEC strength to the currently estimated channel error rate at the data link layer. FECA is suitable for wireless networks whose error rate is high and slowly changing compared to the round-trip time between two communicating nodes. One such example network would be a sensor network in which the average bit error rate is higher than $10^{-6}$ and the detected error rate at one time lasts a few hundred milliseconds on average. Our experiments show that FECA performs 15% in simulations with theoretically modeled wireless channels and in trace-driven simulations based on the data collected from real sensor networks better than any other static FEC algorithms.

• Journal of Advanced Navigation Technology
• /
• v.21 no.4
• /
• pp.347-352
• /
• 2017

In this paper, we propose a method that reduces mobile user's handover call dropping probability by using cognitive radio technology(CR) in cellular - based wireless cognitive radio networks. The proposed method predicts a cell to visit by Ziv-Lempel algorithm, and then supports mobile user with prediction of spectrum holes based on CR technology when allocated channels are short in the cell. We make neural network predict spectrum hole resources, and make handover calls use the resources before initial calls. Simulation results show CR technology has the capability to reduce mobile user handover call dropping probability in cellular mobile communication networks.

• Journal of the Korea Society of Computer and Information
• /
• v.10 no.2 s.34
• /
• pp.133-141
• /
• 2005

We need to study on simulation method of user's mobility Patterns for the performance analysis of the location management in wireless mobile networks. For this purpose ,this paper presents a user mobility model of wireless mobile networks with regular Patterns Sometimes mobile users randomly move , but they show the movement characteristics that regularly change their locations in some patterns in given time slots. So, we suggest the mobility model that can describe user's time related movement patterns. This model consists of some elements-positions, transitions , transition Probabilities which are variable, and some geographical paths for each transitions. We describe the simulation method for users' mobilities with random movements and regular movements , too. The simulation results by the model show that the suggested model can generate movement scenarios having regular patterns related with location and time.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.5 no.3
• /
• pp.107-115
• /
• 2009

Traditionally, simulation method is used to test and evaluate the performance of communication protocol or functional elements for mobile communication service. In this paper, wireless network simulator is implemented using the C++ object-oriented programming language. This simulator can simulate wireless data services, like as ad-hoc networks, by considering the user's mobility. In this paper, the simulator includes network traffic model to reflect wireless data service and traffic source model to represent a user's mobility similar to real service environment and traffic characteristics can be reflected on the simulation, and also more accurate simulation results can be got through that. In addition, by using object-oriented techniques, new service feature or environment can be easily added or changed so that the developed mobile communication simulator can reflect the real service environment all the time. This simulator can be used in adjusting the characteristics of wireless data hosts following the mobility of the user, and also can be used in building new wireless ad-hoc network routing protocols.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2008.10a
• /
• pp.744-747
• /
• 2008

Sensor networks will play an important role in the next generation pervasive computing. But its characteristic of wireless communication brings a peat challenge to the security measures used in the communication protocols. These measures are different from conventional security methods. In this paper, we proposed a security architecture for self-organizing mobile wireless sensor networks. It can prevent most of attacks based on intrusion detection.

• Journal of information and communication convergence engineering
• /
• v.7 no.3
• /
• pp.241-246
• /
• 2009

Advances in mobile and wireless networking technologies have enabled mobile ad hoc networks applicable to a wide range of areas. Many cases of even such ad hoc networks demand to be accessible to the global network. Owing to be diversified in features depending on applications, however, some those networks may consist of devices or nodes which do not facilitate all the same transport protocols. This results in unreachable situations of establishing ad hoc network: such as non-existence of all required access points, faults or contention in a path of particular protocol communication. Interworking between different transport protocols can alleviate such problems. This paper proposes an interworking scheme to improve data transport performance and network accessibility, especially in such a mobile ad hoc network that is applicable to data communications among ships or user's convenient u-health services. Modeling and simulation analysis are used to verify the improvement.

• Journal of KIISE:Information Networking
• /
• v.29 no.3
• /
• pp.224-232
• /
• 2002

The routing protocols designed for wired networks can hardly be used for mobile ad-hoc networks due to limited bandwidth of wireless transmission and unpredictable topological change. Recently, several routing protocols for mobile ad-hoc networks have been proposed. However, when these protocols are applied to support real time services like multimedia transmission, they still have problems in ad-hoe networks, where the topology changes drastically. In this paper, we propose a new route selection algorithm which selects the most reliable rouse that is impervious to route failures by topological changes by mobile hosts. For reliable route selection, the concept of virtual zone (stable lone and caution zone) is proposed. The lone is located in a mobile node's transmission range and determined by mobile node's mobility information received by Global Positioning System (GPS). The proposed algorithm is applied to the route discovery procedure of the existing on-demand routing protocol, AODV, and evaluated by simulation in various traffic conditions and mobility patterns.

• Proceedings of the Korean Information Science Society Conference
• /
• 2000.10c
• /
• pp.111-113
• /
• 2000

We discuss the problem of resource reservation, such as bandwidth, for delay sensitive application in wireless networking environment. As multimedia application is becoming a critical role of the current mobile network, the resource reservation become very important to support the real-time service. In this paper, we propose and evaluate a new resource reservation protocol, called Split Reservation Protocol, in wireless network. The simulation results show that our proposed protocol outperforms an existing protocol called MPSVP in terms of network overhead.

• Journal of Information Technology Applications and Management
• /
• v.17 no.2
• /
• pp.207-223
• /
• 2010

Mobile banking is a subset of electronic banking which underlies not only the determinants of the banking business but also the special conditions of mobile commerce. Nowadays wireless networks are being evolved and diversified. In this situation The wireless e-commerce is in the limelight on new profits of Carriers. Especially from current year when Carriers in domestic plans to provide the services using 2.5G networks the service providers choose wireless e-commerce as the main parts of wireless internet strategy and will provide a various of services. Because of this situation, the importance of mobile billing service is being emphasized. This paper searches the definition and service types of mobile banking, and suggests status and prospects of domestic mobile banking. We suggest the basic direction, the stage of development and functions of services by analyzing the cases of Nonghyup's. Finally we derive the critical factors from those and suggest the effect of introduction and the direction of development. From the customer perspective, mobile banking has many strengths. For example, it allows that all customers access banking service at anytime, anywhere more easily than telephone banking or pc banking. And it reduces the time and the effort for using the service. It enables the company to make a business against global customers. On the other hand, from the company perspective, it has a lot of potential that affect market share and reduce the costs of human and material resources which used to operate and support branches. However, it needs many efforts to reach at the stage of completion. And We will have to solve the problems that develop many contents, expend the range of services and raise the service convenience.

• 한국ITS학회:학술대회논문집
• /
• 2008.11a
• /
• pp.114-117
• /
• 2008