• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.5
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• pp.2338-2356
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• 2019

Vehicular ad-hoc network (VANET) is the name of technology, which uses 'mobile internet' to facilitate communication between vehicles. The aim is to ensure road safety and achieve secure communication. Therefore, the reliability of this type of networks is a serious concern. The reliability of VANET is dependent upon proper communication between vehicles within a given amount of time. Therefore a new formula is introduced, the terms of the new formula correspond 1 by 1 to a class special ST route (SRORT). The new formula terms are much lesser than the Inclusion-Exclusion principle. An algorithm for the Source-to-Terminal reliability was presented, the algorithm produced Source-to-Terminal reliability or computed a Source-to-Terminal reliability expression by calculating a class of special networks of the given network. Since the architecture of this class of networks which need to be computed was comparatively trivial, the performance of the new algorithm was superior to the Inclusion-Exclusion principle. Also, we introduce a mobility metric called universal speed factor (USF) which is the extension of the existing speed factor, that suppose same speed of all vehicles at every time. The USF describes an exact relation between the relative speed of consecutive vehicles and the headway distance. The connectivity of vehicles in different mobile situations is analyzed using USF i.e., slow mobility connectivity, static connectivity, and high mobility connectivity. It is observed that $p_c$ probability of connectivity is directly proportional to the mean speed ${\mu}_{\nu}$ till specified threshold ${\mu}_{\tau}$, and decreases after ${\mu}_{\tau}$. Finally, the congested network is connected strongly as compared to the sparse network as shown in the simulation results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7A
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• pp.770-777
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• 2007

Smaller cell size in the micro-cell or pico-cell structure brings about more frequent hand-overs between cells, and higher speed movement of the mobile terminal makes short the permissible time interval for executing these hand-over procedures. In this situation the hand-over failure may occur or some packets may be lost during the hand-over. Moreover a rapid degradation of throughput is triggered by packet re-transmission for compensating such errors. The QoS (Quality of Services) of mobile multimedia applications with higher bits rate requirements and higher speed mobility are severely affected by even shot service interruption. This paper proposes a new hand-over scheme to provide seamless services in the next generation mobile communication systems. Simulation is done to evaluate the performance of the proposed scheme based on its hand-over failure rate and packet loss rate.

• Journal of IKEEE
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• v.22 no.1
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• pp.29-37
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• 2018

In recent years, there have been increasing interests in the mobile crowdsourcing that exploits multiple sensors, communication and user interfaces, and the computation power of widespread smartphones. In this paper, we present a novel mobile crowdsourcing-based driver assistance systems (MC-DAS) that crowdsource the sensor data of smartphone app having already passed a road segment, generate its profile information through a massive data processing, and forward this profile to the smartphone app of vehicle entering the road segment. Based on the MC-DAS platform, we also design and implement a new navigation system that advices the vehicle speed depending on the speedbump and on the road curvature profile. We expect that the proposed MC-DAS platform will be used as a platform for emerging new mobile crowdsourcing applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9B
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• pp.563-568
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• 2007

This paper proposes a routing establishment method for improving path stability in mobile ad-hoc networks. In mobile ad-hoc networks, the network topology is highly dynamic due to the node mobility unlike wired networks. Since the existing methods are based on the shortest path algorithm with the minimum hop count regardless of the path stability, it could lead to packet loss and path disconnection in mobile ad-hoc networks. In particular, if control packets and critical data are transmitted on the unstable path, it causes serious problems. Therefore, this paper proposes one approach in order to minimize packet loss and path disconnection by considering the node mobility. After the destination node receives multiple RREQ messages, it selects the stable path through the proposed MinMax algorithm according to the node speed.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.234-239
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• 2012

Next generation mobile communication systems have been studied and applied to support various services. In next generation mobile communication systems, the most interested research is the integration of various communication systems and the offer of various services by using high-speed data transmission. The integration of communication systems has been researched by using multi standard modem, while the high-speed data transmission for the offer of various services has been applied by using OFDM. This paper has proposed the method to reduce PAPR by using multi standard modem. with EVM, this paper has also suggested the method to compensate in-band distortion while reducing PAPR. By using the proposed methods, this paper has analyzed and simulated the decrease efficiency of PAPR, the performance of CCDF, and the performance of BER in next generation mobile communication systems. The simulation results improved the performance of next generation mobile communication system can be seen that.

• Journal of Convergence Society for SMB
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• v.1 no.1
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• pp.67-73
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• 2011

Handover in high speed mobile communication service, in particulary mobile WiMAX is supported efficiency mobility to 120km/h speed. But, in order to accommodate number of user increment in a cell, wireless network is increment to microcell and picocell by allocate bandwidth and by decrease cell size. handover is occurrent and increment connection failure ratio In this result. IEEE 802.16 standard is support seamless connection through handover optimization scheme. But because authentication process is abbreviate, network weakness is exposure. In this paper, we propose handover scheme for support realtime service as VoIP, Picure communication, Streaming Data Service in order to support partially encryption method. In experiment, proposed scheme is proof which process time is increment 20% more than previous scheme.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.3
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• pp.91-99
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• 2009

Development of high-speed Internet services and the increased supply of mobile devices have become the key factor for the acceleration of ubiquitous technology. WiBro system, formed with lP backbone network, is a MBWA technology which provides high-speed multimedia service in a possibly broader coverage than Wireless LAN can offer. Wireless telecommunication environment needs not only mobility support in Layer 2 but also mobility management protocol in Layer 3 and has to minimize handover latency to provide seamless mobile services. In this paper, we propose a fast cross-layer handover scheme based on signal strength prediction in WiBro environment. The signal strength is measured at regular intervals and future value of the strength is predicted by Exponential Smoothing Method. With the help of the prediction, layer-3 handover activities are able to occur prior to layer-2 handover, and therefore, total handover latency is reduced. Simulation results demonstrate that the proposed scheme predicts that future signal level accurately and reduces the total handover latency.

• Journal of Information Processing Systems
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• v.14 no.4
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• pp.989-1009
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• 2018

Rapid advances in science and technology with exponential development of smart mobile devices, workstations, supercomputers, smart gadgets and network servers has been witnessed over the past few years. The sudden increase in the Internet population and manifold growth in internet speeds has occasioned the generation of an enormous amount of data, now termed 'big data'. Given this scenario, storage of data on local servers or a personal computer is an issue, which can be resolved by utilizing cloud computing. At present, there are several cloud computing service providers available to resolve the big data issues. This paper establishes a framework that builds Hadoop clusters on the new single-board computer (SBC) Mobile Raspberry Pi. Moreover, these clusters offer facilities for storage as well as computing. Besides the fact that the regular data centers require large amounts of energy for operation, they also need cooling equipment and occupy prime real estate. However, this energy consumption scenario and the physical space constraints can be solved by employing a Mobile Raspberry Pi with Hadoop clusters that provides a cost-effective, low-power, high-speed solution along with micro-data center support for big data. Hadoop provides the required modules for the distributed processing of big data by deploying map-reduce programming approaches. In this work, the performance of SBC clusters and a single computer were compared. It can be observed from the experimental data that the SBC clusters exemplify superior performance to a single computer, by around 20%. Furthermore, the cluster processing speed for large volumes of data can be enhanced by escalating the number of SBC nodes. Data storage is accomplished by using a Hadoop Distributed File System (HDFS), which offers more flexibility and greater scalability than a single computer system.

• The Journal of the Convergence on Culture Technology
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• v.5 no.3
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• pp.333-338
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• 2019

Cultural contents are the most important factor in high speed and high quality data communication. High-quality content includes VR and AR technology, and a variety of high-quality content can be streamed over wireless mobile phones via smartphones. In addition, network and wired/wireless communication are inevitably required in an Internet of Things (IoT) environment in which things are connected to a wireless Internet. IoT is used in various network technologies such as 4G, 5G mobile communication, WIFI wireless LAN, Bluetooth and so on. It is a technology that can use the connection between things anytime, anywhere, and can be achieved in a wireless mobile communication environment. Therefore, in this paper, we study data error compensation estimation method which can reduce data error based on mobile communication channel environment analysis so that high quality contents can be serviced even in high speed mobile environment.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.1
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• pp.79-89
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• 2014

It has been an increase in consumers who want a high-capacity and fast speed by the newly diffused mobile device(Smart phones, Ultra books, Tablet PC). As a result, the demand for Flash Memory is constantly increasing. Flash Memory is separated by a NAND-type and NOR-type. NAND-type Flash Memory speed is slow, but price is cheaper than the NOR-type Flash Memory. For this reason, NAND-type Flash Memory is widely used in the mobile market. So Fault Detection is very important for Flash Memory Test. In this paper, Proposed PMBIST for Pattern Test of NAND-type Flash Memory improved Fault detection.