• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.3
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• pp.309-316
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• 2016

Recently, the voice service over a mobile communication system tends to be provided based on the packet-based technology. Even though the sufficient transmission rate is supported by LTE mobile communication system, the quality of VoIP service that is experienced by the user can be degraded by the change in the transmission conditions and the terminal mobility. This paper has established an environment on which experiments are conducted for the different values of the major parameters that represent the transmission conditions. The result can contribute to the decision of the requirement that the mobile system should meet for maintaining the quality of VoIP service.

• Journal of Satellite, Information and Communications
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• v.12 no.1
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• pp.43-48
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• 2017

Recently, demands on civilian UAV (Unmanned Aerial Vehicle) has been increasing and appropriate communication system is required for the UAV. In this paper, the performance of the UAV communication system using commercial wireless mobile network is discussed. The main service area of the wireless mobile network is ground level however the flying range of the UAV is normally in high altitude. Because of this mismatch of service area the performance of the UAV communication system is degraded in high altitude. To compensate performance degradation of the UAV communications system in high altitude, adaptive array antenna is introduced which is able to overcome altitude limitation of the UAV communication system.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06d
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• pp.287-288
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• 2011

In this paper, we propose a hierarchical P2P architecture using clustering mobile peers. The proposed scheme utilizes the maximum connection time of connected peers to form the mobile network, which makes the network topology relatively stable. The connection time of connected peers can be determined by the location, velocity vector and communication range of each mobile peer. Therefore, the update overhead of the network is decreased and the success rate of contents search is increased. Experiments have shown that our proposed scheme outperforms the existing schemes.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1451-1454
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• 2002

In recent years, there are growing concerns about land mobile satellite (LMS) communication systems and mobile stratospheric communication systems (SCS) for the purpose of service upgrade of personal and mobile communications in near future. It is important to possess accurate channel model for prediction of the above system performance. Thus, in this paper, we evaluate the bit error rates of a coded BPSK system based on realistic channel model which can be applied to stratospheric communication systems. The channel data was made by fitting the parameters of probability distribution model to measured data. This approach was proposed by Corraza〔1〕and modified by You〔2〕. And also the effects of channel codings on the system performance are analyzed. As results, we can get the performance curve characteristics on realistic Rician log-normal fading channels with various communication environments.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.247-250
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• 2003

Mobile wire technology is a publicly available general purpose for Radio Frequency(RF) communication for short-range and point-to-multi point voice and data transfer. In this paper, we proposed a new technology of the synchronized frame structure which is based on the CDMA technique, and it's implemented into the VLSI design by FPGA. The developmental technique consists of an assigned coded type mobile communication equipments and available local mobile or wireless communication scheme quasi BT(Blue Tooth)'s functions as multiplexer or do-multiplexer for each other applications. We implement this architecture with special proposed frame structure in the local area network. Also, we expect the above proposed structure extend into the DS3 network architecture and applicable to the TE(Terminal Equipment) in the local communication area and the other one etc.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2222-2224
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• 2001

This paper presents the implementation of an efficient car tracking system based on Inverted DGPS (IDGPS) using mobile phone and internet for data communication link. The IDGPS technique, which may provide the same level of accuracy as DGPS, is subject to degradation in real time applications when transmission time delays occur in the communication links. Therefore, an effective communication system is the key element for successful application of the IDGPS. The combination of internet and mobile phones provides a high data rate, unlimited communication packet size, flexible data structure, and wide coverage without additional communication devices. An implementation of such a data link system is described. Field test results are included to evaluate the performance of the proposed system.

• ETRI Journal
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• v.44 no.6
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• pp.936-944
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• 2022

The mobile network allows redundant transmission via disjoint paths to support high-reliability communication (e.g., ultrareliable and low-latency communications [URLLC]). Although redundant transmission can improve communication reliability, it also increases network costs (e.g., traffic and control overhead). In this study, we propose a reliability-guaranteed multipath allocation algorithm (RG-MAA) that allocates appropriate paths by considering the path setup time and dynamicity of the reliability paths. We develop an optimization problem using a constrained Markov decision process (CMDP) to minimize network costs while ensuring the required communication reliability. The evaluation results show that RG-MAA can reduce network costs by up to 30% compared with the scheme that uses all possible paths while ensuring the required communication reliability.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.4
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• pp.266-271
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• 2007

In mobile channel environments, the effect of the multi-path fading reduces the performance of the mobile communication severely. Previous studies on the effect of the multi-path fading show that, only the channel between fixed base stations and mobile terminals are considered. However, the future mobile communication service such as telematics may use the communication between moving mobile terminals, so called mobile ad-hoc communication, the studies on the channel is required for such situations. In this paper we have measured the mobile channel and analyzed the fading characteristics when using the linear array antennas. In the data measurements, we sent the QPSK modulated signal with carrier frequency of 2GHz band and received the signal using the array antennas equipped on moving vehicles. We have analyzed the fading characteristics and the effects of the fading reduction using the CDF of fading depth using data collected from two moving vehicles. The simulation results show that the beamforming technique adds 6 or 7dB to the fading margin than that of the selection diversity depending on channel environments.

• Asia-Pacific Journal of Business
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• v.3 no.1
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• pp.10-16
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• 2012

India is having a high growth rate of Mobile subscribers which has opened up a new marketing channel of communication with customers. There is a need to study the factors affecting Mobile user's attitude towards Mobile marketing and the relationship between these factors. To study the mobile users attitude towards mobile marketing 489 mobile users opinion is taken on 12 statements for a period of 5 months. Using factor analysis method these 12 statements are grouped into 5 groups they are Mobile advertisement, Mobile Usability, Mobile Promotions, Mobiles shopping and Mobile Marketing. Confirmatory Factor Analysis (CFA) was performed to confirm the findings. SPSS Statistics 17.0 is used to conduct factor analysis and the validity of the model. Once the model was validated, SPSS Amos 18.0 was used to fit a model based on Structure Equation Model to analyze the factors affecting Mobile user's attitude and the relationship between these factors. The present study revealed that Mobile Advertisement and Mobile Sales Promotion are having positive effect on Mobile Marketing where as Mobile Shopping and Mobile Phone Usability is having negative effect on Mobile Marketing. The impact of indicators like Mobile Phone user's permission and personalization of Mobile Phone communication on Mobile Marketing are also discussed in this article.

• The KIPS Transactions:PartC
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• v.11C no.5
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• pp.613-620
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• 2004

Traditionally, simulation method was used to test and evaluate the performance of communication protocol or functional elements for mobile communication service. In this Paper, PCSsim(Personal Communication System Simulator) was realized that can evaluate and review the call process of mobile communication service or to predict its performance by using the object-oriented simulation platform. PCSsim can simulate the base station and mobile host by considering the user's mobility, call generation rate and call duration time. In this paper, based on the simulation, presented the simulation results of hand-off generation ratio according to call generation, user's moving speed and call duration time both in residence area and commercial area, and it was confirmed that the hand-off rates in simulation and actual service environment have similar features. PCSsim can be used in adjusting the characteristics of base station fellowing the dynamic hand-off buffering or the characteristics of user's call in the design stage, and also can be used in building new mobile communication network by reflecting the characteristics of region where the base station is located and the mobility of the user.