• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.628-643
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• 2014

The idea to conduct this study stemmed from the following question: What is the appropriate interpretation of the recent change in the user behavior of radio listeners? For some terrestrial radio programs, traditional listeners who mainly listen to them real-time through terrestrial radio broadcasting has been outnumbered by those who access them on smartphones and other mobile devices in a nonlinear way outside the pre-scheduled time slots of the programs. In the research, how terrestrial radio listeners use the new service called podcasting to access and consume audio content were examined by using Q methodology. As a result, three different types of user behavior and perception were modeled. This shows a prominent change in radio content use, which is moving away from the conventional user behavior pattern of radio content, one of the key media for mass communication in the 20th century. Such a development opens up new opportunities to create the same or even a greater user base compared to the existing one for terrestrial radio programs with the users' newly gained mobile access and to replace current radio content by using podcasting as a new service.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.88-88
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• 2004

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.4
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• pp.462-472
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• 1998

In this paper, considering the Rayleigh fading, the lognormal shadowing, and the man-made noise which is occurred in urban area randomly, the mobile radio channel and the radio propagations are analyzed. The system affected by the noise is compared to other modelings. The fading, shadowing, and background noise are wholly considered to evaluate the mobile radio propagation effectively. For N=0.000001, the outage probability in the absence of noise is $5.264{times}10^{-6}$, in the fading only $3.1796{times}10^{-4}$, and in the presence of noise $6.0{\times}10^{-3}$. The analysis with the presence of noise is very important for the performance evaluation of mobile radio system.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.3
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• pp.321-329
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• 1999

An efficient location management for mobile stations plays an important role in mobile communication network. This paper studies a movement-based registration(MBR) method with a selective paging scheme. In the movement-based registration method, a mobile station performs a location registration when the number of cell boundary crossings since the last registration equals to the given movement threshold. In the selective paging scheme, the network first partitions the location area of the called mobile station into a number of subareas and then pages each subarea one after another until the MS is found. To reduce the paging and registration load, we propose a modified MBR(MMBR) method in the aspect of minimization of signaling traffic on radio channels. First, we propose a new establishment of the paging area to reduce the paging load on radio channels and then analyze its effects. Next, we propose the MMBR to reduce the registration load. Numerical results show that our proposed movement-based registration provides the better performance compared with the conventional method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.8
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• pp.679-689
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• 2015

The 5G mobile communication technologies have been extensively developed with the era of mobile broadband, but spectrum policy for this service has not yet set up. In this paper, We have investigated the 5G mobile service and analyzed the 5G spectrum policy taking the developing technologies into account. Based on the results of these analyses, We propose an expansion of spectrum sharing in the 3~5 GHz bands, spectrum harmonization of 5 GHz bands, and restructuring of spectrum management administration from currently three distributed management to centralized spectrum management structure.

• ETRI Journal
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• v.19 no.3
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• pp.116-140
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• 1997

The base station transceiver subsystem (BTS) of the CDMA Mobile System is interfaced to mobile stations over the air and to the wired network through a packet switched interconnection network. The potential benefits of CDMA technology are achieved when the transmitter and the receiver are properly designed and implemented. The physical layer of the interface at the base station is implemented with the CDMA ASICs and control circuits in channel card of the BTS. We present the design perspectives and structural illustration of the BTS. Base station modem ASICs and their control to implement the CDMA receiver, Baseband and RF signal processing blocks, and BTS controller are described. Elaborate power control is essential to ensure the high capacity which is one of advantages of the CDMA technology. The closed loop reverse link power control and the forward link power control operated in the BTS are described.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3775-3788
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• 2014

With the increasing number of the wireless and mobile networks, the way that people use the Internet has changed substantively. Wireless multimedia services, such as wireless video streaming, mobile video game, and mobile voice over IP, will become the main applications of the future wireless Internet. To accommodate the growing volume of wireless data traffic and multimedia services, cognitive radio (CR) and Information-Centric Network (ICN) have been proposed to maximize the utilization of wireless spectrum and improve the network performance. Although CR and ICN have high potential significance for the future wireless Internet, few studies have been conducted on collaborative operations of CR and ICN. Due to the lack of infrastructure support in multi-hop ad hoc CR networks, the problem is more challenging for video streaming services. In this paper, we propose a Cross-layer Video Streaming Mechanism (CLISM) for Cognitive Radio Ad Hoc Information Centric Networks (CRAH-ICNs). The CLISM included two distributed schemes which are designed for the forwarding nodes and receiving nodes in CRAH-ICNs. With the cross-layer approach, the CLISM is able to self-adapt the variation of the link conditions without the central network controller. Experimental results demonstrate that the proposed CLISM efficiently adjust video transmission policy under various network conditions.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.3
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• pp.62-72
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• 2010

As the applications for Mobile Ad-hoc NETworks (MANETs) have varied, performance analysis has become one of the main research areas. They commonly offer only simple radio propagation models that neglect obstacles of a propagation environment. The radio wave propagation model has a strong impact on the results of the simulation run. In this paper we present the new experimental results of the impacts of the various propagation models on MANETs' performance. Intensive simulations have been presented using the group mobility which models typical ad-hoc situations such as military movements or disaster recovery activities under the supervision of a group leader. Comparisons of conventional simple models with more complicated models, i.e., shadowing, Raleigh, and Ricean models, show that, in spite of the models' popularity, the free space and two-ray ground models are too optimistic in describing real ad-hoc group mobility situations.

• Journal of Korea Multimedia Society
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• v.16 no.7
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• pp.862-869
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• 2013

In order to support a cell-independent traffic asymmetry, the conventional TDD system cannot avoid crossed time slot (CTS) interference. Moreover, the TDD/FDD hierarchical overlay cellular systems is taken into account as a generally accepted cell model in a heterogeneous radio environment. In this paper, we propose an interference resolving radio resource allocation technique in a TDD-OFDMA cellular system that overlays a FDD-CDMA cell. In our proposed scheme, we exploit under-used FDD-CDMA uplink resource by TDD mobile abiding by a region based time slot(TS) allocation which in turn mitigates CTS interference considerably. It is demonstrated that combined with under-used resource utilization scheme based on mobile's location, the proposed technique can reduce CTS interference considerably and support the asymmetric traffic in TDD system.

• ETRI Journal
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• v.30 no.5
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• pp.634-643
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• 2008

One of the ubiquitous technology fields that have received the most attention recently from technology communities worldwide is mobile radio frequency identification (RFID). Mobile handsets loaded with RFID readers enable the identification and retrieval of information on RFID tagged objects. In Korea, a variety of mobile RFID services are currently being piloted, and their commercial roll-out looks imminent. The goal of this study is to propose, ahead of the commercial launch of mobile RFID services, a customer satisfaction index (CSI) model for this service category and to then measure the CSI to derive practical implications for their providers and pointers related to the improvement of service. A web survey was conducted on Korean mobile phone subscribers who had participated in a mobile RFID pilot program. Using the results of this survey, we tested the CSI model and its hypotheses by employing a partial least-squares-based structural equation model analysis and calculated the index. We further conducted an importance-performance analysis in order to provide insights that may be useful for improving the quality of mobile RFID services.