• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.51-56
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• 2014

TETRA(TErrestrial Trunked RAdio) provide specialized disaster radio communication services as a standard European for digital TRS(Trunked Radio System). Especially, DMO(Direct Mode Operation) feature is used effectively in the radio shadow areas which base station does not propagate radio signal because it can communicate directly with terminal to terminal without base station's relay function. However, to effectively used DMO feature, radio coverage prediction information should be provided to users. Therefore in this paper, we were calculated link budget of TETRA DMO terminals which were distributing and operating in the country and then predicted reaching distance about radio propagation to be applied with path loss model.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.122-137
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• 2007

In this paper, compatibility between different radio services or systems is analyzed when they are in adjacent band or co-channel. The first step of the compatibility analysis is establishing an interference scenario. And an interference pobability from an interfering transmitter to a victim receiver is calculated by means of Monte-Carlo simulation techniques. Then the calculated result is compared with the predefined interference criteria, maximum permissible interference probability and we can determine compatibility in accordance with the active interferer density, channel bandwidth, cell radius, distance between interfering transmitter and victim receiver, and duty cycle. It is assumed that Propagation modes are the free space model and extened Hata model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.754-756
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• 2005

RFID(Radio Frequency Identification) is used to describe a system that transmits the identity of an object or person wirelessly using radio waves. RFID is recognized as a key technology of USN(Ubiquitous Sensor Network). ISO/IEC JTC1 and EPCglobal are developing RFID related standards for global supply chain management. RFID is an important solution not only for the supply chain management, but also for USN and future services. Recently, mobile RFID which provide various services using RFID reader in mobile phone, is being standardized in Korea. In this paper, we analyze trends of RFID standardization activities in ISO/IEC JTC1 and EPCglobal and mobile RFID, and propose an convergence scenario of IPv6 and RFID.

• International Journal of Computer Science & Network Security
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• v.23 no.12
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• pp.13-26
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• 2023

Recently, the development of wireless network technologies has been advancing in several directions: increasing data transmission speed, enhancing user mobility, expanding the range of services offered, improving the utilization of the radio frequency spectrum, and enhancing the intelligence of network and subscriber equipment. In this research, a series of contradictions has emerged in the field of wireless network technologies, with the most acute being the contradiction between the growing demand for wireless communication services (on operational frequencies) and natural limitations of frequency resources, in addition to the contradiction between the expansions of the spectrum of services offered by wireless networks, increased quality requirements, and the use of traditional (outdated) management technologies. One effective method for resolving these contradictions is the application of artificial intelligence elements in wireless telecommunication systems. Thus, the development of technologies for building intelligent (cognitive) radio and cognitive wireless networks is a technological imperative of our time. The functions of artificial intelligence in prospective wireless systems and networks can be implemented in various ways. One of the modern approaches to implementing artificial intelligence functions in cognitive wireless network systems is the application of fuzzy logic and fuzzy processors. In this regard, the work focused on exploring the application of fuzzy logic in prospective cognitive wireless systems is considered relevant.

• 한국ITS학회:학술대회논문집
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• v.2007 no.10
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• pp.289-296
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• 2007

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.256-259
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• 2007

Multicast and Broadcast Service (MBS) provides flexible and efficient transmission of the same information to multiple users using shared radio resources on WiBro network. The advantage of this service is to achieve the most efficient use of radio and network resources as well as to lessen sender's processing load when sending the same information to multiple users. Though radio resources are saved since a multicast or broadcast transport connection is associated with a service flow, it is hard to change MBS service channel dynamically. In this paper, we propose a Radio Resource Management System (RRMS) for supporting dynamic scheduling of MBS service channels. Results show that our proposed scheme using Radio Resource Allocation Table (RRAT) can efficiently support MBS services by providing dynamic schedule for MBS service channels.

• ETRI Journal
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• v.28 no.5
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• pp.652-655
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• 2006

In this letter, we introduce a new middleware architecture and its generic application programming interface (API) (called the T-DMB MATE API) for terrestrial digital multimedia broadcasting (T-DMB). Middleware in T-DMB enables inter-operable applications to be downloaded from both broadcast and telecommunication networks in advance and to be executed in any type of T-DMB receiver. The middleware we introduce here is especially designed to support a proposed method for application provisions applied to a concept of application module appropriate to the service environment of T-DMB. We also verify the designed T-DMB MATE API through the implementation of the middleware and its application in a PC-based receiver.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1229-1234
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• 2010

High quality and high speed multimedia services will be required in the next generation mobile communications. To satisfy these services, powerful error correction techniques are used. ARQ(Auto Repeat Request) techniques, aspects of the throughput, and FEC(Forward Error Correct) techniques have disadvantages in terms of reliability. H-ARQ(Hybrid Auto Repeat Request) systems have been studied extensively as a solution of these disadvantages. In this paper introduce double layer coding and H-ARQ type, proposed H-ARQ system using double layer coding methods. Simulate BER performance and throughput. And we suggest that according to channel condition suitable H-ARQ type.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.7
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• pp.2668-2717
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• 2021

Demands for high-speed wireless data services grow rapidly. It is a big challenge to increasing the network capacity operating on licensed spectrum resources. Unlicensed spectrum cellular networks have been proposed as a solution in response to severe spectrum shortage. Licensed Assisted Access (LAA) was standardized by 3GPP, aiming to deliver data services through unlicensed 5 GHz spectrum. Furthermore, the 3GPP proposed 5G New Radio-Unlicensed (NR-U) study item. On the other hand, artificial intelligence (AI) has attracted enormous attention to implement 5G and beyond systems, which is known as Intelligent Radio (IR). To tackle the challenges of unlicensed spectrum networks in 4G/5G/B5G systems, a lot of works have been done, focusing on using Machine Learning (ML) to support resource allocation in LTE-LAA/NR-U and Wi-Fi coexistence environments. Generally speaking, ML techniques are used in IR based on statistical models established for solving specific optimization problems. In this paper, we aim to conduct a comprehensive survey on the recent research efforts related to unlicensed cellular networks and IR technologies, which work jointly to implement 5G and beyond wireless networks. Furthermore, we introduce a positioning assisted LTE-LAA system based on the difference in received signal strength (DRSS) to allocate resources among UEs. We will also discuss some open issues and challenges for future research on the IR applications in unlicensed cellular networks.

• ETRI Journal
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• v.19 no.3
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• pp.202-227
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• 1997

This paper describes the development of the CDMA mobile station to support non-speech, mobile office services such as data, fax, and short message service in addition to voice. We developed some important functions of layer 2 and layer 3. To provide non-speech services, we developed a terminal adapter and user interface software. The description of development process, software architecture and external interfaces required to provide such services is given. The description of a TTA-62 message analysis tool, a mobile station monitoring software, and an automatic test system developed for integration tests and performance measurements is also given.