• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.490-490
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• 2006

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.326-326
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• 2006

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.269-269
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• 2006

• Information and Communications Magazine
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• v.26 no.12
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• pp.41-49
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• 2009

3GPP LTE/LTE-A and IEEE 802.16m have recently been submitted to ITU as IMT-Advanced candidates. MIMO is one of the core technologies that enable both standards to achieve the tough requirements specified by ITU. This paper provides an introduction to the core downlink MIMO features of both standards.

• Electronics and Telecommunications Trends
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• v.27 no.2
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• pp.31-40
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• 2012

광대역 통신 기술은 일반 사용자를 대상으로 고속의 데이터 전송 및 고품질의 음성통화와 영상통화 등을 포함하는 멀티미디어 서비스 제공을 위해 발전 중이다. 나아가 국민의 안전과 생명보호를 위한 공공안전 및 재난구조(PPDR, Public Protection and Disaster Relief)를 위한 범국가적 통신망과 원격 감시, 측정, 보고 및 제어 등을 위한 스마트그리드(smart grid) 및 M2M(Machine-to-Machine) 통신을 위한 광대역 통신망 구축이 기대된다. 본고에서는 공공안전 및 재난구조 통신과 M2M 통신 응용을 지원하는 광대역 무선접속 표준화 동향과 기술 개념을 살펴보고자 한다.

• Information and Communications Magazine
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• v.24 no.5
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• pp.7-14
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• 2007

Mobile WiMAX의 도입으로 광대역 무선 이동통신 시스템에 대한 관심이 커지고 있는 상황이다. 이러한 Mobile WiMAX 시스템의 커버리지 확대등을 통한 시스템의 도입의 활성화등을 목적으로 IEEE802.16에서는 Relay Task Group을 만들어 모바일 와이맥스의 릴레이 확장을 도모하고 있다. 본 고에서는 Relay Task Group의 생성 및 현재까지의 논의되어서 포함된 PHY및 MAC 계층에서의 기술내용과 표준화 현황에 대해서 상세히 살펴보고자 한다.

• The KIPS Transactions:PartC
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• v.16C no.5
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• pp.661-668
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• 2009

The Extended real-time Polling Service (ErtPS) is proposed tosupport QoS of VoIP service with silence suppression which generates variable size data packets in IEEE 802.16e systems. If the silence is suppressed, VoIP should support Comfort Noise Generation (CNG) which generates comfort noise for receiver's auditory sense to notify the status of connection to the user. CNG mode in silent-period generates a data with lower bit rate at long packet transmission intervals in comparison with talk-spurt. Therefore, if the ErtPS, which is designed to support service flows that generate data packets on a periodic basis, is applied to silent-period, resources of the uplink are used inefficiently. In this paper, we proposed the Improved ErtPS algorithm for efficient resource utilization of the silent-period in VoIP traffic supporting CNG. In the proposed algorithm, the base station allocates bandwidth depending on the status of voice at the appropriate interval by havingthe user inform the changes of voice status. The Improved ErtPS utilizes the Cannel Quality Information Channel (CQICH) which is an uplink subchannel for delivering quality information of channel to the base station on a periodic basis in 802.16e systems. We evaluated the performance of proposed algorithm using OPNET simulator. We validated that proposed algorithm improves the bandwidth utilization of the uplink and packet transmission latency

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.255-263
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• 2012

In this paper, the performance evaluation results of the timing synchronization schemes are presented for aeronautical mobile airport communication systems (AeroMACS). AeroMACS, which is based on IEEE 802.16e mobile WiMAX standard, uses the aeronautical frequency band of 5GHz with the bandwidth of 5MHz. The simulation model of AeroMACS is constructed and the evaluation for the timing synchronization performance is performed with the various channel models such as apron (APR), runway (RWY), taxiway (TWY), and park (PRK).

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.1-9
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• 2008

This paper presents transmission parameters of DH(Dog-Horse) systems based on IEEE802.16e(WiBro) systems. DH requires higher uplink multimedia data rate, which is different from commercial WiBro systems. This paper designes some transmission parameters satisfying the DH system requirements and demonstrates link performance evaluation based on the parameters. For the transmission parameters, the number dwon/up link OFDM symbols are determined by 6/30, respectively. For reliable transmission of control signals, downlink modulation and coding rate are selected by QPSK, 1/2 coding rate and that of uplink is chosen by 16QAM 1/2 and 3/4 coding rate. Based on these parameters, computer simulations demonstrate the system performance of DH system.

• The Journal of the Korea Contents Association
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• v.16 no.10
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• pp.299-310
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• 2016

In this paper, we perform analysis of the performance of low-power communication technology, IEEE 802.15.4 MAC (Media Access Control) protocol used in internet of things. Wide variety of devices in internet of things generate different kinds of traffic characteristics and heterogeneous traffic environment is therefore considered in contrast to existing works. With the help of the Markov chain the performance of the protocol is derived as a function of the MAC parameters and based on the results a framework to determine energy-efficient optimal MAC parameters for applications in real time is proposed. Proposed method is shown to be more efficient in terms of energy consumption through performance comparison over application scenarios compared to operation with fixing MAC parameters, and its practicability on small devices with limited computing power is verified through evaluating the accuracy and speed of the proposed framework.