• The Journal of Korean Association of Computer Education
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• v.5 no.3
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• pp.19-25
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• 2002

Bluetooth, in radio network environment, is a small local radio communication that is available with low expense and little power use. It is specified for the wireless connect in a small area between Network Excess Point, portable devices such as mobile phones. PDAs and portable PCs, and other per peripheral equipment. Bluetooth is consisted of a master and a piconet having seven slaves in a maximum and finally has a scatternet gathering lot of piconet. The thesis tries to design the most effective structure of a scatternet by the number of nodes and the type of scatternet such as linear and ring for its mechanism. then the performance evaluation is realized through the Bluehoc simulator based on the NS. Finally the most appropriate radio network environment is made by the comparison and analysis of the characteristics of liner and ring scatternets.

• Journal of the Korean Society for Railway
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• v.9 no.3 s.34
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• pp.257-263
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• 2006

This paper presents an optimization approach to the configuration of train radio communication network for CBTC. The target specifications of CBTC communication systems are derived from technical requirements for CBTC. The proposed communication system has a ring-topology backbone communication network between stations and a radio network based on IEEE 802.11b wireless tan between trains and wayside devices. The proposed method has been applied to the standardization of the signalling system of urban transits.

• Journal of KIISE:Information Networking
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• v.27 no.1
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• pp.22-29
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• 2000

In this paper, we analyzed the performance of EY-NPMA(Elimination Yield-Non-preemptive Priority Multiple Access) protocol-channel access control protocol of HIPERLAN(HIgh PErformance Radio Local Area Network) type 1 specification, adopted as european high speed wireless LAN standard by ETSI(European Telecommunication Standards Institute). We established a system model for EY-NPMA protocol analysis, analyzed success probability in a channel access cycle, and derived expressions for the average length of contention phase. Using a M/G/1 model, we approximated the normalized delay, and throughput, and we evaluated these results by simulations.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.120-123
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• 2005

본 논문에서는 무선 홈 네트워크에 사용될 홈 내 무선 LAN(Local Area Network)용 안테나에 대해 연구하였다. 홈 내의 천장 부근에 안테나를 설치할 경우, 전파의 외부 노출을 피하고 최소한의 전력이 각 홈 별로 공급되어야하며, 각 홈 내에서의 전파를 홈 내 위치마다 균등하게 분배되어야 한다. 이를 위하여 모노폴 안테나와 다이폴 안테나 및 마이크로스트립 패치 안테나를 무선랜 주파수 2.4GHz를 중심으로 설계 제작하여 그 특성들을 고찰하였다. 그 결과 브로드사이드 방향으로 최대 또는 null 지점 발생, 좁은 빔폭 등 무선랜용 안테나로 사용하기 적합하지 않았다. 따라서, 구조적 변형 등을 통한 방사 빔의 개선 연구가 필요하다.

• ETRI Journal
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• v.32 no.3
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• pp.475-478
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• 2010

A multiband meandered monopole antenna is proposed for digital video broadcasting handheld (DVB-H), global positioning system, personal communications service, wireless broadband (Wibro), and wireless local area network (WLAN) applications. The proposed antenna consists of a meandered line, a shorted length strip line, and a conductor strip between a meandered line and a microstrip feed line. By tuning a short strip and a conductor, a multiband impedance matching is achieved. The proposed antenna has an omnidirectional radiation and yields an antenna gain of greater than -3 dBi in the DVB-H band and 4.5 dBi in the Wibro and WLAN bands. Details of the proposed antenna design and experimental results are presented.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.286-289
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• 2006

Measurement results are presented for the effects of people moving near and across short-range indoor propagation links at 2.45 GHz (ISM band). Excess loss due to scattering and blockage by human bodies in the vicinity of one terminal were measured for different radio links in an office environment. Statistics on fades due to human body motion are given. Polarization coupling (depolarization) for various radio links was measured, and correlation of polarization components is discussed as a basis for using polarization diversity reception in short-range indoor systems.

• Journal of Broadcast Engineering
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• v.19 no.1
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• pp.14-23
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• 2014

This paper proposed controlling methods for SDN(Software Defined Network) based multiple radio access technology as the solutions of following two issues which were mainly occurred by explosive increasing of video traffic. The first one is a requirement for traffic off-loading caused by 3rd-party video service providers from the mobile network operator's viewpoint. The other one is a provision of high-speed video contents transmission services with low price. Furthermore, the performance evaluation was also conducted on the real test-bed which is composed of OpenStack cloud and SDN technology such as OpenFlow and Open vSwitch. A virtual machine running on the OpenStack provide a video service and the terminal which is able to use multiple radio access technology supports two 2.4GHz WLANs(Wireless Local Area Network) and three 5GHz WLANs, concurrently. Finally, we can get 820Mbps of the maximum transmission speed by using that five WLAN links for the single service at the same time.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.4
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• pp.323-332
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• 2009

In this paper, we introduce a modified short-circuited stub bandpass filter suitable for ultra-wideband(UWB) applications utilizing low temperature co-fired ceramic(LTCC) technology. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate($\varepsilon_r$ = 40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825 GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter has been measured with an insertion loss less than 1.0 dB and return loss better than 10 dB in the pass bands. A bandwidth ratio of 109.49 % has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are $4{\times}8{\times}0.57\;mm^3$.

• Electronics and Telecommunications Trends
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• v.6 no.3
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• pp.148-174
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• 1991

본 고에서는 고도 정보 사회의 발달에 따라 업무의 신속성, 사용의 편리성, 설치의 융통성 그리고 사용자의 이동성 등의 필요에 의해 급격한 수요 증가가 예상되는 무선 데이터 통신 서비스의 현황에 대해 개괄적으로 정리하였다. 무선 데이터 통신 서비스 분야로는 패킷무선(packet radio), trunked 시스팀, 셀룰러(cellular) 시스팀 그리고 무선 LAN(Local Area Network) 등을 중심으로 하였으며, 미국, 일본 그리고 유럽을 검토 대상국가로 하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.1077-1093
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• 2013

This paper proposes a new network coordinator node design to select the most suitable wireless technology for WBANs by using fuzzy logic. Its goal is to select a wireless communication technology available considering the user/application requirements and network conditions. A WBAN is composed of a set of sensors placed in, on, or around human body, which monitors the human body functions and the surrounding environment. In an effort to send sensor readings from human body to medical center or a station, a WBAN needs to stay connected to a local or a wide area network by using various wireless communication technologies. Nowadays, several wireless networking technologies may be utilized in WLANs and/or WANs each of which is capable of sending WBAN sensor readings to the desired destination. Therefore, choosing the best serving wireless communications technology has critical importance to provide quality of service support and cost efficient connections for WBAN users. In this work, we have developed, modeled, and simulated some networking scenarios utilizing our fuzzy logic-based NCN by using OPNET and MATLAB. Besides, we have compared our proposed fuzzy logic based algorithm with widely used RSSI-based AP selection algorithm. The results obtained from the simulations show that the proposed approach provides appropriate outcomes for both the WBAN users and the overall network.