• International journal of advanced smart convergence
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• 제7권4호
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• pp.10-18
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• 2018

For the information services supporting requests of data items from a great number of mobile clients, wireless data broadcasting is an effective way because it can accommodate any number of clients. In the wireless data broadcasting, various air indexing schemes and data scheduling schemes have been developed in order to enable the clients to access their desired data items efficiently. The broadcasting system needs a method to simulate newly designed air indexing and scheduling schemes of the system, and to evaluate the performance parameters of the schemes. In this paper, we design an expandable and efficient simulation framework for the wireless data broadcasting based on the partition of data ID space. The framework can adopt regular and irregular space partition and evaluate various performance parameters of the broadcasting system. We implement a testbed of the broadcasting system using the framework, that adopts IIP, GDI and EXP as its air indexing schemes. We simulate the system using the testbed and evaluate the performance parameters of the system. Thus, we show the efficiency and expandability of the designed and implemented framework.

• 한국인터넷방송통신학회논문지
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• 제16권6호
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• pp.153-158
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• 2016

다중홉 무선센서네트워크에서 플러딩(또는 브로드캐스팅) 전송은 경로 탐색, 주소설정, 메시지 전송과 같은 기본 작업이다. 그러나 플러딩 기법은 'Broadcasting Storm' 현상을 발생시키며, 메시지 충돌, 혼잡, 불필요한 네트워크 자원을 소모하게 된다. 따라서 이러한 단순 플러딩 기법의 단점을 보완하기 위한 다양한 Flooding 기법이 제안되었다. 이러한 플러딩 기법은 확률기반, 카운터 기반, 거리기반, 이웃 기반 기법으로 분류할 수 있다. 본 논문에서는 이러한 대표적인 플러딩 기법의 장단점을 소개하고, 컴퓨터 시뮬레이션을 통하여 단순 플러딩 기법을 포함한 각 기법의 성능과 효율성을 비교 분석하였다.

• 한국인터넷방송통신학회논문지
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• 제10권5호
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• pp.89-96
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• 2010

본 논문은 방송현장에서 TV중계차와 EFP카메라 또는 ENG카메라간의 카메라 케이블 연결이 방송프로그램 제작시 여러가지 장애물과 거리에 한계가 있어 자유로운 카메라 촬영활동에 불편을 주고 있는바, DVB-T방송에서 사용하는 무선영상 전송장치와 수신장비를 제작하여 본 연구에 응용하는 사례로, 야외는 물론 실내에서도 카메라 촬영활동이 자유스러운 "Wireless 카메라 영상전송 시스템"의 개발을 목표로 하였다. 본 연구는 연구접근이 용이한 아날로그 콤포지트 영상신호 출력을 갖는 카메라와 이 영상신호를 압축하는 MPEG-2시스템, COFDM 전송방식을 이용하는 영상전송시스템으로 제작실험하게 되었으며, 그 결과 영상 및 전송장치에 대하여 양호한 QoS값을 얻게 되었으며, 본 실험을 통해 TV방송제작 현장의 활용은 물론, 무선 CCTV 장치산업의 적용 할 수 있는 가능성을 갖게 되었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.527-530
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• 2002

The frequencies for HAPS used in fixed wireless access are allocated in the millimeter wave bands. The systems using these frequencies can have a serious impact on the radio communication qualities due to rain. In this paper, we compare the specific rain attenuation using CM(combined) raindrop size distribution with those using different sevral raindrop size distributions for the frequency bands 28/48㎓. The rain attenuations using CM raindrop size distribution for the path between the earth and HAPS platform according to the elevation angle are described.

• ETRI Journal
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• 제33권2호
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• pp.279-282
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• 2011

Coexistence analysis is extremely important in examining the possibility for spectrum sharing between orthogonal frequency-division multiplexing (OFDM)-based international mobile telecommunications (IMT)-Advanced and other wireless services. In this letter, a new closed form method is derived based on power spectral density analysis in order to analyze the coexistence of OFDM-based IMT-Advanced systems and broadcasting frequency modulation (FM) systems. The proposed method evaluates more exact interference power of IMT-Advanced systems in FM broadcasting systems than the advanced minimum coupling loss (A-MCL) method. Numerical results show that the interference power is 1.3 dB and 3 dB less than that obtained using the A-MCL method at cochannel and adjacent channel, respectively. This reduces the minimum separation distance between the two systems, which eventually saves spectrum resources.

• 정보통신설비학회논문지
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• 제11권1호
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• pp.10-15
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• 2012

Ultra wideband (UWB) technologies have been developed to exploit a new spectrum resource in substances and to realize ultra-high-speed communication, high precision geo-location, and other applications. The energy of UWB signal is extremely spread from near DC (Direct Current) to a few GHz. This means that the interference between conventional narrowband systems and UWB systems is inevitable. However, the interference effects had not previously been studied from UWB wireless systems to conventional wireless systems sharing the frequency bands such as broadcasting system. This paper experimentally evaluates the interference from two kinds of UWB sources, namely an orthogonal frequency division multiplex UWB source and an impulse radio UWB source, to a broadcasting transmission system. The S/N ratio degradation of broadcasting system is presented. From these experimental results, we show that in all practical cases UWB system can be coexisted 35m distance in-band broadcasting network.

• Journal of electromagnetic engineering and science
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• 제6권1호
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• pp.76-81
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• 2006

Ultra wideband(UWB) technologies have been developed to exploit a new spectrum resource in substances and to realize ultra-high-speed communication, high precision geo-location, and other applications. The energy of UWB signal is extremely spread from near DC to a few GHz. This means that the interference between conventional narrowband systems and UWB systems is inevitable. However, the interference effects had not previously been studied from UWB wireless systems to conventional wireless systems sharing the frequency bands such as Broadcasting system. This paper experimentally evaluates the interference from two kinds of UWB sources, namely a orthogonal frequency division Multiplex UWB source and an impulse radio UWB source, to a Broadcasting transmission system. The receive power degradations of broadcasting system are presented. From these experimental results, we show that in all practical cases UWB system can coexist 35 m distance in-band broadcasting network.

• International Journal of Advanced Culture Technology
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• 제11권2호
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• pp.315-322
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• 2023

Intelligent IoT environments that accommodate a very large number of clients require technologies that provide secure information service regardless of the number of clients. Wireless data broadcast is an information service technique that ensures scalability to deliver data to all clients simultaneously regardless of the number of clients. In wireless data broadcasting, clients access the wireless channel linearly to explore the data, so the access time of clients is greatly affected by the broadcast cycle. Data compression-based data broadcasting can reduce the broadcast cycle and thus reduce client access time. Therefore, a simulation framework that can evaluate the performance of data broadcasting by applying different data compression algorithms is essential and important. In this paper, we propose a simulation framework to evaluate the performance of data broadcasting that can adopt data compression. We design the framework that enables to apply different data compression algorithms according to the data characteristics. In addition to evaluating the performance according to the data, the proposed framework can also evaluate the performance according to the data scheduling technique and the kind of queries the client wants to process. We implement the proposed framework and evaluate the performance of data broadcasting using the framework applying data compression algorithms to demonstrate the performances of data compression broadcasting.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1335-1338
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• 2002

This paper presents the analysis of the required limit on a multibeam active phased array antenna (APAA) aperture using the statistical simulation for a High Altitude Platform Station (HAPS). The simulation takes into account the random errors caused by the non-identity of the array elements and the inaccuracy of the antenna calibration. The results of our statistical simulation show that the strict requirements on the sidelobe envelope for HAPSs can be met when the amplitude and phase distribution errors are minor, a condition which may be achieved by using digital beam forming.

• 한국정보통신학회논문지
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• 제5권4호
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• pp.716-722
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• 2001

본 논문은 3세대 및 그 이상의 무선망에 대한 기본적인 망의 구조를 IP를 바탕으로한 무선망으로 정의하고 이때 무선 접속망에서의 폭주제어 방법을 제안한다. 기본적으로 제안하는 방법은 ECN(Explicit Congestion Notification)을 바탕으로 하나 무선망과 IP망의 Broadcasting에서의 장점을 이용하여 ECN Broadcasting을 무선 서브망에서 수행하도록 하여 미래의 무선망에서의 이동성 지원으로 인한 폭주제어에 있어서 효율성을 갖도록 하였다.