• 한국멀티미디어학회논문지
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• 제21권3호
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• pp.415-422
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• 2018

Advances of telecommunication technology bring various changes in journalism field. Reporters started to gather, edit, and transmit content to main server in media company using hand-held smart media and notebook computer. This paper tried to testify valid bit-rate of visual news content using LTE network and mobile phone. Field news like natural disasters need real-time transmission of video content. But broadcasting company normally use heavy ENG system and transmission satellite trucks. We prepared and experimented different types of visual content that has different bit-rates. Transmission tool was LU-60HD mobile system of LiveU Corporation. Transmission result shows that bit-rate of 2Mbps news content is not suitable for broadcasting and VBR (Variable Bit Rate) transmission has better definition quality than CBR (Constant Bit Rate) method. Three different bit-rate of VBR transmission result shows that 5Mbps clip has better quality than 1Mbps and 3Mbps. The higher bit-rate, the better video quality. But if the content has much movements, that cause delay and abnormal quality of video. So optimizing the balance between stability of signal and quality of bit-rate is crucial factor of real-time broadcasting news gathering business.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1355-1359
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• 2004

The two way subscriber transmission systems have tendency to spread its carrier frequency bandwidth or information bit rate and average bit error rate according to popularization of high speed information through the digital communication system, transmission medium and the Internet. This fact is an important incentive to realize new systems. These two way subscriber transmission systems usually use same cable or same carrier frequency bandwidth for up stream channel and down stream channel. In the systems, the disturbances of noise, crosstalk or fading affect the characteristics. Specifically, these disturbances cause the decrease of information bit rate and degradation of transmission quality. This paper proposes the improved method of their degradations using the particular feature of two way subscriber transmission systems and it makes clear proposed method is effective by theoretically and some numerical examples.

• International Journal of Advanced Culture Technology
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• 제6권4호
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• pp.266-274
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• 2018

Securing field screens through LTE broadcasting is a very valuable technology in news production because of its locality and concurrency. TV has the advantage of being able to deliver news faster than newspapers and make live coverage on the scene of events and events. To maximize this, not only middle-end broadcasters but also existing broadcasting stations are taking an active role in broadcasting using LTE. However LTE broadcasting has yet to secure any conflicting values of broadcasting stability and securing high-definition. The key to solving this difficulty is the transmission rate of Bit Rate. This paper compares the Bit Rate transmission method, which is variable and fixed, to provide more on-site screens through LTE, and presents the Bit Rate adjustment method as a method of screen stabilization through experiment. Consequently, the most stable broadcast screen can be obtained when transmitting and connecting it to broadcasting in a variable 5M method.

• Journal of Communications and Networks
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• 제10권1호
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• pp.79-88
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• 2008

In this paper, we propose efficient peer assignment algorithms for low-latency transmission of scalable coded images in peer-to-peer networks, in which peers may dynamically join and leave the networks. The objective of our algorithm is to minimize the transmission time of a requested image that is scalable coded. When an image is scalable coded in different bit rates, the bit stream encoded in a lower bit rate is a prefix subset of the one encoded in a higher bit rate. Therefore, a peer with the same requested image coded in any bit rate, even when it is different from the requested rate, may work as a supplying peer. As a result, when a scalable coded image is requested, more supplying peers can be found in peer-to-peer networks to help with the transfer. However, the set of supplying peers is not static during transmission, as the peers in this set may leave the network or finish their transmission at different times. The proposed peer assignment algorithms have taken into account the above constraints. In this paper, we first prove the existence of an optimal peer assignment solution for a simple identity permutation function, and then formulate peer assignment with this identity permutation as a mixed-integer programming problem. Next, we discuss how to address the problem of dynamic peer departures during image transmission. Finally, we carry out experiments to evaluate the performance of proposed peer assignment algorithms.

• 한국통신학회논문지
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• 제25권6B호
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• pp.1002-1011
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• 2000

본 논문에서는 $2{\times}2$ DCT(Discrete Cosine Transform)와 임베디드 제로 트리(Embedded Zero Tree)를 이용한 공간(Spatial) 및 비트율(bit-rate) 계위(scalability)를 갖는 순차 영상 전송 기법을 제안한다. 제안된 방법은 영상의 다해상도 표현을 위해 $2{\times}2$ DCT를 사용하여 고차 웨이브렛 필터에 비해 계산량이 많이 감소하여 실시간 응용에 적합하도록 하였으며, 공간과 비트율 계위를 동시에 가지도록 하여 수신자의 계위 요구에 적응적으로 대응하도록 하였다. 실험 결과 고차 웨이브렛 필터를 이용한 순차 영상 전송과 비교하여 계산량의 상당한 감소에도 불구하고 화질의 차이는 거의 인식할 수 없었다.

• Journal of Communications and Networks
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• 제7권4호
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• pp.462-470
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• 2005

We propose a multi-rate and multi-BEP transmission scheme using adaptive overlapping pulse-position modulator (OPPM) and optical power controller in optical code division multiple access (CDMA) networks. The proposed system achieves the multi-rate and multi-BEP transmission by accommodating users with different values of OPPM parameter and transmitted power in the same network. The proposed scheme has advantages that the system is not required to change the code length and number of weight depending on the required bit rate of a user and the difference of bit rates does not have so much effect on the bit error probabilities (BEPs). Moreover, the difference of transmitted powers does not cause the change of bit rate. We analyze the BEPs of the four multimedia service classes corresponding to the com­binations of high/low-rates and low/high-BEPs and show that the proposed scheme can easily achieve distinct differentiation of the service classes with the simple system configuration.

• 디지털콘텐츠학회 논문지
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• 제13권1호
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• pp.111-118
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• 2012

버스트는 가변 비트율로 저장된 비디오 데이터를 전송하려는 경우 급격하게 높은 전송률이 요구되는 것으로 네트워크 자원의 비효율적인 사용의 원인이 될 수 있다. 스무딩은 이를 방지하기 위해 가변 비트율로 저장된 비디오 데이터를 고정 비트율로 변환하는 전송 계획을 세우는 기법으로, CBA, MCBA, MVBA 알고리즘들이 있다. 본 논문에서는 기존 CBA, MCBA, MVBA 알고리즘들의 버스트 감소 정도를 평가하기 위해, 가변 비트율로 저장된 비디오 소스와 스무딩 알고리즘에서의 전송 계획을 버스트에 영향을 미치는 요소들로 비교한다. 사용된 평가 요소는 최대 프레임 바이트 수, 최대 GOP 바이트 수, 프레임당 전송률 변화량, GOP당 전송률 변화량이다. 실험 결과, 실험에 사용된 모든 스무딩 알고리즘들의 버스트 관련 평가 요소들이 특정한 경우를 제외하고 원래 비디오 소스보다 낮았다.

• 한국위성정보통신학회논문지
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• 제5권1호
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• pp.6-16
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• 2010

Since OFDM system suffers from high peak-to average power ratio(PAPR) drawbacks, more energy has been converted to seek for a new substitutable system which can maintain OFDM system's inherent virtues while avoid its defects. Consequently, a new multicarrier system called as CI/OFDM system has been proposed which applied carrier interferometry(CI) code to OFDM system. Due to its low PAPR advantage and orthogonal property, it has received more and more attention. Simultaneously, an old technique called single carrier(SC) system has retaken its attractions for the same purposes. This paper analyzes two cyclic prefixed transmission schemes variants of OFDM system: 1.carrier interferometry-Orthogonal Frequency-Division Multiplexing (CI/OFDM); 2. Cyclic prefixed single carrie(CP-SC) with frequency domain equalization. We compare the achievable bit rate transmission of the two systems in terms of signal to noise ratio(SNR) by mathematical derivation. We demonstrated that CI/OFDM achieves a bit higher transmission bit rate to that of the CP-SC with frequency domain equalizer.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.2056-2059
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• 2003

The rate control is very important to solve the difficulties arising from bit-rate on transmission through channel and to improve video quality. It is very important to point out that the amount of output bit obtained the encoding process using rate controller brings many problems on the transmission of channels and furthermore output bitstream decoded affects directly on the visual quality of displayed subject. In this paper, the effective rate control algorithm by rate-distortion modeling using MPEG-4 encoder is proposed. The proposed rate control has applied different weighting by VOP prediction type and even in the same VOP prediction type, the predicted reference allocates more bit. Through these bit allocation the minimization of distortion can be achieved preventing propagation of quantization error The amount of saved bitstream obtained by the proposed algorithm in this thesis is allocated to I-VOP using region of interest(ROI) selective enhancement on the next GOV encoding process and this process brought the improvement of visual quality.

• Journal of the Optical Society of Korea
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• 제14권1호
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• pp.22-27
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• 2010

Bit error rate (BER) monitoring is the ultimate goal of performance monitoring in all digital transmission systems as well as optical fiber transmission systems. To achieve this goal, optimization of the decision threshold must also be considered because BER is dependent on the level of decision threshold. In this paper, we analyze a pseudo-error counting scheme and propose an algorithm to achieve both BER monitoring and adaptive decision threshold optimization in optical fiber transmission systems. To verify the effectiveness of the proposed algorithm, we conduct computer simulations in both Gaussian and non-Gaussian distribution cases. According to the simulation results, BER and the optimum decision threshold can be estimated with the errors of < 20% and < 10 mV, respectively, within 0.1-s processing time in > 40-Gb/s transmission systems.