• 융합신호처리학회논문지
• /
• 제2권2호
• /
• pp.20-27
• /
• 2001

입체영상의 부호화 및 전송 기술은 제한된 전송 채널에서 입체영상 정보의 전송에 필수적 인 기술로 입체영상 매체를 이용한 정보통신 서비스 분야에서 매우 중요하다. 본 논문에서는 시차정보를 이용하여 입체영상을 압축하고 MPEG-2의 스케일러빌리티 (scalability)를 이 용하여 전송하는 기법을 제안한다. 왼쪽 영상은 기본계층에, 오른쪽 영상은 고위계층에 각각 대웅하고 고위계층은 좌우영상의 시차정보와 고위계층간의 예측정보를 포함한다. 또한, 본 논문에서는 시차정보 탐색시간을 줄이기 위해 이전 입체영상 쌍으로부터 탐색한 시차정보를 이용하여 다음 입체영상 쌍의 시차정보를 예측하는 방법을 제안하고, 전송율 제어는 MPEG-2 TM6에서 제안한 방법을 사용한다. 실험 결과 제안한 탐색 방법을 사용한 경우 전체 코딩 시간이 기존의 전역 탐색 방법을 사용한 경우에 비해 현저히 단축되고 목표한 전송율에 도달됨을 알 수 있었다.

• ETRI Journal
• /
• 제28권4호
• /
• pp.513-516
• /
• 2006

Experimental demonstration of bipolar spectral encoding code-division multiple-access with modified pseudorandom noise codes is presented. Bipolar spectral encoding is achieved with an erbium-doped fiber amplifier amplified spontaneous emission source and arrayed waveguide gratings. The bit-error rate performance of 1.25 Gbps signal transmission over 80 km single mode fiber is measured in a multiple-user environment.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1999년도 추계종합학술대회 논문집
• /
• pp.287-290
• /
• 1999

In the transmitter of optical fiber transmission systems, a time-division multiplexer combines several parallel data streams into a single data stream with a high bit rate. In this paper, we design a 2:1 (2-channels) time-division multiplexer using SiGe HBT with emitter size of 2$\times$8${\mu}{\textrm}{m}$$^2$. The operation speed is 10Gbps, the rise and fall times of 20-80% are 34ps and 35ps, respectively and the dissipation of power is 0.86W.

• 대한전자공학회논문지
• /
• 제25권3호
• /
• pp.327-334
• /
• 1988

In this paper, the performance of PRA (pel recurdive algorithm) and BMA(block matching algorithm), which are the most well-known motion estimation techniques, is compared and the effects of the motion estimation accuracy on the motion compensated coding are described. Results of computer simulation on the real images indicate that the TSS (three step search), which is one of the BMA,is slightly better than the PRA in terms of the accuracy however, the required bit rate is 6.6-8.2 Kbps higher that of the PRA because the TSS requires a transmission of motion estimation vectors.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
• /
• pp.233-236
• /
• 2001

Orthogonal freqency division multiplexing (OFDM) is an attractive technique for achieving high-bit-rate wireless data transmission. However, the potentially large peak-to-average power ratio (PAPR) has limited its application; An OFDM signal with the large PAPR can cause power degradation (In-band distortion) and spectral spreading (Out-of-band distortion) by being clipped passing through a power amplifier. Thus, we propose the combining algorithm of Hadamard transform and phase shift, which is ascribed to the relation between the correlation of the IFFT input sequence function and PAPR. Extensive computer simulations show that the combining algorithm is an effective technique to reduce PAPR.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
• /
• pp.2351-2354
• /
• 2003

A new transform coder for arbitrarily shaped image segments is proposed. In the encoder, a block-based DCT is applied to the resulting image block after shifting pixels within the image segment to block border and padding the mean value of the pixels to empty region. For reducing the transmission bit rate, the transform coefficients located in padded region are truncated and only the remaining transform coefficients are transmitted to the decoder. In the decoder, the transform coefficients truncated in the encoder are recovered using received transform coefficients and a block-based inverse DCT is performed.

• 한국통신학회논문지
• /
• 제23권8호
• /
• pp.2042-2051
• /
• 1998

압축 저장된 비디오 스트림들은 사용된 압축 알고리즘의 구조와 화면의 복잡도 등에 따라 다양한 형태의 트래픽 발생 특성으로 인하여, 송신측과 수신측 사이의 자원할당을 어렵게 한다. 본 논문에서는 VoD서비스를 제공하기 위한 단일 서버와 복수개의 클라이언트들이 단일 미디어의 공동망에 연결된 환경에 효과적으로 적용될 수 있는 적응적 대역 평활화 기법을 제안한다. 이를위해 우선, 본 논문은 한 개의 비디오 스트립에 효과적인 대역 평활화 기법으로 기존에 제안된 MVBA알고리즘을 분석한다. 이를 바탕으로 복수개의 클라이언트들이 임의로 서버에게 압축 저장된 비디오 스트립을 요구할 때, 각 클라이언트의 연속적인 복호와 재생을 유지하면서 동시에 다중화된 전송률을 적응적으로 평활화하는 알고리즘올 제안한다. 모의 실험을 통하여 제안된 방식은 기존의 단일 비디오 스트립을 독립적으로 제어하는 기법에 비해, 전송률의 첨두치율, 표준편차, 전송율의 변화 횟수 등의 척도에서 뛰어난 성능 개선을 보인다.

• 한국통신학회논문지
• /
• 제21권9호
• /
• pp.2328-2340
• /
• 1996

Until now, the transmission of data for VOD(Video on Demenad) was based on a real time modelling of video data. Markow Modulated Fluid Sources(MMFS) and Markow Modulated Poisson Sources(MMPS) are the most widely used modelling methods. But the charactersitics of the VBR(Variable Bit Rate) signal prevents modelling from actually being "real-time". Also these methods call for the use of large buffers for the abolishment of cell loss. These modelling methods are, of course, useful i case of teleconferences where a real time modelling of video traffic is inevitable, but they are insufficient in cases where the characteristic infomation of video traffic can be obtained beforehand-cases such as VOD. Video data is speial in that if one file is preprocessed all other products can simply be copied from that onepreprocessed file. This characteristic helps reduce the overhead arising from the job of drawing out characteristic information to almost zero. But still, compared to the existing real time modelling method data transmission using characteristic information succeeds in raising the efficiency of data transmission. In tis paper we will outline a method of dta transmission which use the characteristic information of each video stream, and evaluate this method through some experiments.periments.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제6권1호
• /
• pp.322-340
• /
• 2012

Orthogonal Frequency Division Multiplexing (OFDM) is usually regarded as a spectral efficient multicarrier modulation technique, yet it suffers from a high peak-to-average power ratio (PAPR) problem. Among all the existing PAPR reduction techniques in OFDM systems, side information based PAPR reduction techniques such as partial transmit sequence (PTS) and selective mapping (SLM) schemes, have attracted the most attention. However, the transmission of side information results in somewhat spectral loss and this does not significantly improve the bit error rate (BER) performance. Parallel combinatory (PC) OFDM yields higher spectral efficiency (SE) and better BER performance on Gaussian channels,while is a little but not obvious PAPR improvement over the ordinary OFDM system. This investigation aimed to design a 'perfect' OFDM system. We introduce the side information to rotate the subcarrier phases of our novel PC-OFDM system structure, and call this new system the SIPC(Side information based Parallel Combinatory)-OFDM system. The proposed system achieves better PAPR and SE performance. In addition, considering the tradeoff of system parameters, the proposed system also has the properties of a higher BER.

• 전자공학회논문지S
• /
• 제34S권2호
• /
• pp.33-42
• /
• 1997

In this paper, a video coding method in wavelet transformed multi-resolution image using variable block sized motion estimation and multi-codebook is proposed. In the propoed method, the accuracy of motion estimation is increased by using variable block matching algorithm based on edge type of blocks which estimation is increased by using variable block matching algoritm based on edge type of blocks which is classified accoridng to the magnitude of wavelet coefficients in vertical subband and horizontal subband of the highest layer. Also, we increased the flexibility of bit allocation and decreased vector quantization error for motion compensated error transmission by using importance of each subband. Some experimental results confirm that he proposed mothod has fine reconstructed images without blocking effect at low bit rate, and especially reconstructs edges well to which human eyes are sensitive.