• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.18 no.2 s.117
• /
• pp.151-157
• /
• 2007

We have presented a compact two-wire helical antenna adopted an open stub in opposite to a feeding point, which is for a T-DMB antenna of mobile devices. By adjusting the length of the open stub or pasting a dielectric material on the open stub, the input impedance around 200 MHz, bands of the T-DMB, can be easily control, even though the total height of the antenna is less than 8 cm(0.053 $\lambda$ at 200 MHz). The operating mechanism of the antenna is explained by using equivalent circuits of two modes, an unbalanced mode and a balanced mode. Based on the analysis of the equivalent circuits, the effects of using the open stub are validated. Several proposed antennas have been fabricated and measured. One of the fabricated antennas has -10 dB impedance bandwidth of $196{\sim}204$ MHz(8 MHz) whose value covers one channel of the T-DMB(6 MHz). The measured $S_{21}$ of the antenna is -38.6 dB which is about 17 dB higher than that of a monopole antenna whose height is same with the proposed antenna.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2008.05a
• /
• pp.689-692
• /
• 2008

Hierarchical modulation has been considered for achieving higher data rates in Terrestrial-DMB(T-DMB) systems. And for achieving a higher data rates transmission, the low-priority (LP) data, which is used to carry additional data, such as video data, audio data and textual data, should be perfectly decoded in a certain value of $E_b/N_o$. Unfortunately, the man-made noise badly affects the high-priority (HP) symbol, which is used to carry the conventional data in the existed T-DMB system; and since the advanced T-DMB system is proposed to fit for the legacy T-DMB receivers, the low-priority symbols in the hierarchical modulation are much worse affected by the neighbors, who are both in the same quadrant. Because of the feature that mentioned previously, the turbo code has been considered to deal with the LP data. And due to the degradation which caused by the shortened symbol distance, the error performance of LP data is not sufficient by only using the turbo code. In this paper, we propose a Reed-Solomon code used outside of turbo code, and with the turbo code, it becomes a concatenated code. In this paper, there are some simulation results, within the comparison of those performances, we can see how a Reed-Solomon code is utilized for degradation of error performance which is caused by the hierarchical constellation, and how to design a Reed-Solomon code which is suitable for improving the degradation of error performance.

• Proceedings of the KIEE Conference
• /
• 2008.04a
• /
• pp.86-88
• /
• 2008

지상파 방송(DMB: Digital Multimedia Broadcasting)은 음성, 영상, 데이터와 같은 다양한 멀티미디어 신호를 디지털 방식으로 변조하여 이동 중에 방송을 청취 할 수 있는 차세대 디지털방송 서비스이다. 하지만 한정된 대역폭으로 인한 비디오 전송율의 한계에 따라 최대 CIF(Common Interleaved Frame)급 화면해상도까지 서비스가 가능하다. 그러나 지상파 DMB 전송 고도화망에서는 계층 변조(Hierarchical Modulation)전송 기법을 통하여 추가의 전송대역폭을 확보할 수 있다. 또한 스케일러블 비디오 코딩(Scalable Video Coding)부호화 방식을 이용하여 고전송효율/고품질의 이동 멀티미디어 방송서비스를 제공할 수 있는 고품질 AT(Advanced Terrestrial)-DMB 시스템이 가능하다. 이러한 고품질 AT-DMB의 개발에 있어서 여러 방식들이 제시됨에 따라 시뮬레이터를 통한 다중화 시스템의 분석이 필요하다. 본 논문에서는 고품질 AT-DMB가 가능한 스케일러블 비디오 방식을 JM8.8을 사용하여 구현하였으며, 다중화 시스템의 실험을 하였다. 또한 시뮬레이터를 통하여 확보된 계층 간의 화질 차이와 엔지니어를 위해 비트스트림의 분석화면 및 PSNR을 제공 하였다.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.179-180
• /
• 2008

본 논문에서는, 고품질 AT-DMB 시스템을 위해서 각 계층 ES(Elementary Stream)을 MPEG-4 over PEG-2 시스템과 Eureka-147 DAB 시스템을 통해 서로 다른 채널로 전송한다. 계층별 전송으로 인한 시간 지연에 대처하여 수신 입력부에서는 각각의 계층으로 전송된 ES들이 동기화 되어 복호화 되도록 SVC의 계층적 비트스트림 구조와 적응적으로 동작되는 다중화 시스템 구조를 제작하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.10a
• /
• pp.755-757
• /
• 2009

Since the research of advanced terrestrial digital multimedia broadcasting system is still in progress, and in our previous paper, in which we introduced how to combine one conventional transmitted symbol with two additional bits to form a new symbol transmission, the bit error performance of LP bits is not realizable, because even we implemented the turbo code to protect the LP bits transmission, to obtain a certain good bit error probability, the value of $E_b/N_0$ cost highly. In this paper, we modified the composition of low-priority symbol and high-priority symbol, and through the system presented in previous paper we get a better simulation result of the LP symbol transmission.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.7
• /
• pp.1172-1179
• /
• 2006

Recently, the H.264/AVC, which was standardized jointly by ISO/IEC and ITU-T, has been expanding its applications in various areas. This standard includes many advanced component techniques compared to the existing MPEG techniques. Intra prediction which is to predict the spatial data in an intra frame in one of them. But it has a serious defect that it needs large amount of calculation. To overcome this defect, this paper proposed a method to reduce about 60% of the amount of calculation with only O.02dB of image quality degradation. This method determines the calculation directly without much pre-calc cluation process by referring the left block(s) and upper blocks(s) that were processd already. Comparing to the exi sting methods, its image quality degradation is so small that it is expected to be used in many areas. Especially in the wireless appliances such as DMB phone which has restricted power source, we expect it would be used efficiently.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2009.05a
• /
• pp.40-41
• /
• 2009