• ETRI Journal
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• v.34 no.3
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• pp.450-453
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• 2012

IEEE 802.11n standards introduced a mixed-mode format frame structure to achieve higher throughput with multiple antennas while providing backward compatibility with legacy systems. Although multi-input multi-output channel estimation was possible only with high-throughput long training fields (HT-LTFs), the proposed scheme utilizes a legacy LTF as well as HT-LTFs in a decision feedback manner to improve the accuracy of the estimates. It was verified through theoretical analysis and simulations that the proposed scheme effectively enhances the mean square error performance.

• Journal of Broadcast Engineering
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• v.12 no.1 s.34
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• pp.2-10
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• 2007

We analyzed the receiving performance of the DVB-S2 transmission system in the BC(Backward Compatibility) mode. The transmitter employs the hierarchical modulation, and the receiver can be implemented by the direct demodulation or the hierarchical demodulation. The performance of each demodulation scheme is analyzed by a statistical method and a computer simulation for the AWGN and nonlinear channels. The ratio of the LP/HP streams which is proper in the domestic satellite broadcasting environments, is also suggested.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.185-191
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• 2004

이 연구는 DVB-S2 BC(Backward Compatibility) 모드에서 대역폭 효율을 개선하기 위한 새로운 계층적 변조방식을 제안하였다. DVB-S2 표준은 기존 DVB-S 방송 서비스와의 역호환성을 위하여 비대칭 8-PSK를 사용하며, 이 방식은 DVB-S의 경우보다는 대역폭 효율이 개선되나 DVB-S2 NBC(Non Backward Compatibility) 모드보다는 개선도가 미약하다 이러한 문제점을 해결하기 위하여 DVB-S2 NBC에서 사용하는 16APSK 변조방식을 DVB-S2 BC 모드에서 사용할 수 있도록 변형하였으며, 변형된 16-APSK 방식에 대한 수신 성능을 통계적 방법을 통하여 분석하였다.

• Journal of Satellite, Information and Communications
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• v.3 no.2
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• pp.38-42
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• 2008

In 2005, DVB-S2 spec. was finalized. But with a large number of DVB-S receivers already installed, backwards compatibility may be required for a period of time, where old receivers continue to receive the same capacity as before, while the new DVB-S2 receivers could receive additional capacity broadcasts. To facilitate the reception of DVB-S serviced by DVB-S2 receivers, implementation of DVB-S in DVB-S2 chips is highly recommended. For the backward compatibility the system adapt the hierarchical modulation scheme. And the system has to meet system margin, so in this paper analyzes the effect according to the deviation angle and shows the BER performance. And finally this paper shows the result of the system implement using FPGA chip.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.169-174
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• 2004

이 논문에 서 는 DVB-S2 BC(Backward Compatibility) 모드에서 복조방식 에 따른 수신성 능을 분석하였다. 송신기는 DVB-S(HP)와 DVB-S2(LP) 스트림을 계층적 비대칭 8-PSK로 변조시킨 신호를 전송하며, 수신기는 계층적 변조 신호를 복조하기 위하여 LSB 에서 MSB순으로 복조하는 방식과 사분면 추정지수와 LLR 계산기를 이용한 계층적 복조방식을 적용할 수 있다. 이 논문은 두 복조방식에 대한 성능분석을 AWGN 및 비선형 채널에서 통계적 분석과 모의실험을 통하여 수행하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.21-27
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• 2011

In this paper, we describes about implementations of Advanced Terrestrial DMB prototype system which can provide high higher efficiency of transmission and better quality of service than Terrestrial DMB(T-DMB) system for performance improvement of conventional mobile multimedia broadcasting system. And also we analyze field test results of the system. Advanced T-DMB system has been developed to increase data rate up to double of conventional T-DMB in same bandwidth while maintaining backward compatibility, using hierarchical modulation and turbo code. We conducted field tests to verify the performance of the proposed system through implementing of test system. As a result, we confirmed 0.576Mbps and 1.152Mbps were added to mode B and mode Q of Advanced T-DMB respectively than T-DMB system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.85-91
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• 2007

Satellite Digital Multimedia Broadcasting (S-DMB) is the digital convergence service of broadcasting and communication for mobility and portability. Broadcasting service of S-DMB can be taken by the mobile phone or vehicle terminals anytime and anywhere. S-DMB system is currently providing 11 video channels and 26 audio channels. As the demand of multimedia service is recently increasing, S-DMB system needs high quality and new contents service. Therefore we need to make efficient S-DMB with more channel ability and high transmission quality. In this paper, we propose new S-DMB system that can be applied to powerful channel coding scheme and hierarchical 8-PSK(8-Phase Shift Keying) modulation with Backwards Compatibility modes that simultaneously can support both current and new system. And we analyze the performance of current S-DMB system and verify a possibility of advanced S-DMB through computer simulation.

• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.261-270
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• 2013

A stereoscopic 3D video service is able to provide a 3D video service while keeping backward compatibility with the existing 2D video service. In the terrestrial digital television (DTV) system, a stereoscopic video codec is required to have high coding efficiency in order to provide a 3D video service in the same channel capacity. A hybrid codec consisting of MPEG-2 for base video and H.264/AVC or HEVC for 3D auxiliary video is considered. Furthermore, Non-Real-Time (NRT) delivery of stereoscopic video is also considered as a service scenario for 3DTV services to overcome the limited bandwidth. In this paper, we propose a stereoscopic video coding scheme using adaptive loop filter (ALF) which had been considered in HEVC as a pre-/post-filter for enhancing coding efficiency in NRT-based 3DTV services. In order to apply ALF as a post-filter to the reconstructed additional view coded by H.264/AVC, we devise a method in which ALF is adaptively applied based on a structure determined by using macroblock (MB) coding information such as MB mode type and reference index instead of coding unit (CU) structure on which ALF is applied in the HEVC. Experimental results shows that the proposed stereoscopic video coding scheme applying ALF obtains up to 24.9% gain of bit saving.