• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.7-10
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• 2009

지상파디지털멀티미디어방송(Terrestrial-Digital Multimedia Broadcasting: T-DMB) 시스템 수신기는 이동 환경에서 방송신호의 원활한 수신을 요구한다. 따라서, 일정 레벨 이상의 전계강도와 단일 주파수 망(Single Frequency Network: SFN) 구축을 반드시 요구하게 된다. 본 논문에서는 단일 주파수 망을 통해 T-DMB 신호를 서비스하기 위해 설치하고 있는 등화형 T-DMB 동일채널 중계기(Equalization-Digital Multimedia Broadcasting On-Channel Repeater, E-DMBR)의 성능 및 신호 품질을 측정하기 위한 T-DMB RF 신호 모니터링 장비(T-DMB Monitoring System : DMR)에 대한 요구사항을 고찰하고, 그러한 요구사항을 만족하기 위한 모니터링 장비의 구조 및 구현 방법을 제안하며, 이를 이용한 개발 사례에 대한 결과를 보인다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.23-26
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• 2008

본 논문에서는 T-DMB 시스템의 단일 주파수 망 구성을 위해 궤환신호 제거기를 가지는 등화형 OCR (Equalization On-Channel Repeater, E-OCR)을 제안한다. 제안된 OCR은 송/수신 안테나의 충분치 못한 분리도로 인해 야기된 궤환신호를 궤환간섭 제거기를 통해 제거하여 송신출력을 높일 뿐만 아니라, 송신기와 중계기 사이의 다중경로 신호를 등화기를 통해 제거하여 우수한 출력신호 품질을 보장한다. 또한, 본 논문에서는 전산실험을 통해 제안된 OCR의 성능을 살펴보고 실험실 테스트를 통해 실제 구현된 OCR의 성능을 검증한다.

• ETRI Journal
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• v.31 no.4
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• pp.357-364
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• 2009

In this paper, we propose a novel equalization on-channel repeater (OCR) with a feedback interference canceller (FIC) to relay terrestrial digital multimedia broadcasting signals in single frequency networks. The proposed OCR not only has high output power by cancelling the feedback signals caused by insufficient antenna isolation through the FIC, but also shows better output signal quality than the conventional OCR by removing multipath signals existing between the main transmitter and the OCR through an equalizer. In addition, computer simulations and laboratory test results demonstrate that the proposed OCR successfully cancels feedback signals and compensates channel distortions and provides a higher quality transmitting signal with higher output power than conventional OCRs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3A
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• pp.327-334
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• 2008

Conventional on-channel-repeaters (OCRs) have a crucial problem that the power of a re-transmitted signal is highly limited by a feedback signal due to antenna coupling. The power limitation problem in OCRs has been solved by incorporating a demodulation-type feedback canceller which eliminates unwanted feedback signals by estimating a feedback channel. In applying the demodulation-type feedback canceller to T-DMB repeaters, there is a troublesome problem of unfrequent known pilot symbols, resulting in poor convergence performance of channel estimation. To solve this problem and enhance the accuracy of estimation, we propose a partitioning method of the Phase Reference Symbol (PRS) transformed in time domain. Since filter coefficients are updated every one partitioned subgroup, the number of updates is increased by the number of partitioned subgroups and thus the convergence speed is enhanced. The improved performance of feedback-channel estimation is directly connected with the feedback-cancellation performance. Simulation result shows that the feedback canceller incorporating the proposed partitioning method has a good performance in terms of residual feedback power.

• Journal of Broadcast Engineering
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• v.14 no.2
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• pp.107-113
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• 2009

In Digital On-Channel Repeaters (DOCR) of Terrestrial-DMB (Digital Multimedia Broadcasting), there exist feedback signals generated from transmit antenna and re-entering at receive antenna. Therefore DOCR becomes unstable unless the feedback signal is properly eliminated. Previous research proposed a feedback canceller to estimate the feedback channel to deal with this problem. However formerly used estimation algorithms show unsatisfied performance in terms of convergence rate and quality although their implementations are simple. This paper applies PNLMS (Proportionate Normalized Least Mean Squares) adaptive algorithm to feedback channel estimation and evaluates the performances which solve the problem of feedback signal effectively.