• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2041-2047
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• 2013

In this paper, we proposed high speed LDPC decoding algorithm based on DVB-S2 standard. For implementing the high speed LDPC decoder, HSS algorithm which reduce the iteration numbers without performance degradation is applied. In HSS algorithm, check node update units are update at the same time of bit node update. HSS can be accelerated to the decoding speed because it does not need to separate calculation of the bit nodes, However, check node calculation blocks need many clocks because of just one memory is used. Therefore, this paper proposed dc-split memory structure in order to reduced the delay and high speed decoder is possible. Finally, this paper presented maximum split memory and throughput for various coding rates in DVB-S2 standard.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.7
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• pp.515-520
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• 2014

In this paper, the protograph-based block low density parity check (LDPC) code, which improves the performance and reduces the encoder/decoder complexity than the conventional Digital Video Broadcasting Satellite Second Generation (DVB-S2) LDPC code used for the marine satellite communication, is proposed. The computer simulation results verify that the proposed protograph-based LDPC code has the better performance in both the bit error rate (BER) and the frame error rate (FER) than the conventional DVB-S2 LDPC code. Furthermore, by analyzing the encoding and decoding computational complexity, we show that the protograph-based block LDPC code has the efficient encoder/decoder structure.

• Journal of Satellite, Information and Communications
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• v.1 no.2
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• pp.51-55
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• 2006

Digital satellite communication systems are usually integrated with terrestrial systems to provide various services. In these cases, they should satisfy the performance objectives defined by the terrestrial systems. Recommendation ITU-R S.1062 specifies the error performance objectives of digital satellite communication systems operating below 15 GHz. The error performance are given in terms of bit error probability divided by the number of the average bit errors in the burst ($\alpha$). This paper presents a theoretical method to estimate $\alpha$ that is a very important parameter in the satellite communication systems to analyze the error performance objectives. We show performance estimation result of DVB-RCS turbo code using the presented method, and verify them by comparing to the simulation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2143-2149
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• 2012

DVB-S2 employs LDPC codes which approach to the Shannon's limit, since it has characteristics of a good distance, error floor does not appear. Furthermore it is possible to processes full parallel processing. However, it is very difficult to high speed decoding because of a large block size and number of many iterations. This paper present HSS algorithm to reduce the iteration numbers without performance degradation. In the flooding scheme, the decoder waits until all the check-to-variable messages are updated at all parity check nodes before computing the variable metric and updating the variable-to-check messages. The HSS algorithm is to update the variable metric on a check by check basis in the same way as one code draws benefit from the other. Eventually, LDPC decoding speed based on HSS algorithm improved 30% ~50% compared to conventional one without performance degradation.

• Journal of Broadcast Engineering
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• v.14 no.6
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• pp.676-691
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• 2009

Recently mobile broadcast standards that have IP layer between transport layer and service layer such as DVB-IPDC, OMA-BCAST have been commercialized. Specially, IP abstract layer of OMA-BCAST makes it possible to interface diverse transport layers. Service guide, that is important for user interface, of these mobile broadcast standards has complex structure and heterogeneous schema. ESG schema is not interoperable, therefore terminals should have various implementations of service layer to support more than one service layer at a time. In this paper, not only for enabling interoperability of DVB-IPDC and OMA-BCAST but for supporting basic scenarios of mobile broadcast, simple ESG schema was developed. This new schema can be used as an independent ESG schema, especially for the integrated mobile broadcast middleware environment.

• Journal of Broadcast Engineering
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• v.21 no.4
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• pp.506-514
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• 2016

In this study, HEVC over DVB-T2 systems with a bandwidth of 6 MHz is considered, particularly for the terrestrial 4K-UHDTV broadcasting service in the Republic of Korea. The threshold of visibility carrier-to-noise power ratio (ToV C/N) and the receiver minimum required input level (sensitivity) for satisfying the subjective picture failure (SPF) condition are measured in the laboratory. It is observed, for transmitting 26.37 Mbps data stream correctly, that ToV C/N is 18.8 dB on average, and the receiver sensitivity is varied from minimum -84.2 dBm to maximum -80.0 dBm. Based on the results, the receiver noise floor is calculated by -100 dBm on average.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.55-61
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• 2017

In DVB-S3 standard of satellite broadcasting systems, FTN technique is applied to LDPC codes with (1+7) PSK modulation. In standard, BICM-ID and BCJR decoding method are considered to alleviate performance degradation due to FTN processing. BICM-ID method improves performance by calculating a new LLR from hard-decision value of decoder output. BCJR also improves performance by calculating forward and backward matrix each other. However these two methods require high computational complexity. Therefore this paper proposed modified decoding method in order to reduce computational complexity without performance degradation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.592-598
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• 2008

In this paper, a novel pilot-aided integer frequency offset estimation scheme is proposed for orthogonal Sequency division multiplexing (OFDM)-based digital video broadcasting (DVB) systems. The conventional pilot-aided integer frequency offset estimation scheme proposed for OFDM-based DVB systems exploits the partial information of combinations provided by pilots. Thus, in this paper, we propose a novel integer frequency offset estimation scheme exploiting all information of pilot combinations. To compare the performance of the proposed scheme with that of the conventional scheme, we conduct a simulation in additive white Gaussian noise (AWGN) and multipath Rayleigh channels, which shows that the proposed scheme outperforms the conventional scheme in terms of the probability of integer frequency offset estimation failure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.676-684
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• 2008

In digital video broadcasting-terrestrial (DVB-T), which is the European digital terrestrial television standard, the orthogonal frequency division multiplexing (OFDM) has been adopted for signal transmission. The main reasons using OFDM are to increase the robustness against the frequency selective fading and impulse noise, and to use available bandwidth efficiently. However, channel variation within an OFDM symbol destroys orthogonality between subcarriers, resulting in inter-carrier interference (ICI), which increases an error floor in proportional to maximum Doppler spread. This paper provides an ICI analysis in both time and frequency domains while existing literatures analyze the ICI effects mainly in frequency domain and proposes the algorithms that estimate the channel impulse response and channel variation using least square (LS) algorithm which is the most simple channel estimation technique. And we propose adaptive channel estimation algorithm that estimates the velocity of terminals. The simulation results show that proposed algorithm has similar performance with about 1.5% computational complexity of noise and ICI reduction LS algorithm in low speed environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.2
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• pp.702-721
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• 2012

In the DVB-T2 system with a multiple-input single-output (MISO) transmission mode, Alamouti coded orthogonal frequency division multiplexing (OFDM) signals are transmitted simultaneously from two spatially separated transmitters in a single frequency network (SFN). In such systems, each transmit-receive link may have a distinct carrier frequency offset (CFO) due to the Doppler shift and/or frequency mismatch between the local oscillators. Thus, the received signal experiences dual CFOs. This not only causes dual phase errors in desired data but also introduces inter-carrier interference (ICI), which cannot be removed completely by simply performing a CFO compensation. To overcome this problem, this paper proposes an iterative detection with dual phase errors compensation technique. In addition, we propose a successive-iterative ICI cancellation technique. This technique successively eliminates ICI in the initial iteration by exploiting pre-detected data pairs. Then, in subsequent iterations, it performs a fine interference cancellation using a priori information, iteratively fed back from the channel decoder. In contrast to previous works, the proposed techniques do not require estimates of dual CFOs. Their performances are evaluated via a full DVB-T2 simulator. Simulation results show that the DVB-T2 receiver equipped with the proposed dual phase errors compensation and the successive-iterative ICI cancellation techniques achieves almost the same performance as ideal dual CFOs-free systems, even for large dual CFOs.