Dae-Ig Chang

Performance analysis of APSK modulation for DVB-S2 transmission over nonlinear channels

For increased bandwidth efficiency and receiver performance, standards for satellite broadcasting systems are evolving by utilizing efficient transmission techniques. The second-generation digital video broadcasting for satellites (DVB-S2) adopts the amplitude phase shift keying (APSK) modulation for enhanced performance over nonlinear channels. In this paper, we derive error rate bounds for APSK modulated symbols and generalize the bounds to the case of distorted constellation, which occurs when the maximum transmission amplitude is saturated by the soft-limiter type channel. The derived bound is shown to significantly improve the previously known result, to accurately predict both the symbol error rate and bit error rate in the entire signal-to-noise ratio (SNR) region of interest. Using the derived formula, the optimal input power level for the soft-limiter channel is determined, and the corresponding minimal error rates for 16- and 32-APSK are quantified. The result is also interpreted in terms of optimal input back-off (IBO) for nonlinear power amplifiers by evaluating the performance degradation as a function of IBO. Copyright

Enhanced Frame Synchronization for DVB-S2 System Under a Large of Frequency Offset

This paper investigates the possible robust technique of frame synchronization for DVB-S2 system. Basically, we focus on the improvement of correlation characteristic, instead of establishing the strategy of frame synchronization with optimal scenario due to variable transmission frame lengths of DVB-S2 standard. To cope with a large frequency offset as a maximum 20% value normalized to symbol rate, the differential generalized post detection integration scheme is newly proposed in the paper. The fruitful results of the paper are described by the suitable analytical approach through parameter optimization. The proposed scheme is shown to provide a good trade-off relation between complexity and performance and is verified in detail their improved performance.

Simplified soft-decision demapping algorithm for DVB-S2

This paper presents a simplified soft-decision demapping algorithm for Digital Video Broadcasting via satellite, Second Generation (DVB-S2). To achieve a good Bit Error Rate (BER) performance of a Low Density Parity Check (LDPC) code decoder, the received signal should be soft-decided rather than hard-decided. However, the soft-decision demapper requires high hardware complexity to support higher-order modulation modes. The proposed soft-decision demapping algorithm can reduce computation complexity by eliminating a square operation. In addition, simulation results show that the proposed algorithm has negligible performance degradation compared with the conventional algorithms.

Low complexity soft-decision demapper for high order modulation of DVB-S2 system

This paper presents an efficient soft-decision demapper interface and a low complexity demapper for high-order modulation scheme. The proposed soft-decision demapper interface can operate at a symbol rate and replace the parallel to serial converter by locating between the M-PSK demodulator and the soft-decision demapper. In addition, the proposed soft-decision demapper can reduce the hardware complexity by reusing the multipliers. Moreover, the proposed demapper can support high-order modulation modes. The proposed architectures have been thoroughly verified using a FPGA board having the the Xilinxtrade Virtex II.

Analysis of the Rain fading channel and the system applying MIMO

The aim of the research is to increase the capacity of the satellite communication in rain fall environment. Therefore, the paper analyzes and implements the rain fading channel model, and then applies results of analysis to proposed satellite MIMO system. The proposed system is composed of two satellites. A comparison between Rayleigh and Morita model is also treated. We can insist that the rain fading channel has better condition than Rayleigh model, and performance of proposed MIMO system is substantially good comparison with the existing satellite system

Robust frame synchronization for the DVB-S2 system with large frequency offsets†

This paper tackles the problem of frame synchronization design for the Digital Video Broadcasting standard via Satellite (DVB-S2) system. In particular, the design of a novel frame detection scheme exhibiting robustness against large frequency errors is proposed. Post-detection integration (PDI) is exploited to provide coarse frame alignment with limited complexity with respect to classical approximate maximum likelihood (ML) solutions. The novel scheme, denoted as differential generalized post-detection integration, derives from a pragmatic adaptation of the well-known generalized PDI scheme (IEEE Trans. Commun. 2007; 55(11):2159–2171), which eliminates its inherent source of weakness in the presence of large frequency offsets, i.e. its non-differential component given by non-coherent PDI. The proposed approach manages to reduce the remarkable performance gap with respect to approximate ML techniques available in the literature (IEEE Trans. Commun. 2002; 50(7):1062–1065), providing the designer with an interesting performance/complexity trade-off. Performance is numerically evaluated in terms of receiver operating characteristics and mean acquisition time (MAT), handling the acquisition procedure according to a single-dwell approach. Both threshold crossing and MAX criterion are contrasted to identify the best design solution. Copyright

Analysis of interference and availability between satellite and ground components in an integrated mobile-satellite service system

Summary An integrated mobile-satellite service (MSS) system is one of the most promising infrastructures for the efficient use of satellite frequency, and the satellite coverage can be extended by reusing the satellite frequency in its ground components. However, the co-channel interferences caused by the frequency reusing technique may lead to the performance degradation. This paper presents the interference analysis for an integrated MSS system that is composed of a multi-beam satellite, complementary ground components (CGCs), and mobile earth stations, by using statistical simulations. These statistical results are then used to evaluate the availability of the system. Our simulation results reveal that the satellite frequency reuse in the CGCs of the integrated MSS system can increase efficiency of satellite spectrum utilization with a tradeoff between CGC network capacity and intra-system interferences. Copyright

Link Layer Coding for DVB-S2 Interactive Satellite Services to Trains

The railroad satellite channel is characterized by frequent signal outages due to tunnels, bridges and electrical trellises. While for medium/long tunnels the main option to offer reliable and uninterrupted connectivity deals with the adoption of gap-filling techniques, signal outages due to small bridges/tunnels or electrical trellises can be faced with ad-hoc recovery techniques. In this paper, we face the problem from a link layer perspective, showing how a proper design of an erasure correcting code operating at link layer represents a valuable countermeasure against short outage events. The performance evaluation is developed in comparison with a more traditional technique based on physical layer coding in combination with a long channel interleaver. Advantages of the link layer coding scheme will be shown.

Efficient coarse frequency synchronizer using serial correlator for DVB-S2

This paper proposes an efficient coarse frequency synchronizer for digital video broadcasting - second generation (DVB-S2). The input signal requirement of acquisition range for coarse frequency estimator in the DVB-S2 is around plusmn1.5625 Mhz, which corresponds to 6.25% of the symbol rate at 25 M baud. At the process of analyzing the robust algorithm among data-aided approaches, we find that the Luise & Reggiannini (L&R) algorithm is the most promising one for coarse frequency estimation with respect to estimation performance and complexity. However, it requires many multipliers and adders to compute output values of correlators. We propose an efficient architecture identifying the serial correlator with the buffer and multiplexers. The proposed coarse frequency synchronizer can reduce the hardware complexity about 92% of the direct implementation. The proposed architecture has been implemented and verified on the Xilinx Virtex II FPGA.

Efficient channel equalization technique for DVB-S2 standard

This paper deals with design of the appropriate time domain equalizer based on DVB-S2 specification for mobile application. Firstly, we consider different ISI effect under various channel condition through field measurement. With reflection of channel effect, we suggest adaptive filter as channel condition and synchronization step mode like code start/hot start. Finally, we implement the blind FS equalizer compatible with entire DVB-S2 specification. In addition, at the practical point of view, we seek the performance impact by nonlinear satellite channel condition plus freq. selective channel and optimize it to minimize the performance loss.