Min-Hyuk Kim

Analysis of Turbo Coding and Decoding Algorithm for DVB-RCS Next Generation

This paper analyzed performance of three dimensional turbo code and turbo codes proposed in the next generation DVB-RCS systems. In the view of turbo codes, we proposed the optimal permutation and puncturing patterns for triple binary input data. We also proposed optimal post-encoder types and interleaving algorithm for three dimensional turbo codes. Based on optimal parameters, we simulated both turbo codes, and we confirmed that the performance of turbo codes are better than that of three dimensional turbo codes. However, the complexity of turbo is more complex than that of three dimensional turbo codes by 18%.

A cooperative communication system using cross-layer coding method base on Hybrid-ARQ

MIMO system generally requires more than one antenna at the communication device. However, many wireless devices are limited by size, cost or hardware complexity to one antenna. To overcome such restrictions, we used a new technique, called cooperative communication. We propose a new cooperative transmission strategy system using cross-layer coding method base on H-ARQ for optimal communication. And we confirmed simulation result better performance than general one by one communication in using proposed cooperative communication system.

Performance Analysis of Upper Layer Coding Method Based on DVB-S2 for Mobility

Recently, it is studied actively that DVB-S2 for mobility standard(DVB-S2M) is combined with DVB-H, DVB-T and conventional DVB-S2 standard for continuous satellite broadcasting and internet service. Especially, overcoming deep fading by tunnel is main subject. For overcoming deep fading, DVB-S2M proposed cross layer system is consist of upper layer and physical layer. Thus, this paper proposed optimal upper layer coding system fixing the physical layer coding under the simulation results by coding methods, train speed, data rate, interleaver size and IP packet size.

High-speed LDPC encoder architecture for digital video broadcasting systems

In this paper, we propose a high-speed LDPC encoder architecture for the DVB-S2 standard. The proposed LDPC encoding architecture is based on parallel 360 bit-wise operations. The key issues for realizing a high speed are two kinds of index addresses and making efficient use of memory. We implemented a half-rate LDPC encoder on an FPGA, and confirmed that its maximum throughput is up to 10 Gbps with a 100 MHz clock.

Rate-compatible turbo product codes with non-symmetry block codes for satellite return link transmission technology

Soft-based linear block codes combined with linear modulation cannot obtain coding gains by increasing the number of iterations. In this paper, we propose rate-compatible turbo product codes with extended BCH codes using zero padding and shortening the row and/or column to adapt a next-generation (NG) Digital Video Broadcasting-Return Channel by Satellite (DVB-RCS) system. In addition, in order to make various coding rates for the required standard, we used different coding rates between row and column codes. At a bit error rate (BER) of 10-4 the performance is better at around 1.5-2 dB compared to soft-based extended BCH codes at the same coding rates.

A Study on Efficient CNU Algorithm for High Speed LDPC decoding in DVB-S2

In this paper, efficient CNU(Check Node Update) algorithms are analyzed for high speed LDPC decoding in DVB-S2 standard. In aspect to CNU methods, there are some kinds of CNU methods. Among of them, MP (Min Product) method is quite often used in LDPC decoding. However MP needs LUT (Look Up Table) that is critical path in LDPC decoding speed. A new SC-NMS (Self-Corrected Normalized Min-Sum) method is proposed in the paper. NMS needs only normalized scaling factor instead of LUT and compensates the overestimation of MP approximation. In addition, SC method is proposed. It gives a faster convergence toward a decoded codeword. If a message change its sign between two iterations, it is not reliable and to avoid to propagate noisy information, its module is set to 0. The performance of SC-NMS has a little degrade compare to MP by 0.1 dB, however considering computational complexity and decoding speed, SC-NMS algorithm is optimal method for CNU algorithm.

A FPGA Design of High Speed LDPC Decoder Based on HSS

LDPC decoder architectures are generally classified into serial, parallel and partially parallel architectures. Conventional method of LDPC decoding in general give rise to a large number of computation operations, mass power consumption, and decoding delay. It is necessary to reduce the iteration numbers and computation operations without performance degradation. This paper studies horizontal shuffle scheduling(HSS) algorithm and self-correction normalized min-sum(SC-NMS) algorithm. In the result, number of iteration is half than conventional algorithm and performance is almost same between sum-product(SP) and SC-NMS. Finally, This paper implements high-speed LDPC decoder based on FPGA. Decoding throughput is 816 Mbps.

Development of Hydrodynamic Capacity Evaluation Method for a Vertical-Axis Tidal Stream Turbine

Abstract − This study deals with the investigation of the scale effect for the vertical-axis tidal stream turbineby evaluating the hydrodynamic efficiency of turbine rotors of different diameters at different flow con-ditions. Numerical analyses are made for the turbine rotors with a same shape, but different sizes obtainedusing the diameter evaluation equation suggested in this paper. It is shown that the performance of turbineis clearly dependent upon the rotor size and inflow velocity, i.e. Reynolds number dependency of different-scaled turbines showing better efficiency with increasing Reynolds number. The sudden decrease of effi-ciency is also noticed around the transition region of Reynolds number. The hydrodynamic capacity eval-uation method needed at initial stage of turbine design is suggested and exercised with some test cases. Itis recommended that the method is expected to be useful for turbines with demanding powers between 10 kWand 300 kW.Keywords: Tidal stream energy(조류발전), Vertical axis turbine(수직축 터빈), Reynolds number(레이놀즈수), Scale effect(축척효과), Turbine diameter(터빈직경), Numerical analysis(수치해석 )

Low Computational Algorithm of Soft-Decision Extended BCH Decoding Algorithm for Next Generation DVB-RCS Systems

In this paper, we proposed the low computational complexity soft-decision e-BCH decoding algorithm based on the Chase algorithm. In order to make the test patterns, it is necessary to re-order the least reliable received symbols. In the process of ordering and finding optimal decoding symbols, high computational complexity is required. Therefore, this paper proposes the method of low computational complexity algorithm for soft-decision e-BCH decoding process.

A Study on Application of Shortened TPC Algorithm for DVB-RCS NG Systems

In this paper, we analyzed the performance of soft decision e-BCH codes which presented in DVB-RCS NG system. However, the performance of soft-decision decoding for e-BCH is not much improved as to increase the iterations. Therefore this paper proposed rate-compatible TPC which makes various coding rates by zero padding the row and/or column to adapt next generation (NG) DVB-RCS system. And so we proposed new model of extended BCH code and researches how to develop performance of extended BCH code.