Research And Application Of LDPC Code Used In DVB-S2 Standard

LDPC code is a type of error correcting block code with very sparse check matrix, which was put forward by Gallager in the early 1962 and also called Gallager code. After this, Mackay et.al restudied LDPC code, and discovered its wonderful features: capability of approaching the Shannon limit, easy description and realization, convenient analyse and research in theory, simple coding, ability of parallel performance and suitable for implementation with hardware.DVB-S2 is the next generation standard of the digital satellite broadcasting, which adopts the more effective technique of channel coding and self-adapting code modulation, 30% higher transmission efficiency than DVB-S. Among them, channel coding adopts LDPC as its inner code and BCH as its outer code.This paper discusses the basic principle of LDPC encoding and decoding firstly, and then explains the LDPC encoding and decoding in the standard of DVB-S2. The next, it puts forward the software realization of the LDPC encoding algorithm based on DVB-S2 standard. It also works out the theory capability of LDPC with Matlab. After this, it discusses algorithms of LDPC decoding, and according to the regularity of the DVB-S2 coding matrix, it puts forward the idea to apply λ - min decoding algorithm which will improve the efficiency of the LDPC decoding to this standard. Then it mainly discusses the hardware design of the key unit in LDPC decoder—check functional unit. In order to improve the efficiency and the security of the design, this paper adopts the method based on the System Generator. This design is achieved in the FPGA chip xc2s100 of Xilinx and also be verified by the logic analyzer. At last it builds a simplified end to end model of the transmission system for DVB-S2 which further validates the use of this hardware module, also points out the existing shortage and the direction for further research.