LDPC Codes And Its Application For Multi-Gbps 60-GHz WPAN Systems

Low density parity check codes have attracted considerable attention in the coding community because they can achieve near-Shannon limit performance, and LDPC codes have been widely used in deep space communications, optical communications, satellite digital video, and digital watermark, and magnetic/optical/holographic storage, mobile and fixed wireless communications. QC-LDPC codes (Quasi-Cyclic LDPCcodes) are a class of structured LDPC codes, the parity-check matrix method using quasi-cyclic structure, with the realization of the characteristics of low complexity, easily implemented in hardware. This thesis studies the LDPC codes of encoding theory, decoding algorithm, and focuses on the girth, stopping set and other aspects which are important for constructing QC-LDPC codes. Some key technologies of Multi-Gbps LDPC coded 60-GHz WPAN Systems are also studied.The main works are as follow:1. The necessary and sufficient conditions for QC-LDPC code without small cycles and correspongding check algorithms are proposed.lt is significant for us to analyze and optimize the design of LDPC codes.2,Some theorems of the QC-LDPC codes without small stopping sets are proposed. Applying these theorems and corresponding check algorithms, we could not only design good QC-LDPC codes without small stopping sets and girth, but also count the numbers of stopping sets and girth. A construction of good QC-LDPC codes based on the row vectors of generator matrix is proposed. A construction method based on the p-plane to design high-girth and high-stopping set QC-LDPC code is proposed.3,A construction of three-diagonal structure based irregular QC-LDPC code is proposed, which can effectively solve the singularity of parity-check matrix of LDPC codes, and ensure the quasi-cycle characteristic of the generator matrix. A construction of back-substitution based irregular QC-LDPC code with linear coding complexity is proposed, which has better BER performance.4,A new channel estimation sequence based on complementary Golay sequence and Frank-Zadoff sequence for time-domain channel estimation for the Multi-Gbps LDPC coded 60-GHz WPAN System, respectively.To facilitate using LDPC codes for SCBT system, a new log-likelihood ratio (LLR) calculation method was proposed based on Pilot Symbols (PS).The simulation results show that the proposed method can significantly improve the LDPC decoding performance in SCBT system. This is very promising to support ultra high-data-rate wireless transmission.