Ldpc Decoding Algorithm And Simulation

As the need for wireless data and multimedia services, the future mobile communication system must achieve the data transmission with high data rate. So it is very important to ensure the reliability of data communication, researchers on the channel coding theory are given a good opportunity again.Low Density Parity-Check (LDPC) Codes were first discovered by Gallager in the early 1960s and recently have been rediscovered and generalized. This class of codes decoded with soft-in soft-out (SISO) iterative decoding performs amazingly well. Since their rediscovery, design, construction, decoding, analysis and applications of LDPC coded have become focal points of research. Among them, the decoding algorithm and its implementation design are the focus of this thesis.In the first chapter, the basis of communication and channel coding theory is introduced briefly, the present situation of the development of error-correcting code and LDPC Codes are pointed out. The second chapter introduces the TDD Beyond 3G system model, including the system's demand, the system's target and the system's basic parameter. The third chapter researches the application of LDPC Code in the beyond 3G wireless communication system, including the code design, the encoding design and the decoding design, with the results of a huge number of simulations, we show that LDPC Code can perform very well in B3G systems.The forth chapter focus on the researches of decoding algorithm, first studies the decoding theory and decoding approaches of several iterative message passing algorithms for LDPC Code, because of the conflict between simplification and reduced performance of BP decoding algorithm, the thesis analyzes the calculation complexity of each algorithm, and simulates the performance of each algorithm, by considering the tradeoff between hardware complexity and error performance, we get two algorithms which are much easier to implement: Bp-Based and Normalized Bp-Based decoding algorithm, especially, the last one achieves considerable improvement with almost the same complexity.The fifth chapter analyzes the fixed-point error of Bp-Based and Normalized Bp-Based decoding algorithm, and gives the final simulation results of each decoding algorithm. With the simulation results and the considering the tradeoff between hardware complexity and error performance, some key parameters and finite precision analysis for the hardware implementation of LDPC decoder have been performed.In the sixth chapter, a linear calibration of BP decoding algorithm is put forward which can simplify calculation complexity and make hardware convenient without negative effect on the performance of algorithm process.