Gmsk-based Ldpc Encoding And Decoding System

The thesis introduces the fundamental principle of LDPC encoding and decoding and the design from digital module of GMSK receiver and transmitter based on software radio.The main works involved as following:1. The paper introduces the fundamental principle of LDPC code, including LDPC code's basic conception, construction, encoding and decoding algorithm, And Then discusses conventional encoding and efficient encoding using special sparse parity check matrix in encoding algorithm,and control the BER at 0.01. the results achieve good BER performance.2. The paper focuses on the study on digitialization of GMSK. Base on related literatures, a improved quadrature waveform storage GMSK modulation signal generation method is studied. The method does not have the shortage of accumulated phase error in traditional method,and reduces the device resources significantly. Simulation results and FPGA realization results show that the method has the advantages of small computation, less resources and easy to realize high sidelobe suppressed GMSK signal; the demodulation technologies in digitalization method is studied. A 1-bit demodulator is designed and released. Simulation results and FPGA realization results show that scheme designed can demodulate GMSK signal effectively.3. This Paper deals with the design and implementation of Digital Up Conversion (DUC) by field-programmable gate array (FPGA).Firstly,the related theory and algorithm of DUC is introduced. Secondly,using Top-Down design method,DUC is divided to many function modules. At last,every function module Designed in this Paper simulated by FPGA. The results show the design is correct.The study of the thesis is carried out by the method of theoretical analysis, scheme comparisons, simulations and FPGA verifications. Results shows that the scheme designed is feasible,and can be adopted in practice system after further optimization.