The Performance Of The LDPC Codes Based On Single-carrier Frequency Domain Equalization System

Based on Shannon theorem, channel coding has become one of the research areas. How to construct close to the channel capacity of the encoding method, how to design a corresponding encoding method and decoding method and how to guarantee information transmission reliable and efficient has become the important subject in channel coding areas.Low Density Parity Check (referred to as the LDPC code) is an important field of channel coding research. It has the following many advantages:simple description, the low decoding complexity, parallel implementation, the use of a relatively flexible, low error platform, may be approaching the Shannon limit and so on. These excellent performance make LDPC codes become one of the the current hot research topics in the field of communications, and is also a key research technology in the B3G/4G mobile communication system.Now,wireless broadBand access technology has become a necessity. In the broadBand wireless communication, due to the presence of multipath transmission, cause frequency selective fading, thereby causing serious influence on the reliability of the communications. What transmission technology to effectively resist the impact of multipath fading, has become a key issue for the study of the physical layer of such systems. The emergence of the single-carrier frequency domain equalization (SCFDE)system, bring a new direction to the study of the physical layer. Technical characteristics of the SCFDE:joint simple time domain feedBack equalizer performance,similar to orthogonal frequency division multiplexing (OFDM)in Performance(even in case of high bit rate performance is more excellent), no PAPR big problem, not sensitive to such OFDM in terms of phase noise and frequency offset, also has better fusion with OFDM technology. With the development of SC-FDE technology, it has been more and more attention in the researchers and SC-FDE technology has been suggested as one of the proposed physical layer transmission schemein in broadBand wireless communication protocol IEEE802.16a.This paper firstly analyzed the principle and structural characteristics of the composition of low density parity check code, proposed two coding method based on the802.16e standard, and analyzed three universal decoding algorithm. By reading a lot of literature, we proposed a decoding architecture suited to802.16e standard check matrix, detaile introduced entire process of decoding steps, and on this basis achieve code structurethe simulation of unity of LDPC codec functions. Secondly, researched dsingle-carrier frequency domain equalization system,analyzed the block diagram of the transmitter and receiver, equipped with the entire simulation system, researched the performance of the LDPC codes based on single-carrier frequency domain equalization system.In AWGN channel,1344yards long, different rate and different modulation schemes under different Doppler frequency we came to the simulation results and analysised all results.