Research On Technology Of Coding And Modulation

To improve reliability and efficiency of transmission is always the goal of communications work. However, in the digital communication system, reliability and efficiency are two major contradictions. Thus, in the era with an increasing scarcity of band resource, how to guarantee the reliability and improve the efficiency of communication system is the hot spot in the communication field.Channel coding is an effective way to improve system reliability. The re-introduction of Low Density Parity-Check (LDPC) codes has set off a revolutionary wave in the channel coding field. Recently, the quasi-cyclic LDPC codes are applied in the practical communication field, and rate-compatible LDPC codes have played an extremely important role in packet data communication. This paper proposes a coding method for the rate-compatible quasi-cyclic LDPC codes. The performance of these codes outperforms Turbo codes in 3 GPP. Moreover, with low complexity and small storage space, this method is very easy for encoding and decoding, which makes it applicable to the code field of future mobile communications and deep-space communication.Diversity plays an important part in the fading channel. With the best condition of diversity, the error probability will decrease exponentially as the average SNR increases. This paper provides a rotational modulation diversity method for MIMO system which characterizes in high efficiency and high spectrum utilization. The method utilizes the characteristic of time diversity, spatial diversity and modulation diversity, which can resist types of interference in fading channel and improve the performance of communication system. The system we proposed outperforms the BICM-MIMO system. It can reduce the transmission errors and improve transmission reliability.