Cmmb Channel Estimation And Synchronization Algorithms

Along with the vigorous development of domestic and foreign mobile multimedia broadcasting technology, China Mobile Multimedia Broadcasting standard CMMB also came into being. CMMB standard is based on the OFDM technology and its advantage is the ability to effectively resist the effects of multipath in the radio channel, and to reduce the interference between system symbols. The OFDM technology use mutually orthogonal sub-carriers by the time domain for transmission, and the inter-subcarrier spectrum is mutually overlap each other, so that the CMMB system has a higher bandwidth efficiency.Technology of channel estimation and synchronization is an important part of the CMMB receiver, and largely affects the pros and cons of the system performance. This article is mainly carried out a detailed study of CMMB receiver channel estimation and synchronization algorithm. Channel estimation part draws in part on the research of senior classmate Liujia, and make some algorithm improvements on the basis of his research.This paper first introduces the mobile multimedia broadcasting standard of the domestic and international mainstream, analysis their features, then introduces the key technologies of OFDM and the basis characteristics of the radio channel. The radio channel affect the received signals significantly, radio channel environment also has a crucial impact on the entire wireless communication system performance. The purpose of channel synchronization and channel estimation at CMMB system restore the received data of the receiver to the original state of the transmission side data at the greatest degree.The channel synchronization techniques include carrier synchronization, symbol synchronization and sampling rate synchronization, in which OFDM system is most sensitive to carrier frequency offset, so this paper describes the influence of carrier synchronization deviation to the system and the carrier synchronization algorithm in detail, for further, the symbol synchronization algorithm is also studied and introduced. Finally, according to the characteristics of the CMMB standard the paper summarizes a series of suitable CMMB standard synchronization algorithm, and the simulation of these algorithms.CMMB system in the channel estimation uses pilot-based channel estimation algorithm, which in turn comprises two parts, the estimation of channel information at pilot positions and the estimation of channel information at data positions. The estimation of channel information at pilot positions uses the least squares method, and the estimation of channel information at data positions uses the secondary order interpolation algorithm, which is suitable for CMMB system. Finally, the paper also makes simulations of these channel estimation algorithm, and gets the satisfied simulation result at last.