Mimo Quasi-orthogonal Space-time Code Algorithm Research And Improve The Design,

As the demand for data communication and the development of multimedia services, the fourth generation mobile communication has become more popular ,which would meet the mobile data, mobile computing and mobile multimedia operational needs. Nowdays requirements on the data transmission rate and reliability are higher and higher. The existing point to point communication methods limited by the spectrum of resources and fading channel has been unable to meet demand. Multiple-input multiple-output (MIMO) antenna system using space diversity to improve the capacity of wireless communication systems and information rate, is the mainstream of the development of next generation mobile communication structure. In addition to achieving diversity in the receiver to receive signals, researches have being focused on base station transmit diversity of MIMO technology in recent years. By the capability of full transmit diversity gain and full-rate, the orthogonal space-time block code (STBC) has therefore become one of the major coding.Currently studies on the performance of STBC have been relatively comprehensive, so research focus is shifting to optimize code structure and reduce the decoding complexity. This paper presents a quasi-orthogonal space-time block code algorithm on flat fading MIMO channel model platform, which overcomes the defects that the orthogonal STBC with more than 2 antenna of full diversity gain can not achieve full rate transmission, can achieve full diversity and full rate in any antenna configuration. Decoding algorithm using quasi-orthogonal decoding has a structure of low complexity and small performance loss.This article also combines MIMO quasi-orthogonal space-time block code and orthogonal frequency division multiplexing (OFDM) modulation technologies, to overcome the multipath effects of wireless communication. Channel coding technology as an important means to improve the reliability of communication systems has been widespread concern. The low density parity check codes which approach the Shannon limit, because this good properties and low decoding complexity, it is being more and more attention. Finally, this article gives a MIMO system model based on quasi-orthogonal space-time coding combined with multi-LDPC multi-LDPC channel coding technology, and confirms that MIMO quasi-orthogonal space-time encoding and decoding technology can reduce the error rate, improve system performance by software simulation results.