Mimo Systems With Stbc Joint Beamforming Technology

The current wireless communication systems can provide limited data rate, people of strong demand for broadband communications are larger and larger. The traditional resources to enhance wireless communication data transmission rate: spectral bandwidth and transmission power, are in the verge of saturation currently, Improving the data rate by increasing the consumption of these two resources is not feasible. People naturally have to study a new mobile communication technologies. Today, the 3G standards has been basically finalized, also has entered a phase of large-scale commercial use. However, because the 3G is also traditional wireless communication technology in a large extent, which only can provide limited data transmitting rate,so the operators can not give more attractive business to attract customers, so the 3G's large-scale commercial applications in the global is not very good. At this point, a new kind of technology appears, that is, MIMO (Multiple-Input Multiple-Output, Multiple Input Multiple Output) wireless communication technology,which configure multiple antennas at the transmitter and the receiver to send and receive signals. Theoretical analysis shows that a system with a large number of transmit and receive antennas and the receivers know the independent flat fading channel, the capacity grows linearly with the minimum number of antennas. So we can say that the MIMO system is a revolution in wireless communications.MIMO technology can significantly improve the link capacity, but the problem is that what kind of transmission scheme can achieve the channel capacity and how to effectively use the space resources of MIMO system to improve the data transmitting rate we have to face. Space-time block coding technique will be able to do this. The technology is based on multi-antenna theory, it can obviously upgrade the reliability of wireless links, while improving the system performance.Therefore, this article will aim to research MIMO system capacity and performance of space-time block coding. We will verify the MIMO system capacity compared to traditional single-antenna systems through theoretical analysis and computer simulation approach; and space-time block encoding's encoding and decoding methods, and its bit error rate(BER) performance. But we know that the space between the multi-antenna array elements,the DOA of the antenna, as well as the impact of the scatters etc., will lead to the antenna element has a certain correlation each other.And this kind of correlation will declined the performance of the system.Therefore,we must find ways to solve such a problem.Therefore, this article also analyzed the impact on system performance of the correlation between antenna elements.In this paper we develop an beam-former which based on the statistical water-fills principles.the scheme can improve system performance. The program use the second-order statistical properties of the channel state information to optimize the power allocation in transmitter, so it can improve the system performance. Computer simulation shows that the program can improve the system performance very obviously.