The Research Of MIMO Adaptive Transmission Technology Based On Markov Model

With the the rapid development of wireless broadband data services and people's growing needs of the high-speed wireless data transmission, wireless resources, in particular, the spectrum is becoming increasingly strained. How to make use of the limited spectrum resources to provide higher transmission rate and better service quality has become the focus of the study of wireless communications technology.MIMO (Multiple-Input Multiple-Output) technology is one of the key technologies of the next-generation wireless communications system. It has aroused extensive attention in recent years. With the use of multi-antenna technology at both the transmitter and receiver of wireless communication systems, MIMO technology can make full use of space resources without increasing the system's bandwidth and transmission power, it can effectively resist the wireless channel fading and greatly increase the spectral efficiency and channel capacity of the communication system.We can take adaptive transmission technology to furtherly increase the spectrum efficiency and improve the performance of the system. Adaptive transmission technology is to adjust the transmit parameter according to the channel state, in order to achieve certain optimization objectives. According to the change of channel caused by channel fading, it can be used to increase capacity in fixed BER system and improve the quality of transmission in fixed throughput system. Combination of MIMO technology and the adaptive transmission technology can better optimize the performance of the system.The finite-state Markov model is often used to study the characteristics of random process. In the Markov model, the random process is partitioned into a set of discrete state, and the dynamic behavior of the process can be captured by the transitions among the states. We introduce the finite-state Markov model in detail and analyze the Rayleigh fading channel through it. We verify its accuracy through simulation.Based on finite-state Markov model, on the target of maximizing the spectral efficiency, according to the instantaneous receiver output SNR, we propose an adaptive modulation method in MIMO-MRC systems under Rayleigh flat fading channel. The output SNR of the MIMO-MRC receiver is modeled as a finite-state Markov chain. As to each state, a correspondent modulation mode is used. The switching threshold of modulation based on output SNR is found according to the proposed Markov method. The accuracy of the method is verified by simulation experiment under MIMO Jakes channel. On the target of maximizing the spectral efficiency,it outperforms the traditional threshold method.Finally, we analyze the error performance of the diversity and multiplexing system. Based on the criteria of the minimum Euclidean distance, we analyze the error performance diversity and multiplexing mode switching system, and simulation showed that performance of the switching system is better than diversity or multiplexing alone. MIMO channel condition number can be modeled to a two-state Markov chain, in which each state is corresponding to a transmission scheme. With the Markov model, we analyze the switching error probability caused by the feedback delay.