Channel Estimation Analysis Based On Space-time Block Coding In The MIMO System

Multi-Input Multi-Output (MIMO) technology adopts multi-antennae (or array antenna) and multi-channel at transmitting and receiving terminals to improve the capacity of communication system and spectral utilization ratio efficiently without increasing bandwidth. Since performances of the wireless communication system will be influenced by wireless channel, and the propagation path between transmitter and receiver in MIMO system is very complicated, it is critical to estimate channel accurately in real time for signal detection and mobile wireless system design. And then channel estimation is closely related to space-time block codes and multi-antenna transmission technology. This paper focuses on researching channel estimation techniques in MIMO system, including the combination of space-time block codes and pilot auxiliary channel estimation. The specific work is as follows:1. This paper studies the general channel model of Alamouti space-time codes and its channel model under multi-antenna. Then the LS algorithm is adopted to estimate the performance of the two channel models by computer simulation. The simulation results show that the scheme with two transmitting antennae and Nr receiving antennae, achieves the same diversity gain as that with one transmitting antenna and 2Nr receiving antennae.2. This paper studies the LS and the MMSE algorithm based on the channel model of orthogonal space-time block codes (OSTBC), and improves MMSE algorithm to achieve RMMSE algorithm. Adopting computer simulation to compare the performances of these three channel estimation algorithms, the results show that the complexity of RMMSE algorithm is lower than the MMSE algorithm, and the accuracy is higher than the LS algorithm, which has more practicability.3. Firstly, the paper compares the channel performance of OSTBC and QOSTBC under the channel model of quasi-orthogonal space-time block codes (QOSTBC). The simulation results show that QOSTBC is better than OSTBC as the SNR is low, but it is worse than OSTBC as the SNR is high. Secondly, the paper puts forward the rotated QOSTBC. whose channel performance is improved obviously. Whether in low or high SNR, the rotated QOSTBC is superior than OSTBC. Channel estimation algorithm plays a momentous role in MIMO system. Choosing suited channel estimation algorithm under different environments and different system requirements can promote demodulating and decoding performance and show up advantages of MIMO system sufficiently.