Mimo-ofdm Systems, Key Technology Research And Implementation,

Being in the days of rapid development of wireless communication, how to use the limited spectrum bandwidth for more data transfer has becoming an important research topic. The technology of Multiple-Input Multiple-Output (MIMO) can not only take advantage of spatial multiplexing gain to increase the channel capacity, but also make use of space diversity to improve the reliability of the channel. Orthogonal Frequency Division Multiplexing (OFDM) technology divided the frequency selective channel into many flat sub-channels, this can avoid inter-symbol interference (ISI) effectively. So the MIMO-OFDM system can enhance the system capacity and reliability.The article is completed based on a MIMO-OFDM HF communications system, which is using the hardware platform of DSP and FPGA cooperation to reach the high-speed data processing. All the following work is designed and tested based on this hardware platform.Firstly, the dissertations completed the research and implement work on the HF channel parameter measurement, which based on the method of pulse compression sounding technique using PN sequence and cross-correlation. Besides, it also did the channel simulator testing and ground wave testing. Through the field's channel parameter measurement, we can get the measured data of the real transmission environment. And, obtaining the channel transmission characteristics after analyzing the large amounts of this statistical data, this method could be very good for us to study the channel transmission characteristics.In addition, the dissertations researched the pre-distortion PAPR iterative restoration technology caused by the high PAPR in the OFDM system. Adding this method to current system and carried out the channel simulator test. The receivers can use the pre-distortion iterative restoration technology to recovery the signal, which was suppressed by the transmitter PAPR, and thus improve performance eventually.Finally this dissertation proposed two typical interference in the wireless transmission environment, multi-tone interference and narrowband interference. For multi-tone interference suppression using time domain interference elimination and narrowband interference was suppressed by limiting. Both methods also were added to the project program, achieved by DSP, and passed the test of channel simulator. In time-domain elimination method, it is difficult to find out a well-performed parameter estimation algorithm. When the estimated parameters are not accurate, it does not only fail to eliminate the interference but also introduce another new kind of interference, which may on the contrary affect the effectiveness of the method. As the narrowband interference suppression using limiting method, it could only go on the interference signal suppression, and not well eliminated, but this method is more suitable for practicing of wireless transmission system.