Characteristics Of Mimo-ofdm System Shortwave Channel Measurement

Communication system is composed of information source, sink and channel. Information source is birthplace of signals. Information sink is the destination of signals. The channel is between the source and the sink. When we are research the communication system, we do see the source and sink. As the channel, if the channel is fibers or cables, we can see it with our eyes, but how about the wireless channels? We even can not feel it.Thus, this article is mainly focus on the wireless channel research. In our project, the next task is going to figure out a communication system on shortwave. So the article could be a preparation for our next task. In order to ensure the communication quality in shortwave environment we have to get familiar to the characteristic of the shortwave channel.For this purpose, we first read many books and materials about shortwave channel. We learn about the concept and application of shortwave channel, the type of transmission of shortwave channel. With our research going on, we find the most important characteristic of shortwave channel, that is multi-path delay and Doppler spread. Till now, hunman can just know about this extent of shortwave, if we want to make full use of the shorwave system, we have to do lots of work.Channel estimation is one of that kinds of work. After research the methods of channel estimation, we try to make use of them to shortwave channel estimation.The estimation we made in the article is also focus on multi-path delay and Doppler spread. The method we chose to detect the shortwave channel is pulse compression sounding technique using PN sequence. In this algorithm, the communication system is composed by one sending antenna and one receiving antenna. At last, we do simulation in matlab by m language program. The simulation results prove the correctness and feasibility of our method. Besides, we also model the Doler sectrum with classic and Gaussian sectrum and validate the rogram.As we refered before, using communication system in shortwave is our purpose. So in the article, we also try to figure out the cross-correlation of two antennas in MIMO-OFDM system. The simulation environment is composed of two sending antenna and two receiving antenna. The algorithm is MIMO-OFDM channel estimation using pilot sequence. In the last, we also simulate the system in matlab program. The simulation results make our further job easier.Finnaly, we put both of the two algorithms into experiment. The article introduces the composition of the experiment equipment, the flow chart of the dsp program and the type of the chips. In the end, we test the shortwave channel with the help of the channel simulation equipment, which can simulate a real shortwave channel by itself. We compare the result with the matlab simulation result and the theory value.