The Research Of IEEE802.11n Protocol Based On MIMO

The limited radio frequency spectrum appears more and more precious as the growth of requirements for the wireless communication technique. Moreover, the wireless transmission environment is also becoming more and more complex. Therefore, improving the transmission rate, network capacity, and reliability for wireless communication technique is an important and challenge work. MIMO(Multiple-Input Multiple-Output) generates multiple parallel data channels in wireless channel using multiple antennas at the receiver and transmitter. Not only can it increase the data transfer rate and improve the quality of the transmission, but it does not need additional bands. Based on MIMO technology,the transmission rate of the WLAN standard IEEE 802.11 n increases from 54Mb/s to 300Mb/s.In this dissertation, MIMO and 802.11 n protocol are deeply studied and an integrated 4*4MIMO communication links are designed, which the links are tested by setting up a real wireless channel environment based on WARP at last.Firstly, we give a simple introduction to the IEEE802.11 n protocol, expound its feature, and detail the key technologies including Forward-correcting Encoder, Short GI, Maximal-Ratio Combiner, and Channel bundling. Based on 802.11 n protocol, we also analyze the principle of MIMO and OFDM then introduce the MIMO+OFDM model. Moreover, the MIMO technologies of 802.11 n including channel estimation, Space-Time Coding, and MIMO signal detection are analyzed and simulated by comparing the BER at different SNR.Secondly, we design an integrated 4*4MIMO communication links which is based on IEEE802.11 n protocol. The system model contains several modules. The transmitting terminal contains modulation, pilot signal, space-time coding, Antenna mapping, Inverse Fast Fourier Transform, and A cyclic prefix. Then the signal could reach the receiver over wireless channel. At last, the receiver uses reverse coding technology to get the original signal. Its main module is composed of MIMO detection and demodulation. The entire link is simulated and analyzed with MATLAB.Thirdly, in view of the real wireless channel environment, we set up a real-time communication protocol simulation platform with WARP. Using this platform, we transmit a video and test the performance of 4*4MIMO.