Simulation And Research On OFDM Technique Applicated In Wireless Local Area Network IEEE802.11a

With the accelerating of society informationize, people have more expectation to wireless multi-media communications. We urgently need one kind of wireless communication technology that provide high-speed data transmission ability. Realize anybody carrying out any kind information exchange in any time, any place and anybody.To realize wireless personal communication, next generation Wide-Band Multimedia Communication System(WBMCS)are been investigated by a lot of organization in the whole world. The Orhogonal Frequency Division Multiplexing technology (OFDM) supports high rate data wireless transmission and has high spectrum efficiency, and the hardware realization is easy. Recently years, OFDM has been applicated in various fileds, especially in the fields of wide-band wireless access technology wireless local network, high rate data wirless communication and Multi Input Multi Output-MIMO technology that introduces the multi-antenna technology which provides the diversity gain and the multiplying gain. Since the diversity gain can enhance the system power efficiency, the multiplying gain can enhance the system frequency efficiency. The MIMO-OFDM technology was considered core technologies in the 4GIn this thesis, an introduction to the concepts of wireless communications, wireless local area network (WLAN)and multi-carriers technology is given at first. The emphases are put on the researches on the key technology of realizing OFDM, the application in WLAN system and the combination of OFDM and MIMO. The main researches and results are shown following:(1) The key technology of realizing OFDM is reserched and the dynamic simulation platform for baseband OFDM has been established by MATLAB. First, studies and researches on the principles of OFDM and the theory how to realize OFDM systems using FFT/IFFT technology. Then researches and analysis the OFDM systems frame model, researches on the dynamic simulation of OFDM with the Simulink toolbox of MATLAB software, the simulation model of the base band OFDM systems are built. The simulation plateform provides a valuable tool for more investigation. (2) The simulation research on OFDM applicated in WLAN systems. Applying to WLAN physical layer, there are many kinds of encoding and modulating modes. Such systems can support multi-speed transmission mode, higher transfer speed, spectrum efficiency and have better system performance. As an example, the system structure of IEEE 802.11a-WLAN is discussed.(3) The simulation research on MIMO-OFDM technology in WLAN systems. Combining MIMO with OFDM, the MIMO-OFDM technology has superiority in increasing system capacity and reliability. The application of MIMO-OFDM in WLAN IEEE802.11a systems for two input two output space diversity facts has been analysised, the analysis and simulation results have been shown that the space diversity technology application in IEEE802.11a systems has superiority in increasing system capacity and reliability, and MIMO-OFDM technology is very suitable for high rate data transmission and wide-band mobile system in WLAN.