Research On Adaptive MIMO-OFDM System Based On IEEE 802.11ac

OFDM(Orthogonal Frequency Division Multiplexing)technology due to its advantages of high spectrum efficiency and resistance to Frequency selective fading,has already become one of the most popular in the wireless communication system modulation technique.MIMO(Multi Input Multi Output)technology uses multiple antennas to achieve signal in spatial and temporal multiple reuse,without any increase in bandwidth and antenna under the condition of sending power,improve spectrum efficiency will be multiplied,also can to some extent against multipath fading.Based on the above advantages,MIMO-OFDM technology has become the focus in the field of wireless communication system.WLAN(Wireless Local Area Networks)technology because of its high speed,simple cloth net,low access threshold,low cost,etc,and become a family,school,office and other indoor environment of preferred Wireless access solutions,widely exists in every corner of the us.IEEE 802.11 ac is the WLAN technology the latest standard,uses the MIMO-OFDM as its core technology,equipped with adaptive modulation coding,LDPC coding,MIMO antenna for more,carrier aggregation technology,such as the highest can provide 1 Gbps throughput.In this paper,based on the IEEE 802.11 ac physical frame format,the baseband part of uses the technology to compare the comprehensive introduction.At the same time for its core MIMO-OFDM technology,on the principle of OFDM technology and a variety of FFT algorithm is studied.The implementation principle of MIMO system and channel estimation and detection problem is also analyzed.In addition,the principle of adaptive modulation coding techniques and resource allocation algorithm is studied.Finally,the adaptive MIMO-OFDM wireless baseband transmission system,this paper proposed a parallel multiplexing FPGA realization method of radix 4 FFT/IFFT algorithm,and made the research and simulation of FPGA implementation for adaptive digital modulation,STBC coding and FFT/IFFT module.The simulation results show that the design realized the function of the modules,and good performance,has certain application value.