Design And Implementation Of MU-MIMO Physical Layer Based On 802.11ax

With the rapid development of wireless local area network technology,wireless local area networks are more and more widely used in various scenarios,and Wi-Fi is more closely connected with people's lives.In this case,people put forward new requirements for Wi-Fi technology: faster data transmission rate,more users accessing the same scene,etc.In order to better address these problems and provide users with a better experience,the IEEE Association has officially released a new generation of wireless local area network standard protocol-802.11 ax standard in 2019.Compared with the previous generation of802.11 ac protocol,802.11 ax adds downlink MU-MIMO technology,and the transmission rate has doubled.At the same time,in order to change the impression that the naming of each generation of Wi-Fi version of 802.11a/b/g/n/ac/ax is too long,the Wi-Fi Alliance simplified the new generation of Wi-Fi technology 802.11 ax in 2018.It is Wi-Fi6.This thesis mainly studies the algorithm design and hardware implementation of the MU-MIMO system of the receiver in the 802.11 ax prototype.The main work of the thesis is as follows:First,the structure of the MU-MIMO system based on the 802.11ax protocol is analyzed,and the algorithm design and hardware circuit realization are carried out.On the basis of determining the structure of the MU-MIMO system in the 802.11 ax receiver,the coherent demodulation method and the non-coherent demodulation method are compared and analyzed.The performance of the coherent demodulation method is about 3d B.Finally,the coherent demodulation method is adopted.Coherent demodulation requires feedback of channel state information,and the channel matrix is ??fed back to the access point.Therefore,a channel estimation and channel compression feedback scheme based on the least squares method is designed,thereby realizing effective real-time estimation of the channel,and providing a basis for the transmitter to transmit data with beamforming.At the same time,in order to complete the functional simulation verification,the bitmatch logarithmic platform was also designed.After comparing with the algorithm results,the results showed that the algorithm design was implemented correctly.Second,on the basis of in-depth research on receiving MIMO decoding algorithms,a comparative analysis of classic MIMO signal detection algorithms is made.Although the ML algorithm is about 2d B better than the MMSE algorithm in performance,it is too complex and takes up too much hardware resources.After comprehensive consideration,the MMSE method is finally adopted.After the MMSE algorithm completes channel equalization,due to the presence of Gaussian noise in the channel,in order to obtain accurate transmission signals,the MMSE is designed to perform channel equalization first,and then the constellation de-mapping scheme is completed.The design and functional simulation of the channel equalization and demapping of the MMSE algorithm,after the bitmatch platform and the algorithm logarithm,show that the hardware design results are consistent with the algorithm design,the algorithm design is correctly implemented,and the completeness verification is passed.In the implementation process,optimization techniques such as ping-pong operation,pipeline operation,module multiplexing,and time division multiplexing are used to optimize the hardware design.The design and implementation results of this circuit have positive significance for the development of Wi-Fi receivers.