Research And Implementation Of Synchronization Algorithms For IEEE802.11ac Standard

IEEE 802.11 ac standard based on the MIMO-OFDM technique is one of the wireless local area network(WLAN)standards,which has the throughput up to 6000 Mbps.The basis of theory and practice of IEEE 802.11 ax standard can be obtained by studying IEEE 802.11 ac standard.At the same time,it has contributed to break the monopoly of the foreign chip market and improve the ability to research and design chips.In the dissertation,the synchronization algorithms for IEEE 802.11 ac standard are researched,and the main research contents are as follows:(1)The development of the MIMO-OFDM synchronization technique is introduced,including the synchronization techniques for MIMO-OFDM systems without the fixed signal standard and WLAN systems.Then the IEEE 802.11 ac standard physical layer is analyzed,and the signal structure of the IEEE 802.11 ac standard and its key technique MIMO-OFDM are introduced.Next,the dedicated channel model(TGac)for IEEE 802.11 ac standard is presented.(2)The receiver scheme for IEEE 802.11 ac standard is proposed,where the working principle of IEEE 802.11 ac baseband receiver structure and the synchronization scheme for IEEE 802.11 ac standard are described in detail.Then,the synchronization algorithms for IEEE 802.11 ac standard are studied,including energy detection algorithm,frame detection algorithm,symbol timing algorithm and frequency offset estimation algorithm.Next,waveform simulation is performed for energy detection algorithm,and the influence of the SNR and fixed threshold on detection probability of frame detection algorithm is analyzed.And also a conventional symbol timing algorithm is introduced,and the performance of frequency offset estimation algorithm is compared,through MSE performance analysis.The results prove the correctness of the synchronization algorithm and the feasibility of the receiver structure and synchronization scheme.(3)Based on the conventional symbol timing algorithm,three improved symbol timing algorithms are proposed,including symbol timing algorithm assisted by frame detection,conditional constraint symbol timing algorithm and amplitude accumulated symbol timing algorithm.Then,the three improved symbol timing algorithms are compared.The result proves that conditional constrain symbol timing algorithm meets the needs of hardware implementation,due to its high symbol timing accuracy and low hardware complexity.(4)The frequency offset estimation algorithm is improved,and two improved frequency offset estimation algorithms are proposed,including the moving average multi-antenna averaging frequency offset estimation(A-MIMO-AFOE)algorithm and the moving average multi-antenna phase accumulation frequency offset estimation(A-MIMO-PFOE)algorithm.Then the performance of the two improved algorithms is also compared by the MSE performance analyses.The result proves the superiority of the A-MIMO-AFOE algorithm,when the number of receiving antennas is an integer multiple of the number of transmitting antennas.(5)The FPGA implementation of IEEE 802.11 ac standard synchronization algorithm is studied,including energy detection module,frame detection module,symbol timing module,frequency offset estimation module,and frequency offset compensation module.The block diagram of the implementation of the algorithm is also given,and the structure and principle of each module are described in detail.Finally,the functional simulation waveforms are given by ModelSim software and the feasibility of the algorithm is proved,which provides reference for the design of dedicated synchronization chip of IEEE 802.11 ac standard physical layer.