The Research Of Ultra High Speed WLAN Transmission Scheme And The Hardware Implementation Of Receiver

With the widely use of smart portable devices, wireless LAN plays a more and more important role in people's lives. In order to make the rate of data transformation obtain breakthrough growth, more and more new technology started to be used in wireless LAN standard. The system transmission rate of IEEE 802.11ac protocol improved by introducing multi-user MIMO technology in the downlink and using the optional short guard interval technology. This paper does studies on the key technologies and new schemes in IEEE 802.11ac protocol. Based on NI-PXI platform, the paper designed the framework of MIMO prototype system. Also the paper focused on the hardware implementation algorithm of synchronization and interleaving module, improved the resource consumption and system performance, and complete hardware implementation of the receiver. The main work of this paper is as follows:1. The paper does research on the specific structure of IEEE 802.11ac physical layer packet and the function of each field, and analyzes the data generation process in the transmitter of the IEEE 802.11ac system using BCC coding as well as the process of receiver system.2. This paper made research on the interleaving algorithm with three level of replacement in the IEEE 802.11ac standard, analyzed the function and hardware implementation algorithm for each level of replacement. On the base of flexibly transforming the method to realize interleaving, the paper proposed an improved hardware implementation algorithm, which changes the algorithm implementation from in serial to in parallel. The improved algorithm performs well in terms of resource consumption and interleaving delay.3. The paper discussed the synchronization schemes in OFDM system. After studying the existing OFDM timing synchronization schemes, a multi-antenna software synchronization algorithm which is more suitable for hardware complementation of MIMO-OFDM system is proposed base on the forward difference auto-correlation algorithm. The algorithm shows the appropriate cost function, and is implemented on the hardware platform. This algorithm can make better trade-off between the received bit error rate and frame leakage rate. Besides, the paper studied the carrier frequency synchronization scheme and implemented it on the hardware platform after making appropriate simplify based on MIMO-OFDM system. Also, the paper carried out the phase correction work to eliminate the remaining phase after the carrier frequency synchronization.4. According to the presentation of the NI-PXI platform used here, the paper showed the framework of IEEE 802.11 ac 4×4 MIMO prototype system based on NI-PXI platform, completed the data processing module in physical layer of the receiver side, and carried out the presentation of the entire system both in received constellation and real-time transmission of video.