The Research Of IEEE 802.11AC And Its Implementation Based On NI-PXI Platform

With the continuous development of broadband wireless communication technology, WLAN is rapidly growing. As the new generation of broadband of very high speed WLAN protocol, IEEE 802.11ac combines OFDM and MIMO technology and also provides more transmission bandwidth and abundant modulation and coding schemes(MCS) in the 2.4GHz and 5GHz bands, together with the MU-MIMO technology in the downlink so that the transmission rate increases exponentially.This paper mainly focuses on the key technology for IEEE802.11ac. Based on the hardware implementation, the paper works on the algorithm description and performance simulation of some important modules for transmitter and receiver. In hardware implementation, the paper introduces time synchronization and signal detection process in detail for the MIMO-OFDM system. For the time synchronization process, an optimized scheme for hardware implementation is proposed based on traditional algorithm. For signal detection, the paper introduces algorithm description and hardware implementation for four kinds of matrix inversion, together with the fixed-point simulation for signal detection. The main work of this paper can be described as follows.1. For the physical layer, this paper discusses the specifications of IEEE802.11ac in detail, including core technology, packet structure, baseband process of transmitter, baseband process of receiver and channel model. Besides, NI-PXI development platform is introduced so as to support the hardware implementation.2. According to core technology and new characteristics of IEEE802.11ac, the design of PSK-QAM constellation mapping scheme is proposed for hardware implementation. Moreover, a joint processing scheme for IFFT, cyclic shift and cyclic prefix process is discussed.3. For the time synchronization process at the receiver, the paper introduces some traditional methods for frame synchronization and symbol synchronization. Furthermore, the paper proposes differential autocorrelation joint time synchronization scheme based on the L-STF training sequence.In addition, an improved algorithm is proposed to realize the time synchronization for hardware implementation.In the premise of ensuring the performance of the synchronization, the proposed scheme greatly reduces the complexity of hardware implementation.4. According to the signal detection at the receiver, the classical detection algorithms are discussed under the V-BLAST system structure. For the signal detection in MIMO environment, the paper discusses channel estimation based on the LS standards and different kinds of channel equalization algorithm with the simulation and performance analysis.5. According to the signal detection for MIMO-OFDM system, the paper gives the description of hardware algorithm and the hardware implementation about matrix inversion. There are four methods for matrix inversion which we discuss about their hardware implementation algorithm including chessboard block inversion, block LU decomposition inversion, QR decomposition inversion based on Schmidt orthogonalization and QR decomposition inversion based on improved Givens rotation. Then the paper gives the evaluation of hardware resources and time delay estimation. Finally, the performance of fixed-point simulation is discussed for the hardware implementation of MIMO signal detection.6. The paper also introduces the constitution of NI-PXI hardware development platform. Then the architecture of hardware implementation for the high-speed real-time transmission system is proposed which could be used to give the presentations of prototype system based on IEEE802.11ac. Finally, a summary is carried out about the work above, together with the proposal of research in the future.