Transmission System Based On Ieee802.11a Ofdm Receiver Algorithms And Fpga Implementation

As a rising wireless application service, wireless LAN is implementing in many areas such as school, air station, conference room, even home, accelerating high speed wireless data service market growing. In current, there are a lot of wireless LAN standards which are supported by some big companies. IEEE802.IIa is undoubtedly a very special standard among these wireless LAN standards. It's a large advantage that it transmits data through OFDM which can help increase transmission rate, improve signal quality and has much robustness of multi-path fading.So many people pay more attention to it.In order to apply this hign speed wireless LAN into real life,we give the primary implementation of the transmitter and the receiver of OFDM system based on IEEE802.11a in our project , and the important work of this thesis is to implement the inner receiver. The inner receiver include two parts:synchronization and channel estimation.However, there are some difficulties on some key techniques implementation for OFDM system, including synchronization, channel coding, channel estimation, user detection, reducing PAR. Many studies still talk about these techniques in theroy.So this thesis studies many algorithm for channel estimation and synchronization,and presents a FPGA-realizable algorithm for channel estimation and synchronization in OFDM systerm based on IEEE802.11a.Firstly,this thesis summarizes present algorithms for channel estimation.and studies detailedly the algorithms for channel estimation which may be fit for the OFDM systerm based on IEEE802.1 la:(1)this thesis presents the LS algorithm and the LS-average algorithm by 10 short training symbols,and makes a comparision about their performance on AWGN channel and muti-channel.proves the latter is better than the former.In order to improve the performance ,this thesis presents ulteriorly the NRA(noise -removed algorithm) based on the LS-average algorithm.(2) this thesis presents DFT Interpolation algorithm aided by pilots.Secondly this thesis summarizes present algorithms for synchronization. Synchronization of OFDM include timing synchronization and carrier synchronization,and timing synchronization also include symbol synchronization and clock synchronization.the most important task in this thesis is to study timing synchronization and simply discussion about carrier synchronization. Timing synchronization is divided to coarse timing synchronization and fine timing synchronization, coarse timing synchronization is aided by the short training symbol and CP,and fine timing synchronization is aided by pilots.Lastly,this thesis sort out one timing synchronization and channel estimation algorithm which can be FPGA-realizable.Complying with carrier synchronization presented by the associate,the inner receiver of OFDM is implemented.