Design And Implementation Of Digital Intermediate Frequency Ofdm Radio Unit

The OFDM technology has been widely used in the field of the civil wireless communications such as WLAN and WMAN along with IEEE802.11a and IEEE802.16a being put out. The OFDM technology is also expected to be used in the fields such as the maritime communications and the military communications. However, the remote wireless communications will face the abominable transmitting condition for NLOS radio wave in field. In this condition, the channel has great time delay and deep power decline according to different frequencies, which leading to low SNR. Because the falling of SNR will reduce the data rate and do harm to the reliability of the transmit, we try to design and choose several key techniques used in the OFDM communicate system for a broad band radio.This thesis analyses the key techniques of three high performance overseas radioes on the basis of IEEE802.11a, and then designs the hardware frame and the software frame for our OFDM system. In order to offset the affect of the abominable trasmit codition as well as carry out a communicate system simply, we use the AR model to optimize the algorithm of sample frequency symchronization and use the reliability of channel to improve the performence of the decoding algorithm. The results measured after carrying out the OFDM system has proved the efficiency of the improvement to these algorithm.