A Large Frequency Offset Estimation Algorithm for IEEE 802.11a System

According to the packet structure of IEEE Standard 802.11a and the characters of short training symbols, a new frequency offset estimation algorithm is presented. A two stages strategy based on auto-correlation algorithm is used to solve the contradiction between estimation accuracy and estimation range. At the first stage, the coarse frequency offset estimating bases on the identity of half cyclical short training symbol. Then the exact frequency offset estimating can be done by the cancellation operation of long training symbols. The simulation based on 802.11a PHY model is done. And the simulation result shows that this algorithm not only overcome the influence of carrier frequency offset but also eliminate the carrier frequency offset. Comparing with the traditional algorithm this algorithm can reduce the complication of the calculation, and the estimation range can be expanded to 2 times. Furthermore, the precise estimation can be acquired as well.