Closed Form SER Expressions for QPSK OFDM Systems With Frequency Offset in Rayleigh Fading Channels

In this letter, the performance of QPSK OFDM systems with frequency offsets is investigated. Closed form expressions for the symbol error rate (SER) that are valid for any frequency offset in Rayleigh fading channels are derived. To achieve this, a modification to the result of the integral of the product of two Q-functions over the Rayleigh distribution is provided. The modification makes the result of this integral valid in any case whether the arguments of the Q-functions are positive or negative. Simulation results are provided to demonstrate the accuracy of the derived expressions.