The Impact of the I/Q Mismatching Errors on the BER Performance of OFDM Communication Systems

Orthogonal frequency division multiplexing (OFDM) signals are very sensitive to radio frequency (RF) impairments. One of the major impairments is the mismatching errors between the in-phase (I) and quadrature (Q) branches in the up and down-conversions. The I/Q mismatching errors can include phase and amplitude mismatching errors. These mismatching errors make the signal constellation expand and rotate, which severely degrades the performance of OFDM systems. In this paper, a closed-form expression for the bit error rate (BER) of the OFDM system in I/Q mismatching error environments is derived as a function of phase and amplitude mismatching error parameters. This enables a convenient and useful evaluation of the performance of OFDM communication systems with I/Q mismatching errors. The derived analytical expression is validated by the fact that computer simulation results closely match with the analytical derivation results.