I/Q mismatch cancellation for MIMO-OFDM systems

MIMO-OFDM systems are gaining prominence in high data rate applications due to their increased spectral efficiency, in MIMO-OFDM systems, I/Q mismatch causes interference between the frequency mirror subcarriers. This can significantly degrade and limit the performance of the system. We present a mathematical analysis of the effects of I/Q gain, delay and phase mismatches in MIMO-OFDM systems. We show the impact of I/Q mismatch when more antennas are added. We also derive a linear optimal solution to cancel all three I/Q mismatches and an RLS based adaptive filter for the same. We show simulation results and results on an experimental testbed.