Joint I/Q mixer and filter imbalance compensation and channel equalization with novel preamble design

In this paper, we consider the problem of analog signal imbalances between I- and Q-branches of the modulator/demodulator in OFDM systems. A novel compensation approach is proposed to solve this problem using baseband processing techniques, allowing for flexible RF design for high speed wireless systems. In particular, the proposed solution models transmitter and receiver impairments due to mixer and filter imbalances observed through channel related distortions. The solution is obtained by joint estimation and compensation of I/Q imbalance caused by the above impairments. The problem is studied for an OFDM wireless system and an analytical solution is presented in this paper. A novel preamble design is proposed to enable reliable estimation of the solution. Performance evaluations using MATLAB simulations are presented to confirm the effectiveness of the proposed method under various scenarios.