Joint Tx and Rx IQ Imbalance Compensation of OFDM Transceiver in Mesh Network

The direct conversion is an attractive architecture, as compared to the traditional heterodyne approach, for both transmitter and receiver design. In spite of its great advantages in hardware implementation, direct conversion results in several negative effects, such as IQ imbalance, flicker noise, DC offset, etc. In this paper, we study the IQ imbalance problems occur at both transmitter and receiver in an OFDM-based mesh network. The contributions of this paper are three-fold. First, we propose a self-calibration scheme at transmitter. Therefore, the IQ imbalance at transmitter is compensated before communication. Second, we design a standard-independent IQ imbalance estimation scheme at receiver. Finally, three different equalization schemes for IQ-mismatched receiver are studied. It is shown from our simulation results that the proposed schemes are feasible for solving Tx-Rx IQ imbalance problems in OFDM systems.