IQ Imbalance Compensation Scheme for MB-OFDM with Transmit Diversity

Currently, multi-band OFDM (MB-OFDM) is considered as one of the modulation schemes of UWB and is actively investigated. It is necessary to provide low cost receivers for consumers in order to receive wide support for MB-OFDM system. Such receivers can be achieved by utilizing direct conversion architecture. The direct conversion architecture has been investigated for the purpose of cost minimization, miniaturization, and low power consumption of wireless receivers. However, the balance between the in-phase component and the quadrature-phase component of demodulated signals is lost when direct conversion architecture is used. This phenomenon is called IQ imbalance. IQ imbalance is one of the problems for the direct conversion receiver. IQ imbalance causes intercarrier interference (ICI) in the demodulated signals. In this paper, a new scheme of IQ imbalance compensation using transmit diversity is proposed. This scheme enables the system to achieve frequency diversity and compensate the influence of IQ imbalance at the same time. It is shown that the performance of the proposed scheme is better than the conventional IQ imbalance compensation scheme