I/Q imbalance mitigation for time-reversal STBC systems over frequency-selective fading channels

Direct‐conversion radio frequency transceivers are well‐substantiated structures for today's wireless communication systems due to their ability in complexity reduction, cost, and power consumption. The unavoidable mismatch between the in‐phase (I) and quadrature‐phase (Q) branch of the analog front‐ends in the direct‐conversion transceiver leads to degrading the performance of communication systems. In this article, we address the estimation and compensation of the IQ imbalance (IQI) parameters for both the transmitter (TX) and receiver (RX) in multiple‐input/multiple‐output systems with space‐time block code (STBC) in the digital domain. This article proposes a pre‐combiner estimation and compensation of the channel and the frequency‐independent IQI scheme based on the repetitive transmission of the pilot sequence using the least square technique. It is worth noting that the proposed method can be extended to any orthogonal STBC. Moreover, the study is applied to IQI in other scenarios including only TX and only RX. Simulation results show that the proposed method achieves better performance in comparison with the existing post‐combiner technique. Furthermore, the proposed method requires lower computational complexity when the number of receive antennas is limited.

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“…There are an extensive research for IQI problem in the literature 20‐31 . Most of studies concentrated on MIMO OFDM systems 20‐27 .…”

Section: Introductionmentioning

confidence: 99%

“…Authors in References 23‐27 studied IQI in MIMO OFDM for Alamouti STBC. The IQI effects in

2 \times 1

time reversal STBC was studied in Reference 28. The IQI estimation at both TX and RX in a MIMO space‐time coded Alamouti transmit diversity system based on the continuous transmission of training sequences was addressed in Reference 29.…”

Section: Introductionmentioning

confidence: 99%