Joint I/Q imbalances and CFOs compensation for multiuser wireless networks in the presence of IBI

This paper deals with the synthesis of a time-domain equalizer, based on the constrained minimum mean-output energy (C-MMOE) criterion, for the uplink of a single-carrier interleaved frequency-division multiple-access (SC-IFDMA) wireless network. Over highly-dispersive channels, the length of the cyclic prefix (CP) may be insufficient to compensate for the interblock-interference (IBI). In addition, the in-phase/quadrature-phase (I/Q) imbalance, introduced at each transmitter, and the carrier frequency offsets (CFOs) between the transmitters and the receiver may cause severe performance degradation. The proposed receiver performs first blind C-MMOE channel shortening of all the user channels, without requiring a priori knowledge of the channel impulse responses to be shortened, or compensation of the CFOs and transmitter I/Q imbalances. Then, after channel shortening and CP removal, the C-MMOE criterion is also employed to compensate for the CFOs and mitigate I/Q impairments.Monte Carlo computer simulations are carried out to assess the effectiveness of the proposed receiver.