This paper considers frequency-domain receiver

design for OQPSK signals (Offset Quaternary Phase

Shift Keying). It is shown that conventional QPSK receivers

are not suitable to OQPSK schemes since they

lead to significant interference between in-phase (I) and

quadrature (Q) components. To overcome this problem

we propose several linear receivers where there is no

I-Q interference. Our receivers are suitable to OQPSK

schemes, significantly outperforming frequency-domain receivers

designed for QPSK modulations.