Outage performance analysis of secondary user under Tx/Rx IQI in cognitive radio systems

Local oscillators in direct conversion transceivers result in in-phase and quadrature-phase imbalance (IQI) which severely affects the performance of communication systems. In this work, we consider cognitive radio (CR) communication based on orthogonal frequency division multiplexing (OFDM) experiencing IQI at the receiver as well as at the transmitter. First, we derive an approximate expression for outage probability under joint Tx and Rx IQI. Second, we derive exact outage probability expressions under Tx IQI only. Numerical results demonstrate the validity of derived closed form expressions in CR systems.