I/Q Imbalance in AF Dual-Hop Relaying: Performance Analysis in Nakagami-m Fading
Journal article, 2014

We analyze the performance of amplify-and-forward dual-hop relaying systems in the presence of in-phase and quadrature-phase imbalance (IQI) at the relay node. In particular, an exact analytical expression for and tight lower bounds on the outage probability are derived over independent, non-identically distributed Nakagami-m fading channels. Moreover, tractable upper and lower bounds on the ergodic capacity are presented at arbitrary signal to noise ratios (SNRs). Some special cases of practical interest (e.g., Rayleigh and Nakagami-0.5 fading) are also studied. An asymptotic analysis is performed in the high SNR regime, where we observe that IQI results in a ceiling effect on the signal-to-interference-plus-noise ratio (SINR), which depends only on the level of I/Q impairments, i.e., the joint image rejection ratio. Finally, the optimal I/Q amplitude and phase mismatch parameters are provided for maximizing the SINR ceiling, thus improving the system performance. An interesting observation is that, under a fixed total phase mismatch constraint, it is optimal to have the same level of transmitter (TX) and receiver (RX) phase mismatch at the relay node, while the optimal values for the TX and RX amplitude mismatch should be inversely proportional to each other.

Nakagami-m fading

Amplify-and-forward relay

I/Q imbalance

outage probability

ergodic capacity


Jingya Li

Chalmers, Signals and Systems, Communication, Antennas and Optical Networks

Michail Matthaiou

Chalmers, Signals and Systems, Signal Processing and Biomedical Engineering

Tommy Svensson

Chalmers, Signals and Systems, Communication, Antennas and Optical Networks

IEEE Transactions on Communications

0090-6778 (ISSN)

Vol. 62 3 836-847 6730887

Areas of Advance

Information and Communication Technology

Subject Categories


Signal Processing



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