In this series:
- RF Imperfection and Compensation, Part 1 – The Effects of IQ Imbalance and Compensation on Receiver Performance
- RF Imperfection and Compensation, Part 2 – IQ Imbalance Compensation in MIMO OFDM Systems
- RF Imperfection and Compensation, Part 4 – The Effects of Phase Noise and Compensation on Receiver Performance for MIMO OFDM Systems
In today’s post we carry on with our blog series on RF imperfection and compensation by addressing the effect of phase noise on MIMO OFDM system performance. We have shed light on the effect of IQ imbalance where we have seen that this type of impairment results in a subcarrier being interfered with by its mirror image subcarrier. The issue is deemed to be more severe in fading channel, where the constellation in M-QAM will undergo random shift and noise.
In case of phase noise the effect is twofold depending on the cut off frequency of the local oscillator SSB (single sideband) phase noise power spectral density’s (PSD) -3dB bandwidth (SSB phase noise PSD’s -3dB BW). As depicted in the figure below, the contribution of the low and high SSB phase noise PSD’s -3dB BW causing constellation rotational and additive effects is apparent. Equal to all subcarriers, the rotational effect is analytically isolated in a common phase error (CPE) term in the signal model while the additive effect is regarded as inter-carrier interference (ICI)